sv650 top fork

[stranger12]

Hi All,

What is the torque setting for top fork bolt ?

In haynes it says 32nm which seems too low for a bolt that takes a 24mm socket .

I did make a stupied mistake of opening both tops and the bike suddently dropped all the way so had to use jack under the oil sump to lift it and fix it .

I did loose a bit of oil each side as I was pulling the springs out to check them , does that matter much ?

thanks

[jambo]

All the cap has to do is sit snug and not fall out, it's a very fine aluminium thread on the cap so you really don't want to monster it as you'll make a mess of it.

You want to back off the top yoke clamps, do up the fork caps and then do the top yoke clamps back up so it's not being squished while you're doing it up or undoing it.

Jambo

[stranger12]

many thanks, but question is if it is holding so much pressure or the wieght of the bike by pressing the spring down , does that need a higher torque?

when the bike dives, I guess a force is exerted on the top cap as the spring wants to jump out , right ?

[wideguy]

What keeps it from popping out is the shear strength of the threads, and making it tighter doesn't make the threads any stronger, in fact, too much torque will start to deform the threads, which is the beginning of stripping them completely out.
Snug it up, torque the clamp bolt properly, and don't worry.
And no, loss of a little bit of oil won't matter much, forks gradually lose oil while in use anyway. Periodic replacement of the oil is part of routine long term maintenance.

[jambo]

When the forks compress the weight of the bike is transferred forwards and spread across both forks, but the threads on the forks are fully engaged as soon as the cap is nipped up, as above, doing them up tighter does not make them stronger.

There is also an O-ring which forms an air seal, setting the air gap affects how much pressure is build up in the fork by compressing this air, and makes up part of the effective spring rate (because this air spring is progressive, all forks are effectively progressive provided the forks are sealed).

What materials and threads are used generally dictate the torque needed, a couple of course steel threads on a large diameter such as M12 can take a lot of force for instance, where as the sump bolt goes into the aluminium of the engine casing and will strip that out without a huge amount of trouble if you're over zealous.

In this case I don't think I usually use as much as 30Nm but I'm sure it'll be fine, there is no need at all to do these up overly tight, it'll just end in tears. Generally I knock a little off the specified torque figures for most jobs as they are given as "dry assembly" figures and I've usually used an oil or grease on the threads, which means you will put more force into a bolt before meeting the same force to turn it (torque).

Jambo

[nutzboutbikes]

Fork cap is 23Nm same as the pinch bolts.

[Bibio]

In this case I don't think I usually use as much as 30Nm but I'm sure it'll be fine, there is no need at all to do these up overly tight, it'll just end in tears. Generally I knock a little off the specified torque figures for most jobs as they are given as "dry assembly" figures and I've usually used an oil or grease on the threads, which means you will put more force into a bolt before meeting the same force to turn it (torque).

Jambo

listen to Jambo.

i have seen more threads stripped with people using torque wrenches than people not and one of the reasons i recommend 3/8'' socket sets. when tightening fairing bolts and non structural things i always tell people to use the head of the ratchet in their hand rather than grip the handle, the bigger the lever the more force can be applied = stripped threads.