V2 Diff rebuild + Gear Ratio Swap (4.10)

[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

[bigjae46]

Thanks James for all the help mate!!! Really helps to have another set of eyes!!!

that bearing tool was a god sent, as chiseling out the race is very annoying! So the McMaster shims I found were like made for this application. My OCD makes me still wish to have the OE depth tool just see what it would say. But as you and I chatted, is just splitting hairs.

Also crushing the crush sleeve is an event!

I now have like 7 OE pinion shims in varying sizes I won’t need lol.

Happy to help! The feeling of getting the job done is amazing especially after you drive it for the first time.

[maupineda]

I always pray to god almighty before pressing in the pinion that the pinion depth is good and I don't need to f with the shim. Handling all of the diff parts gets tiring with a high risk of a smashed finger.

I didn't catch this before but the marking compound needs to be applied evenly and all the way down into the root. The first pic probably looks high because the diaper rash cream isn't all the way down into the root. Gear marking compound is a little thicker and easier to apply evenly. For anyone doing this in the future...use gear marking compound. I also found out that diaper rash cream tends to smear.

That looked like an adventure! Glad you got through it! I went through 4 crush sleeves on my first diff...lol...wasn't funny then but I laugh now.

Thanks James for all the help mate!!! Really helps to have another set of eyes!!!

that bearing tool was a god sent, as chiseling out the race is very annoying! So the McMaster shims I found were like made for this application. My OCD makes me still wish to have the OE depth tool just see what it would say. But as you and I chatted, is just splitting hairs.

Also crushing the crush sleeve is an event!

I now have like 7 OE pinion shims in varying sizes I won’t need lol.

[bigjae46]

I finished up setting up the diff. I only added 0.1 shim to the pinion bearing, and now that have seen many online photos, I am not sure I needed to shim it at all. Feel free to comment, my first pattern was a bit high on the tooth but also had a bit larger area, with the 0.1 shim it lowered a bit but the coast side seems thinner? I think is very minor and is fine either way, if it was not so difficult to remove everything again, I would probably take the 0.1 shim out.

I always pray to god almighty before pressing in the pinion that the pinion depth is good and I don't need to f with the shim. Handling all of the diff parts gets tiring with a high risk of a smashed finger.

I didn't catch this before but the marking compound needs to be applied evenly and all the way down into the root. The first pic probably looks high because the diaper rash cream isn't all the way down into the root. Gear marking compound is a little thicker and easier to apply evenly. For anyone doing this in the future...use gear marking compound. I also found out that diaper rash cream tends to smear.

That looked like an adventure! Glad you got through it! I went through 4 crush sleeves on my first diff...lol...wasn't funny then but I laugh now.

[maupineda]

I finished up setting up the diff. I only added 0.1 shim to the pinion bearing, and now that have seen many online photos, I am not sure I needed to shim it at all. Feel free to comment, my first pattern was a bit high on the tooth but also had a bit larger area, with the 0.1 shim it lowered a bit but the coast side seems thinner? I think is very minor and is fine either way, if it was not so difficult to remove everything again, I would probably take the 0.1 shim out.

all other things came out perfect

2Nm of friction torque for the pinion and carrier unit
0.0025 of backlash

i never updated about the timesert I had to put on the front bushing joint, but that was done also.

[sapote]

My expectation that the pinion depth was going to be ok was wrong, despite the pinion top face being equally tall on both, the center point relative to the ring and housing may be deviated and so my depth is a bit shallow.

Now the deal breaker. First image is drive, the second one is coast.

I'm not surprised that measuring the pinion gear head length on the precision table turned out not a reliable method to find pinion depth. Since the end of the pinion gear usually edged or stamped with the matching pair numbers and other information, so its face is a rough uneven surface, not a reliable for any dimensioning purpose. Most manufacturers added the unique pinion depth on this face so the installers don't have to do trial error method to set the pinion depth.

On the gear pattern, I would use less of the gear marker paste -- only a thin coat -- for a clearer pattern.
Yes, it shows the pinion needs more shim; I would add additional 0,010 to 0.015" shim to see how far the contact pattern moved toward the bottom of the teeth, then reduce the shim if needed.

I would add a sencond the gear marker 180* from the first marker just to be sure the installed ring is flat.