Brake Caliper bolts

[Nev]

Twice now I've found my brake calipers to be slightly loose and allowing some movement. This is where the caliper fixes to the lower landing gear around the axle. There are 3 bolts installed there, which is probably less than optimum, but at the time I couldn't see how to add more. The access is quite tricky in that area.

Does anyone have advice on how to solve this issue ? Part of the problem is that gain full access (and tighten the bolts) the wheel and brake needs to be removed. Has anyone welded the nuts in place - is that even an option ? Or Loctite ?

Any advice appreciated.

[DBeaulieu]

Nev, if you got elastic lock nuts there, try using all metal locknuts?

[Nev]

Good suggestion. I'll check what I've used.

[geraldmorrissey]

Without seeing it, just a guess, drilled head bolts, safety wire and lock nuts?

[jaredyates]

I would also want to verify that the bolts are getting loose by turning and not by some other means. Safety wire would determine that.

[Steve W]

I would try and get a fourth bolt in too. Not aware of only three bolts on a calliper plate. Only have ever seen 4. Just sayin.
I would imagine that the plate is flexing under load with only the three bolts there.

[Nev]

That's a good point Steve. From memory the bolt pattern suited either 3 or 6 bolts. Can you see any issues with 3 in a triangular pattern, and a fourth ad hoc?

[Steve W]

If you have an issue with loosening bolts and there are provisions to apply 6, I’d use 6. I think you’d get some twisting even though it’s all in shear, I believe it would deform or move with 3. Not fully aware of what your mission is, big tires, double puck callipers, heavy braking stol etc. Some calliper plates have a number of clocking positions available but I thought the attach ring or washer welded or bolted to the axle assembly had 4 holes.

[kestrel]

I would also want to verify that the bolts are getting loose by turning and not by some other means. Safety wire would determine that.

Torque seal?

[Battson]

I think the Bearhawk book used to say "install at least 3 bolts for single puck, and at least 4 for double puck".

Some Grove brakes came with shims for smaller bolts - don't use those shims if you have them. Use the largest size bolts the holes allow for, naturally.

It's not pretty, you just have to use whichever holes you can get to, and modify the bolts to suit. You'll probably need to grind down the nuts to get them to fit, several of the nuts on mine are missing large parts of the nut body and even some of the thread, but they have never come loose. I have removed and reinstalled them a few times over the years, just reusing the same old nylock nuts.

Metal locking nuts could be a good idea, as suggested by @DBeaulieu, they are generally a bit smaller?

[Nev]

Good advice, I'll see how many more bolts I can get into place.

[Nev]

I completed this task today and added two additional bolts to each brake caliper, and torqued all bolts to spec with a little Loctite Red on a couple of them for good measure. Not sure why it wasn't obvious to do this during the build (It was the one of the first jobs when I started building). Adding the extra bolts was very easy. To do this I first welded up an extended shank drill - I wish I'd thought to do this the first time around. Then after drilling from the axle side I reamed the holes from the inside. So now with 5 bolts each side I'm hoping the issue will disappear.

Thanks to those who replied above with suggestions, much appreciated.

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[spinningwrench]

A little too late for you but I managed to get four bolts in my brake mount. The two AN4 bolts I tapped into the backing plate as well as adding nuts. Hopefully this will keep things from moving around.
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[Nev]

That's a good way to do it.

[svyolo]

I seem to remember the manual said either 3 of the larger(6), or 4 of the smaller(5) size bolts. I just looked and I have two of each per brake. One of them per brake was a very tight fit.