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Cross threaded and need to fix...HELP!!!!!!

firstgear

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Oct 11, 2003
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1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED
I was adjusting my front suspension for the caster, camber and toe in and found a way to bugger up the threads on the upper a-arm attachment point. It is so buggered up that the first three threads are a total mess and I can't get a tap started.

I can't go in the other way because when the part was fabricated the threaded holes at each end were started from the ends and not through.

I almost feel if there was a thread chaser that I could collapse and insert past the bad section that I could then thread it back out and cut the threads cleanly again.

Anyone got any ideas on what could be done????

regards, Herb
 

firstgear

Well-known member
Joined
Oct 11, 2003
Messages
1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED

firstgear

Well-known member
Joined
Oct 11, 2003
Messages
1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED
helicoil is probably my next to last thing I will try. the thread is 5/8-18
that backtap is exactly what I need if I can find the size.....
 

henny496

Well-known member
Joined
Jul 27, 2004
Messages
318
Location
Beaverton Ontario
Corvette
1963 Corvette coupe(pro street)
Hello Herb
How much thread engagement does the other side have in total?? Can you take the shaft out of the car?
You can drill out the first few threads(5/8 drill) and then tap it deeper, or try to get a bolt and cut a slot on one side going 90* to the threads, so when you run it in, it acts like a tap. Does it have a chamfer on the shaft. You want one anyway, for this very reason
Many times at work we drill out the first threads , it has to have some type of lead in on the shaft anyway. You need 1 to 1.5 times thread engagement, so see how far the bolt is engaging on the good side
Send me an e-mail, or phone me if you wish
take care
Tom
Tom
 

firstgear

Well-known member
Joined
Oct 11, 2003
Messages
1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED
Hello Herb
How much thread engagement does the other side have in total?? Can you take the shaft out of the car?
You can drill out the first few threads(5/8 drill) and then tap it deeper, or try to get a bolt and cut a slot on one side going 90* to the threads, so when you run it in, it acts like a tap. Does it have a chamfer on the shaft. You want one anyway, for this very reason
Many times at work we drill out the first threads , it has to have some type of lead in on the shaft anyway. You need 1 to 1.5 times thread engagement, so see how far the bolt is engaging on the good side
Send me an e-mail, or phone me if you wish
take care
Tom
Tom
you have mail.....

Also, how close does close need to be for caster and camber settings?
 

henny496

Well-known member
Joined
Jul 27, 2004
Messages
318
Location
Beaverton Ontario
Corvette
1963 Corvette coupe(pro street)
Hello Herb
You asked about caster/camber. Are you taking this to a front end shop for alignment purposes afterwards?
To check it yourself would require you to take the springs off and run the suspension through it's travel. I am not sure if you have any stock car friends with a bump gauge, but if not, a front end alignment shop should be able to help you out
If you had a level you could set it on the side of the front rotor while running the suspension up and down(w/o springs) If you have a digital level you can check the caster while the car is at ride ht
I kind of made a bunch of pcs for mine(custom) so I set things up with a digital level, but I probably still will take it to a front end shop
I am sorry if I have missed pics of the front suspension of your car, if they have been posted. I would like to see a pic if you can post one
It does sound like you are making lots of progress
take care
Tom
 

SPANISHVETTS

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Nov 5, 2002
Messages
1,143
Location
El puerto de Santa Maria Spain
Corvette
before 60,63&82 now 90 383 Stroker & 91 ZR1-Sold
The Back-Tap is only available in 10, 12, 14 & 18 MM. Looking at the picture I think that you could make one. Start with a hi-quality tap. Bore it to about 80% of its diameter and slice a cut down its length wide enough to compress it smaller than the ID of the threads to be chased. If you do not to bother with making one you could use a left handed bolt with a bushing for the mandrel.
The hardest part of the job will be to get the tap to set into its new smaller size. This will take heat and could destroy the temper of the tap. I am thinking the best way would to taper bore an old piece of round stock starting with original diameter of the tap and tapering down to the compressed size that you want the tap to be and then taping it until the tap is completely compressed. Remove the tap, super freeze the round stock, thread the tap back in and heat the back end of it until it is nice and red.

I do not have a clue if this will work but I am going to try to make one on the next rainy day.
 

firstgear

Well-known member
Joined
Oct 11, 2003
Messages
1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED
The Back-Tap is only available in 10, 12, 14 & 18 MM. Looking at the picture I think that you could make one. Start with a hi-quality tap. Bore it to about 80% of its diameter and slice a cut down its length wide enough to compress it smaller than the ID of the threads to be chased. If you do not to bother with making one you could use a left handed bolt with a bushing for the mandrel.
The hardest part of the job will be to get the tap to set into its new smaller size. This will take heat and could destroy the temper of the tap. I am thinking the best way would to taper bore an old piece of round stock starting with original diameter of the tap and tapering down to the compressed size that you want the tap to be and then taping it until the tap is completely compressed. Remove the tap, super freeze the round stock, thread the tap back in and heat the back end of it until it is nice and red.

I do not have a clue if this will work but I am going to try to make one on the next rainy day.
thanks for the suggestion, I was thinking the same thing....however the damage has been done on the threads and after talking with Jim Meyer Racing it was agreed that the best solution was to take out the damaged threaded tube and replace it with a good one. So I will cut out the existing tube and weld in the new one and not ever look back again. I had visions of the front end coming apart after hitting a big bump and then in the ditch.

Thanks everyone, I appreciate the comments from everyone!

regards, Herb
 

firstgear

Well-known member
Joined
Oct 11, 2003
Messages
1,895
Location
Norwalk, Ohio
Corvette
15 Z06, 01 Vert, 63 SWC & 60 ALL RED
Hello Herb
You asked about caster/camber. Are you taking this to a front end shop for alignment purposes afterwards?
To check it yourself would require you to take the springs off and run the suspension through it's travel. I am not sure if you have any stock car friends with a bump gauge, but if not, a front end alignment shop should be able to help you out
If you had a level you could set it on the side of the front rotor while running the suspension up and down(w/o springs) If you have a digital level you can check the caster while the car is at ride ht
I kind of made a bunch of pcs for mine(custom) so I set things up with a digital level, but I probably still will take it to a front end shop
I am sorry if I have missed pics of the front suspension of your car, if they have been posted. I would like to see a pic if you can post one
It does sound like you are making lots of progress
take care
Tom
yes, I will take it to a shop to get it sorted out. I want to get it as close as possible first.

Herb
 

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