I have a 2005 R53/JCW. Has 20,482 miles on it, as of this afternoon.

I've been learning how to complete a backyard wheel alignment. Why me, because I've been screwed by "professional" shops...twice. Paid with no joy.

Anyway, I have a lot of paperwork from the previous owner. One of those pieces of paper is the original window sticker. The original owner paid an extra $500 for a Limited Slip / Positraction unit.
The other day, I noticed that with the right side front tire off the ground, I gave the tire a soft rotation, not expecting it to turn or turn very hard, since the left side tire was on the ground. A snapping sound came from the gearbox. The tire/wheel had very little resistance to rotating.
The next day after doing some suspension adjustments, I took the car for a short drive. As I pulled into the driveway, I stopped and did a mini burnout of about four feet. After putting the car where I wanted it, I looked at the "mark" on the concrete driveway.
Only the right side tire spun..!?

Is this an indication of a broken Limited Slip unit, or some other odd thing that I don't know about with this car.
Any good thoughts / ideas appreciated.

My background is the last 60 years of American car hot rodding. This is my first offshore car.

Mike

P.s. - The Dynamic Traction Control was turned off (always..!).

 

Do both front wheels rotate by hand in the same direction when you have the front off the ground?

 

Do you know how the "stock" mini limited slip unit works ?

I ask because, just having both tire rotate the same way isn't telling in todays world of the various designs available.
- A spring loaded, clutch type yes, both tires spin the same direction.
- A gear unit, no...they act like an open differential when spun with no load.

I could be wrong, but the drawing of the OEM unit, may not spin both tires without a load, (like my little short burnout). But...no joy there and the snapping in the gearbox when one tire was rotated, has me a bit annoyed / concerned.
In any case, I will lift the front and see what happens.

Thanks.

Mike

 

you cannot test a oem lsd that way, they only work when there is torque being applied inside the unit.

 

Snapping sounds are never good.

There's quite a bit of info on our factory-option LSD from Miata guys because their Tochigi-Fuji is essentially our GKN SuperLSD.

keyword:

"notorious failed tabs"


Snapped tabs on the taper rings seem to be a common failure point.



Pic from a Miata forum:

 

Mr.Blah -

That's what I figured.
Thanks.

----------------------------------------------------------------------------------------
Oldboy -

Great, I wondered if I have parts floating around in the oil, now I know. So now I can wait for parts to lockup as I'm driving down the street..!
There seems to be a handful of limited slip differentials on the market, what's your thoughts on a good one ?
I see that some units weigh a few pounds, some weigh MUCH more. I know that rotating weight is a power killer, so I'd like to be on the lighter side, but lets say...stronger than the OEM unit..!.
I'm not racing, but I do (did !) have plans on doing some Auto-X.

Thanks for the info...and photos.

Mike

 

I'm doing my clutch soon and was planning on getting the tried-and-tested Quaife.

My car is a JCW with stock LSD and I'm sitting at 136,000 miles right now so I expect that the % rate of the LSD has gone down with all the miles...

...I seem to remember somewhere reading that as they age they lose their effectiveness, need to search NAM for it again because I think it was an official reply by GKN.

GKN has stated that in our application the Torque Bias Ratio was 1.8 - 2 and the intended design life was around 150,000 miles,
as reported here:
https://www.northamericanmotoring.co...-from-gnk.html

:

TBR info from Quaife seems hard to come by...

...found on a Focus forum (they have the same Getrag gearboxes as us)
Quaife stated:

"We do not use or quote TBR figures as they don't really mean much to anyone. The TBR is a very difficult thing to measure (we know this from our work with OEM diffs) and actually not very useful.

Essentially the TBR is a complicated way of comparing the helix angle of the internals (sun gears and pinions) and the vast majority of our diffs have the same angle internals although some of the very large and very small diffs have different angles."

https://www.focaljet.com/threads/tor...n-here.597609/

:

The snap sound you heard may be a normal part of operation,
maybe the sound of the tabs popping in/out of location?

The major complaint about the factory LSD's when new was a groaning noise,
so much so that a TSB was issued:

Fluid - Differential: Customer Interest

Drivetrain - LS Differential Noise On Low Speed Turns

SI M 23 01 06

Manual Transmission
March 2006
Technical Service

This Service Information bulletin supersedes S.I. M23 01 06 dated February 2006.

SUBJECT
Droning Noise from a Limited Slip Differential

MODEL
R53, R52 with W11 and G285 Getrag 6-speed equipped with Limited Slip Differential option(from 01/2005 up to 03/2006 production)

SITUATION
Customer may complain of a droning (grinding) noise from the transmission area during cornering at low speed in the first or reverse gear. In most cases, complaints occur on low mileage vehicles.

CAUSE
Friction noise from the limited slip differential (surface roughness of the taper rings).

CORRECTION
On a customer complaint basis only, the transmission fluid should be replaced with Texaco MTF94 trans fluid (P/N 83 22 0 403 247).

For draining and refilling procedure refer to MINI TIS RA 00 11 229 (G285 transmission fluid capacity is 1.7 liter;
filler/drain plugs tightening torques are 43 +/- 4 Nm).

After refilling the transmission with MTF94 and with the vehicle at operating temperature, drive in tight circles (approximately 10 circles in each direction) until the grinding noise disappears.

 

The Quaife might be a good choice. The ring gear flange hs been lightened, that's a very good thing. I have a similar worm gear style limited slip units in two of my American cars, an old fashioned clutch type in the third car.

The torque bias theory is very difficult to base a positive "ratio" on. There are millions of different scenarios that the two tires will go through in their life that will force the differential into different ways of solving the problem of the tires spinning with different loads that have been put upon them.

Anyway, my problem, yea, I sort of...thought about the snapping MIGHT be "normal", but that I'd never heard that sound before out of a rear end that was...all in "one" piece..!
BUT...the main telling thing for me, no matter what sound, no matter what the wheels do with both off of the ground, no matter of anything else...in my short (4ft.) burnout...ONLY the right side spun. Not even a hint of the left side trying to spin.
So...the way I see it, something's...broken.

Oldboy - Thanks again for all of the good info. I've still got a fair amount to learn about these little cars !

So now -
1 - Which limited slip unit to buy. The Quaife sounds like a good possibility, but will do some studying on the subject.
2 - Do I replace an essentially new clutch (20K miles) with another...new clutch. Most likely.
3 - If I replace the clutch, I need to study up on clutches also..!
4 - Do I do the work...or do I pay someone ? Special tools ?
5 - Will the pieces floating around in the case damage anything else ?

Hmm, five simple questions, no simple answers.

Mike

P.S. - There is no odd noises/sounds while driving the car, while in corners or going straight, easy or hard on the throttle.

 

Definitely do your research, but my unsolicited opinion is the quaife is fantastic. I had one put in my transmission while having the clutch replaced (exedy smf) and after 4,500 miles and 1 fantastic track day I couldn't be happier with the diff. I don't notice it during 99% of daily driving, but at the track, or in the occasional fast street turn it's uncanny the way it makes the car just pull out of the corner. It was phenomenal at the track. I still haven't really wrapped my head around how much sooner I can get on the throttle because I got so used to waiting for the front outside tire to have enough traction available to apply power. I don't know what supply is like now, but I bought mine from Orrange in the UK because all of the american distributors were out of stock. The bonus was between not having to pay VAT and the exchange rate, it was something like $150 cheaper than the cheapest US supplier.

 

Racingguy -

Thanks for the info.
Seems many like the Quaife.

Mike

 

Autocrosser. Swear by it.

STX R53, and STU F56.

Lifetime. No worries. Done.

Cheers,

Charlie

 

Charlie -

Thanks, I'm leaning that direction.

Mike

 

Maybe a dumb question, but I gotta ask...

Is it possible to remove the transmission/differential with the engine in place ? Without a bunch of work, or is it better just to remove the engine and trans. as a package ?

After a little YouTube watching, it seems that the differential swap is simple enough.
My only question, is the bearing placement. There's no way that the new bearings on the new differential will be exactly the same width as the original parts. I don't want to stress the case OR have the differential loose in the bearings.

Thanks

Mike

 

I always leave the engine in place, follow mod mini's youtube video

unhook the temp sensor off the back of the head and be careful around it, i've broken two of those stupid things removing transmissions

 

Thanks much.

I watched a coupla videos, one or two from this guy, but missed this one (trans. only removal). I guess I'll "give it a go", as the Brits say.
Still not sure about the differential vs. case width deal though.

Mike