Limited slip diff or not ?

[Paul02]

Hello again , my car is (still ) in the process of having the 3.0cs engine swapped for an 81 , E12 , 3.5 . I have decided to not fit the dogleg box but look for a normal 5-speed with the correct speedo drive etc.

My question , for general every day use , not racing etc , should I fit the E12s lsd or keep my 74 , 3.0 cs diff .

Pros and cons please bearing in mind my usage. Also I have been offered good money for the E12 diff.
Cheers Paul

 

[x_atlas0]

What are the respective diff ratios involved? I thought both had a 3.45.

 

[Paul02]

I don't know what the ratios are , apart from that what is the reason for a lsd , better traction and would it give you any better grip at motorway speeds say on a wet road ?
Cheers Paul

 

[Paul02]

Atlas , just read the spec of your car on your avatar. Are you running an lsd ? and is a getrag 265 an overdrive or dogleg box.
Cheers Paul

 

[gazzol]

I'd deffinately fit the lsd. You get better traction off the line with less tendancy to wheelspin although with the 3.5 you can spin the wheels easily if you want. The ratio fitted to the E12 M535 was 3.07:1 so you will get slightly better economy at the expense of acceleration although with the added tourque/power of the larger engine I wouldn't worry about it. My own car has the M535 motor + diff but with the over drive box I used to have the dog leg but concluded that with the width of the torque curve of the M90 motor a close ratio box was pointless and now I can get 30 mpg on a run. The whole point of a close ratio gear box is to keep a motor with a narrow power band "on song". The M90 engine has a torque curve like a 3 year old drew a table ie its a flat line with an almost vertical bit at either end so like I said a close ratio box is a bit pointless.

 

[Paul02]

Thanks Gazzol for that info.
Paul