Cracked Bell Housing

[mrgizmo04]

This is way I advised people not swap the bell housing when doing the SMG to manual conversion.

Lang and a bunch of other shops have off the shelf machined "random" bellhousings. These conversions have been popular for years, I'd think we would hear about failure cases?

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[bigjae46]

There is a preload spec for the input bearing…just like every radial bearing it needs to be preloaded or the bearing will eventually fail. When swapping bellhousings will it make a huge difference? Not sure.

Trust me on this…find a GOOD TIG welder. Old oil and grime contaminated cast aluminum can be a challenge to weld. The metal has to be very clean to get a good weld. You can MIG weld it but it puts a lot more heat in the metal.

Or clean the cracked area really, really well and then hit it with a map torch to get the aluminum hot and cook off any contamination. Then take it to get TIG welded.

[Slideways]

Lang and a bunch of other shops have off the shelf machined "random" bellhousings. These conversions have been popular for years, I'd think we would hear about failure cases?

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Same with Kaiv's conversions. On the old forum, I believe he said that it was not an issue.

[sapote]

Hate when that happens.

Banned for life

[sapote]

Preloaded radial bearing is a total different application; they are used on shafts with little or no thrust force, I.e alternator, water pump. They are preloaded with spring washer to avoid spinning around the housing, and balls rattling.
All bearings carry thrust load, I.e. Diff and transmission input shaft need to be shimmed precisely with flat shims, not spring washer.

[sapote]

I remember a few people asking for new bearing source - bearing noise developed after swapping the BH.

[George Hill]

I remember a few people asking for new bearing source - bearing noise developed after swapping the BH.

Reference to these posts?

Honestly you could likely get away with doing nothing here, I wouldn't but you could.

IF this is a track car I would take this time to ditch the 420g and swap to a ZF5. You need a clutch, (flywheel?), money investment into the transmission anyways. Do you have a chassis mounted shifter as is? Your spending delta might just be a transmission, crossmember and driveshaft plus a shift rod. Then selling your 420g as is (and driveshaft) might put you not far above what you are spending now, but with a significant weight savings and better shifting trans.

[sapote]

Reference to these posts?

post #54

https://www.e46fanatics.com/threads/m3-manual-input-shaft-bearing-replacement.1287901/page-3

post #37

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/2844-smg-to-6mt-conversion/page3#post44201

[George Hill]

post #54

https://www.e46fanatics.com/threads/m3-manual-input-shaft-bearing-replacement.1287901/page-3

This post from that thread says he fixed his bad bearing by installing a used one...


[QUOTE=sapote;n192155]
post #37

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/2844-smg-to-6mt-conversion/page3#post44201

You meant post #36.

Both of those posts did not follow-up saying that the noise was fixed by replacing the bearing. The only post that I saw said he fixed his noise with a used bearing. I'm not saying you are wrong, but with the hundred(s?) of BH that have been swapped I haven't seen a definite instance where someone had an issue that hey FIXED by either replacing the bearing or reinstalling their original bearing. For all we now those (2) instances could have been installation issues.

[sapote]

You meant post #36.

Post #37. He got the BH from a manual then swapped into his SMG, then the noise. The other guy also said the same.

[bimmer]

Well just to close the loop, had the BH welded. My friend ended up not wanting to tackle so cost me $300. Guy found a few more cracks underneath the grime once he cleaned it up. Apparently this is a common job for him. Everything went back together smoothly and car is driving fine. We'll see how it holds up come track season.

[sapote]

Everything went back together smoothly and car is driving fine. We'll see how it holds up come track season.

Nice!
How do you prevent the flywheel dowel pins backing out again?

[bimmer]

Nice!
How do you prevent the flywheel dowel pins backing out again?

I got a new flywheel so hopefully this one holds it's dowels for another 160K miles 🤞. I didn't do anything special but perhaps I should have 🤔

[sapote]

I got a new flywheel so hopefully this one holds it's dowels for another 160K miles 🤞. I didn't do anything special but perhaps I should have 🤔

If the pin cannot go pass the PP then even if it's loose on the flywheel it won't be able to back out. This means if the PP has a blind hole, or the end with peen deformation to block the pin backing out.