fork clamp bolt sizes

[dazm]

Hi,

Anyone know the correct sizes for the bolts and studs for the fork clamps on a 78F2?. Or better still, can anyone point me in the direction of somewhere to purchase replacement stainless hex headed ones?

Many thanks daz

[MarkCR750]

I'd be wary of using stainless bolts in clamps unless they are stainless as standard, high tensile steel bolts are usually used in such applications, David Silver spares will sell you original Honda bolts for pence, I just got a a set of brake arm bolts for about 70p each from him, not stainless but plated they shouldn't rust for a few years.

[MarkCR750]

True, I could be wrong about HT, I was in a bolt suppliers recently, the owner is restoring Z1, someone came in and asked for stainless bolts for his brake callipers, the owner wouldn't sell him any, he said stainless is to soft, that said I guess there are different grades of stainless etc and maybe it would be ok in fork clamps, I would just use original standard bolts myself in safety related applications.

[Trigger]

There is 2 basic types of stainless A2 and A4. A2 are very soft but, polish up nice.

[neilb]

If you want to be sure and have your mind at rest go for a grade 8.8 carbon steel bolt, probably get them from screwfix. They will be marked on the bolt head.There isnt really any tensile loading on a fork clamp so a stainless A2 or A4 would probably be ok.

[Trigger]

There is tensile load on fork clamps. Think of the load if you hit a pothole at 50mph. The weakest points of a bolt is in the stressed area in the thread root. It is all down to the type of thread ie, coarse threads are used for clamping and fine threads are weak.Stress area of a bolt are calculated to the number of threads per inch. 

[neilb]

The bolt itself does not stop the fork stanchion sliding through the yokes, its down to friction between the stanchion & yoke. If you could grip it enough with a jubliee clip (bit extreme !) it wouldnt move. Not sure where your going with the thread sizes, I work on marine engines with power in excess of 30000 bhp, and our cylinder head studs are very fine thread, certainly not metric or bsw !

[Trigger]

Your be using HT grade 8 then.

[neilb]

if you like

[Trigger]

What size are the bolts on this 3000bhp engine. Love to know so i can work out the tensile strength.

[neilb]

30,000 bhp, is this what you do on your night off?!

[Trigger]

Opp's missed a 0 out. 

[neilb]

is this the 5 minute argument, or the full half hour !

[Trigger]

who mentioned argument? I know nothing about marine engines, apart from they must be diesel. But i know a lot about tensile strength and motorcycle engines. 

[neilb]

I think we're detracting from the original topic here !, still no takers on my k2 !