Stripped Threads
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Stripped Threads
I stripped the threads inside the alluminum carrier. This was the smaller of the three bolts that hold the spring in place. It's a 12MM size bolt. What are my options? I thought about drilling it larger and retapping with 14mm but that's a huge bolt. I thought of filling the whole with JB weld and retapping it.. you know.. bubba it.. but that doesn't make me feel good.. The guy at the hardware store said he thought they made a repair sleeve.. Anyone ever use one.. Any help or options appreciated.. :cheers:
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Stripped Threads (Koz)
They are called Heli Coils. The hole is drilled a small amount bigger, then tapped with a special tap then a steel insert is screwed into the hole. The insert has the same theard as original so the oringinal bolt can be used. This is a common repair for stripped threads or for reinforcing a thread in aluminum.
You need a complete kit or take it to a machine shop that does this.
You need the helicoil tap, the proper drill, the heli coil itself and the installation tool
Good luck
[Modified by norvalwilhelm, 8:07 AM 4/17/2003]
You need a complete kit or take it to a machine shop that does this.
You need the helicoil tap, the proper drill, the heli coil itself and the installation tool
Good luck
[Modified by norvalwilhelm, 8:07 AM 4/17/2003]
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Re: Stripped Threads (Gordonm)
Thanks. So I called the local shop.. It's the newest of three private parts stores in my area.. He's got one kit in stock.. $69.. but needed to know the thread.. pitch..? Casue he only had one in stock. Told him I'd stop down with the bolt. Then I decided to call one of their other stores. He had two in stock.. 175 and 125.. for $49. It's the same owner of all three stores and a $20 difference in kit price.. Go figure.. Would anyone know the pitch for these bolts.. I keep saying pitch but I'm not sure that's the right name for it.. I plan on matching it up to the bolt befor buying but if it's not a 125 or 175 then I'll continue to call around.. maybe their third store.. :lol: Thanks!
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Re: Stripped Threads (Koz)
I recently made this exact repair to a 80.... I got the kit and the long inserts from McMaster Carr. I used the "long" inserts instead of the standard inserts to achieve maximum thread engagement. The kits usually come with the standard inserts (.5).
Sometimes they can be doubled up or "stacked" if necessary... depends on the original thread depth.
The inserts are dirt cheap... the tooling is expensive.
Sometimes they can be doubled up or "stacked" if necessary... depends on the original thread depth.
The inserts are dirt cheap... the tooling is expensive.
Melting Slicks
Joined: Aug 2001
Posts: 3,039
Likes: 121
From: Wichita KS
Re: Stripped Threads (Koz)
I had a machine shop do my 1980. One (long) bolt had snapped off flush with the surface of the carrier so it had to be removed. The other long bolt had damaged the carrier threads. Removal of the snapped off bolt and Helicoils for both (long) bolts was around $100.
The long bolts are M12 x 1.75 x 90, the short bolt is M12 x 1.75 x 30. (1.75 threads per mm)
A 14mm bolt might throw off the alignment of the spring, and the JB weld (great stuff) is not appropriate for this application (suspension component).
I chose to have a machine shop do mine given that the bolt had to be removed, the cost of the heli coil kit, and the fact the kit would not likely ever be used again.
The long bolts are M12 x 1.75 x 90, the short bolt is M12 x 1.75 x 30. (1.75 threads per mm)
A 14mm bolt might throw off the alignment of the spring, and the JB weld (great stuff) is not appropriate for this application (suspension component).
I chose to have a machine shop do mine given that the bolt had to be removed, the cost of the heli coil kit, and the fact the kit would not likely ever be used again.
Guest
Posts: n/a
Re: Stripped Threads (Tom454)
Where do you buy the long inserts. I questioned this and the guy didn't suggest anything longer.. Just my luck. Your right, the kit came with 6 shorties.. How long is a long? I need to use this on the short bolt.
Now I'm trying to find a 31/64 drill bit.. The auto parts place didn't have one and Homey Depot doesn't sell that size either..
Now I'm trying to find a 31/64 drill bit.. The auto parts place didn't have one and Homey Depot doesn't sell that size either..
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Stripped Threads (Koz)
31/64th is a very common drill size and I just looked in my box of drills and it is part of a complete set. Any drill set up to 1/2 inch should include this drill bit.
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Melting Slicks
Joined: Aug 2001
Posts: 3,039
Likes: 121
From: Wichita KS
Re: Stripped Threads (Koz)
Where do you buy the long inserts. ... Now I'm trying to find a 31/64 drill bit.. .....
Is the differential carrier on or off the car? Easier to work on if it is off the car. The Dana differential carrier on my 1980 was easy to remove. (Unlike the carriers on earlier cars, as indicated by some threads on this forum.)
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
'll send the link to you.
Check here for the long inserts... I think they have 3 different lengths in the 12-1.75 size.
http://www.mcmaster.com/
This is not a "Corvette Supplies" vendor that competes with our supporting vendors, so maybe I can post it without fear of retribution. If it gets wiped out, just email me and I'll send the link to you.
Select Helicoil inserts and then "standard" inserts, and size etc.
[Modified by Tom454, 1:56 PM 4/17/2003]
http://www.mcmaster.com/
This is not a "Corvette Supplies" vendor that competes with our supporting vendors, so maybe I can post it without fear of retribution. If it gets wiped out, just email me and I'll send the link to you.
Select Helicoil inserts and then "standard" inserts, and size etc.
[Modified by Tom454, 1:56 PM 4/17/2003]
Guest
Posts: n/a
Re: Stripped Threads (mapman)
Thanks.. I found the bit at a local hardware store. The wife is picking it up now.. :D I'll check my set when I get home. Maybe I'll get lucky and can save the $18 on the new bit..
The carrier is back in the car. I was installing the spring after redoing the whole back end.. and I really don't want to pull it out again. I had to tap one of the long front bolts that broke when I was replaceing the spring last year. I did it while it was on the car so I'm hoping this will be as easy.
Thanks Tom454.. I'm going to try a few local places first and if not available I try online. The bolt is not that long so the short inserts just might work.
Thanks! :cheers:
The carrier is back in the car. I was installing the spring after redoing the whole back end.. and I really don't want to pull it out again. I had to tap one of the long front bolts that broke when I was replaceing the spring last year. I did it while it was on the car so I'm hoping this will be as easy.
Thanks Tom454.. I'm going to try a few local places first and if not available I try online. The bolt is not that long so the short inserts just might work.
Thanks! :cheers:
Guest
Posts: n/a
Re: Stripped Threads (Koz)
I just wanted to close this out in case someone else searches the archives in the future. Helicoil did the trick. Real easy to use and holds better than original threads.. Autoparts store had the kit.. tap, coils, and coil insert tool.. Had to buy the drill bit seperately. I found longer coils at a local store but I could have doubled up the smaller ones that came with the tool. IM if you want more info.. Thanks to everyone for your help! :cheers:
Melting Slicks
Joined: Oct 2001
Posts: 2,062
Likes: 1,360
From: Halifax, Nova Scotia, Canada
Re: Stripped Threads (Koz)
Sorry, coming in late on this thread. Just some additional information.
A helicoil does a great job.
However if you need "extra" strength in repairing a damaged hole, Timesert makes a great product. http://www.timesert.com
Stronger than a helicoil, however, more expensive.
Thanks, Barry
A helicoil does a great job.
However if you need "extra" strength in repairing a damaged hole, Timesert makes a great product. http://www.timesert.com
Stronger than a helicoil, however, more expensive.
Thanks, Barry