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JiI
Samba Member
Joined: February 18, 2006
Posts: 1845
Location: Michigan
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 Posted: Thu Oct 27, 2016 7:38 pm Post subject: Stripped tranny mount stud |
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Got a 915 tranny and one of the front tranny mount stud holes is stripped out. Any thoughts on repairing this? Thanks.
Jeff |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76897
Location: Sneaking up behind you
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| Posted: Thu Oct 27, 2016 7:43 pm Post subject: Re: stripped traanny mount stud |
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JB Weld
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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JiI
Samba Member
Joined: February 18, 2006
Posts: 1845
Location: Michigan
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| Posted: Thu Oct 27, 2016 8:13 pm Post subject: Re: stripped traanny mount stud |
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Will that be strong enough and work with the aluminum/ magnesium?
Jeff |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76897
Location: Sneaking up behind you
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| Posted: Thu Oct 27, 2016 8:15 pm Post subject: Re: stripped traanny mount stud |
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Heli coil
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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AXAM
Samba Member
Joined: November 02, 2003
Posts: 314
Location: Gods country,ca
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| Posted: Sun Nov 20, 2016 6:50 pm Post subject: Re: Stripped tranny mount stud |
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Timesert. Kits are pricey. If near by, bring it by and I can do it
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JiI
Samba Member
Joined: February 18, 2006
Posts: 1845
Location: Michigan
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| Posted: Sun Nov 20, 2016 6:52 pm Post subject: Re: Stripped tranny mount stud |
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I think Illinois is a bit far, don't you? 
Jeff |
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AXAM
Samba Member
Joined: November 02, 2003
Posts: 314
Location: Gods country,ca
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| Posted: Sun Nov 20, 2016 9:20 pm Post subject: Re: Stripped tranny mount stud |
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Yep! May be a little warmer out here.
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JiI
Samba Member
Joined: February 18, 2006
Posts: 1845
Location: Michigan
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| Posted: Sun Nov 20, 2016 10:05 pm Post subject: Re: Stripped tranny mount stud |
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| It's 20.5 right now. It sucks! |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21510
Location: Oklahoma City
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| Posted: Mon Nov 21, 2016 7:59 am Post subject: Re: Stripped tranny mount stud |
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| JiI wrote: |
I think Illinois is a bit far, don't you?
Jeff |
DO NOT use a Time-Sert or Helicoil type insert for this repair. Use an EZ-Lok or any solid wall insert that does not require a distorted thread to lock it in the bore.
READ THIS CAREFULLY. This is an easy repair but you need to test fit carefully.
Just use an EZ Lok insert for a repair like this. You can use standard or thick wall inserts. Use the thickest wall you can get with the most coarse outer thread you can get. I have used them for many transmission stud repairs and I use them for all type 4 cylinder head exhaust stud repairs.
DO NOT use a heli coil or any spiral/spring type thread insert in aluminum or magnesium unless its hardened or one of the better engineering alloys.
Yes they can work...but the probl3m is that aluminum and magnesium are malleable and easily distorted by torque and heat expansion.
When that happens even a little bit......the coil insert itself ....is flexible and moves. However the steel bolt is not. It cracks the threads across the lands over time......and sooner or later simply turns out when the nut comes off. The problem is that since it shears out the outside threads....there may not be enough metal left for a third chance at new threads.
EZ lok and even time serts are solid eall carbon steel inserts. Time serts are onoy expensive because you need a special locking tool.
The Time sert is not any better than the EZ Lok for this application. Its superior for a spark plug thread.....but its benefits have no specific need with your repair.
The EZ Lok can be installed with a flat blade screwdriver.....or you can make an install tool with a threaded rod and a nut and a little Dremel tool work.
The object with this type of repair and also exhaust stud repair.....is to drill the hole to an exsct depth that is between 1 to 2 thread lengths deeper than the length of the insert.......but....only actually thread the bore to the exact length of the insert....and 1/2 thread more.
You do this so that the insert will screw in ....and bottom out in the tapped threads.....at exactly 1/2 thread below flush on the outer surface. This is important so that whatever part or mating surface comes up against the transmission case.....does not press on the threaded insert and apppy load to the insert that could in turn apply load to the magnesium threads holding the insert in.
Once the insert is 1/2 thread below flush as nd bottomed out in its tapped thread in the magnesium.....the slight amount of torque you apply to it cracks the microspheres in the pink epoxy voating that is in the threads of the EZ Lok insert....and mixes the epoxy and cements the insert in.
The other reason you want the insert 1/2 thread below flush on the outer surface.....is so that you can take a sharp punch and peen the surrouning material into the installation screwdriver slots in the outer face of the insert....as further insurance against the insert turning outward.
You will need to by two bottoming taps to install EZ Lok inserts in a blind hole like you have on the transmission stud or a cylinder head exhaust stud. The first tap is used to put as much thread into the bore as uou can.
The second tap.....you will grind or better still....use a Dremel and cut-off wheel to trim the tap so there is no more tapered snout left. This way you can finish the threads down to nearly the bottom of the bore.
You do not want the insert to go all the way to the bottom of the bore. It needs to go down to no more than about 2 thread lengths from the bottom of the bore. You want the insert to go down to the bottom of the threads you cut.....so you can make it up tight....but you do not want it to bottom out in the bore......because if you overtighten....or heat expansion causes excess pressure....it loads the threads in the magnesium bore and can fracture them.
Likewise...you need about 2 threads of blank space in tue bottom of the bore so that the stud can protrude about one thread so you know it is using full length of the threaded insert.....but is also not bottoming out in the bore. If the stud bottoms out in the bore...it can "jack" the insert right out of the case. It can do this with any of the threaded insert brands.
So during installation....you need to take one insert and remove the pink epoxy from the outside with a wire brush and acetone. You will be using this one for test fitting tapped thread depth. You tap a little thread....maybe two threads at most....screw in the test insert....and see how deep it goes. Repeat until it is just 1/2 threar below flush when it locks up.
With threads like the cylinder head exhast studs that are quite shallow.....you adjust the length of the insert by grinding material off the bottom. For deep studs like your transmission mount stud.....you can buy deeper studs from EZ lok. If they are not long enough you can stack shorter inserts in the bore.
WHY YOU SHOULD NOT USE TIME-SERTS IN THIS REPAIR:
Time-Serts are a FINAL CHANCE repair. Because the install tool distorts the inner thread by rolling it.....to lock the insert in.......if the inner bore of the Time-Sert insert ever gets damaged and you need to put a new insert in......when you go to remove a Time-Sert insert.....that distorted locking thread....DESTROYS all of the threads in the part it is tapped into.....when you are turning it outward.
This means that you would have to redrill yet again...and tap to the next largest size insert.
Ray |
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AXAM
Samba Member
Joined: November 02, 2003
Posts: 314
Location: Gods country,ca
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| Posted: Thu Nov 24, 2016 10:11 am Post subject: Re: Stripped tranny mount stud |
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Question. The ez loc and timesert look very similar. The thread pitch appears different. I have had very good luck with time serts from 4m to 18m. I have used them in several mag and alum applications with no issues. So what am I missing?
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Life is Good! Have a Nice Day!-don't worry about the jerks out there on the forum, in the end... they fall, and fall hard!
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21510
Location: Oklahoma City
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| Posted: Thu Nov 24, 2016 2:46 pm Post subject: Re: Stripped tranny mount stud |
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| AXAM wrote: |
| Question. The ez loc and timesert look very similar. The thread pitch appears different. I have had very good luck with time serts from 4m to 18m. I have used them in several mag and alum applications with no issues. So what am I missing? |
I explained the difference in my last post.
Other than both being threaded inserts.....that is their onpy similarity. They are totally different in how they lock.
The EZ lok are a classic threaded insert available in three wall thicknesses and a wide rwnge of thread combinations some of the Time-Sert have a different external pitch but you can get them pretty much in the same ID and OD pitch for either brand. You lock them either by peening the bore opening so they cannot turn out....or with the high temp epoxy compound they come with on their threads....or both.
The Time-Sert....is locked into place by using a special tool to roll or distort the very bottom thread in the bore to form a "cuff" so that the insert cannot back out. While this sounds like a very positive lock and it is....it is very exacting to install and you MUST have the tool set or access to at least basic machine tools to install them right. If they are installed wrong....they will back out......which with any other threaded insert would be no big deal....but with a Time-sert.....that rolled thread will destroy all of the external threads on its way out. You may not get another chance to install a larger threaded insert if the insert is too oversized.
I use time-serts for sparkplug holes only. Ray |
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AXAM
Samba Member
Joined: November 02, 2003
Posts: 314
Location: Gods country,ca
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| Posted: Thu Nov 24, 2016 3:14 pm Post subject: Re: Stripped tranny mount stud |
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Thanks
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Life is Good! Have a Nice Day!-don't worry about the jerks out there on the forum, in the end... they fall, and fall hard!
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