Anybody got a fork link bolt they could measure please

[grumpar]

Hi anybody have a loose fork link bolt that takes the lock washers nicely that they could measure for me i've got some stainless steel ones in mine but there too short to take the washer cheers

[dickie]

Perfect timing.
I'm just cleaning the garage and stumbled across one.......


It's 50mm excluding the hex head. 10mm threaded.

[drivera]

Just measured one , 36mm of shank and 15mm of thread

[dickie]

Just measured one , 36mm of shank and 15mm of thread

You've got 1mm more and you think that makes you the man. Well I've got news for you..... It's how you use it that counts.

[drivera]

I know

[grumpar]

Thanks mines 51mm 36 and 15 more problems these forks are really starting to piss me off now i will probably have to have some made

[dickie]

Thanks mines 51mm 36 and 15 more problems these forks are really starting to piss me off now i will probably have to have some made

Eh? I don't get it. You have 1mm more than me and 5mm more thread and mine were fine in my forks.

What do you mean by "lock washers"? There should be one star washer per link and a plain washer on the right side only as the cable guide does the job on the left leg.

[grumpar]

Thanks mines 51mm 36 and 15 more problems these forks are really starting to piss me off now i will probably have to have some made

Eh? I don't get it. You have 1mm more than me and 5mm more thread and mine were fine in my forks.

What do you mean by "lock washers"? There should be one star washer per link and a plain washer on the right side only as the cable guide does the job on the left leg.

Your quite correct just these forks i have Eibar li150s series 3 are wider than the normal the 51mm comes flush with the nut without a washer or anti shake washer the side with the very thin cable guide the bolt is not coming through the nut . ive ordered some 60mm bolts anti shake washers and plain washers in stainless steel all under 10 quid just have to polish them myself

[drivera]

Have you tried tightening them to the correct torque to see if the fork boot compresses a bit , they are only a 3 sided box section so can compress a tad ?

[grumpar]

Have you tried tightening them to the correct torque to see if the fork boot compresses a bit , they are only a 3 sided box section so can compress a tad ?

Hi just striped one out and put the caliper gauge on it. The bolts only 48mm i have 43mm overall across the fork including powder coat the nuts 6mm and the cable clips 1mm Total that's giving me 50mm a old anti vibration washer i have that has already been compressed is 1.5mm say 1mm compressed would give me the 51mm nut to end of the bolt which would be exact I think that's the size of yours but i'm working with stainless steel re manufactured parts so chances of it all working is unlikely. i've ordered some bolts at 60mm and 55mm so should have a couple of mm spare that i can rework before polishing them.

[dave411]

Is the tensile strenght of the stainless bolt the same,or greater,than the original?

[dickie]

Is the tensile strenght of the stainless bolt the same,or greater,than the original?

I don't mean to be a pedant but the important thing here is really shear strength. I don't know the original grade, but I doubt it would be an 8.8.

Assuming it was 8.8 though, that would have shear strength around 3.5 tonnes whereas an a4-70 (good but not exotic) is about half that.

Now that may make you think it's no good but how do you think you're going to put nearly 2tonnes through each of those bolts? Normal safety factor for this type of application is 3 so even allowing for shock loads, you could happily put 300kg through each of these bolts if they are a4-70.

I'd suggest that they are that diameter primarily because they act as a shaft for the link bush to turn on.

[HxPaul]

If you use longer bolts make sure that the tyre valve doesn't hit the end of the bolt when the wheel is rotated.

[grumpar]

:Are you saying i'm fat

No seriously
I had to cut The originals out with a junior hacksaw so doubt that that they were ever 8.8 that being a high tensile steel and taking other factors into account such as stresses etc over 50 years there probably technically not as strong as they were.

The 3.5 ton shear strain I think is a little excessive I personally think as you say the A2-70 310 n/sqmm is sufficient
when you take into account that the calculation for this bolt is the point the bolt will snap when tightened between two fixed pieces of steel a guillotine effect for a shear weight being dropped .. . I think if we take into account the fact that there is spring dampers bump stops and nylon liners to relive this the risk of a 12mm A2 bolt shearing in a fork link is minimal so can be ruled out so agree its to achieve a good pivot point.

I am using the A2-70 310 n/sqmm this i think this is sufficient i'ts part threaded so the 12mm pivot point is on the round bar part and not on the threaded part and probably a lot stronger than the inferior Indian steel

For reference these shear numbers are those annoying numbers on the top you have to grind off before you polish

[grumpar]

If you use longer bolts make sure that the tyre valve doesn't hit the end of the bolt when the wheel is rotated.

Cheers going to cut them down and polish there longer for the size of the round bar section for the pivot point