Stripped tranny oil pan bolt

[VAL]

I have a stripped transmission oil pan bolt on my 700r4. I noticed the holes go all the way through the case. Can I put a longer bolt with a washer and a nut? Or is there another fix?

 

[chengny]

Val, you must mean that you stripped the internal threads in the transmission casing right?

You aren't saying that the threads on the bolt are wiped off, are you?

Can I put a longer bolt with a washer and a nut? Or is there another fix?

If you're not kidding and the bolt is the part that is stripped (not the internal threads in the casing), hoo boy - that's a tough one.

But I'm sure someone will have a trick up their sleeve that will bail you out of this fix you've got yourself in.

Do you know anyone with a lathe that knows how to cut machine threads? Maybe you could find a short length of mild steel stock, turn it down to the correct OD and cut the threads in at the proper pitch. When you have that done, test it in the threaded bore in the casing.

If it screws in nicely, you have the rough form of a stud. Just crop it to the proper length (depth of the bore + thickness of the washer + 1 1/2 the thickness of the nut). Chamfer the threads at each end to remove any burrs. With the pan still off the casing, set the stud into the appropriate hole using the double nut method. A drop of Loctite Blue might not be a bad idea as well.

Done. Lift the pan into place, install the rest of the bolts, and thread a nut/washer onto the new stud. Go around the pan and torque the bolts/stud to normal spec.

After that, all you can do is pray. It's in God's hands from then on.

If only there was some place where a new bolt could be purchased for a reasonable amount - it would save so much time.

But it's like the old saying: "Yeah, and if my aunt had balls, she'd be my uncle"

 

[VAL]

Val, you must mean that you stripped the internal threads in the transmission casing right?

You aren't saying that the threads on the bolt are wiped off, are you?

Can I put a longer bolt with a washer and a nut? Or is there another fix?

If you're not kidding and the bolt is the part that is stripped (not the internal threads in the casing), hoo boy - that's a tough one.

But I'm sure someone will have a trick up their sleeve that will bail you out of this fix you've got yourself in.

Do you know anyone with a lathe that knows how to cut machine threads? Maybe you could find a short length of mild steel stock, turn it down to the correct OD and cut the threads in at the proper pitch. When you have that done, test it in the threaded bore in the casing.

If it screws in nicely, you have the rough form of a stud. Just crop it to the proper length (depth of the bore + thickness of the washer + 1 1/2 the thickness of the nut). Chamfer the threads at each end to remove any burrs. With the pan still off the casing, set the stud into the appropriate hole using the double nut method. A drop of Loctite Blue might not be a bad idea as well.

Done. Lift the pan into place, install the rest of the bolts, and thread a nut/washer onto the new stud. Go around the pan and torque the bolts/stud to normal spec.

After that, all you can do is pray. It's in God's hands from then on.

If only there was some place where a new bolt could be purchased for a reasonable amount - it would save so much time.

But it's like the old saying: "Yeah, and if my aunt had balls, she'd be my uncle"

Yeah, the bolt is fine, its the threads in the casing. I always noticed that there was a small leak some where, now that I got into fixing the lock-up, and had to remove the pan, I found out why. Its the corner bolt right over the front drive shaft where it meets the transfer case.

 

[89Suburban]

Use a nylon locking nut on top if there is room or heli-coil repair it.

 

[VAL]

Use a nylon locking nut on top if there is room or heli-coil repair it.

Whats heli-coil?

 

[DoubleDingo]

I couldn't get an image, but this should help with the description...

http://www.stanleyengineeredfastening.com/brands/heli-coil

 

[VAL]

Here's a pic, its the one in the corner.

You must be registered for see images attach

 

[HotRodPC]

There is enough room for a Helicoil. I've done many many in pan bolts, valve body bolts and even front pump bolts. That being on a corner, really needs to be fixed right. Helicoil that bitch and make it like new again.

I guess I'll do a quick write up on how to do a Helicoil since I had pics and pretty much did a write up on FB the last time I had to do one on front pump bolt. What sucked, it was a trans that I had just built and didn't want to pull it all back apart, so I had to be carefull not to get any shavings inside the case or it would trash my whole build. It's been working perfect and no problems for at least 2 years now.

 

[VAL]

I hadn't even heard of heli-coil, till Paw Paw mentioned it earlier. I did some reading on it, and it seems to make the union even stronger and better than before.

 

[HotRodPC]

I hadn't even heard of heli-coil, till Paw Paw mentioned it earlier. I did some reading on it, and it seems to make the union even stronger and better than before.

Your thread themselves will be stronger, and sure, with the threads biting into a bigger hole, they will hold just as good as the original hole. I love Helicoils. I've fixed spark plug holes with them, and many many transmission bolts as said earlier in valve body bolts that are torque critical as well as pump and pan bolts. I've also Helicoiled a FREE Eddy Torker ll Intake manifold before when an idiot stripped out his thermostat bolts, so he just went and bought another intake. He had it laying in his scrap aluminum pile. I asked about it and said take it. He thought I was going to practice polishing aluminum with it and didn't think I could fix it. Of course when my truck spanked his cars ass with a new cam, and his intake, he knew then I fixed it.

I just got back from getting gas and smokes so I'll dig up some pics and do a quick write up on this pump bolt I fixed. Irishman has seen it before. I did post it on my FB page long ago when I did it.

 

[chengny]

Wouldn't the easiest repair be to just drill and tap for the next bigger bolt size. There is plenty of meat surrounding the existing bore. I'm guessing the bolts are 1/4" - 20 .

The difference in drill size from a 1/4" - 20 bolt to a 5/16" -18 is minimal. The proper drill bits are a 7 and an F. Using the closest fractional bit sizes the increase in diameter is only 3/64" (.046"). Divide that by 2 - for conversion to radius - and the edge of the new hole only moves .023" closer to the perimeter of the casing.

Looks like he's got about 1/8" (.125) of meat left at the closest point. So there is room for a 5/16" -18 bolt hole.

Don't neglect the fact that the Helicoil process requires oversized drilling to accept the insert. The specified bit for a 1/4" Helicoil insert is an H (.2660). That diameter is actually larger by .090" than the bit size (.2570) recommended for a 5/16" - 18 tap.

So, in the end, the use of a 5/16" - 18 bolt would require the removal of less surrounding metal than a 1/4" Helicoil insert.

 

[HotRodPC]

And there you go. Really not all that hard. Take one of your pan bolts with you to make sure you get the right kit. I have a feeling that one may be metric.

http://www.gmsquarebody.com/forum/showthread.php?t=10470

O'Reilly's carries the kits, but I don't think Auto Zone and Advance does. The others may carry another brand or similar type product, but I don't of any others than HeliCoil. I'm sure there's others by now since HeliCoils have been around since the 60 and 70's that I've been told of.

http://www.oreillyauto.com/site/c/search.oap?keyword=heli-coil+inserts

 

[HotRodPC]

Wouldn't the easiest repair be to just drill and tap for the next bigger bolt size. There is plenty of meat surrounding the existing bore. I'm guessing the bolts are 1/4" - 20 .

The difference in drill size from a 1/4" - 20 bolt to a 5/16" -18 is minimal. The proper drill bits are a 7 and an F. Using the closest fractional bit sizes the increase in diameter is only 3/64" (.046"). Divide that by 2 - for conversion to radius - and the edge of the new hole only moves .023" closer to the perimeter of the casing.

Looks like he's got about 1/8" (.125) of meat left at the closest point. So there is room for a 5/16" -18 bolt hole.

Don't neglect the fact that the Helicoil process requires oversized drilling to accept the insert. The specified bit for a 1/4" Helicoil insert is an H (.2660). That diameter is actually larger by .090" than the bit size (.2570) recommended for a 5/16" - 18 tap.

So, in the end, the use of a 5/16" - 18 bolt would require the removal of less surrounding metal than a 1/4" Helicoil insert.

Yes, he could do that too. Just go with the next bigger size. So long as whoever pulls the pan next time KNOWS that one is different and don't put the oversize bolt in the rest of the holes because then there will be more to drill and tap bigger.

 

[DoubleDingo]

I'm sure there's others by now since HeliCoils have been around since the 60 and 70's that I've been told of.

I haven't ever used a heli-coil, but I remember seeing them at grandma & grandpa's Western Auto store when I was about 4, which was 1974. Grandpa had a little clear plastic case of them with varying sizes.

 

[mtnmankev]

My opinion, for what it's worth .......
I have used helicoils many times in the past, and they work great.
I would be skittish about using one here because of the amount of material lost when you drill it out to thread it and insert the coil.
If it was me, I would drill it out and tap it for the next size bolt, the 5/16-18.
That leaves more structural strength in the case.