What oil to use - no seriously

[oroepke]

No worries, this is not an engine oil question

I am rebuilding my forks and was wondering what weight oil everyone is using. FSM says ATF oil, but I assume there are better things out there!

[NobleHops]

ATF is nominally equivalent to 10W fork oil. I am #230 and prefer 15W oil, at 140mm (EDITED) air gap - measured with the fork collapsed and the springs removed, 10w will be plusher, 15w better damped.

[JoeInTUS]

I think you meant 140 mm.

247 ml of fork oil will get you real close to 140 mm on a twin shock.

[SteveG]

My method (works super in my 79 750F with 35 mm tubes, 81 900F and 82 CBX with 39 mm tubes) is 15 weight fork oil (I weigh 230 +/-) filled to 6 inches (150 mm) from the top of the tube, with the spring removed and the tube completely sacked (gently of course) into the leg. I overfill the tube, then use a suction device (turkey baster / miti-vac / .....) to suck out fluid down to 6 inch level.
Freddie Spencer I am not, but I love a spirited ride.

Steve

[oroepke]

Thanks everyone. I didn't mention it (and just updated my signature) I have the 1980 model with the air forks. Will dig into that soon, but my charging system gave up on me today, so not sure where to start first....

[oroepke]

Fixed my chanrging issues anf started digging into the forks. I had some issues getting the bottom bolt out of one fork leg, it was just spinning and the damper was turning. Blocked the bolt with a small screw driver and drilled it out, not what I had planned but it worked!

[NobleHops]

Fixed my chanrging issues anf started digging into the forks. I had some issues getting the bottom bolt out of one fork leg, it was just spinning and the damper was turning. Blocked the bolt with a small screw driver and drilled it out, not what I had planned but it worked!

Next time just invert the (assembled) fork assembly, with a plug in your air cap orifice, and bump the damper rod bolt with a cordless impact to loosen. Turn the bolt back in by hand just enough to prevent making a mess and then disassemble as normal.

N.

[daves79x]

I'll add that once you get the damper bolts out, chase the bolt and damper threads so re-assembly goes smoothly, and future disassembly does as well.

Dave

[oroepke]

Noblehops, I had first tried just with an Allen wrench and it started turning and only after that I used the impact driver. I think if I had started right away with the impact driver it may have worked. Lucklily, drilling it out was not too big of a problem.

Good advice, Dave.

[daves79x]

The thing that has worked for me on a couple of stubborn ones that even an impact wouldn't loosen, is to clamp the assembled fork leg horizontally in a vice. You have spring pressure obviously, but now lean heavily on the fork lower to compress the spring as much as possible, then zap it with the impact. Worth a try before drilling.

Dave

[oroepke]

The thing that has worked for me on a couple of stubborn ones that even an impact wouldn't loosen, is to clamp the assembled fork leg horizontally in a vice. You have spring pressure obviously, but now lean heavily on the fork lower to compress the spring as much as possible, then zap it with the impact. Worth a try before drilling.

Dave

I have tried that too, but my mistake was that I tried with an Allen wrench first and the damper had started spinning inside the forks already. I have the feeling that if it hadn't moved first, it could have worked. I left the other leg installed in the tripe tree and hit if from below with the impact, pushing up pretty hard. No problem, came out easily. Lesson learned I guess!