Well, that happens when the lower was clamped in a vice and is now oval inside instead of round, lol. We had to replace one of the lowers on my buddy's '80 SPII because of this.
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What the fork is wrong with my seals?
- Thread starter bosco659
- Start date
Well that would be bad news, but could explain what’s happening. When working on the forks, I never clamped the lower like that, but that’s not to say the po might have done it
. I always held it in the vise by the caliper mount lugs. As mentioned, it only does this when fully compressed, so with the spring in, it never gets close to the place where it “sticks”. Lucky for me! I think it should be fine once reassembled with the spring in.
Yes, the P.O. could have very well clamped it at the bottom and that part is now oval inside. If the tube never gets that far in with the spring installed then maybe you'll be fine. Start watching for another left (?) fork lower.
Stayed up and figured it out. The lower is ok
. What was sticking was the cone shaped fitting on the end of the damper rod, fitting too snugly in the opening of the piston inside the bottom of the upper fork tube. The aluminum fitting is tapered and fit too nicely into the piston whose opening had squared off edges and are quite sharp. When the upper is pushed into the lower, the sharp edge of the piston was digging into the tapered surface of the damper rod end. I eased the edge slightly with a touch of the Dremel tool and some emery cloth. No sticking now.
. What was sticking was the cone shaped fitting on the end of the damper rod, fitting too snugly in the opening of the piston inside the bottom of the upper fork tube. The aluminum fitting is tapered and fit too nicely into the piston whose opening had squared off edges and are quite sharp. When the upper is pushed into the lower, the sharp edge of the piston was digging into the tapered surface of the damper rod end. I eased the edge slightly with a touch of the Dremel tool and some emery cloth. No sticking now.
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Excellent sleuthing there, lol. Nicely done, and I'll have to remember to watch for that.
I think I know the answer on this one.
the aluminum "Bumpstop" with inner taper isn't aligned with the damper rod. Have had it happen before, loosen bottom bolt with fork cap off, drop the tube, snug the bolt, a battery impact driver is helpful here, then assemble and finish torque, see if that "fixes" it. This is hard to do if there is old locktite on the bolt....
Thx. Is the correct torque for the bottom bolt 14.5 ftlbs?
Or two oogy doogies. ;✓}
Do I have the pistons in the end of my fork tubes assembled incorrectly, hence the sticking problem I’ve experienced? The bottom most component of the 4 pc piston assembly will fit into the fork tube either way, with the wider opening at the retaining clip (B) or with the shouldered end at the retaining clip (A)? I had it assembled in config (A). In this configuration, the tapered aluminum end of the damper rod wedges itself into the piston. In configuration (A), the aluminum piece slides inside the piston.
Do I have it assembled backwards? Note - the spring is not symmetrical - one end has a larger OD than the other. If assembled backwards the spring will get jammed in the piston assembly - no need to ask me how I know.
Do I have it assembled backwards? Note - the spring is not symmetrical - one end has a larger OD than the other. If assembled backwards the spring will get jammed in the piston assembly - no need to ask me how I know.
It's a taper? wider end down.
Here’s what the piece looks like. I’m thinking I had it in upside down. The open end “A” should be down pointing to the bolt??
Looks like the piston may have been assembled incorrectly. Don’t know if this was the work of the po or myself. Just trying to verify correct orientation of pieces.
Please see my drawing and comment. Thx
In the future, I don't think you need to remove that stuff from the tube. On the '78 and later tubes, you can't, it's "crimped" in place.
Sorry for the delay.
Got it, thanks! I’m thankful I made a nice holding tool for the damper rod. Makes re/re the bottom fork bolt a breeze.
Bike’s all back together and out for a quick spin in the afternoon. Everything is working well now but what a difference between new bikes and the old XS’s stock suspension. I could spend a ton trying to make the suspension better, but I accept it for what it is, considering the age of the bike and ‘70’s technology. Hopefully that’s the last work I need to do on it this season.
Well I’m back to messing with the forks again. Although I installed new seals (Alls Balls), applied special fork seal grease in the recess of the seals, checked the tubes for bends, I am still getting “stiction” of the seals to the fork tubes and sometimes this causes to forks to require extra force for compression and extension.
See the pics for the goop that built up on the tubes after a 20km ride tonight. The black stuff is sticky and difficult to remove with a dry rag. With a bit of solvent it comes off easily.
Is this normal for new seals until they’re bedded in or is something else going on? I just changed the fork oil from 25W to 10W and it’s doing the same thing.
Any thoughts?
See the pics for the goop that built up on the tubes after a 20km ride tonight. The black stuff is sticky and difficult to remove with a dry rag. With a bit of solvent it comes off easily.
Is this normal for new seals until they’re bedded in or is something else going on? I just changed the fork oil from 25W to 10W and it’s doing the same thing.
Any thoughts?
34mm seals on 35mm forks?
Reason I ask that is your bike was modified quiet a bit by the PO. You sure he didn't swap in the bigger forks too?
