Ok, knowing these LSDs were used on Mazdas previously I found this thread that is somehow useful at the second page:

http://forum.miata.net/vb/showthread.php?t=76795

 

Yes, Lance explains things in a little better layman terms, but some of his statements are theoretical conclusions...

Also, every statement, article or random babbling I've read so far ALL refer to the MINI LSD as being 30% slip, so I suspect the BMW ETK has some incorrect information, but that wouldn't be the 1st time.

Here's a link to the ETK stating 25%, this is the only place I've ever read that value...
http://www.realoem.com/bmw/showparts...49&hg=23&fg=05

 

I too have wondered whether I received my factory ordered LSD and how to test it. A month ago I had my daughter watch my car as I punched the throttle in the snow. I could hear/feel the wheels spinning and my car did move forward. My daughter told me that one wheel was spinning much faster than the other, but both wheels spun. I assumed that meant I had LSD, but was surprised to find out both wheels were not spinning at the same speed. Is this the 25% or 30% your referring to above. That one wheel will turn 30% faster than the other? Or is this thing not working correctly? I thought what I was ordering was more like posi-traction and both wheels would spin at the same rate.

 

Or... just call yr dealer with the VIN (or MINI-USA) and they will be able to tell you.

 

did you disable DSC?

 

Yes.

 

Posi-trac (and the MINI's LSD) don't force the wheels to turn at the same rate. That would be a "locked differential", which is great for drag racing but lousy for going around corners.

The way the MINI LSD works is by detecting wheelspin and shifting torque away from the slipping wheel to the wheel with better grip. The MINI system can't transfer 100% of the torque, so the slipping wheel may still turn, and it may even turn faster than the wheel with grip, depending on how slippery the surface under the slipping wheel is.

Picture an extreme example, where your left wheels are on dry pavement and your right wheels are on wet ice. Let's say that as you're accelerating away, the engine/transmission is putting 100 ft-lbs or torque to the wheels. (I'm just picking 100 ft-lbs to make the math easier, not to represent any "typical" value).

The differential will initially try to send 50 ft-lbs to each wheel, but when it detects your right wheel slipping, it will transfer torque away from the right wheel to the left wheel. Let's say it can transfer a maximum of 25% from one wheel to the other. That means that the left wheel will get 62.5 ft-lbs of torque and the slipping right wheel will be left with 37.5 ft-lbs.

The 37.5 ft-lbs of torque that's still going to the right wheel will probably be enough to make the wheel slip, and since wet ice is very slick, the right wheel may spin very fast - even faster than the gripping left wheel. But overall, you're still better off than you were before, because you have 62.5 ft-lbs on the "good" wheel working for you, whereas you only had 50 ft-lbs before the LSD did its thing.

On some non-LSD cars, the differential would actually work *against* you in the above scenario. When one wheel starts slipping, it becomes the "path of least resistance" for the transmission, and the differential would actually send all of the torque to the *slipping* wheel, leaving you with nothing at all at the "good" wheel.

 

So since the both wheels were spinning, it sounds like my car passed the LSD test. Thanks Scott.

 

Was the mechanical LSD an option for base coopers or just for MCS?

 

It was MCS-only, standard transmission only, and only available on 2005+ first-gen MINIs (so 2005 & 2006 coupes, and 2005-2008 convertibles).

 

Seems from the other threads I went over the 07-09 R56 Minis had the option as well, until early 2010. Anyway, that's too bad

 

Sorry, you're correct. I thought MINI dropped the mechanical LSD with the introduction of the R56, but it looks like they kept it around through 2009.

 

np - but again only for the mcs correct? Though, wasn't the 6 speed trans between the base and the mcs the same?

 

I had it on my 2008 MCS

 

I may just be getting old, but I don't remember the Getrag six-speed manual even being an option on the base model, much less standard equipment.

 

gotcha - it is standard six speed, i assumed it was the same getrag. i'll keep looking for more info, thanks

 

You have a first-gen base-model Cooper (R50) with a six-speed manual?? I really don't remember such a thing ever being available. Is it a US-spec car?

For the base Cooper, I only remember the CVT automatic, the five-speed Midlands (a troublesome unit), and the five-speed Getrag.

If you do a Google search on "six-speed R50", the results are all about swapping in a six-speed from an MCS, with no results that even mention a factory six-speed in the base model.

 

Sorry for the confusion, I've been talking about the Base R56 (07+) this whole time. Don't have a Mini yet, I've got an 06 Evo IX MR, looking into a reliable daily w/ good mpg that is very competitive in it's stock SCCA auto-x class - hence the Mini, and hence my interest in the LSDs.

::
On the website, it does show the Base Mini has the Getrag six speed (http://www.miniusa.com/feature-six-s...Top_Features-m) though I guess it's the 2012/2013 MY and things could have changed since the 07-09 when LSD was available. In any case, it does bring up the point that the LSD was a factory option for the Minis, and there is some sort of provision for that for autox - I'll bring it up in the other thread.

 

R56 Coopers all had the Getrag six speed as the manual option. No Cooper (as opposed to a Cooper-S) has had a mechanical LSD. The best you can do for H Stock is a newer R56 which has DTC as an option. DTC devolves into EDLC (Electonic Differential Lock Control) an eelctronic LSD when you turn off the DTC modes. I'm not entirely convinced by how good EDLC is, we have than on our JCW, its probably better than nothing. I'm not sure which years DTC was available, probably 2010+.

 

Thanks, your answer pretty much wraps this up.

 

Yup, he did a great job summarizing it!

 

No, the confusion is all my fault. I hadn't posted in this thread for four years, and I forgot that it was in the 2nd-gen subforum.

 

I am not sure this holds true for the Mini but I would think it does since I have done it in many other cars.

Jack the front of the car off of the ground, but car in neutral (make sure to black rear tires so you don't get crushed please ) spin one wheel. If just the one wheel spins it's an open diff, if wheel #2 spins also when you spin wheel #1 then you have an LSD.

Also, wheel #2 may spin opposite direction when you spin wheel #1, just fyi

 

FYI both wheels will always spin. If you do not have LSD, they will spin in opposite direction and if you have LSD they will spin in the same direction.

 

Hmmm are you sure on this? And is this a Mini specific thing? Because the 240sx I used to have with the factory LSD both rear wheels would spin in opposite directions.

EDIT: Braminator I am sorry but you are most definitely incorrect. I just jacked up my wife's '03 Justa, and as I described she has an open-diff and when you spin one wheel both wheels do not spin, only the wheel that you spin will spin.