Repairing Stripped Muncie side cover bolt holes

[Bill L.]

Replaced the gasket on my M20 side cover plate. All but two bolts torqued to 20 ft lbs spec. The other two appear to be stripped and will not torque but do snug up.

Do I heli coil? I used a very small amount of RTV on both sides of the gasket. Any other options?

Thanks,


Bill

[Stephen L.]

Re: Repairing Stripped Muncie side cover bolt holes

You might get away with leaving the bolts "as is". However, put some RTV on all the bolts... especially the bottom row as they might "weep" over an extended period.

[Bill L.]

Re: Repairing Stripped Muncie side cover bolt holes

How about thread sealer to prevent the weeping like on the intake bolts versus RTV?

I was pretty disappointed when they did not torque.

Thanks, Bill

[Tom P.]

Re: Repairing Stripped Muncie side cover bolt holes

Try the bolts with a sealant and see if it holds. If it does, leave it alone until the next time the tranny comes out.
But, if it persists in leaking around the side cover, then a very good fix is a Helicoil. Over MANY, MANY years I have used Helicoils on many parts with excellent results------------------------including Helicoils as small as 8-32 on FI units.

[Paul J.]

Re: Repairing Stripped Muncie side cover bolt holes

As previously mentioned, a helicoil will work, or you can use an oversized bolt.

[Bill L.]

Re: Repairing Stripped Muncie side cover bolt holes

Well they are pretty snug now. I am going with the sealant as suggested and will see how that works before going heli coil.

Thanks,


Bill

[Terry M.]

Re: Repairing Stripped Muncie side cover bolt holes

Well they are pretty snug now. I am going with the sealant as suggested and will see how that works before going heli coil.

Thanks,

Bill

Bill,
If it comes to a rethreading, you should be aware that Heli Coils have a habit of leaking when they are used in an application that requires them to retain fluid. If it becomes necessary to recreate the threads you might want to consider a Time-Sert for this application. Although these are more expensive than Heli Coil, they will provide a longer lasting result as they actually have new threads.

http://www.amazon.com/TIME-SERT-16-SAE-Thread-Repair/dp/B0025MQ63Q/ref=sr_1_1?ie=UTF8&qid=1388343263&sr=8-1&keywords=time+sert+5%2F16

[Bill L.]

Re: Repairing Stripped Muncie side cover bolt holes

Hi Terry,

I looked at a video showing how to properly use The Time-Sert. Very interesting. I just may have to go that route. I was never a huge fan of heli coils but have used them in the past.

My question is regarding the concern I have about making sure to drill straight either way.

Bill

[Joe L.]

Re: Repairing Stripped Muncie side cover bolt holes

Hi Terry,


My question is regarding the concern I have about making sure to drill straight either way.

Bill

Drilling AND tapping straight is the BIG problem. With the transmission out of the car you can, of course, use a drill press, at least to DRILL straight. Tapping straight is another matter.

What I do is to make a drilling and tapping FIXTURE. However, this is a BIG PAIN and requires a lot more effort and expense than the repair itself. Worse yet, you usually have to make a unique fixture for each application. Then, you'll probably never use that unique fixture again in your lifetime.

[Bill L.]

Re: Repairing Stripped Muncie side cover bolt holes

Drilling AND tapping straight is the BIG problem. With the transmission out of the car you can, of course, use a drill press, at least to DRILL straight. Tapping straight is another matter.

What I do is to make a drilling and tapping FIXTURE. However, this is a BIG PAIN and requires a lot more effort and expense than the repair itself. Worse yet, you usually have to make a unique fixture for each application. Then, you'll probably never use that unique fixture again in your lifetime.

Exactly as I thought. How about a machine shop?

Bill

[Dick W.]

Re: Repairing Stripped Muncie side cover bolt holes

Heli coils with a sealant such as Loctite PST. Have used Heli coils for almost 60 years with no problems.

[Joe L.]

Re: Repairing Stripped Muncie side cover bolt holes

Exactly as I thought. How about a machine shop?

Bill

Bill-----


Some machine shops might take the job. However, if they do, they'll likely want a bare case to work with and not a fully assembled transmission. If the trans is installed in the car, forget it.

[Timothy B.]

Re: Repairing Stripped Muncie side cover bolt holes

That side cover bolt is probably 5/16 x 3/4" long, with respect to the other posters I would not hesitate one bit to drill and install the heli-coil just don't drink any beer the night before. Wait, if you got the shakes it may be better to get a few first and then drill. :-)

The new thread repair will be better than the original tapped in the aluminum. Can you get a 90* drill there to drill the hole to size.

[Tom P.]

Re: Repairing Stripped Muncie side cover bolt holes

Here is a Helicoil tip that I have used, and still use, MANY times------------------on ALUMINUM, repeat, ALUMINUM parts.
ALUMINUM, NOT STEEL/IRON!

Rather that try to drill a straight hole where the threads are stripped in an alum part, insert the bolt and continue to finish stripping out the threads completely. Then insert the Helicoil tap and slowly turn it using plenty of lubricant. What remains of the original stripped out threads will "guide" the Helicoil tap straight and true into the hole. I do this ONLY on alum parts because it is a much softer metal than iron/steel, and the tap can easily follow and cut new threads in the alum. It just makes it TOOOOOOOOOOOOOOO EASY!

[Bill L.]

Re: Repairing Stripped Muncie side cover bolt holes

That side cover bolt is probably 5/16 x 3/4" long, with respect to the other posters I would not hesitate one bit to drill and install the heli-coil just don't drink any beer the night before. Wait, if you got the shakes it may be better to get a few first and then drill. :-)

The new thread repair will be better than the original tapped in the aluminum. Can you get a 90* drill there to drill the hole to size.

Transmission is out so a drill is no problem. The new clutch assembly and flywheel is in so I thought I would replace some leaky shift lever seals and side cover gasket while the trans is out. It ended up with a complete M20 rebuild once we opened up the side cover.

The two bad holes snug up pretty well. I was actually thinking of using a little teflon tape to see it would give just a little extra bite.


Bill