V2 Diff rebuild + Gear Ratio Swap

[maupineda]

I have been sitting on a 4.1 ring a pinion set for almost three years. And just a few days ago I was lucky enough to find a cheap rear diff that would let me attack the rebuild and gear swap without having to first take the diff off the car and decomission it for who knows how long.



An interesting surprise happened when I openned the differential only to find a V2 unit. The intent of buying a spare one off an e46 M3 was to get a V1, what were the odds to get one of the last ones :S




I will try to document the process, but only those things that are really worth or for which there is not a lot of data on the net. There are several videos, but sometimes there a key details that are not mentioned or explained in detail.

Taking the diff apart is not difficult, and there is really not a lot to say as the videos we there are already explain this well enough. I will list the videos that I think are the most useful to tackle this process

Latest videos from racing diffs explaining their rebuild kits

V1 - https://youtu.be/RlqnD7k2HMU?si=oTM9VWwIc4VCPuNV
V2 - https://youtu.be/2G8PTSL4lrg?si=Xyc7-ThBcqA6Gyd1

Now here some documentary videos I have found extremely useful

From our fellow member created:

Nuances when ordering: https://youtu.be/8cRbYSChJkY?si=RIilO2N2QDLSsy13
Rebuild V1: https://youtu.be/G9pUsKDc5iE?si=YAfm--v1UMJH7XFS

Rebuild videos from racing diffs
V1 - https://youtu.be/F7QTGKCcWVU?si=fmOTr6WWLOgeX7vd
V2 - https://youtu.be/Bwtnud_ObwM?si=0EFIVfL1ft_3zKt8
Gear Swap - https://youtu.be/qt2OmQMT_l8?si=pyIYXnmR-GcGcd9J

Rubuild video from YEVS builds
V2 - https://youtu.be/jd3d0EqjBR8?si=s8Nixa-Yfj1auQzT

Now, since I am limited in space and tools. I am buying tools as I go, but my approach is to buy those things that will really make the rebuild process smoother and easier.

One thing I will for sure try is a pinion bearing puller.

Bearing puller tool - https://youtu.be/xtxgtDX7M8E?si=nyAd7_J1bFbrM6em

However, the V2 design is already making me doubt I can use the tool, in which case, I would just return it if I cannot make it work. The issue is that the V2 output flange bearings have very little space to use this tool, and for the pinion, well I am chanign to a new one, so if I still need to cut the races off to swap the bearings, I will return the tool.

Bearing puller tool - The next tool is a time-sert kit, my spare diff came with that bolt hole stripped!!!

[sapote]

An interesting surprise happened when I openned the differential only to find a V2 unit.!

Find the numbers on the output flanges which tell it is V1 or V2. I posted about this before.

[maupineda]

I do not need to. The photo tells what it is already, and when I checked it to buy I could not recall the details and I saw the play on the driver side and forgot that was on the V2. I would have bought it anyway, but mentally I was expecting to be the easier to work with.

[Cubieman]

My spare diff. also turned out to be a V2, I too have 4.10's I am trying to get away from so I will watching for updates!

I had told myself that I would just send it out but I need to be in money saving mode for a while unfortunately so a DIY rebuild makes sense for multiple reasons, unless I mess up.

[maupineda]

My spare diff. also turned out to be a V2, I too have 4.10's I am trying to get away from so I will watching for updates!

I had told myself that I would just send it out but I need to be in money saving mode for a while unfortunately so a DIY rebuild makes sense for multiple reasons, unless I mess up.

So you have 4.1 and want 3.62? Interested in a full unit swap instead? that is the whole reason I am doing this :P

[Cubieman]

So you have 4.1 and want 3.62? Interested in a full unit swap instead? that is the whole reason I am doing this :P

That's correct, I have a 4.10 currently and like it but want to try a stock gear ratio. I town at low speeds around 35mph I am either way too high in the RPM's in 2nd gear or bogging it in 3rd not to mention when on the highway the RPMs are a bit high for my liking.

I fell a 3.91 would be about right or even a 3.85. I do want to keep both diffs so I can change my mind. I may just throw some new fluid in my spare 3.62 and try it out as it did come from a running vehicle.

I will likely install it as is decide if I like it, and if so then rebuild it. It will be unfortunate to loose the 4.10's "pep" but I feel the stock gearing might suit be driving environment better.

[Obioban]

That's correct, I have a 4.10 currently and like it but want to try a stock gear ratio. I town at low speeds around 35mph I am either way too high in the RPM's in 2nd gear or bogging it in 3rd not to mention when on the highway the RPMs are a bit high for my liking.

I fell a 3.91 would be about right or even a 3.85. I do want to keep both diffs so I can change my mind. I may just throw some new fluid in my spare 3.62 and try it out as it did come from a running vehicle.

I will likely install it as is decide if I like it, and if so then rebuild it. It will be unfortunate to loose the 4.10's "pep" but I feel the stock gearing might suit be driving environment better.

Stock gearing is perfect.

[maupineda]

That's correct, I have a 4.10 currently and like it but want to try a stock gear ratio. I town at low speeds around 35mph I am either way too high in the RPM's in 2nd gear or bogging it in 3rd not to mention when on the highway the RPMs are a bit high for my liking.

I fell a 3.91 would be about right or even a 3.85. I do want to keep both diffs so I can change my mind. I may just throw some new fluid in my spare 3.62 and try it out as it did come from a running vehicle.

I will likely install it as is decide if I like it, and if so then rebuild it. It will be unfortunate to loose the 4.10's "pep" but I feel the stock gearing might suit be driving environment better.

Yes, I plan for the same, have the two and see which I like the most, though swapping is such a PITA that I already know it will very likely be a one time deal lol. I find the 3.62 ratio barely okish for my use, when going on canyon drives I find second and 3rd kind of long and it should be pretty fun to have a peppier second coming out of low speed turn. At the same time the stock ratio have me either too high on revs if left in 2nd, but out of puff if left in 3rd. So it can be binary as 2nd is either short or long.

[maupineda]

This is the time-sert kit I went with. I hope I do not regret this as is a copycat. Also, the inserts in this kit do not work as some of the key characteristics for the repair to work according to Time-sert are:

https://www.amazon.com/dp/B09JNX2V87..._TE_sc_as_ri_0

• Use longest possible insert such as the bolt extends past the insert at least 1-3 turns/threads - need to measure this still
• I anticipate I will need the longest possible, which I think is 26mm
• Though not recommended by the manufacturer, I plan to use red Loctite as in my view this is a permanent repair and should not need to undo the insert.
• I plan to run the torque setting recommended for a 8.8 grade to be on the safe side, with also a bit of thread locker, which is 150NM and not the 200NM, this is 75% if the OEM recommended value, but I do not know if I stick to the OE spec I could back out the insert upon removal.

I was also thinking about using stainless, I know it has the potential of galling, which in this case may be ok to lock the insert there and avoid pulling out.

[sapote]

[*]Use longest possible insert such as the bolt extends past the insert at least 1-3 turns/threads - need to measure this still
.

I had done 14 Timeserts for the head bolts on the block when my wife drove the car with no coolant for 8 miles -- enough to pull the threads out of the blocks on her 325iT.

As long as the bolt gets to the end of the Timesert, it pushes out to expand the Timesert and lock to the diff. To avoid it backout, I added JB weld on the Timesert outside threads.

Don't use a drill bit and hand drill to drill out the damaged threads as it will jam suddenly and might break. Maybe just use a masonry drill bit or something with no sharp edges.

Btw, why you want to change the bearings? I assume the diff was removed bc the bad front mount threaded hole, so I would look at the roller bearing and outer races for any damages, and continue to use them if no damage. The clutch stack is worn I assume and need new parts, then add 2 output flange seals and 2 o-rings, and input seal.

[maupineda]

As long as the bolt gets to the end of the Timesert, it pushes out to expand the Timesert and lock to the diff. To avoid it backout, I added JB weld on the Timesert outside threads.

…

Btw, why you want to change the bearings? I assume the diff was removed bc the bad front mount threaded hole, so I would look at the roller bearing and outer races for any damages, and continue to use them if no damage. The clutch stack is worn I assume and need new parts, then add 2 output flange seals and 2 o-rings, and input seal.

this is very helpful!! Thanks Sapote

as for your question on bearings, the proceedings of the diff is unknown, I have no idea if it was quite, mileage, etc. the races and bearings seem fine, but I did see some color markings on the race. But is tough to assess by look and I do not have a precise way of measure race wear. I also have the Koyo bearings for the pinion and output shafts. I also have all seals and o rings.

[maupineda]

I have measured the shim sizes

the long one of the driver side is 1.75



the short on the passenger side is 1.45



I also measured the depth of the front bolt and is very deep, 39mm


I need to measure the bushing width and see what length of time-ser works best as is key to make sure the bolt ends passed the insert inside the cavity.

now, I measure the hole and is 12.7mm, by the look of it is like the threads are stripped, but I wonder if it is only corrosion and I should try a thread chaser first

[sapote]

If you decide to use JBweld or thread-locker on the Timesert, then after installing the Timesert, turn the bolt in until it bottomed out and a little more to jack the Timesert out (preload it) to minimized JBweld between the loading threads before the compound set. This will maximize the strength of the Timesert.

[liam821]

I'm going to be tackling my diff here soon, so this is helpful. For me, I'm swapping to a 3.25 so I can use a DCT trans. Cheers for the links.

[maupineda]

All right. I received the copycat timesert kit and is not good. Here the issues with it:

1 - The tap just seems like a regular M16 metric tap thread, and it should be an STI tap.

2. The installation tool is nothing but an M14 threaded shaft, to which the insert screws like a glove, it does not have the correct shape to form and expand the insert in place.

3 The inserts, though inox, do not have the partially formed threads to lock the insert in place, although I already knew I couldn’t use these as they were very short, they are not actual inserts and rather threaded bushings.

Photos for reference. These will be returned and will get the real deal.

the kit…



See how the insert was screwed past the threaded end of the “install” tool.