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TR2/3/3A Brake caliper brake pad retaining plate bolt hole?

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karls59tr

Obi Wan
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The bolt hole is stripped out and the plate went missing. Has anyone had to re tap this hole and remember what size tap they used?I imagine I have to go one size bigger than the original bolt? Anyone tried to fill the hole with JB Weld epoxy and then tap the hole to the original bolt size? Guess I'm asking what is the best way to do the repair?
 
My preference would be a helicoil or at least tap it out for a larger size. However, the brake caliper is very hard, and you probably would need carbide tools to do that. Big $$$.

For a noncritical, low-torque application like this, you can use an epoxy thread-repair kit.


You clean the hole, smear in the epoxy, apply the thread-release compound to a screw, and carefully thread it in. Then wait for the epoxy to set up, remove the screw, and you have a decent new hole. I've used one of these a couple times, and while it's totally unsuitable for anything that has to be torqued much, it should be OK for what you are contemplating.
 
karls59tr said:
What size helicoils did you use? Never installed a helicoil ....is it a fairly straightforward process?I
Click to expand...
I don't recall what size, but I would just use one size up from the existing bolt. The helicoil kit includes a drill and tap, and an installation tool. Very simple. Just drill the hole out, tap it, put the insert in, and tap the tool with a hammer to break off the tang.
 
You will need the correct helicoil drill and tap also the insertion tool. The tool is a bit like a piston ring compressor in that it compresses the helicoil down to the hole size. Then just wind the helicoil in to the newly threaded hole.
When the end of the helicoil is below the surface you need to break off the tang at the bottom of the hole.
Check on you tube I am sure you will find videos to show the process,

David
 
The bolt is 1/4 28 (Type 2 caliper although I think the others are the same). Buy your Helicoil (a brand name for thread repair insert) in that size. The drill size, usually included, is of course larger as is the tap, which is also included. The drill and tap sizes are critical so I use the kits that include them.
The caliper is cast iron or cast steel and not particularly difficult to drill and tap. Use cutting oil and go slow and gently as it's a pain if you break the tap.
Tom
 
TomMull said:
Buy your Helicoil (a brand name for thread repair insert) in that size.
Click to expand...
This is correct. My earlier comment to use a bolt one size up was wrong.

You could just tap the hole one size up and use a bigger bolt (no Helicoil), but the Helicoil is generally the better solution.
 
Always an option.

Tom
 
Epoxy loses strength with heat, as does JB Weld. I'm not sure I would use anything on the brakes that loses strength with heat.
 
I would try and tap the existing hole with a new blunt end tap the same size and go slow, may an 1/8 of a turn at a time then back up and turn out the cutting. I have done that on rocker pedestals on heads. Some of the old threads might true up and you might get a couple more towards the bottom and perhaps get a bolt about 3/16 longer for the last threads. It should not take much to hold that clip.
 
Exactly. I have had steel brake discs glowing red...how hot would that be? Plus, all polymers lose strength at any elevated temp. 500 is just the point where they decided it was still "strong enough". The question is, "strong enough for what"? You can use it if you want...I'm just saying I would not want to ride in a car with the brakes held together with JB Weld. But that's just me.

The entire plate is not that expensive, here is one on Ebay for barely more than a Heli coil kit:

www.ebay.com

Triumph TR3 Brake Mounting Plate Left side | eBay

Find many great new & used options and get the best deals for Triumph TR3 Brake Mounting Plate Left side at the best online prices at eBay! Free shipping for many products!
www.ebay.com

I'd just OBO this guy and never worry again.
 
CJD said:
Exactly. I have had steel brake discs glowing red...how hot would that be? Plus, all polymers lose strength at any elevated temp. 500 is just the point where they decided it was still "strong enough". The question is, "strong enough for what"? You can use it if you want...I'm just saying I would not want to ride in a car with the brakes held together with JB Weld. But that's just me.

The entire plate is not that expensive, here is one on Ebay for barely more than a Heli coil kit:

www.ebay.com

Triumph TR3 Brake Mounting Plate Left side | eBay

Find many great new & used options and get the best deals for Triumph TR3 Brake Mounting Plate Left side at the best online prices at eBay! Free shipping for many products!
www.ebay.com

I'd just OBO this guy and never worry again.
Click to expand...
We are talking about the 1/4" bolt (Moss # 322-170) that holds the pad anti-rattle retaining plate & spring. What was wrong with the braking system on your car that would cause the brake discs to glow red?
 
I was a brand new 15 year old driver, trying to be smooth with the grandparents on board. I road the brakes until they went away! I remember standing with both feet as hard on the pedal as I could, but no braking at all. When I got stopped the brake discs were cherry red!
 
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