E86 - Diff and shiny new bits!

[Street]

I'm part way through a rear axle tear down on a 220k coupe. The subframe and components will hopefully be back from the powdercoaters tomorrow ready for new bushes all round. Turning to the diff it was covered in oilly crud. No noise when running but so much oil all seals need replacing.

Given the mileage I'm contemplating a bearing replacement but im a newbie to this and also dont have a press. Whats the difficulty rating?
I've contacted a local transmission specialist for a quote but the point of having the old girl is to play with jobs like this and learn. From anyone thats done it what would you advise?

Thanks

 

[PDJ]

You are close enough to pop into JC Racing and just let him do it

If it is the same basic set up as the diff in the Z4M you need to spark erode a ball bearing type pin/plug to strip it

 

[Street]

You are close enough to pop into JC Racing and just let him do it

If it is the same basic set up as the diff in the Z4M you need to spark erode a ball bearing type pin/plug to strip it

Thanks PDJ. I’ll give him a call today

 

[Spriteracer]

Just to add - I have my E86 3.0SI diff in bits to rebuild incl. new pinion bearings. It was all quite straightforward to strip. The only slightly tricky bit is cutting off one of the bearing tracks on the pinion where there is no space for a puller. Fairly easily done with a small angle grinder and a steady hand to carve a groove in the track. Then hit the track with a cold chisel and the track cracks and becomes loose. I have not put it back together yet and although I do have a press, I believe most of it can be done with freezer and heating to get the new tracks back on the pinion. There are quite a few YouTube videos of this.

 

[Street]

Just to add - I have my E86 3.0SI diff in bits to rebuild incl. new pinion bearings. It was all quite straightforward to strip. The only slightly tricky bit is cutting off one of the bearing tracks on the pinion where there is no space for a puller. Fairly easily done with a small angle grinder and a steady hand to carve a groove in the track. Then hit the track with a cold chisel and the track cracks and becomes loose. I have not put it back together yet and although I do have a press, I believe most of it can be done with freezer and heating to get the new tracks back on the pinion. There are quite a few YouTube videos of this.

Thats interesting and gives me a little hope. I've been given an estimate of £700+ to have someone rebuild it which isn't viable for this old girl.
One specialist said they couldn't do it as they didn't have the pre-tension figures from BMW. Any idea how you'll takle that when rebuilding?

For now I'm going to replace the seals and see how long it lasts. I'd buy a secondhand replacement next time and tear that down further.

 

[Spriteracer]

Hi Street. I bought this bearing s kit from https://www.bearingkits.co.uk/BMW-Z4-E85-&-E86-SERIES-3.0si-N52-REAR-DIFFERENTIAL-NOISE-REPAIR-KIT/941.htm#gsc.tab=0. The chap there - Mark was his name I think, was very helpful and the kit includes info and a tool to set the pinion preload. As I said mine is still in bits - I have another diff in the car, but it looks reasonably straightforward.

 

[Street]

Bad news today from bearingkits.co.uk that the bearing kit for the E86 is now obsolete. They can make one swapping over to E89 bearing types at a cost of £480. They confirmed the pinion preload tool is included in the kit but no confirmation on the specs.

 

[Street]

I had to share the shiney new bits back from the powder coaters. Tomorrow I’ll start rebuilding. I’m wishing I’d taken the easy option of poly bushes but I’ll wrestle the trusty oem rubber numbers in

Oooooo shiney and clean

 

[Spriteracer]

Pity about bearing kits.co.uk. I bought mine in August last year, and the quoted price was £320+vat for the 3.0si kit although I think the actual bill was a bit less. The 3.0i kit wasn't available then even.

If it is any consolation on the polybushes, I have them in the subframe and the diff, and am about to take them all out again and replace with OEM. I might just be getting old but they seem a bit too harsh and transmit too much noise for my taste. Hard to tell how much worse they are than rubber ones in that respect as they were replacements for some old original hard oem ones when I bought the car.