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Triumph TR6 - Hub to Trailing arm studs

Well guys, I guess you could say I have got my self in to a fine mess!
While putting the driver side rear hub back on I ran nuts down the studs to pull the hub and brake plate back tight to the trailing arm ( not tight). I then proceeded to put the nylocks on with some 242 locktite. 2 of the 6 tightened to 14 lbs. ok. The rest...well...just using a 1/4" drive to snug them up before the torque wrench they just kept turning. I stopped and pulled the hub off. I removed the 4 studs and they brought with them a nice little coil of the trailing arm on the thread.
I do not think I am the first to have this happen. Soooo... any thoughts on repair would be appreciated. I would like to repair without having to remove the trailing arm. I have considered using metal epoxy. I re-tapped one of them and it is sloppy but with some epoxy (metal weld) it would hold???? I consider this only because we are only talking 12 lbs torque and this load is distributed across 6 studs.
I have also considered drill/tap larger hole then have a machine shop turn down and thread the outer part of stud to 5/16-24 proper thread.
All help appreciated.
Rick C
Rick Crawford

Hi Rick
If they are available in your part of the world 'Hellicoils' are the easiest solution for this type of problem. Baically the kit gives you a special tap & 20 or so steel threads. you tap the stripped hole with the special tap & insert the 'Hellicoil' with the tool supplied & your back in business
All the best Ron
r algie

Hi Rick,
You've opened Pandora's box now haven't you?
I've never used helicoils myself but I hear they work
great. Try installing one on a scrap piece of aluminum
first so to get the hang. You could also try drilling straight through, using a longer bolt and securing
it with a nut on the other end.
You could also drill slightly larger, tap a larger
thread and screw in a permanent stud with loctight into the trailing arm and then use a nut to hold on the brake back plate on.
Christopher Trace

Rick, Ron hit it on the head, use Helicoils or one of the other brands of thread repair kits available. You should find these available at most high quality parts stores, NAPA etc. They are available in the 1/4-28 thread pattern needed for these studs. Don't feel bad, this is very common and is sometimes caused by corrosion besides being over tightened. I have fixed many of these over the years with excellent luck. Basically the kit you buy will contain a specific oversized tap, a handful of thread inserts and the install tool. You will need to drill the holes out with a larger drill bit of the size noted in the kit and tap the holes with the kit tap. Then you just thread in the inserts with the tool until flush with the hub. Then you just install the studs as usual. What I normally do is also use some loctite or JB Weld while installing the studs for a bit of added security. Not a hard task. Steve
Steve Yott

Hey Rick- BUMMER
Don K.
DON KELLY

Hi All
Further to my earlier post I think the problem is caused by a bad design. I was always under the impression that a tapped hole in soft metal should be a course thread ie UNC and from memory I think it is 5/16 UNF. If going the Hellicoil way it might be worth putting in UNC Hellicoils and using UNC/UNF studs.Hope this makes sense Ron
r algie

Just did this, but as I could'nt match the thread locally, used 8 mm helicoils (virtually identical in size and strength to 5/16 UNF) with 8mm studs , all available from NAPA for a few bucks. Helicoils are actually far stronger than original threads in aluminum castings. Was able to cinch 'em down hard.Peter
Peter Gooch

Thanks guys
Well it looks like this is not as bad as I first thought. Ron, could not agree more...very poor design. It was so easy to "pull" them out using only 1/4" drive. Well The brighter side is that the hellicoil repair sounds like will be better than original. Also glad I found this now and not at 200KPH......;). Also Ron, I have seen the UNC/UNF (yes, 5/16") studs at local parts supply...he will have hellicoil also. JB weld will aso be used.
Ron and Peter, obviously the drill is larger than 5/16" for a 5/16" UNC hellicoil. My concern is that there will not be a lot of "meat" left around the hole after drilling...any thoughts or comments?
Thanks again guys
This thread is deffinitely one to remember for others who have the BUMMER thing happen to them.....an under statement Don.....
Rick C
Rick Crawford

Rick

I have Heli coil set. Will get back just on way out don't buy till I check think I have lots.

Bill
Bill Brayford

Hi Rick
My back wheels havn't fallen off----yet, so hopefully the metal is thick enough.
Ron
r algie

Rick

I have 5/16 UNF original heli coil part # 5402-5 special order 13 years ago with about 2 missing out of pack of 24 coils with drill, tap, inserter. Works perfectly I found way better than original. all industrial grade.

Bill
Bill Brayford

Ha Ron
Glad to hear the wheels have not fallen off:)
Well Mr Bill..... You are slightly late. Just got back from Ideal supply. Darn expensive...With tax $45.00 then went to Car Quest and got the 5/16" stud with what Ron said... one end NC (for the heli coil) the other NF both 5/16". The drill required is 21/64" so only slightly bigger.
My job for for tomorrow morning.
Will let yuall know how it goes. Thanks again and thanks Bill for the offer. One more special tool to collect dust.
Rick C
Rick Crawford

Well Mr. Speedy Rick. Off to the parts store faster than my wife shopping with a paid up Platinum card!!!

I'm slightly late???

I read of your problem this morning. Replied immediately saying don't buy should have lots.. Went over to the shop to double check on state and quantity of heli coils. Returned about 11:30. Replied I have lots,with all the goodies specificly for that job.. Top of the line O/E Helicoil stainless and they work.

Then thought Geeees better call him in case he doesn't look at this. Make long distance call To RJassoc.. Knocking off a little early for lunch there aren't you Rick? Leave message on answering machine. And pack kit in box to ship.

Continue trying to make a living. Come in for parts and to call you again lunch @2:30 or so and see this message.

Geeeees what do you want 9AM service. I don't see a call from Rick I don't see an e-mail from Rick. You got da number and da mail ana you no call the guy who has screwed up everthing at least once on a TR over the last 25 years.. No psycics here. :)

Anyway my opinion only don't use thread locker on Nylocs and low torque bolts. NF even old nylocs won't come loose in our lifetime. Anti-sieze only. I also don't recommend the cold weld stuff on disimilar metals.

Bill



Bill Brayford

UPDATE with success
Well I finally dropped the rear end off of the stands and she is happy to be on her back feet:)
My update is for future reference of this thread:
4 of the 6 studs stripped right out when first trying to tighten down the hub. All was removed and got the heli-coil inserts 5/16-NC. With a 21/64" drill I got a piece of rectangular 1x2 tube steel...purpose to make a "guide" for straight drill of the trailing arm holes. Well the holes where not dead straight after installing the heli-coils and studs. The hub would not go on. I removed 3 of the studs and the hub would go on. With the hub in place the studs would screw in easily. After discussion with Bill, I decided to use 1-1/4" NC bolts instead of the studs for these 3 holes. I got 3 inside star washers and applied 242 to the threads. All the stud nuts and bolts are torqued to 18LBS. This is much better than original. I am almost tempted to do the other side of the car this way.

You might recall the whole purpose of the removal of the entire rear end was because I had a "clunk" when engaging reverse gear ( I also wanted to replace the u-joints just incase). WELL the clunk is gone after doing the reinforcment plates to the front dif supports. Thank you again Dr. Bill for the plates, they fit perfectly..( my son did the welding ..did not have to get dirty at all:)
Talk about a lot of extra work but I now know the rear end is solid!
Thanks guys
Rick C
Rick Crawford

This thread was discussed between 15/05/2003 and 24/05/2003

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