Limited slip differentials

[longhamrob]

I would like a lsd in my 131R.  I have noted the optional original lsd was a little unreliable but have come accross 2 others in the long time i have been looking.  One that was offered on ebay as a 131 diff but turned out it didnt fit my car.  The second, a current model Bacci Romano model DAE04, didnt either.  Both would not accept my driveshafts that appear too big.  I am sure my 1981 car is standard.  Anybody out there solve this??

[TOAD]

   
  This would be a complete wast of money due to the fact that the pinion sheds teeth at the drop of a hat, and the lsd will not fix this.

  Change the Axle for a stronger one and then slipper that.

      Regards

         Roger.............

[miro-1980]

I am not sure about 131 R stock optional LSD but it seems the flange of the shaft does not fit the flange of the diff.

You should be able to buy a diff flange on ebay.

Re: utility of the LSD ...

For daily driving it should not make any difference. It is more reliable on slippery surfaces , but  depending on setting may require a bit of getting used to. It is much better on soft (sand -gravel- snow.

However the LSD pates in the diff are not indestructible, and typically needs maintenance. it also is noisy 

I am not sure why TOAD believes you need to change the axles for stronger ones, .. it depends on the way you drive but I would agree with him that LSD for a recreational / pleasure driving is not generally recommended. Unless you use it mostly or exclusively for sports I believe LSD is an overkill  and can cause you more problems than it will solve.   

Miro   

[longhamrob]

Thank you for your comments.  The noise would be an issue so maybe not such a good idea.  The only reason i was interested is that, twice, when pushing the car hard into a right hand corner (nobody around) the o/s rear wheel spins & you can feel and hear the loss of traction. Maybe a strut brace may eliminate this....

[TOAD]

Miro,   

  My thinking is if he drive's fast enough to make good use of a slipper, the Pinion is not strong enough,  I think the problem lies in the Pinions fatigue life and not just its strength.

   Roger........

[131rally]

Im not sure, but I have thought the 131 LSD is "plate"LSD, which shouldnt keep noice if correct oil is used. For example my ex-rally service van, Ford Transit. It had this kind of LSD, if you used normal 80w/90 LSD oil, it started popping and snapping. It needed special Ford LSD fluid on top of the oil, 2dl amount of, very expensive. This totally stopped the noice with the same actual oil used... Without it the plates started kind of glue to each other making the snapping and popping.

The Fiat 132 (and propably 124/125) uses the "cone" LSD. That is very stupid LSD, it has kinda ice cream cones, of steel, plate springs push the positive cones to negative chamber. When you drive the car on curve you can hear the steel slipping against another, WRICK-WRICK-WRICK-WRICK..... Very annoying, though not very loud noice.

[Thotos]

The optional 131 LSD is a plate unit in which you must use the special LSD oil. Use of normal 80/90EP oil will damage the plates. I used to have the LSD differential in my silver Sport and I used Castrol B373 which is for competition use. I couldn't get the Fiat recommended road-use LSD oil (can't remember what it was called) or Castrol LS which is their road-use product. I spoke to Castrol about the differences between B373 and their LS and I was told that the LS version has extra anti-wear and anti-noise additives while the B373 is less concerned with wear and noise and designed for maximum LSD efficiency. Castrol also offered to sell me Castrol LS oil as long as I ordered a pallet of 100x500ml bottles!  

I don't know if it was the use of the B373 oil (I doubt it) but the LSD diff in my Sport was more trouble than help. The plates wore quickly and had to be re-shimmed every 20,000 miles or so. When firstly shimmed I found it too 'tight' and would actually slow the car down if going through a tight corner quickly.  When in its 'tight' stage it was very good in snow and on grass but I no longer drive my 131 in snow or on grass (or other slippery surfaces) so it would be of no use to me now. Eventually after about 60,000 miles the diff stripped the teeth off the pinion so I replaced the whole diff with a standard one which is still going strong in my current Sport now   http://www.131mirafiori.com/smf/index.php?topic=3332.msg25510#msg25510

So unless you expect to do a lot of snow or wet or loose surface driving in your 131, I wouldn't recommend having an LSD. I don't think noise will be a major problem but getting the LSD set up properly and keeping it working well will be a major headache. If you decide you need a LSD for your car, try and find a TORSEN differential that can be made to fit. My Maserati was fitted with a Quaife Torsen Diff and that worked extremely well for a very long time. They are fitted to most (all?) TVRs and a number of other British cars so might be easy to find a used one. But finding one to fit a 131 axle won't be easy!