Hi all,

I am going through the bellhousing on my a833 transmission cleaning up threads. When I got to the four bolts that hold the bellhousing to the transmission I found one was noticeably stripped compared to the others. Internal diameter difference is 0.419 vs 0.364 on the good bolt hole. That said, I can still screw the bolt in with my fingers and it seems sturdy.

My thoughts are that I should drill out and tap for a slightly larger screw or insert a healicoil. I really don't want to drill out the actual mounting hole on the transmission. The bellhousing and transmission body are aluminum. Has anyone run into this issue before?

Sincerely,

Paul Barrow

Maybe it is catching some treads further in the hole. I would use the longest bolt you can and some tread locker.

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Hyper_pak

Hi Hyperpack,

It's not that there aren't threads in the hole, it's that they are significantly worn. The bolt will grab all the way down, but I'm concerned about it holding up long term. If you look down the hole you can actually see a noticeable lip where the threads are better. Heck, there are even voids on either side in can stick a pick into (casting issue?). Talking to a friend, they recommended drilling it out, tapping for a 1/2 inch, and then seating a stud into the hole. This was explained to me that it would put less stress on the threads.

Thoughts?

Paul

I would fix it properly. Either a heli-coil or other kind of thread insert.

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I have helicoiled lots of the bellhousing bolt threads on my 904.

That's the way to fix it.


Greg

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Hi all,

I had thought of that. Really not being a smart ass here, but why would a helicoil be better/stronger/correct way to repair?

Paul

Thread inserts are stronger because they have a larger outside diameter and grab more of the soft aluminum. Solid Time-Serts are better than wound Heli-Coils. http://www.timesert.com/ I used Time-Serts to fix a cast iron bell I had threaded badly.

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Joshua

What they said!
But I really don't think you are going to have a problem with it.
Helicoils were and are a very good repair.

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Hyper_pak

I really don't know how much clearance there might be between the bell and the rotating pressure plate, but you might want to be a touch conservative with a longer bolt. Wouldn't want the pressure plate to bang against the end of the bolt. Me, I'd entertain having a local welder fill the bad hole by TIG welding, then re-drill and tap for the correct threads.
Maybe it would work to "glue" a correct length and thread bolt in from the inside of the bell so that it would act as a stud when you hang your trans back up. (That could be risky, though, as if it broke loose the next time, it would be a bear getting the trans out.)

Roger

There's lots of room there. Remember the to bearing s height at a minimum is clearance.

Greg

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Get a long button head bolt and screw/loctite it in from the inside and use a nut on the outside.

Or use a Time-sert.

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