Which ratio diff do i have?

[sajad09]

This is the diff on my car at the moment.. can anybody tell me which ratio it is and is it suitable for a 325i auto? Or should i change it?

Car was originally a 320i manual

Thanks in advance

[Brianmoooore]

It's a 4.27, as clearly marked on the tag, and will also be the weaker small case version.
Having that in a 325 would quickly drive me nuts and always looking for a sixth gear. Wouldn't do any favours for the fuel consumption either.
3.91 is standard, but IMHO, a 3.73 would be better.

[Speedtouch]

Many non-Sport 325i models were fitted with a 3.64:1 diff, which gives a good overall gearing/top speed/economy compromise, though I'm not sure about the automatic versions...

The 4.27:1 was only fitted to 320i Cabriolet and Touring models, according to the Zone Wiki:

http://www.e30zone.net/e30zonewiki/inde ... fferential

[sajad09]

Thanks guys... i need to check what the car im breaking has got in it and then swap over if needs be.

[sajad09]

Right just had a look under the other car and that say 3.73 on the tag... fairly rusted tag but just made it out.. there is a letter and a space before the 3.73 but i cant make it out as to rusty.. last 4 digits are 9022

Is this suitable to use? And will all fittings be the same?

[sajad09]

The diff its self does look to be a bit bigger... or maybe its just me?

[Brianmoooore]

The diff. is physically bigger (and stronger) but it still fits straight in, with a possible slight adjustment of the propshaft rear section by slackening off the clamp nut and sliding the splines.

[sajad09]

Thanks Brian... out of interest if iv jacked the car up at the back and turn the wheels and one spins but the other dosent, is this a possible indication that it could be an lsd? If i turn the wheels really fast then the opposite wheel will turn but very slowly.. not as fast as the wheel that im turn by hand.

[Brianmoooore]

Sorry, it's a good indication that it's not a LSD - at least not one in working order.

[sajad09]

Hahaha, thanks... thought i had struck gold for while... i know nothing about diffs or ratios... so am just going to do more reserch before stripping this one out as iv never seeen this car run so am taking a gamble with it.