Stripped Bolt Question on My Guardsman...

[Big Blzn]

So, I finally got my Guardsman all painted up looking purdy and went to install it and 2 of the 6 bolts stripped out the inner threads on the housing. I checked with Kert at DIY and he said to torq them to 65ft/lbs and I also thought that is what I read in a manual as well.

Now, the OEM bolts, 7/16", didn't have more than 4 threads locking them down and the longer ones from kert are 1.5" (only 4 threads had contact with these too) to compensate for the add thickness of the Guardsman but those are the ones that stripped out so I went and bought new bolts that are 1.75" long to get a better grip. I also got the proper heli-coil kit to fix the repair. This should be fine to use the heli-coil, right? I looked with a flashlight and felt around with a pick but can't tell if the back of the bolt holes open up into the inside of the diff housing. When I blow compressed air into the hole is seems to blow back out at me but I ask this because the OEM bolts have A LOT of what looks like old black gear oil saturating the bolt threads. I just don't want to do the heli-coil drilling and tapping and have it all fall into the diff housing. And do you think the torque spec of 65lbs is too much or did the excessive oil on the threads make the bolt over-torque itself?????

 

[4X4HIGH]

IIRC those are all blind hole (meaning they bottom out and do not go into the gear area). Also there should be ALOT more than 4 threads engagement. It is possible that all the holes in your housing have some stripped threads at the end from someone else using too short of a bolt at some point in the past.

 

[Big Blzn]

It is possible but the 1-ton I got it from was just an unmodified 2wd truck and the date on the R/P was from the original date of manufacture, 1980. They look to be stock bolts and when I put them up to the housing with the guardsman off the OEM bolts seemed to have the same depth of thread engagement as the longer DIY supplied one with the guardsman in place. Scott, you think I'll have any problems using the helicoils in this application and what torque would YOU put them at? It was def four threads as when I realized I had stripped the holes and pulled the bolts out I unscrewed four threads from the housing that were still engaged on the bolts threads.

 

[bp71k5]

There should be a lot more than 4 threads engaged. Mine had at least 1/2" of engagement when I installed the pinion housing. 65 ft/lbs sounds right, but not if the bolt is too short.

 

[4X4HIGH]

A heli coil will work no problem (not sure why so many people are afraid of them). I also would still torque it to 65 ft/lbs.

Like Brian said, there should be at least a 1/2" of thread engagement. I would suggest checking the depth of the hole and using a bolt that is slightly shorter then the depth so you have the most thread contact possible.

 

[BGKYK5]

Double check that the bolt holes aren't filled with RTV etc. too.

 

[rdn2blazer]

If the holes are deep enough tap them as far as you can with a plug tap, them a bottom tap to the bottom, you can use a longer bolt. I do this on everything for holding power. I threaded hold it hard to strip with deep thread engagement.

 

[4X4HIGH]

I threaded hold it hard to strip with deep thread engagement.

Wow, was that some kind of foreign language?

 

[bp71k5]

Wow, was that some kind of foreign language?

Maybe he meant he was engaged to a stripper named deep throat?

 

[Big Blzn]

Not afraid of the helicoil since I have had to use one already on the same axle. Pretty simple process especially for a noob mechanic like myself.