Guys - this is a 97 xj with the aw4. I've got a couple stripped bolt in the trans pan. I'm told I can get a slightly larger bolt size and firmly torque it in to self tap it.

Can someone give me guidance?

I Believe the old bolts are M6-1.0x10 - which I think means its a metric, 6 mm thick, with 1mm threads, and a 10mm head.

I read the self-tap is 1/4-20 - but I'm not sure what that means?

 

OK, I see that M6-1.0x10 means 10mm length of thread, 1.0 pitch and 6mm width.

Sooo... the net size up would be an 'imperial' size bolt of 1/4 inch (slightly wider than 6mm) and with a pitch of 25.40. But the closest I can get is 20 threads per inch?

Is that right?

I want a 1/4-20 bolt (about a half inch long)?

And then just get the threads started on the old smaller threads and firmly, with consistent pressure, drive that sucker in there?

Thanks...

 

I would advise using a thread tap instead of trying to self tap it. The only issue with a 1/4" bolt is it's 6.36mm at its widest which I can't see gripping much. One option would be an M7-1.0, that way you can get the full 1mm of thread from the stripped hole.

 

I have done both re-tapping and if it's badly stripped, just pressing the 1/4-20 firmly in the hole and slowly crank it in and letting it reform the aluminum to the slightly larger size. Stick a paperclip in the hole and make sure the new bolt isn't too long. Do not go too tight! 10-ft*lbs is all those screws need, which is moderately snug with a small ratchet. Any more and you risk ripping out the soft aluminum threads and deforming the edge of the pan (which just causes it to leak and the next guy will think he just needs to tighten the screws....)

 

I did several and had the tap, but I was also able to just self tap to the next size up, I guess its safer to have the tap, its only a few $

good to have a torque wrench that measures that low, as especially the cork gasket relaxes a lot after a new item is installed

 

Thanks guys. @lawsoncl , @awg what size did you use when self-tapping?

@boxburn What size should I tap it to if I do tap it? M7-1.0x10?

I suppose if I go that route, I might as well heli coil it back to M6???

Thanks again.

 

1/4-20. I didn't use self-tapping screws, just a regular bolt.

 

That's what I want to do also, just put a bigger bolt in there.

I might heli-coil instead though.

Thanks.

 

Helicoil is definitely the way to go!

 

Not needed, the 1/4 bolt just threads in nice and tight when you self tap.

If you tap first, its still good, just not as tight

I would not helicoil in the first case...how often do you need to drop the pan ?

I was confident the 1/4 bolt could be removed and re-fitted if needed