Extra "stiction" after fork rebuild

[TamSV]

I rebuilt the right hand fork on the RGV (USD cartridge forks) with new OEM seal and bushes. The left hand wasn't leaking so just changed the oil.

Now it's all back together there seems to be a fair bit of stiction. If I push down on the bars and let the front rise gently the forks settle at a certain height. If I pull up and let it down slowly they settle at a point about 12mm higher. I can feel just a wee bit of resistance when I push it through that 12mm.

I don't know if this is something that will free off or if something's up. I've not had it with rebuilt forks before but then I've not done that many.

All the fork components were straight and I've double checked;

- forks are the same height in the yokes
- forks are properly aligned
- spindle is straight

Any other suggestions or will it be right?

When I rebuilt the fork, this plastic guide on the cartridge rod was cracked so I chucked it and didn't replace it.

[Sid Squid]

It's not unknown, and a certain amount is to be expected, of course only you can decide if it's excessive. As long as you're sure all the bits are in good order and fitted correctly, ride it for a while and check again, new bushes and seals have been known to 'run in' a bit.

[TamSV]

Cheers Sid,

I'm confident it's all together properly, and I don't think it's dangerous in any way, so I'll give it a couple of hundred miles and see if there's any change.

The motor's getting run in anyway so I won't be going daft.

RGV upside down forks?. What torque have you done the yokes up to?. Use the correct torque otherwise too tight can cause stiction on the fork. See this a fair bit and doesnt take much to cause them to stick.

How did you set the air gap?..springs in or out. Not hard to get it wrong, if unsure, take apart and do again.

[TamSV]

Thanks. Hadn't thought of that.

Torqued as per manual but I'll loosen the bottom yoke and see if it changes anything.

I set the air gap without springs

[yorkie_chris]

Air gap wouldn't cause that stiction.

[johnnyrod]

I'd guess the forks aren't quite parallel. Not sure about USDs but for normal forks you slacken the top yoke pinches and any clipon locating bolts, bounce the front a few times, and do it all up again.

[TamSV]

I hate an unresolved thread, so thought I should update.

Ignoring this and hoping it would go away didn't work.

Originally Posted by SV650Racer

What torque have you done the yokes up to?. Use the correct torque otherwise too tight can cause stiction on the fork.

I double checked the torque settings and took them closer to the bottom of the specified range but it was still the same. I also slackened everything off and bounced the front a bit and torqued everything back together and the problem was still there.

I've got some slight handling issues (which I think are probably down to the wrong sized tyres) but thought I'd better get to the bottom of this issue first.

Exhaustive front end check went as follows;

- Removed the forks. Took out the springs, spacers and cartridge rods. Inspected everything carefully. No problems.

- I didn't separate the fork stanchions and uppers, just made sure they were sliding freely. Rotated the stanchion a bit and tried again. All fine with no sticky points.

- Checked the spindle and top yoke for straightness. All OK.

- Inserted the forks in the bottom yoke and torqued them up, then spent some time eyeballing them from a distance until I was completely convinced they were parallel.

- Reassembled the yokes and put the forks back together, but without oil, springs and spacers and with the top nut cracked to let the air in and out. Put the forks in the yokes and torqued them up normally. Again tested they were sliding freely. All fine.

- Put the front axle in (but without the wheel) and nipped up the pinch bolts. Checked the whole assembly went up and down smoothly. Which it did.

- New oil, springs and spacers back in the forks which were then remounted. Torqued up the bottom yoke pinch bolts and put everything back on loosely. Bounced the front end a few times and eyeballed the front tyre and top yoke to make sure they were both straight. Then tightened everything up in the following order; axle, axle pinch bolts, mudguard, top yoke pinch bolts, top yoke nut.

After all that, the stiction has gone from 12mm to just under 5mm and there's none of the resistance I was getting before. Fine and dandy.

Don't know what the problem was, other than I obviously cocked something up the first time that was de-cocked during reassembly.

Feel free to follow the above guide to checking your front end problems or, alternatively, just do it right in the first place.

[Bibio]

did you bleed the cartridges?

[TamSV]

Yep. Did that the last time too though. Everything was done with a bit more care this time, which seems to have made a difference.