Getrag 420G rebuild?

[George Hill]

For the driveshaft, did you have an M3 one lengthened/shortened or did you piece one together from multiple BMW driveshafts?

I personally don't believe in mixing and matching driveshafts unless you have it balanced afterwards and at that point it is usually cheaper and easier to just get a new one custom made to spec. In the pic you can see mine has a 4bolt flange, because I am still running the 325 diff in my car, lol. But I'll be swapping to a M3 diff and will take another look at driveshaft options, maybe a non-m 6MT shaft will work.

Your starter bracket solution seems super straightforward and I'm sure that Ronald (from AutoSolutions) would be able to easily make me a custom shifter carrier that still works with his short shift kit to swap in.

I've actually worked with Ronald on shifters in the past and we have talked about him making a kit for this setup. I just need to pull my car apart to model my current setup (to replicate) and then send him one so he can work his majic on the design. It is a very simple mod to an off the shelf shifter and truly you could use a factory shifter, it's just not 100%.

[Chanman1029]

Hey thanks, yes I run a S6-53 trans from the N5x cars in my S54 swapped touring, I like it a lot compared to a 420g. This trans swap isn't for everyone, while I'd like to say it's the best solution out there, that's not quite the case. If you have a stockish powered 420g car now it probably doesn't make sense to do this conversion (financially) but I think it starts to make more sense if you a running elevated power as the S6-53 is stronger. BUT the S6-53 shifts so nice, it is night and day compared to most of the 420g's I come across, there are some rare exceptions of 420s that still are crisp but it seems like the majority coming through my shop are starting to have some kind of "issue."

So IMO if you want a nicer shifting transmission or are concerned about strength this is the way to go. The swap is pretty straightforward but does require a few "custom" pieces. The starter bolts to the block on the N5x cars and on our S54s the starter bolts to the transmission, so that has to be addressed (what I was talking about in the link Heinzboehmer posted above). Thats the "hard" part, from there a custom slave cylinder hose and shift lever bracket (both easy) and then a custom driveshaft, everything else is a bolt in affair.

Exactly what did you have to do to the shift lever bracket to make it work? Also, would it be necessary to use an N54 flywheel or can I still use the s54 one?

I have this clunk, I getting ready to shotgun a different diff into my car, and if it doesn’t fix my issue, this will be something I will want to do

[George Hill]

Exactly what did you have to do to the shift lever bracket to make it work? Also, would it be necessary to use an N54 flywheel or can I still use the s54 one?

I have this clunk, I getting ready to shotgun a different diff into my car, and if it doesn’t fix my issue, this will be something I will want to do

It's shortened.

You use the clutch/flywheel/slave cylinder that goes with the transmission, in this case it would be for a N5x (early) 8 bolt crankshaft engine.

[Chanman1029]

It's shortened.

You use the clutch/flywheel/slave cylinder that goes with the transmission, in this case it would be for a N5x (early) 8 bolt crankshaft engine.

Got it, you guys sell those starter adapters?

[George Hill]

Got it, you guys sell those starter adapters?

I do, yes.

[oceansize]

Also diffsonline:

https://diffsonline.com/getrag-6-speed-race-prepared-transmission-e46m3.html#.YYhASGBOlPY

[heinzboehmer]

I personally don't believe in mixing and matching driveshafts unless you have it balanced afterwards and at that point it is usually cheaper and easier to just get a new one custom made to spec. In the pic you can see mine has a 4bolt flange, because I am still running the 325 diff in my car, lol. But I'll be swapping to a M3 diff and will take another look at driveshaft options, maybe a non-m 6MT shaft will work.



I've actually worked with Ronald on shifters in the past and we have talked about him making a kit for this setup. I just need to pull my car apart to model my current setup (to replicate) and then send him one so he can work his majic on the design. It is a very simple mod to an off the shelf shifter and truly you could use a factory shifter, it's just not 100%.

Awesome. Interesting to know about the balancing. I thought that was cheaper than getting one custom made, which is why I asked.

I wish your solution was available/I had known about it before I did my transmission refresh about a year ago. I definitely would have swapped this in instead of trying to get the 420G to feel nice.

Oh well. You'll definitely be hearing from me next time I have any sort of trouble with my transmission!

[sapote]

3rd is the worst, and will grind if I shift too quickly even when warm.

The synchro needs times to sync up the two gears and if force it to engage too fast then it wear down fast or grind and no other way around this.

[tnord]

I've been driving manual transmission cars for over 20 years. I've never had this problem. It doesn't happen in my e90 330 either.

It's not me.

[les3002]

My 420G also grinds if you try to shift into 3rd quickly, all the other gears are fine, and it'll change into 3rd without grinding if you do a really lazy slow shift. Worn synchro.

I've got a ZF GS6-37BZ (E46 330i) that I've thought about using, I believe BMW used it with the S54 when fitted in the Z4M, but for some reason they created a new version with a longer input shaft, rather than use the 330i style flywheel and the 330i gearbox with the shorter input shaft. I wonder why they did that? The ZF box does have a much nicer shift feel than the 420G.

[Slideways]

Came across a useful video for 420G gearbox disassembly -

Should be helpful if you need to remove the tail end and reseal the case.

Now, if only there was a good service to replace the syncros.

[S54330Ci]

The only place I know of that rebuilds the 6-speed gearbox is Diffsonline. Their service is expensive and really intended for those who track / race their cars. $5,899.

Getrag 6-Speed Race Prepared Transmission for E46M3 | Diffsonline

[Lee_Enfield]

Hey thanks, yes I run a S6-53 trans from the N5x cars in my S54 swapped touring, I like it a lot compared to a 420g. This trans swap isn't for everyone, while I'd like to say it's the best solution out there, that's not quite the case. If you have a stockish powered 420g car now it probably doesn't make sense to do this conversion (financially) but I think it starts to make more sense if you a running elevated power as the S6-53 is stronger. BUT the S6-53 shifts so nice, it is night and day compared to most of the 420g's I come across, there are some rare exceptions of 420s that still are crisp but it seems like the majority coming through my shop are starting to have some kind of "issue."

So IMO if you want a nicer shifting transmission or are concerned about strength this is the way to go. The swap is pretty straightforward but does require a few "custom" pieces. The starter bolts to the block on the N5x cars and on our S54s the starter bolts to the transmission, so that has to be addressed (what I was talking about in the link Heinzboehmer posted above). Thats the "hard" part, from there a custom slave cylinder hose and shift lever bracket (both easy) and then a custom driveshaft, everything else is a bolt in affair.

There is a S6-53 supposedly of a 550 for sale for under 1k CAD right now. Wonder if I should message the guy and see how many KM/Miles on it and pick it up for a future swap? My transmission is pretty bagged and I like projects (why I bought the Car)

So apart from a custom bracket for the starter, a hydraulic hose, and a modified shift lever, everything else is stock BMW parts?

[sapote]

R and 5/6 shift rod share the same bearing axis.


Don't assemble the bellhousing horizontal as he did as the bottom roller can fall down. Also add Loctite to the 5/6 pivot bar bolt:


How the shifted gear interlock works: there is a locking ball in between shift rod R and 1/2, and between 1/2 and 3/4.
R and 1/2 rods have through holes with a lock pin inside. 3/4 and 5/6 rods have no through holes nor lock pins. The lock pins are slightly shorter than the shift rod diameter. The ball is slightly larger than the space between two rods, and so the rod has a groove to fit the ball.
For example, when 1/2 gear shifted, its rod moves and push left ball into R groove and right ball into 3/4 groove. The ball also pushes R lock pin to left and push the long lock pin into 5/6 groove. So now balls and all lock pins are inside the groove of all the shift rods and prevent them being moved, except 1/2. This prevents accidentally engaging two gears at the same time.

[George Hill]

There is a S6-53 supposedly of a 550 for sale for under 1k CAD right now.

V8 Bell housings are different, IMO this is not the transmission variant you want.

So apart from a custom bracket for the starter, a hydraulic hose, and a modified shift lever, everything else is stock BMW parts?

You will need:

• A way to mount the starter as on the N5x it mounts to the engine and on the S54 it mounts to the trans.
• A custom hydraulic hose from the firewall to the slave cylinder (slave end is a quick disconnect vs E46 that is a screw connection).
• A custom shifter, I adapted an E9x and it was pretty good. I had intended to send it to AutoSolutions to have Ronald recreate it like he does, but there just wasn't enough interest.

But I do sell the hydraulic hose and adapters for the starter if you go this route. Happy to help get you sorted. https://www.hillperformance.com/