Flushing tranny, diff and bleeding clutch.

[igortiger]

Hey guys from my experience:

Tranny - drain and fill?

Diff - drain and fill aswell, but there is a way of doing this. My friend will be helping me.

Bleeding clutch: pump pump pump - bleed - pump pump pump - bleed. The fluid comes from the brakes?

I bought the required redline fluids for the diff and tranny. Wanted to see what you guys recommend for the clutch. If there is anything anyone would like to add on, please do.

[DesktopDave]

Tranny - pull the fill bolt off first!  No use draining it if you can't refill it...make sure you have a pump set up too.  The Redline MT gear oil is great stuff.  Later e36 trannys use ATF, Redline makes a great product for that too.  I suspect you can switch gear oil and ATF anyway.

I still have to get the silly BMW junior-sized flare wrench...what is it, 7mm?  Definitely something you'll want to have.  Pressure bleeders are also a decent idea, as are the Russell Speed bleeders.

Diff is easiest out of the car, but it's not too bad with the car in the air.  Again, pull the fill bolt first!

I'd get four jack stands & do it all at once.  Bleed the clutch & brakes while you're at it.  I used Mobil1 gear oil last time, worked well.  IDK if you need anti-slip additives for the LSD, since the it's a sealed unit.

Clutch fill is from the brake reservoir.  The system runs off the fender side of the brake reservoir out of the front circuit.  You'll see the blue hose that runs down to the master.  No need to bleed the top - just keep the reservoir full.  The clutch is a bit inconvenient to get at.  I use DOT4 for the hydraulics, usually ATE blue/yellow but other stuff works well too.

[igortiger]

Yeah I was wondering where the clutch bleeder was, thanks for clearing that up (I believe it's a 7mm). Im gonna get some rear brakes and dedicate an entire day to all this. While I'm at it, will inspect the rear chassis. When I'm in a lower gear 1, 2, 3, even 4 sometimes something feels loose, it's as if the entire rail in the rear is loose. Hmm I will see. What's the eta on getting the diff out if i decided to go that route?

[DesktopDave]

A squirmy feel might be from the diff 'ear' bushing - it's not solid rubber like the six-cylinder cars and tends to fall apart.  Sub frame bushings are also a common failure on high-mileage cars.

It took me about two hours to drop the rear diff, about the same to get the replacement diff in.  Happily I only stripped one bolt (on the diff speed sensor, I spliced the harness instead of swapping the sensor).  I did PB Blast every bolt I could get at a day ahead of time.

It's really a marvelous PITA (especially on the left side) unless you take the rear exhaust pipe out. Having a helper would be great too - you can have them lock the brakes while you're unbolting the 12 half-shaft hex bolts and the four drive shaft bolts.  That way you can spin the wheels to access all the bolts at once.  I stayed under the car and used a big honkin' screwdriver wedged between bolts to keep the wheels from turning.

If I had to do it again, I'd seriously consider dropping the rear exhaust & the whole axle & fix everything while I'm in there.  To drop the axle you have to unbolt the seven sub frame bolts, the ABS sensors, the calipers and the parking brake cables.  Not all that hard - and it makes those 17mm bolts on top of the diff really easy to get at.

Don't forget to check the parking brake while you're in there, when you're replacing the pads it's a perfect time for that.

New swing arm/subframe/diff/sway bar bushings, inspecting the CV boots, new brake lines, new fuel lines.  I'd estimate it's about $500 in parts alone, but once replaced it'll last another 20 years & I can check it off the list.  I'm going to get a donor subframe to rebuild & repaint, then replace all the rubber and the shocks/springs at the same time.  You'll want a late model six-cylinder for the larger rear bearings like our M42s have.  Early e30's have narrower bearings, as does the 318ti and Z3 four-cyl.