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Meat Popsicle
91 CRX Si
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2,929 Posts
Discussion Starter #1
Long story short, I found out that the threads in one of the bolt holes on my transmission housing are completely gone and I cannot properly torque the mount plate on to the transmission housing. I know I am going to have to re-tap larger threads in the bolt hole but I have a few questions...

1.) Is it absolutely necessary to drill out the existing threads? I would imagine so but I figured I'd check.

2.) If I drill the threads out of the hole, what size bit should I use? If it's a M10 bolt, should I use a 10mm bit or do I need to go to 11mm?

I searched around a bit for the answers to these questions but the information I've read is either over simplified or overly complicated and goes into these calculation charts that I cannot understand.

Perhaps a press-in helicoil would be easier?

Needless to say I'm pretty frustrated at this point. Spend months waiting for my transmission only to find out the damn bolt hole is stripped...:uh:
 

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Meat Popsicle
91 CRX Si
Joined
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2,929 Posts
Discussion Starter #4 (Edited)
This will help:

Tap Drill Sizes

Drill and tap sized are weird, I always keep the bit with the tap so I dont have to look it up all the time.
Awesome, much easier to understand than the others. Thanks

To make sure I'm understanding this right...

8 x 1.25 6.8

This means that if I'm tapping a M8 x 1.25 thread that I'll need a 6.8mm bit?
 

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Banned
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1,234 Posts
Get a helicoil set and be done.
 

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()*#$(*$
93 Legend L Coupe.
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11,404 Posts
A drill press is ideal because most people SUCK at drilling holes completely perpendicular to a surface. I have a LOT of practice and can do it. You have a previously drilled hole to follow. If you are careful you can do it easily.

Timeserts are NEVER to be installed without a drill press, as they are WAY more precise than helicoils, for very good reasons.
 

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Meat Popsicle
91 CRX Si
Joined
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2,929 Posts
Discussion Starter #10
Thanks again for all the input guys. Great info.

I'll be the first to admit that one of the fucked up threads was completely my fault. Now I've learned the hard way what to look for when it comes to damaged bolts and thread bores and what NOT to do.

One flattened thread on a steel bolt + aluminum threaded hole = FAIL!

Definitely going the helicoil route. Time sert looks like a better product but I can't find them locally and I'm in a bit of a rush to get this fixed.
 

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For what youre using them for, helicoil will work great. Now if we were talking headstud or main/girdle stud, I would go time sert. But for the mount, hell, I think one of mine is helicoiled.
 
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