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Quaife ATB differential in an R56: What I've learned

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Quaife ATB differential in an R56: What I've learned

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Old 07-09-2010, 11:22 PM
Vespucci
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Quaife ATB differential in an R56: What I've learned

When I was considering putting a Quaife ATB differential into my 2010 factory JCW, I looked a lot of places for information... including NAM. I found a lot of conflicting/uncertain information from lots of different sources, and I don't think my search here revealed any threads that directly addressed my concerns. That said, I wanted to share what I learned in the process, and I apologize if this thread duplicates information elsewhere on NAM.

The Quaife ATB LSD is listed many places for the R53, but very few specify it for the R56. Quaife UK themselves list it for the R53, and then generically for "all" BMW MINI 6-speed manuals...

I contacted Quaife UK directly, and received somewhat vague confirmation that the Quaife ATB differential (model QDF38Z) will fit/work in any Getrag 6-speed manual transmission for the MINI (R53 or R56). Indeed, the same model (QDF38Z) is listed for both MINI listings on Quaife's own site, as well as for the Ford Focus SVT/ST170 (precursor to the RS?).

What it seems to come down to is that QDF38Z works in ANY car that uses that particular Getrag 6-speed manual tranny, which from what I can tell from Getrag's information, is more specifically the Getrag GMTT280 FWD, 6-speed transverse manual transmission.

I believe (though I have no direct evidence) that this model tranny is used accross many new MINI models and years, even though the part numbers in MINI's parts catalog are different due to their intended installation in different MINI models. What I do know for sure is that the fact that the MINI part number designations across models are different doesn't mean that the actual transmission supplied by Getrag is necessarily different.

The following additional misinformation/conundrums seem to be out there:

Q1) Other 3rd party parts suppliers list the Quaife ATB as being for particular model years, but not MINI models. Whats the deal?

A1) I think this kind of info should be ignored in favor of a direct differential-to-transmission match.

Q2) Quaife will not make an ATB for the R56 until they get a certain number of orders.

A2) I suppose that may have been true at some point, but today (as of 2010) it seems to be no longer applicable. I read a rumor that there was a revision of the QDF38Z at some point which may have involved testing and an update that ensured it was compatible in all MINIs, (I think it was also weight-reduced and the bias ratio changed a bit, but I don't know) but again... if the trannys are the same, I imagine that the diff wouldn't have to be different.

Q3) Why bother? Don't worry about solving the Quaife conundrum because the OS Giken is better anyway.

A3) This seems to me to be kinda a cop-out approach... insofar as even though they are both generally called LSDs, each differential accomplishes something slightly different in a technologically different way. I think the choice of which to use depends somewhat on what you hope to acheive with it, what kind of tech you want to use, and how you plan on driving your car.

Again, most everything above is my take on it... conclusions/speculations I've reached based on the research I did to answer my own questions. While I've consulted Quaife UK, MINI techs, etc... I can't necessarily confirm every fact in such a way as to make the above information scientifically unassailable... but I think its pretty much right.


What I can report with absolute certainty is that I installed a Quaife ATB model QDF38Z in my 2010 factory JCW two days ago, and it works. I haven't been able to push it yet, and as such I can't really give any kind of performance review over stock, with or without DSC intervention, etc... but we know for sure (barring any kind of cumulative wear, longer term failure) that it does work.

Hope someone out there finds this helpful! And... if you have any further knowledge with which to enlighten us on this subject, or if you know for a fact I'm wrong about something... please let us all know!
 
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Old 07-09-2010, 11:29 PM
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I believe your the first here with a Quaife ATB on a factory JCW R56. Sounds like you did your homework prior to purchase. Glad to hear it works.
 
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Old 07-10-2010, 03:26 PM
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Awesome. Thank you for taking the leap. Is the reason you can't push it yet because of the break in period? If so, how many miles? And when you do finally push it you better be back on here posting your impressions.
 
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Old 07-10-2010, 04:27 PM
robbo mcs
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Hi,

I am have purchased a quaife for my R56 JCW racecar, but have not put it in yet.

Lohen in the UK have been selling the quaife for the R56 for quite a while, and confirmed that it is the same box. They have had one in their racecar for 12 months with no problems, and have sold quite a few to customers with street cars with no problems.

It is definitely the same product, and it is reassuring to know that people have been running it in the UK with no problems.

Cheers

Robbo
 
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Old 07-10-2010, 05:27 PM
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Sweet!
 
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Old 07-10-2010, 07:17 PM
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After the rollbar and JCW rear seats... a Quaife is in my future...


Mark
 
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Old 07-10-2010, 09:12 PM
Vespucci
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Robbo- Thanks for the confirmation/corroboration!

Porthos- Hahahahaaa.... break-in period. Honestly, I hadn't even thought of that but I suppose its a valid concern. Although there are alternative theories on "break-in" other than whats listed in the owner's handbook... No, the real reason I haven't had a chance to push it is the combination of lack of time behind the wheel and lack of availability of traffic-free roads and/or track... but when I have the chance to take a few hours sometime away from congested metro DC streets to find some open space/good roads without lots of other cars in the way...

I absolutely will come back and post my impressions of the Quaife.

I'm glad to see there is still a healthy interest in the Quaife out there! Seemed for a moment like everyone had climbed on the OS Giken bandwagon (not that there is anything at all wrong with that... ). Glad to see I'm not alone!
 
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Old 07-10-2010, 10:48 PM
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I have been looking into a LSD since mine was one of the 1st 100 MCS that came off the production line and does not have one.

Being in the UK I can get the Quaife for about £600 and the OS Giken costs double that here. I can see why a lot of people in the USA go for the OS Giken when there is not that much difference in price but for me I do not feel it will be worth twice the cost here in the UK.

Guess I will wait till fitting new clutch and flywheel before fitting an LSD as I try to combine work and labour rates where I can.
 

Last edited by MattyKHZ; 07-24-2010 at 02:54 AM.
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Old 07-14-2010, 06:07 AM
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Quaife will have my money(when I save some up for it heh). That will be my next upgrade. I put a Quaife in my 95 Taurus SHO and that differential was indestructible...can't say the same for my half shafts lol.
 
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Old 07-14-2010, 01:20 PM
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Now if only it was available for an automatic.
 
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Old 09-05-2010, 09:32 AM
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Update...

Ok guys... now that some time has passed, I'm checking in with an update to this thread, to add various bits of additional information.

First off, I believe a few of you wanted me to post my impressions of the Quaife ATB... and now that I've had some experience with it, I can safely say that I...

Love it, love it, love it, love it, LOVE IT!

It operates silently, and has no perceptible feedback as it engages and/or varies bias ratio... which is precisely how this variety of LSD is supposed to work. You'll barely even know its there, except for the improvement in your car's performance. I have thusfar been unable to push it hard enough around/out of a corner (with DSC et al active) to convince the computer to intervene. When accelerating out of a corner, I find that I have to let off the power due to the natural understeer (I haven't upgraded my rear sway bar yet) long before the electronics need to compensate for loss of traction, which means the Quaife is doing its job. I also feel a quite significant increase in available power out of the corners, etc... that is, I have driven the same corners on the same roads in roughly the same conditions in both a stock MCS and my JCW, and where the lower-torqued MCS's computer cuts power, my Quaife equipped JCW just rockets on down the road. On wet roads, I have also noticed a massive improvement over stock... and admittedly, I haven't yet been able to find that small space where the difference between a torque biasing differential and a locking clutch-type differential really matters (more on this below). But I suspect its a pretty small space...

So before getting all geeky, let me reiterate once more that I love love love my Quaife equipped JCW!

Now on to a bit about torque biasing ratios. Diffs that don't lock and bias up to 100% obviously bias up to some number less than 100%. There were a bunch of rumors floating around the net about what differentials biased to what percentage, and I even got some questions/rumors from people who PM'ed or emailed me as a result of my initial posts in this thread... so I thought I'd try to sort it out as best I could, and did some old-fashioned research.

The rumors I had come accross are the following:

Rumor 1) The factory LSD that mini offered up until 2008 (or whenever they discontinued it) biased 30%, and therefore was kinda worthless (better than nothing, but not great)

Rumor 2) Early versions of the Quaife ATB for the Mini biased 80%.

Rumor 3) Quaife, upon consulting several prominant drivers racing Minis using the original Quaife, significantly reduced the bias down from 80% for more modern versions.


Now, I can neither confirm nor deny these rumors. But in my effort to confirm/deny these rumors, I pinned down the production date of my particular differential, and asked Quaife UK directly for information regarding its bias ratio. As a result of so doing, I found out the following:

Fact 1) Quaife does sometimes revise the differential, but more because they consistantly invest in newer, more sophisticated production equipment and are able to increase tolerances to specifications, etc. While they may at some point have conferred with racing drivers, they did't feel compelled to brag about it to me.

Fact 2) Contemporary Quaife ATBs (model QDF38Z), like mine (which was made late 2009 or early 2010), bias to 75%. I personally think that this is not a terribly significant reduction from the 80% rumored for early Quaife models, and is much higher than the rumored 30% of the old Mini factory LSD. Granted, its not the 100% of the locking/clutch-type OS Giken.


And speaking of that bit about the difference between the Quaife ATB's 75% bias and the OS Giken's 100% bias... I hope to clear up something that was a point of consternation to me when I was choosing which differential to buy. Like most things in life, its not just about the numbers. Its also about understanding how the devices actually work and hopefully thereby understanding what the numbers mean.

Many people claimed that the reason to choose the OS Giken over Quaife has to do with what happens between that 75% bias and the full 100% lock... or rather, what happens when the Quaife's less-than-100% ratio is exceeded. People glibly quip that if the torque ratio between the wheels exceeds that 75%, the Quaife (and all torque biasing diffs, torsen style, etc) "becomes an open differential" and that "you don't want that". The assumption being that if the ratio is exceeded, then NO torque is applied to the wheel with traction, and just like with an open differential, the free wheel just spins faster. With an OS Giken you can't have that problem because 100% can never be exceeded (by definition); 100% is applied to the wheel with the most traction.

While that last bit about the OS Giken is true, this is too simplistic an understanding of what actually happens with the Quaife. Having read the white papers on the quattro/torsen design, and conferred with Quaife UK regarding their design as well, I will try to describe my understanding of what happens as straightforwardly as possible. I will use the case of a turn for the sake of simplicity, but the mechanical situation within the differential is the same whenever there is a difference in traction available to each of the two driven wheels, no matter what the cause of that difference is (water, ice, leaves, turning, whatever). A turn is just a familiar, obvious, and accessible example.

In a turn, two important things change with respect to driving in a straight line (on a smooth even road):

1) The outer wheel (the wheel farthest from the center of the turning circle, with the largest turning radius) has more distance to travel than the inner wheel, but has to travel that greater distance in the same amount of time. The outer wheel must therefore turn faster than the inner wheel.

2) The inner wheel will have less traction than the outer wheel because there will be less downward force acting upon it, due to the transfer of weight away from the inner wheel and toward the outer wheel resulting from the lateral acceleration of the vehicle's mass.

Since the inner wheel has less traction than the outer wheel, it will lose traction more easily. When the inner wheel is overpowered, it loses some (but not all) traction and begins to slip. Please note that there is still some amount of tractive resistance against the tire as a result of friction between road and tire, just not enough resistance to prevent the tire from slipping against the road.

Once the inner wheel starts to slip, it (angularly) accelerates up to match the rotational speed of the outer wheel. At this point, the inner wheel is partially slipping while the outer wheel is not slipping at all. It is at this point the differential kicks in, and "locks".

The result of the differential's mechanism is such that if the difference in traction between the inner wheel and the outer wheel does NOT exceed the maximum torque biasing ratio of the differential (in the Quaife's case, 75%), the outer wheel will have more torque applied to it than is applied to the inner wheel. How MUCH torque is applied to each wheel will vary constantly depending upon the traction available to each wheel, but always within an equilibrium where the inner wheel never receives less than 25% of available torque, the outer wheel never receives more than 75% of available torque, and the sum of torque applied to both wheels always equals 100% of that available.

Now here's where it gets really interesting: if the traction difference between the wheels exceeds the maximum torque biasing ratio, the amount of torque applied to the outer wheel equals the tractive torque of the inner wheel multiplied by the maximum torque biasing ratio, and the remaining available torque is applied to the inner wheel causing it to spin faster.

Read that last sentence again. THIS IS NOT THE SAME AS AN OPEN DIFFERENTIAL. I'll say it another way: assuming a max torque biasing ratio of 75%, the wheel with greater traction will always be receiving three times the amount of torque required to overcome the resistance against the wheel with lesser traction. The only way that the more tractive wheel could be getting zero torque is if the less tractive wheel had zero resistance (because zero multiplied by anything is zero, but any positive number multiplied by another positive number is itself a positive number). And there is never a case where the resistance against the less tractive wheel is actually zero (to be super-duper-geeky, resistance from axle friction and inertial mass of the wheel plus tire are always present).

Ok, but to be fair (because I sense your inner cool kid preparing to beat up my inner geek), there IS a time when that resistance might be PRACTICALLY zero... like when you have a wheel off the ground. But its at precisely this time that its necessary to know how the darned thing actually works, because there are important implications.

Remember, these are modern Minis we're talking about. My JCW at least, even with DSC turned off, still has an active ELD system. That is, if the computer monitors one wheel spinning significantly faster than the other, it selectively applies brakes to the freely spinning wheel. With an open differential, this ELD is a poor-man's LSD... the tractive wheel receives torque equal to the amount required to overcome the force being applied to the slipping wheel by the brakes. But remember how a Quaife (or other torque biasing diff) operates... if the ELD system kicks in on a car with a Quaife installed, the tractive wheel receives three times the amount of torque required to overcome the braking force on the other wheel.

So you could say... on a Mini with ELD, the Quaife makes the ELD system much less likely to be necessary, and three times more effective when it DOES actually get used.

Also, the only time that a torque biasing differential like the Quaife actually could be claimed to behave like an open differential is if the traction at one wheel is practically zero, and sustainably so. This is actually quite rare. A torque biasing differential will behave better and deliver more power to the ground than an open differential in almost every case, including most cases where one or both wheels are actually slipping. And in that rarest of rare cases when one wheel really is completely free, our MINI's computers have a built-in counter-measure thats is vastly more effective in combination with the differential.

And this brings us full circle, back to the point I made in my initial post... the choice of differential depends on what you hope to achieve with it, what kind of tech you want to use, and how you plan on driving your car. I for one don't often find myself with one wheel off the road. I suppose there are some people who race or autocross or whatever who DO routinely get one wheel off the ground, and for them, the OS Giken might very well be a better choice (although I feel like I've read/heard that autocrossers prefer a torque biasing diff). I freely admit that if I were going around some racetrack corner at 90mph and I had a wheel off the ground (and bragging rights and/or prizes were at stake), I could think of lots of reasons why I wouldn't want to have to rely on braking the airborn wheel to get power to the road, or risk being underpowered. But if my wheel is off the ground because I'm going over a pothole at like 30mph, I'm less concerned... and the rest of the time, I'll take that corner at 85mph instead of 90mph if it means I keep all four paws planted firmly on the tarmac.

The Quaife is a design that's an elegant solution to the problems addressed by limited slip differentials, its mechanically robust, low maintenance, instantly responsive, highly and transparently effective over a vast range of situations, and applicable in probably all but the most extreme driving situations. For me, I believe it was the best choice. I can't say for certain because I haven't actually driven an OS Giken equipped JCW Mini for direct comparison. But I'm happy... and so far, the Quaife does what I need it to without disappointment.

I'm sure the OS Giken is pretty freakin' awesome too. It probably does do a better job in some situations. Those that have it claim that the tactile feedback and delay of clutch plates locking together is almost non-existant, that the design and construction are of such high quality that the problems with higher maintenance and lower mtbf of older/more-traditional clutch-type diffs are almost non-existant as well... so if you think the OS Giken is the best for your wants/needs, by all means get it. My goal here is not to convince anyone one way or the other, but just to make sure everyone is adequately informed.

When I was trying to figure out what to buy, I thought I wanted the Quaife but I couldn't be sure... I spent days agonizing over the final decision because there was so much negative misinformation out there. I just want people to choose for the right reasons, and to be confident in their choice. I hope this thread helps.

Also, I don't want anyone to discount the Quaife for bogus reasons... because I really like mine.


Hahahahahahaa... and now that I've spent so much time writing this and focussing on my Mini, it almost makes me sad that I'm going to abandon her today. But the weather here is just too beautiful to not travel by Triumph instead. I'm sure she'll forgive me.
 
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Old 09-06-2010, 09:00 PM
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Wow. Thank you for that great post!
 
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Old 09-06-2010, 09:51 PM
onefish2
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Great write up!!

You left out some important info. How much was the Quaife differential? Did you do the install yourself? What is the degree of difficulty to do it yourself? If you did not do the install yourself, how many hours were you quoted for the install? And lastly where did you purchase it?
 

Last edited by onefish2; 09-06-2010 at 09:57 PM.
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Old 09-07-2010, 04:58 AM
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I just got one question....

Do you love your quaife? You didn't really make it clear, I just wanted to make sure I understood...lol.

Thanks for the great info, a quaife is my next mod once I get the car put back together.

Mark
 
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Old 09-07-2010, 06:10 PM
cmt52663
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FWIW I bloody well love mine. 120k miles since the install, and the car is running at the National Solo finals without a hitch. Particularly with the Works kit, it makes the car pull like a freight train out of corners.

Back in 2005 before the Quaife I used to leave an awful lot of rubber on the inside of corner exits. I pretty much could not use the power...

By the way, the latest issue of Grassroots Motorsports has a nice article on the OS Giken - Per chose that for their project car. Sounds pretty capable also, I have not tried one.
 
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Old 09-08-2010, 03:14 AM
robbo mcs
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Originally Posted by cmt52663 View Post
FWIW I bloody well love mine. 120k miles since the install, and the car is running at the National Solo finals without a hitch. Particularly with the Works kit, it makes the car pull like a freight train out of corners.

Back in 2005 before the Quaife I used to leave an awful lot of rubber on the inside of corner exits. I pretty much could not use the power...

By the way, the latest issue of Grassroots Motorsports has a nice article on the OS Giken - Per chose that for their project car. Sounds pretty capable also, I have not tried one.
Hi,

However, the question of the quaife is very different on the R56 and R53.

I have an R53 racecar, which I have fitted a quaife to, and absolutely loved it. This car really, really needed the diff.

I have a R56 JCW which I am building into a rally car. I bought a quaife diff to fit to it, assuming it would be the same as the R53. However, after racing this car, it is absolutely not the same as the R53. With good suspension and camber settings the R56 is getting the power down surprisingly well without the diff. I still have the quaife sitting in a box in the gargae.

On the R53 it was an absolute no brainer that made a massive difference. On the R56 I think it is probably a more marginal decision. I'm sure that the car will be quicker with a LSD for pure racing, but is it worth it for someone who does a few trackdays occasionally and mainly drives on the street, probably not.

Cheers

Robbo
 
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Old 09-08-2010, 03:52 AM
cmt52663
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Hi Robbo,

Thanks for teaching me on the R56 differences. Mebbe one of the Ogburns will weigh in here at some point, as David the younger (the kart pilot from Texas) whipped me yesterday with their R56.

I will ask today what their diff setup is, and if they are running the OEM approach I'll report back. Frankly I'd be surprised (but so what!).

An R56 Rally car? Too cool.

Cheers,

Charlie
 
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Old 09-10-2010, 01:52 AM
Vespucci
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Onefish2 - So sorry! Here are your answers, best I can give.

I got it for $1135, but I didn't shop around too much because they had it in stock, was relatively close, and I could get it overnighted for like $50. The place was called No Limit Motorsport, in Long Island... they have a website (http://www.nolimitmotorsport.com) but I ordered over the phone. I spoke with someone named Eric, who was very helpful and also helped me with some info that I used when I was tracking down the production date.

The reason I had to get it overnighted is because the transmission had to be pulled for a warranty issue, and I wanted to take advantage of already having the tranny out. And because the tranny out was warranty service, it was done at a dealer shop. As such, I didn't put the differential in myself. However, its not DIFFICULT to do, its just labor intensive.... and having certain tools (like a lift) really "helps". There are some good vids on youtube that show you the process once the tranny is out.

If you paid a shop to do the whole project, I think they'll quote you like 10 hours. I was quoted 4 just for the diff install (in the already-removed tranny) but it ended up only taking like 2.5 hours....

Anyway... the whole thing was a bit unusual because I had some mitigating circumstances, and because I arranged it such that I could save myself A LOT of money. If you pay someone else to do this job and only this job, its going to be pretty expensive (several thousand) once you include labor, parts, etc. If you can concoct a cunning plan, and make the right kinds of deals with the right people, you can pull it in under $1500 and not even have to do any of the work yourself!

And don't bother to point out how crazy it is to take advantage of warranty work to void that very warranty, etc. As the proverb goes, crazy like a fox!


Robbo - R56 JCW Rally! Fantastic plan! I was kinda thinking about doing exactly the same thing... drive mine for a few years, then convert it to rally. Thanks for the great info! I may have some questions for you...

-Vespucci
 
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Old 09-11-2010, 01:13 PM
cmt52663
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BTW...

I inquired of the Ogburns who ran their R56 in STX at Solo Nationals this past week. They were running a Quaife decal, but the car actually does not have one - instead they have found the ELSD adequate thus far.

Their car was quicker than mine by about a second over both days (but I will claim I was out driven...).

Cheers,

Charlie
 
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Old 09-27-2010, 10:48 PM
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Originally Posted by robbo mcs View Post
Hi,

However, the question of the quaife is very different on the R56 and R53.

I have an R53 racecar, which I have fitted a quaife to, and absolutely loved it. This car really, really needed the diff.

I have a R56 JCW which I am building into a rally car. I bought a quaife diff to fit to it, assuming it would be the same as the R53. However, after racing this car, it is absolutely not the same as the R53. With good suspension and camber settings the R56 is getting the power down surprisingly well without the diff. I still have the quaife sitting in a box in the gargae.

On the R53 it was an absolute no brainer that made a massive difference. On the R56 I think it is probably a more marginal decision. I'm sure that the car will be quicker with a LSD for pure racing, but is it worth it for someone who does a few trackdays occasionally and mainly drives on the street, probably not.

Cheers

Robbo
If you have the ELSD then that is probably why the R56 is "superior" to the R53 in stock form, those of us who do not have the ELSD on our R56 are in the exact same boat as you were in the R53.

I have actually driven a Quaife equipped car and a Clutch type LSD equipped car but they were not Mini's, I think the experiance is still relevent though so I thought Id share.

I come from the Probe community (yeah yeah go ahead and laugh), I had a 2.5L V6 with an open diff, I turboed the car and quickly blew up the stock diff, to fix it I bought and installed a Quaife LSD. As said already the diff is virtually invisible while driving normally but traction is significantly increase in all driving conditions. Coming out of corners and wet traction were the biggest two things I noticed with the Quaife, You could put down a huge amount of power (I had double the factory HP/TQ) out of the corners compared to the stock open diff. I had not originally considered wet traction but that turned out to be a very welcome plus, I was surprised to find I could still put down a significant amount of power without wheel spin and could even pull out of the corners in the wet.

I just purchased my 07 MCS about a month ago to replace the Probe that I have now retired and am parting out. The very first thing I noticed while driving is the open diff, and it SUCKS. I have been driving with the quaife for 5+ years and forgot how much it helped. While going through some S curves I nearly when off the road in the Mini due to wheel spin as I was attempting to accelerate out of the corner and this was at a fairly low speed. I've had to relearn to wait on putting the power down until I'm almost completely out of a corner, and even then bring it on much slower then before.
Making left hand turns in traffic is another example of the major improvements you get from a LSD, just this weekend I was trying to "shoot the gap" in traffic and barely made it due to spinning the inside tire the whole way, with relatively little power. Needless to say I'm in this thread looking to put a Quaife in the Mini.

We also have an 07 Jeep Wrangler and it has a clutch type LSD in it, again you never really notice it when driving normally and you get added traction in wet conditions and cornering, though obviously a completely different experience being solid axle and RWD. The Jeep also has a similar feature to the ELSD in the Mini called BLD (Brake Lock Differentials). This is used offroad to keep you moving when you have 1 tire with little or no traction (often completely off the ground). It will apply the brakes on the wheel in the air allowing the power to transfer to the wheel that does have grip and help pull you over the obstacle. The system works fairly well and I can see it being used as an LSD with similar results.


My understanding of the difference between the torsen type LSD's and the clutch type differs slightly from what was posted above though, and break down to the following basic points.....

1. Torsen type LSD's require NO maintenance, Ever.
2. Clutch type LSD's MUST have additives in the gear oil or they will wear out and fail very quickly.
3. The clutches do wear out over time and must be replaced.
4. Clutch type's can be adjusted by varying the pre-load spring tension.
5. Torsen are fixed and can not be adjusted.

A.Torsen type LSD's will not function if one of the tires has zero traction, IE in the air. Yes you will get 75% of the traction on the other wheel but 75% of 0 is still 0. (technically not 0 due to bearing resistance bla bla bla but such an insignificant number it may as well be).
B.Clutch type LSD's WILL function even if 1 tire has 0 traction.


The description of the function of the torsen LSD in a corner was explained to me like this. If you have 1 wheel that wants to spin faster the gears in the diff "ask" the other tire if it wants to slow down, if that tire has loads of traction and refuses to slow down then the other tire is prevented from spinning any faster. If your in a corner the outside tire will ask to spin faster, the inside tire happily slows down and you have a functioning differential. Both tires have to have some ammount of grip to bias off of, this is why the torsen doesn't work in very low grip situations, whatever the tire with traction "asks" to do the other complies because it has little to no resistance and you end up with spinning tires.

So what I found out while researching them is that for track type and daily driven cars a Torsen (Quaife) LSD is the best way to go and for offroad, gravel, ice, etc. conditions where you may have very little grip on one or both of the tires, clutch type is the way to go.
Clutch type is also used in Drifting since it allows even TQ to be applied to both tires even when they are both spinning. If you put down more power then the Quaife can handle they will both spin but you can feel it fighting back and forth between them trying to balance the power as each gains or looses more traction then the other.

Quaife also helps reduce TQ steer, haven't noticed it much in the Mini but it's also bone stock, I imagine that with 200+ HP the Mini starts getting it pretty bad.
 
  #21  
Old 11-14-2010, 02:52 PM
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Originally Posted by Vespucci View Post
When I was considering putting a Quaife ATB differential into my 2010 factory JCW, I looked a lot of places for information... including NAM. I found a lot of conflicting/uncertain information from lots of different sources, and I don't think my search here revealed any threads that directly addressed my concerns. That said, I wanted to share what I learned in the process, and I apologize if this thread duplicates information elsewhere on NAM.

The Quaife ATB LSD is listed many places for the R53, but very few specify it for the R56. Quaife UK themselves list it for the R53, and then generically for "all" BMW MINI 6-speed manuals...

I contacted Quaife UK directly, and received somewhat vague confirmation that the Quaife ATB differential (model QDF38Z) will fit/work in any Getrag 6-speed manual transmission for the MINI (R53 or R56). Indeed, the same model (QDF38Z) is listed for both MINI listings on Quaife's own site, as well as for the Ford Focus SVT/ST170 (precursor to the RS?).

What it seems to come down to is that QDF38Z works in ANY car that uses that particular Getrag 6-speed manual tranny, which from what I can tell from Getrag's information, is more specifically the Getrag GMTT280 FWD, 6-speed transverse manual transmission.

I believe (though I have no direct evidence) that this model tranny is used accross many new MINI models and years, even though the part numbers in MINI's parts catalog are different due to their intended installation in different MINI models. What I do know for sure is that the fact that the MINI part number designations across models are different doesn't mean that the actual transmission supplied by Getrag is necessarily different.

The following additional misinformation/conundrums seem to be out there:

Q1) Other 3rd party parts suppliers list the Quaife ATB as being for particular model years, but not MINI models. Whats the deal?

A1) I think this kind of info should be ignored in favor of a direct differential-to-transmission match.

Q2) Quaife will not make an ATB for the R56 until they get a certain number of orders.

A2) I suppose that may have been true at some point, but today (as of 2010) it seems to be no longer applicable. I read a rumor that there was a revision of the QDF38Z at some point which may have involved testing and an update that ensured it was compatible in all MINIs, (I think it was also weight-reduced and the bias ratio changed a bit, but I don't know) but again... if the trannys are the same, I imagine that the diff wouldn't have to be different.

Q3) Why bother? Don't worry about solving the Quaife conundrum because the OS Giken is better anyway.

A3) This seems to me to be kinda a cop-out approach... insofar as even though they are both generally called LSDs, each differential accomplishes something slightly different in a technologically different way. I think the choice of which to use depends somewhat on what you hope to acheive with it, what kind of tech you want to use, and how you plan on driving your car.

Again, most everything above is my take on it... conclusions/speculations I've reached based on the research I did to answer my own questions. While I've consulted Quaife UK, MINI techs, etc... I can't necessarily confirm every fact in such a way as to make the above information scientifically unassailable... but I think its pretty much right.


What I can report with absolute certainty is that I installed a Quaife ATB model QDF38Z in my 2010 factory JCW two days ago, and it works. I haven't been able to push it yet, and as such I can't really give any kind of performance review over stock, with or without DSC intervention, etc... but we know for sure (barring any kind of cumulative wear, longer term failure) that it does work.

Hope someone out there finds this helpful! And... if you have any further knowledge with which to enlighten us on this subject, or if you know for a fact I'm wrong about something... please let us all know!
I upgraded to the Alta Stage 3 with my 2009 JCW. WOW---lots more power and torque. It needs LSD of some type. I don't like the electronic locking. I'm gonna give the OS Giken diff a try and go with the OS Giken twin disc clutch. The clutch is going ever since the 2nd gear burnouts at the drag strip.

Ray
 
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Old 03-07-2015, 12:51 AM
fjork_duf
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Great thread. Worth the bump. Here it is 2015 I am looking to install a quaife into my '15 R58 JCW. The car definitely unloads the front wheel on tight corners on the road or at the track. I'm thinking the quaife because it's cheaper and doesn't ever need service.

Any quaife owners willing to post an update?
 
  #23  
Old 03-07-2015, 03:27 PM
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Originally Posted by fjork_duf View Post
Great thread. Worth the bump. Here it is 2015 I am looking to install a quaife into my '15 R58 JCW. The car definitely unloads the front wheel on tight corners on the road or at the track. I'm thinking the quaife because it's cheaper and doesn't ever need service.

Any quaife owners willing to post an update?
fjork_duf - it seems as though you are doing your homework too, like the OP of this thread. This is a great thread. We seem to have some of the same interests as we have bounced around some of the same threads. Thanks for bumping these. As I am a step ahead of you with having a Quaife installed, I can give some observations from having driven my MINI with it for a month:
- The most noticeable thing is that you don't notice it at all. The car just seems to do what you expect it to without any drama. In the cold with snow tires on a reverse camber uphill turn the car just pulls with application of gas. Too much gas and the car will push a bit but that is to be expected. Back off a little and it goes back to pulling.
- I got it because of frustration with burning out brakes on the track because of the eLSD. On a track like WGI with an uphill corkscrew turn like the toe the inside front wheel gets a double whammy. Going uphill, the front gets light and because it is a turn the inside wheel gets even lighter and just wants to spin. It is almost impossible for the eLSD to control the power of even the S engine and that brake just gets cooked. I have run with other MINIs with the factory mechanical LSD and they just walk away from me through that turn.
- Based on the explanation given in this thread, I wonder if the eLSD and the Quaife will actually work together. For example, above it states that one problem with the Quaife is that if one wheel has zero traction (eg: it is in the air), then the eLSD will apply the brake on that wheel and add some "traction" which could actually improve things. Maybe wishful thinking, but it would be nice if that is true.
- On thing that is done with the install is that the transmission fluid gets changed. On mine and with the zero deg days, shifting became really stiff. It has loosened up some, but it is still quite stiff when it is cold. The shop tells me this will continue to improve as the fluid "breaks in".

I am very curious to see how it performs once I get it out on the track. I will post again after my upcoming event.
 
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Old 03-07-2015, 05:48 PM
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Neat thread, thanks folks! So I've got a question: since the R56 has a considerable amount of torque steer, does the Quaife affect the torque steer - is the response quick enough to make any difference? Would it not worsen the torque steer i it does? My understanding of torque steer if cause for example through uneven drive shaft lengths, one shaft has more 'give' (the longer one), and so that wheel could be sensed by the LSD to have more grip (turns slower) than the short shaft one. If then more torque is diverted to the long shaft, that could compensate for the torque steer?
In your experience, does the Quaife make any noticeable difference?
TIA!
 
  #25  
Old 03-07-2015, 06:22 PM
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The Quaife is supposed to reduce or eliminate torque steer in the MINI. Can't say that I have any particular experience with the affect with the Quaife on torque steer as I haven't had much chance to test it out. The little that I have gotten on the throttle with the snow tires on dry pavement, there has bee no evidence of torque steer in corners. In fact the steering is best described as "neutral". Now I will say that I never had any appreciable torque steer in my MINI to deal with. Now my 1980 Buick Skylark had it out the wazoo, but not the MINI...
 

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