Can I use LSD part of 2.5L auto in 2.5L manual transaxle?

Started by michaeljc, February 08, 2012, 06:23:36 AM

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michaeljc

I have just picked up a 2.5L manual 75 to join my GTVs for track days. Nice and cheap and I've always been interested in the 75s..... although preference would have been for TS or 3L with better power &/or handling characteristics this 2.5L 75 will be a good fun insight into the 75s.

So first step, with a bit of luck, is to get a 4.1 LSD into it.
I am told that the 2.5L 75 has a 4.1 ratio diff (like TS) but non LSD. Someone can please correct me if I am wrong!!!!!!!!!!

As the auto TA is an approx 3.1 ratio I was wondering if I can use the relevant LSD part of 2.5L auto in 2.5L manual transaxle?
I have not pulled a diff apart before but am ready to have a go and get the enjoyment of learning. I had a chat to Vin and he lost me with a few of his terms but he thought there would be a chance it would work. Either way he is a little bit interested to find out.

I am a little surprised that the LSD bits out of a 3.1 diff would 'marry' with the good bits of a (non LSD) 4.1 diff to give an LSD 4.1 diff ...... but I hope that there is a good chance that they will. .... and I don't mind blowing a couple of hundred bucks learning.

BUT, before I do, could someone please enlighten me on whether this mixture of diffs would get me a 4.1 LSD transaxle, or would I just have a box full of useless cogs????? . If it is a goer I would work with Vin to get a rebuilt and tensioned up unit into the 2.5L.
2001 Subaru WRX
1999 Subaru WRX STI
1984 Alfetta GTV

dehne

I put a LSD diff into my 2.5 box it slotted straight in, as far as I'm aware they will fit and if your in Vic I have a great deal for you, my mate has a 75 auto that has been crashed at the front, the motor is gone but just about everything else is there, its currently on eBay for $250 I think so that's pretty cheap for a LSD
now
1x 85 mdl road 90
2013 Giulietta 1.4
2015 Launch Edition Giulietta
Past
Multiple Alfa 90's, Alfetta's and 147's

scott.venables

But Dehne was it an automatic LSD you put into your 2.5 box?

aggie57

The LSD is a ZF unit common to 105's and 75's.  What is different between the various models is the size of the stub axle and width of the LSD vs. the open diff.
Alister
14 Alfa's since 1977. 
Currently 1973 GTV 2000, 2020 911 C2S MT, 2021 Mercedes GLE350, 2023 Polestar 2 LRDM
Gone......far too many to list

BradGTV

i have been told/read before that auto diff centres are interchanglble into a gtv6 transaxle assuming 75 2.5 is the same?? if so swap your crown wheel on to the lsd centre and slip it in.
79 gtv sr20, 83 gtv, 83 gtv6 3.0, 75 ts x 3, 85 gtv, 76 gt, 91 164, Subey L Series, S13 silvia, Bmw e30 318i, VT SS 6spd

aggie57

Quote from: BradGTV on February 08, 2012, 09:00:09 PM
i have been told/read before that auto diff centres are interchanglble into a gtv6 transaxle assuming 75 2.5 is the same?? if so swap your crown wheel on to the lsd centre and slip it in.

Just make sure the preload/backlash is set up properly.  (or whatever its actually called - Vin knows these things)
Alister
14 Alfa's since 1977. 
Currently 1973 GTV 2000, 2020 911 C2S MT, 2021 Mercedes GLE350, 2023 Polestar 2 LRDM
Gone......far too many to list