Limited Slip Differential - Disadvantages?

Limited slip differentials use clutch plates and commonly need LS oil. Torsen diffs are not LS as such, IIRC the are torque proportionating diffs. There are many different types of diffs but IMHO LS diffs in car axles are a crude waste of money. I have never found substantial traction benefit and they are prone to wear and lose effectiveness at a low useage rate.

Huw

Thanks for your reply, i'd been wondering if it was worth the bother looking for a box with LSD - only found on 96+ turbo versions of the car. I don't think i'll bother as i see no real advantage to me and the disadvantage is the box will be much more worn than that from the naturally aspirated cars.

Thanks again, Paul

ISTR that Huw only drives RWD cars, though I may be wrong. On anything making a lot of power with FWD, a TorSen diff is bloody handy. Compare the Alfa GTA to the Focus RS...

never

bother

anything

I now tend towards four wheel drive, though I have had my share of FWD cars over the years. I had an Audi Quattro with a Torsen diff. I have also owned vehicles with almost every diff type available, including No-Spin, Mechanical locking, hydraulically actuated locking with both clutch packs and dogs, various ratings of front axle LSD's including one particularly nasty and stiff ZF unit. Also viscous coupling controlled centre diffs.

No amount of diff trickery seems to tame the top Focus adequately. Some of these diff types can be quite savage and crude in operation, though Torsen is very good in some applications.

Huw

However the viscous LSDs in the 4WD setups used by Nissan and Subaru for example in their 2 litre turbo models are superb. Especially the Nissan ATTESSA system in the Sunny/Pulsar GTI-R.

I still can't work out why on earth Ford made the RS only FWD. Given it's supposed to look a bit like the rally version which is 4WD, and follow on (sales wise) from the Sierra and Escort Cosworths which are

4WD. I've raced against Focus RSs on the track in a GTI-R, and they just cannot get the power down in any useful manner.

Rich.

Nissan in the late 90's before the financial problems and Renault were producing technical exellence. BTCC etc.

The ones that use silicon as the viscous fluid don't need special oil. The silicon is sealed in the viscous unit and if the seals leak it needs a new viscous unit.

A LSD on the back means that when you give it some going round a corner or out of a junction it keeps driving sideways and is easily controlled. With an open diff one wheel spins and the other loses drive. A LSD on the front means that both wheels spin and you still have some scrabbly drive at the expense of tyre wear. Again an open diff loses all traction often just when you most wanted it. As a LSD causes both wheels to spin and transmit power if sufficient is applied it is possible to run the driven wheels at 105-112% of road speed which gives maximum traction and acceleration (not advised on the road and not at all on FWD as you lose most of the steering).

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Limited Slip Differentials are types that use wet clutch packs to limit spin. They need friction modified oil. There are many other diff types which lock or partially lock but, let's get this straight, they are not limited slip diffs, they are other types. There should be no ambiguity.

Huw

Increased tyre wear.

Properly configured and driven hard, there may be less tyre wear due to less rubber being burnt. Remember that a LSD does allow a limited differential in shaft speeds on corners. IIRC so does a Torsen, otherwise one might well do without a diff altogether, which would make for some entertaining handling LOL

Huw

Any LSD that uses a friction clutch pack has no place on a daily driver road car. The clutch discs wear, need oil changes to prevent build up of wear fragments and need re-shiming to set the bite point far too often.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

I agree. LSD's are absolutely hopeless.

Huw