Helicoils on Brake Calipers

[ZXR400H]

Hi all,

Interested in wether it would be deemed safe to helicoil the caliper threads for the mounting bolts to the forks as the threads in one of my calipers is weak, and replacement calipers are expensive and I dont want to spend out more than I have too if it is safe to helicoil the threads.

Thanks in advance!

[gavinfdavies]

the bolts will be taking lateral forces, so i don't think the helicoil would be a problem. 2 other options spring to mind; 1) simply tap the hole one stage larger then expand the fork hole to take the larger bolt (downside is that you irreversibly alter the forks), 2) use a slightly longer bolt and put a seperate nut the other side to clamp it (downside = clearance ?)

[Mori Man]

These are the chappys to use:

http://www.timesert.com/

Helicoils are shite IMHO , I have had them rip out of cam cap repairs ! The most resent was a repair on my clutch lever bracket - not high tension or any force and the bolt stripped the fooker out ! Never again - threw the kit in the bin which I seem to remember doing some 17yrs ago, doh! :smt013

Timeserts have never failed me yet and would not recommend any other repair other than these ..... on my GPz the cam bolts were getting dodgy and I finally drilled out all the threads and inserted these - stronger than the original soft aluminium alloy threads as your putting in a stainless tube with thread


MM!

[ZXR400H]

Thanks for the replies guys, I'll bear those inserts in mind but ive struck lucky as a new bloke at work is lending me some GSXR K1 calipers to get me out trouble for now. As for the inserts I will deffo source some for a few other areas on the bike!

Thanks once again!

[gavinfdavies]

thought I'd reserect this post due to new information...

it seems that Rolls-Royce Aerospace, makers of the most reliable engines in the world, use helicoils in all holes where steel bolts are going into ally base material. This is to stop the hard bolt threading the softer ally. I know this because I now work there jet powered zxr anyone...?

Considering your experiences MM, I'm guessing our helicoils are of a superior quality to the ones publicly available.

[Mori Man]

I also think domestic repair is a country mile away from industrial precision engineering

ALthough they are using them for the same reason that alloy threads are chocolate club.

MM!

[gavinfdavies]

true, but the principle is the same - ie dril to 7mm, thread for this size, fit helicoil to take an M6 bolt. I believe the helicoils themselves are the same. I'll ask.

That said, some of the bolts we use are silver plated. no really!

[Mori Man]

Silver is a great electrical and thermal transmitter, guessing that will be some of the reason.

Thing is they most likely use a tap that costs more than my months wages to cut the 7mm thread , never mind how much the drill bit cost to make the 6.8mm hole

Now , if they buy Halfords Pro sets - I will eat my hat !

[gavinfdavies]

I'm on placement in one of the manufacturing areas at the moment. Most drill bits are HSS, a few critical ones are coolant channel drills (there are two coolant channels pumping coolant down inside the drill to the tip), most are pretty cheap. well, not £100's per bit anyway.