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Hub Mounting Thread Stripped

Moss Motors
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kayjh Joel K
Winnipeg, MB, Canada   CAN
Hello All,

So, I was putting my hubs and half shafts back in today and unfortunately, one of the studs in the aluminum swingram is stripped. I don't ever recall over tightening this nut, but in any event, it will need a thread insert. All of the rest of the studs are fine. I've never done this type of a repair before.

Can anyone tell me what size and thread the stud is, what size helicoil I'll need and what size I will need to drill the new hole to insert the correct helicoil?

Ideally I'd like to just fix this one hole and leave doing all of them for a winter project. Do I need to remove the brake backing plate to do this or can I do the repair with it in place?

If I get a list of what I need, hopefully I can collect everything at local parts store tomorrow afternoon and have the car back together by evening. smiling smiley

Thanks,

J

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poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
5/16-24 (.469 long) helicoils with a 7/16-14 bottoming tap and a 21/64" drill bit will get it done.



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Edited 1 time(s). Last edit at 2018-05-25 09:59 PM by poolboy.

kayjh Joel K
Winnipeg, MB, Canada   CAN
In reply to # 1535850 by poolboy 5/16-24 (.469 long) helicoils with a 7/16-14 bottoming tap and a 21/64" drill bit will get it done.

Thanks. Do you know if there is a Helicoil kit for that size?

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poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
There is at NAPA AUTO PARTS, down here in the US.



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kayjh Joel K
Winnipeg, MB, Canada   CAN
In reply to # 1535858 by poolboy There is at NAPA AUTO PARTS, down here in the US.

Thanks. I’ll try my local Napa store tomorrow. It’s helpful to have the correct size information. Is this a common problem? The hub has only been removed once before and I torqued to spec.

poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
The car is over 40 years old so the chances of stripping at least one of those threads might be on the high side, depending upon precautions taken or not by previous owners...
I pull my hubs out about once a year so I can grease the splines and outer U-joint, so even though none of the threads were stripped I went ahead and preemptively installed keenserts... I do have a helicoil kit supplied by the previous owner, but between 3 of us TR6 owners at a Tech session we opted for keenserts and went that route.



ZS carb repairs
kencorsaw@aol.com



Edited 1 time(s). Last edit at 2018-05-25 10:50 PM by poolboy.

DeepSix Avatar
DeepSix Silver Member Paul Vovk
Omaha, NE, USA   USA
1974 Triumph TR6 "DeepSix"
I bought the Helicoil kit from Amazon. Came with 12 inserts. I ended up doing nearly all of them even though I started with the idea of only doing the two that didn't even have studs installed. Also bought the bit from Amazon. Was very easy to drill, tap, and install without a jig even though that was my first time. Also, don't overtorque the nuts when you put it back together. I had the brake baking plates off as I disassembled everything to replace TA bushings. Probably could do it with brake plate in place.

kayjh Joel K
Winnipeg, MB, Canada   CAN
In reply to # 1535872 by DeepSix I bought the Helicoil kit from Amazon. Came with 12 inserts. I ended up doing nearly all of them even though I started with the idea of only doing the two that didn't even have studs installed. Also bought the bit from Amazon. Was very easy to drill, tap, and install without a jig even though that was my first time. Also, don't overtorque the nuts when you put it back together. I had the brake baking plates off as I disassembled everything to replace TA bushings. Probably could do it with brake plate in place.

Thanks. I’m going to try and find a kit locally today as I’d like to get the car back on the road. I’ve found a listing for the helicoil size PoolBoy posted, but that supplier is closed today, so I’ll look around this afternoon. Do you know if the brake backing plate can be removed and tied out of the way without disconnecting the brake hose?

I think the most difficult part of this might be getting the new Moss Motirs hub back out. The original one slid back onto the studs on the driver’s side as easily as it came off, but the Moss part didn’t want to slide on easily on the passenger side and I moved it into position by tapping it down (lightly) and then tightening the the nuts on the hub studs to draw it towards the backing plate. It didn’t take mutch but I’m thinking it will need to be pried back off, or better, a hub puller tool to help it off.

And I was so close to getting this job finished. smiling smiley

DeepSix Avatar
DeepSix Silver Member Paul Vovk
Omaha, NE, USA   USA
1974 Triumph TR6 "DeepSix"
On mine, the brake line connected to the wheel cylinder is a non-flexible hard-line. Therefore, I'm more doubtful that the brake backing plate can be removed without disconnecting the brake line, but I'm not sure. When I removed the brake backing plates, the brake lines to the wheel cylinders were already disconnected as I was also replacing the rubber brake hoses (one of them was plugged, causing that rear brake to stick). I think if you are able to remove the hub studs first, you would have a better chance of removing the backing plate.

poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
I mentioned that tech session where 3 of us installed keenserts; FWIW, none of us needed to do anything related to the brakes...Once you remove the hub and if you can see the 6 holes in the TA, you can perform this procedure.



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Krom Avatar
Krom Paul K
San Rafael, CA, USA   USA
While the brake backing plate is directly connected via the wheel cylinder to a metal brake pipe, the metal pipe itself should be connected to a flexible brake hose which affords the ability to lift the brake plate clear of the studs. You can secure it out of the way with string or coat hanger while you work on the trailing arm.

Jamesburg, NJ, USA   USA
Hey Joel, the same thing happened to me. The helicoil is the key. My advice is the check them all and make sure you use the correct torque settings when tightening the bolts.

Nemo74 Avatar
Nemo74 Emile Bergeron
Falmouth, MA, USA   USA
I too had it happen, but I didn't use Helicoils. I drilled and tapped
the holes to accept 3/8-16 bolts. The coarser thread is actually
better in aluminum than the UNF studs that are installed. The
brake drum does not have to be removed but backed out to
give the 3/8" clearance drill someplace to go without drilling in
to the casting. Then drill the casting with the right size tap drill,
tap and you're good to go.

Emile

jimboga8730 Avatar
jimboga8730 Jim Doran
Gainesville, GA, USA   USA
Regarding the correct tap for a 5/16-24 Heli-Coil, the tap is a 5/16-24 STI (screw thread insert) tap, not a 7/16-14 tap. STI taps cut a larger thread to accommodate the Heli-Coil’s wall thickness and maintain the same pitch, in this case 24 threads per inch. It’s usually best to buy a kit (5528-5) which includes the inserts, STI tap (plug style) and the installation tool. The correct drill size (21/64” in this case) is noted on the kit packaging. With a fine thread insert installation is easier with the prewinder style tool included in the kit. Coarse thread inserts don’t require a prewinder style tool.



1980 Triumph Spitfire 1500

kayjh Joel K
Winnipeg, MB, Canada   CAN
Thanks, on my way to pick up this exact kit now. Help is much appreciated

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