Wrote Mini OL and this was their reply:

"Thanks for writing MINI. I'm sorry to hear about your concern with a groan when
you are taking tight turns.

Yes, there is some inherent noise in the sysytem. Since we can't be there to
listen to the noise and see if it is normal, though, I would rather recommend
that you contact your MINI dealer and have them take a listen in person.

If there are further questions I can assist with, please feel free to drop me an
e-mail. I will be happy to lend a hand."

To my question:

"Noticed "groaning" sound when making tight turns on my new
Cooper S with LSD. This did not exist when I picked up the car and became
apparent at around 500 miles. Please comment on this. Is this expected?
Will it go away? Is it the LSD? Do I need it serviced; and if so, does the
gear oil need to be replaced? Any info will be helpful."

Came back from dealership service a few minutes ago and they stated that this was the "EHPS SYSTEM OPERATING AS INTENDED" (I guess they attributed it to the power steering). I am pretty sure it's not the PS but I'll take their word for it, for now. The sound has diminished though, perhaps by how the tech was driving it - as in pushing it through corners as opposed to my gently turning in and out of driveways and parking lots. I will try driving it more assertively for awhile based on the hypothesis that perhaps the LSD just needs some breaking in by harder driving. At the very least,I know that this complaint is on my records for future reference.

 

I have a August build (i think week 32)

I noticed the "groaning" at around 1200 miles, when pulling out of my parking space in the morning. I figured it was the lsd clutch-pack, nice to know others noticed it too. :smile:

 

The MINI LSD does not use clutch packs, it is a cone style tourqe sensing LSD made by GKN Driveline.
http://www.gkndriveline.com/gkn-driv...s/tmd/slsd.jsp

 

Looks very much like an open diff. I'm definitely not impressed.

 

Just because you don't understand how it works doesn't mean it's not effective. Have you driven a MINI with the factory LSD?

 

It's interesting to read about others experiences. Compared to some of the other posts, mine is relatively quiet. For reference, mine is a 7/05 build.

Thanks all!

 

My Jan '05 build car also has the LSD groan. My MINI dealer confirmed the noise and stated that it is normal. I'm still not convinced, but at least it's on record.

 

Had my car in for a few minor things today so I asked the dealer to check out the LSD groan. They confirmed that it was there (this is a major accomplishment - can't tell you how many times they can't replicate a problem, only to have it occur as I'm driving away ).

They didn't have another MINI with LSD on the lot, so nothing to compare it to and they haven't had any other complaints yet. So, they opened up an item (PUMA?) with MINI USA and will get back to me.

They also said they searched for a service bulletin but couldn't find one.

I'll let you know what they say.

 

02/05 MCS on LSD no groan/noise 7800miles

 

Mine does make noise in sharp turns (very sharp) when applying throttle, but I thought it was normal for the LSD. I can also feel something (a slight vibration) through the steering wheel when the noise is occurring. The LSD works well, and I haven't had any reason to think it's broken/malfunctioning. Exactly how loud is the noise that people are hearing? I don't think I could hear it over the radio at low to moderate noise levels.

 

08/05 mcs and i've just heard a slight groan a few times when the car is cold and on full lock wheel turns.

 

I bet you can't make squiggly burns out as you could with Quaife:smile:

 

Just wondering, could the type of LSD used in the MINI be in need of any type of friction modifier oil that is used in many rear LSD gears for pickups/SUVs? On those limited slip designs, they will make a horrible groan with no additive in tight slow turns, but with just a small bottle of friction modifier, all noise goes away.

May be a completely different style. Just a thought.

 

I was told that friction modifier would work (by a very qualified person) still he also said that the LSD of front wheel drives have to work harder and after a long explaination I agreed. HOWEVER he also said he would NOT put in the modifier because of warantee issues and would also contact the manufacturer (GK) to find out exactly what was inside and what they recomend. Mine groans all the time (in turns) kinda like my wife at 4000 miles on an 01/05 build no real problems yet.

 

Hey MISFITOY, I haven't tried that. I try to keep the tires from smoking too much. My wife would crap if I needed new tires after 6 months.

 

If the Mini LSD is a cone type differential then it is an Auburn style LSD. Those are not what is traditionally called "torque sensing" (that would be a Torsen.. and Quaife, which is a Torsen with a clutch so it still works even when one wheel is off the ground). Note they also call a clutch type "torque sensing" too.

Auburns work pretty much like a clutch type diff with the difference of not being rebuildable. Summary of all the types here: http://www.a1.nl/phomepag/markerink/diffs.htm

 

Ditto hear on the symptoms - the weather has turned cooler and the groaning is with full steering wheel turned (or nearly all the way). It does remind me of when my truck is in 4WD, a similar noise coming from the front transfer case (I think).

 

Were you at Sterling? I was there before because of the noise and they said it was my tires. Let me know how things turn out.

 

Instead of spinning in a straight line, I tried yanking the wheel from side to side and the Quaife kept both wheels spinning while making a snake line just like a RWD

 

Yep, Sterling. Is yours making the groaning noise as well? If you wouldn't mind PM'ing me your name, I'll let Tradd Dozier know and maybe he can link them together to build more of a case for their PUMA.

BTW, I've notice some improvement in their service over the past few months - not sure where it's coming from. It wasn't bad before, but my recent experiences they have been going above and beyond.

 

From MINI PR:The unit, manufactured by GKN Driveline, is a torque-sensitive differential that manages torque output under acceleration and offers a 30% slip rate. This means, there is no loss of torque if the difference in grip between the two wheels is 30 % or less. The system also allows the threshold for Dynamic Stability Control (DSC) to be increased without impeding the system's safe intervention in slippery situations.

 

I guess they don't care that everyone else in the world considers Auburns and clutchpack diffs to be friction-type devices, where there is a preload (the source of the groaning sound in turns, and also the only amount of friction when one wheel is in the air) as well as increased friction under load (torque). Torque-reactive, yes, as the spider gears do wedge the clutches together more tightly under load from any source (including brakes). But TORque SENsing, no!

"Torque sensing" diffs invariably have planetary or helical gears, just like the picture of their helical unit shows. The hallmark of torque sensing diffs is that they allow any speed differential so long as it is not caused by torque from the engine. Only torque from the engine locks up the unit. This is accomplished by the curious property of worm gears being able to drive a roller, but not the other way around (think of a Genie worm-drive garage door opener). You can see why this is the type of LSD that is least likely to interfere with things like steering or ABS. It is best to think of them as binding before slip occurs (as soon as load is applied), instead of reacting after slipping begins. It's very different in principle: http://www.torsen.com/files/Traction...ol_Article.pdf. But those GKN guys also classify their "Multi-plate LSD" as torque sensing when this is obviously not the case, because neither it or their "Super" diffs have worm gears.

Speed-sensing diffs like the viscous type they sell, and some lockers, allow a certain speed differential threshold and then lock the wheels together absolutely. Best for off-road traction, but the sudden onset and high degree of locking obviously plays havoc with steering and ABS.

The rated % slip of a friction-type differential doesn't tell you a lot because it depends on the input torque, and they have a limited maximum possible torque transfer. That said, racing diffs rated for 40% slip are actually tighter than those for 30%--so below this maximum torque, you can think of the peak slip to be 70%. This much looseness is required for a street car with this type of diff, or it will mess with the ABS and act like a spool on glare ice.

Torque sensing diffs are rated by their Torque Bias Ratio. That is, if it's 3:1, the wheel with traction gets 3 times the torque of the spinning one. If the spinning wheel can support 50 ft-lbs, the other wheel is sent 3x this or 150 ft-lbs (if the spinning wheel has zero traction the minimum torque that can be sent to the other wheel is determined by the preload. As a classic Torsen has no preload, 3x zero = zero torque transmitted). How is this accomplished without changing gearing? Simple--the spinning wheel just spins a lot faster than the other wheel! So spinning tires may be present even with both friction and torque sensing LSD, but will still result in drive to the other wheel.

 

Great explanation The Quaife/Torsen LSD is quite an ingenious device. Anything else with friction devices are crude by comparision...

 

I never noticed on mine.

 

I've already installed the '05 trans/LSD on my '02 MCS. That has had a bigger performance impact even than installing the '05 JCW tuning kit. I've used a quaiffe on another car in the past. It was perhaps a bit better on straight line getaways, but the MINI LSD is far more predictable in the twisties.