E30 Diff Help...Which ONE is it? Which one will fit????

[timmzey]

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[pacerpete]

Try the technical section, that's where these sort of questions get asked and answered.

[suedenim]

It won't be the diff that's causing the noise if it stops with the clutch depressed. There's no reason why the diff won't keep going even with the usual whine.
You need the same or similar ratio for a 325, can't swap it for one of a 1.6, 1.8, etc. Think yours is 3.64 but happy for correction from someone more knowledgeable.
Put a wanted ad in the correct message board or search sale ads for someone breaking a 325.

[Grrrmachine]

Here's everything you need to know about diffs:

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

And no, an E36 one won't fit.

[timmzey]

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[daimlerman]

If your car started life as a 320i,it most likely has a small case 4:1 diff.This will give about 65mph at 3000rpm.

For a 325i engine,you will be better off with a medium case diff,these came in 3:64,3:73 and 3:91 ratio's,a 3:64 gives 73mph at that same 3000rpm.

Both diff sizes will fit,the bigger unit just needing a simple adjustment to the propshaft length at it's centre joint,however,the bigger unit can be hard to find and expensive,if you are really desperate/broke/enjoy being laid on your back in the cold,then pretty much any ex E30 diff will keep your car running.

Diff swap,working on the drive with the car on axle stands/drive on DIY ramps should take about 3 hours.

[Grrrmachine]

3 hours if someone's loosened all the bolts beforehand! 2 days if some of the driveshaft bolts round off...

Anyway, the problem may not be the diff, so there's no point replacing it just yet (even if, as daimlerman says, better ratios are available).

[daimlerman]

3 hours if someone's loosened all the bolts beforehand! 2 days if some of the driveshaft bolts round off...

Anyway, the problem may not be the diff, so there's no point replacing it just yet (even if, as daimlerman says, better ratios are available).

Angle grinder is your bessy mate here!

TBO,only the torx type have given me grief,these are now routinely replaced with s/s socket head bolts.

My 'best ever' time for dropping a diff is 45 minutes,followed by three solid hours of teaching next door's kids new sweary words as I struggled to line up the bloody sodding top mounting bolts!

[Grrrmachine]

Yeah, diff swapping's an odd one. Last time I fitted on, I struggled on my back for two hours trying to line the bolts up before throwing in the towel. Came back next day, jacked the diff up and got them all tightened up in 20 mins.

[Speedtouch]

(Sorry - CAN MODS/SOMEONE MOVE TO TECHNICAL AREA???)

Hi, had a quick search through the threads but I'm looking to find out which Diff mine is.

I think its on its way out, theres a grinding from (i believe) the back of the car, but it goes off when the Clutch is pressed in.

Sounds like it could be a worn out clutch release bearing - they have a carbon central pad that gets worn down to the metal backing plate, which then grinds on the clutch paddle.

[timmzey]

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[Speedtouch]

Yes, a badly worn clutch release bearing will be noisy even (or more so) when you press the clutch in, because there is metal grinding against metal.

[timmzey]

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[Speedtouch]

Bet that was rather alarming!