V2 Diff rebuild + Gear Ratio Swap

[maupineda]

I think it is over kill the replace those every time. I know BMW spec is to replace but my guess is it goes beyond the fastener wearing out. When BMW repairs a vehicle there is absolutely an expectation of appearance. Rusty or marred bolt heads are a no-go. And I think BMW wants to do everything within reason to avoid a repeat of the symptom. Customer satisfaction. Again, just my opinion.

100% agree, in my case is just to maintain it rust free so in year to come I don't struggle to remove seized bolts. if left as shown above, they are raw, and would rust by just touching them LOL, I will post a pic of how they look with black oxide.

[bigjae46]

I think it is over kill the replace those every time. I know BMW spec is to replace but my guess is it goes beyond the fastener wearing out. When BMW repairs a vehicle there is absolutely an expectation of appearance. Rusty or marred bolt heads are a no-go. And I think BMW wants to do everything within reason to avoid a repeat of the symptom. Customer satisfaction. Again, just my opinion.

[maupineda]

I also wanted to refresh the fasteners but they are too many and changing them for new was expensive, so I got myself a small ultrasonic cleaner and run through in a bath of rust remover for the bad ones, and vinagre for the only dirty ones.

one note, the rust remover does take the zinc coating off, so I will put a coat of black oxide which should be good enough for some time as I don’t drive the car in the rain.

they came out pretty clean

[maupineda]

Have had some complications that set me back, but all is good. The tool I used to install the bushings inadvertently scored the inner of the bushing and opted to change them as they are cheap.



also the Nord lock washer I had was too small for the bolt, and had to source a larger one, also I mis calculated the length of the bolt and ended up a bit short as the Nord Lock are 3.5mm thick, so I went with a 70mm bolt which compensated the washer and now it uses all the threads in the diff housing. Below the prior washer and bolt.

[maupineda]

And the diff is ready to go back on…



I would of liked to do a more thorough refurb and paint the diff and clean better the cover, but I have run out of drive after more than 3 months.

as you can peak, I replaced the bushings as mine were showing signs of wear, I am going with e36 M3 items which are a bit softer for sure. The OE ones are almost solid. We shall see how long these last, my car is a weekend car only so I have no doubts they will last lots.

[maupineda]

Made some more progress, I took the diff off the car, not much I can add that has not been shared online. If anything, just make sure the car is as high as possible.

I also removed the old transmission output flange seal, I used a trim tool to punch the seal and then pry it out without damaging the transmission case, which is very soft. I was getting frustrated as any metal tool will nick the aluminum and you don’t want a scratch on the sealing surface.

[maupineda]

Wow, this is amazing work, great that you are able to document it for the forum.

I do not want to derail your thread, but I have a V2 diff in Z4M and I have a speed sensitive whine off-throttle only. Pinion bearing perhaps? I don't know that I'll find someone willing to open it up so prob will have to go with used or diffsonline.

Though to say, but I would think it can be the bearings. If someone changed the front seal and did not do it right when tightening the nut back on, it can screw things up.

[chris719]

Wow, this is amazing work, great that you are able to document it for the forum.

I do not want to derail your thread, but I have a V2 diff in Z4M and I have a speed sensitive whine off-throttle only. Pinion bearing perhaps? I don't know that I'll find someone willing to open it up so prob will have to go with used or diffsonline.

[maupineda]

What drove me to buy the tool was the removal, if you have the tranny off the car you can be more careful and find a way to pry the seal without damaging the housing, and the tool was perfect for that.

now, I had read that a 15mm socket can drive the seal in, but in my case the 15mm was just not big enough to slide over the shifter rod, and since I had the BMW tool with the old seal on next to me I was like! Oh! Perfect!

But you can very like make it work with other tools, but this was a 3 min job to remove and maybe another to tap it in.

[Cubieman]

Coming back to the shifter rod seal. Here some photos of the tool with the old seal on it. The tool thread into the seal and once it has threaded in 3 or so turns you use the screw provided with the tool and tighten it to pull it out. Then the old seal becomes an adapter and you can use the same tool to drive the new seal in

I'm all in on factory tools but do you think a socket or the like could install the shift shaft seal?
I need to do this soon as well as the output seal and potentially split the case and re-seal.

[bigjae46]

Continuing on… I had issues with racing diffs seal, the vulcanized rubber part bunches up while pressing it. I ended up buying Corteco.

you can see around the edge of the seal the small sections where the vulcanized rubber catches up with the metal edge of the cap, it could be it would be fine but last thing I want is a leak.

the corteco seal went in perfect.

i also bought the seal tools but they really are unnecessary. I will see if I can return them.

Dang. I never used the racing diffs seals out of paranoia. I guess that was a good call...one of m few. lol

[maupineda]

As I mentioned above, the diff seal tools are super nice, cut out of aluminum and thus super light and well made, but the output shaft seal tools does not set the depth as it can go through the cap completely, so the reason Inbought it was to set the depth, otherwise I could just use other bearing drivers I have access to. So will return it.

the pinion seal tool can be skipped also as the seal bottoms out, or set it at 3mm in from the outer surface of the diff.

[maupineda]

Coming back to the shifter rod seal. Here some photos of the tool with the old seal on it. The tool thread into the seal and once it has threaded in 3 or so turns you use the screw provided with the tool and tighten it to pull it out. Then the old seal becomes an adapter and you can use the same tool to drive the new seal in

[maupineda]

Continuing on… I had issues with racing diffs seal, the vulcanized rubber part bunches up while pressing it. I ended up buying Corteco.

you can see around the edge of the seal the small sections where the vulcanized rubber catches up with the metal edge of the cap, it could be it would be fine but last thing I want is a leak.

the corteco seal went in perfect.

i also bought the seal tools but they really are unnecessary. I will see if I can return them.

[maupineda]

The overall project has taken way too long and have found unexpected issues that have added cost and time to the whole thing

I found that my transmission output seal was leaking, so I have to remove the flange, and while at it I chose to also change the shifter rod seal



I also noticed the PO when changing the shifter ( I have the ASS kit) did not put the yellow foam inside the clevis so I got a new one, this may to dampen some vibrations I have when revving above 6k



the flange was a bit grimy and had some superficial rust. So I dipped it in evaporust and then used permatex rust protection, or black oxide solution

before



after evaporust dip



after black oxide



i know this is not bullet proof, but is in a mostly dry area so it will be for sure best than raw metal