Need help! e30 325i LSD blown oil seal

Post Mon May 26, 2014 6:58 pm

Hi guys, I have a 316i that I've built into a 325i sport. First test drive my new diff lost all its oil out of the front seal. Does anyone know if/how I can rebuild the diff and where to source the parts or where I can get another LSD for less then £500 as I have now ran out of money

Post Mon May 26, 2014 7:14 pm

input seal is fairly easy to replace, can be done by just disconnecting the driveshaft. It's not exactly fun this way but certainly doable with the diff still bolted under the car. If it was me, I'd go ahead drop the diff for ease and replace the 2 axle seals as well. It also makes it easier to fill with new oil.

Make sure you mark where the pinion nut lines up to ensure the torque on the crush sleeve is as close to spec as possible. Remove the locking plate around the nut, then remove the nut. Seal will come out with some coercion. Use something large and flat (piece of wood) to tap the new seal in. Replace the nut and make sure the lines you made in it line back up. Replace the locking plate and the driveshaft, then add oil.

Post Mon May 26, 2014 9:22 pm

e30rapidic wrote:
Make sure you mark where the pinion nut lines up to ensure the torque on the crush sleeve is as close to spec as possible..

This is VERY important. Refit the same nut and turn it exactly where it was before.
It doesn't have a torque setting as such, but progressively crushes a collapsible tube as it is tightened, which moves the pinion gear in relation to the crown wheel.

Post Wed May 28, 2014 9:47 am

cheers guys i'll pull it and have a look at real sealing, as i've been running it with no oil for a few day whats the chances the internals will be salvagable?

Post Wed May 28, 2014 7:09 pm

never a good idea to run them that low, although it may have some oil left in it but its really a matter of chance now. It could be okay or it could be on the way out. I suppose you could put the new seal in, fill up with oil and hope for the best. Does it make any noticeable sounds? While the car is off the ground, turn the driveshaft or a wheel to see how much effort it takes.

Post Wed May 28, 2014 9:10 pm

Cheers, well it sounds like a bag of spanners! can't here the engine over the sound of grinding

so I've started looking at a new open diff (money issues) and I've ran into a mine field of case sizes and ratios

. Any help on what size and ratio I need would be of great use. Also I've been told that running low until I fit the new one isn't going to result in my crashing into the pearly gate backwards in a ball of fire is that correct-ish?

Post Thu May 29, 2014 8:57 am

Check your pm

Post Thu May 29, 2014 6:22 pm

being that it started life as a 318, I imagine its whats called a small case diff. It should have a metal tag on the right hand side, under one of the back case bolts.

It's worth getting under the car to visually inspect for case size and ratio. Turn the driveshaft to see how many revolutions it takes to make one complete wheel revolution. That will give you the ratio. Depending upon how well you liked that ratio, you can adjust to a lower or higher one.

Post Tue Jun 17, 2014 12:22 am

If you've got a howling LSD, it's fixable so don't bin it!
If it's a howling open diff, it's still fixable but maybe not financially worthwhile as they're significantly cheaper.

You'd have change in your budget after a full rebuild with all new bearings, seals, clutch plates, paint etc...

An open diff would get you mobile for now though. The ratio wants to be near that of the sport LSD. It's marked on the rusty tag on the backplate. Attack it with emery to reveal the makings!