Alfa Romeo Owners Club of Australia Forum

Does anyone know which models of the Alfa 75 came with the LSD.  Was it all of them or just those past a certain year?

Believe it is all twinsparks and the 3.0 litre V6 - pretty sure the 2.5 V6 missed out.  V6 ratios are taller than twinspark, if you're planning to drop a whole transaxle in.

not entirely correct

2.5 auto came with LSD ... i have a 2.5l with a twinspark in it (highly recommended) but you can fit the diff from and auto 2.5 into standard 2.5l transaxle.

In summary, the Twinspark, 2.5 auto and 3.0 all had LSD, however the 3.0 had a 3.53 diff which makes it unsuitable for comp use.  The others typically had 4.11's.

Hey guys,

I dont understand the whole LSD thing properly and was wondering if someone could explain it to me. I've just got my Ps and have been racing go karts for the past 2 years so i havnt really needed to worry about diffs.

I know how an open diff works and I understand the purpose of the LSD and why you need one over an open diff, basically to get power down out of corners or you'll end up spinning the inside wheel at 100% and going nowhere fast (as well as revving the pants off your poor old volvo 360 :-\)   

Doesnt an LSD lock the wheels together in a certain % ratio using clutches? So for instance the LSD in a 3.0 potenziata is 25% (so im told) so if one wheel is spinning at 100 km/h the other is spinning @ 25km/h?
Am I sort of on the right track ??? Can someone explain the percentage thing??? Why do people put 50% LSDs in for comp use???

So the twinnie and 2.5 had 4.11's and the 3.0L has 3.53, didnt the 3.0L qv potenziata have different again, like 3.73, or 3.93 or something??

Why is the 3.0L unsuitable for comp use? Is it because you cant go as fast in each gear compared to the TS and 2.5? from what i can remember, the TS does 80 km/h in first i think, havnt driven one for a while! So wouldnt the 3.0L ratio be suitable for slower twisty tracks?

Over the next year, I want to slowly build a 3.0L potenziata track car and many people have said go the TS. Is it the diff thing or is there more to it?

cheers

Dean :D

Can one tell if a transaxle has a LSD by jacking the car up out of gear and turning one wheel - if the other turns in the same direction then it has a LSD diff? If the opposite wheel does not turn in the same direction does it definitely mean that it is an open diff?

Rob

Rob: if the opposite wheel turns in the OPPOSITE direction, it is indeed an open diff.

From what I've read, it's not that easy to tell.  Because of the way Alfa LSD's are, the require load before they start to limit slip.  This is of course different to locked diffs where both wheels turn 1:1 in the same direction all the time.  The 25% quoted is where 25% of available torque is transferred to the slipping wheel.  Have a look at: http://www.alfabb.com/bb/forums/milano-75-1987-1989/51915-how-identify-lsd-limited-slip-differential-2.html (http://www.alfabb.com/bb/forums/milano-75-1987-1989/51915-how-identify-lsd-limited-slip-differential-2.html) for another discussion on this and a bit of to-ing and fro-ing.

I think people are probably saying don't turn a Potenziata into a track car, well, because it's a Potenziata! They are reasonably rare. The diff thing might come into it as well because the taller diff ratio in the 3.0 isn't as good for acceleration as the 4.1:1 in the 2.5/TS. 

Cheers, Scott

hey guys,

wondering if anyone can help me identify my spare transaxle. At first i thought it wasnt an lsd cause if i turned one wheel, the other went in the opposite direction. It turns out it is.  :D

the potenziata had a 3.5 or 3.7 diff ratio i believe. I think the spare is a 4.1:1 diff out of a normal 3.0L.

the crown wheel has 41 teeth and has 11 41 bib on the side. that has to be a 4.1 doesnt it???

the id is: 4061 004243 903091 S25

Does anyone know what gear and diff ratios i would need for a 3.0l track transaxle?

cheers.

deano ;D

41 divided by 11 = 3.73