torque convertor stripped bolt hole

[berlins]

Got a used 904 with a 2400 stall torque convertor off someone
a while back and found one of the bolt holes for the torque
convertor is stripped. Bolts look to be a fine thread 7/16". I gather
the best way to repair this is to tap it out to a larger size? Anbody
have thoughts on this? Think the 4 bolts are harder than the normal
bolts you would get at a hardware store. Still a bit amazed that they
use such small bolts - would think an good engine could easily shear
these bolts. The bolts that hold the flex plate on the crank are much
larger and don't think I could use bolts that large on the torque
convertor.

 

[toolmanmike]

You're correct. Tapping to the next size is an option. It could be Heli-coiled but it may not work. If you drill and tap oversize be careful not to drill into the convertor. I would use grade 8 bolts and a little Loctite.

 

[godfatherofchry]

are you saying the head of the bolt is 7/16 if so that should be 1/4 inch. yes I have taped them to 3/8ths and if you buy bolts get at lest grade 8............Artie

 

[66plyValiant]

I haven't seen a factory torque converter bolt sheer off yet

 

[berlins]

I believe the head is 1/2" and the thread is 7/16's fine(I can look that up). Guess I'll try
to find a 3/8" grade 8 bolt and tap it to that. Never heard of one shearing either but still amazes me that those little bolts can handle a high HP motor(not an issue for me - will be a stock 360). Guess that's why you need the grade 8 bolts!!!

 

[Bad Sport]

You could try a metric bolt slightly larger than what you have, and see if it will thread in.

 

[Spenc71]

I'd heli coil it. I don't like the idea of drilling out the flex plate. Just my opioion. Tempered steel plate and what do you do if you want to change your converter later?

 

[68-GTS]

Go this route, All you'll need is a drill.



HLC5528-5 Helicoil
MASTER THREAD REPAIR KIT 5/16-24

Heli-coil professional thread repair kit including tool, drill, tap and inserts for fine thread size, 5/16 inch-24.

 

[daredevil]

After market converters step up to 3/8 bolts. I think stock is 5 /16. I had to drill out my flex plate till I got my b&m certed one

 

[Dodge33]

heilcoil it, DONE IT 10 YEARS AGO, still holding no problem.

 

[trapster]

Couldn't adding a different bolt in one of the 4 holes throw off the balance ?

 

[daredevil]

Probaly less than a chipped ring gear tooth

 

[cudamark]

Couldn't adding a different bolt in one of the 4 holes throw off the balance ?

Yup, that's why I would go the Helicoil route and use all the same size/weight bolts.

 

[70aarcuda]

after market converters use 7/16 threads and the head of the bolt takes a 3/4 wrench..

 

[berlins]

Just ordered the Helicoil kit mentioned above. Have installed them before, just didn't know if they would be good enough for this application. Seems like there will be a lot
of sheer force on those 4 little bolts but after reading all you inputs it seems that I'll
be just fine. Thanks everyone!!!