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Old 12-06-2012, 11:53 AM   #1
disston OP
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What Leaks on the Bottom of Sliders?

I think I have tightened the large plugs and the smaller nut on the damper enough. Every so often I check and there is stickey residue around the rubber plug. It has gotten less, maybe all my fork oil has dripped out? Should I put thread sealer on the threads?

1975 R90/6
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Old 12-06-2012, 12:28 PM   #2
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I overhauled my forks awhile back, used new crush washers at the damper rods, etc. A few weeks ago I noticed a drip of oil on my front tire. I tightened the damper rod nut a bit more and drank a six-pack. So far, no new leaks. I have had my forks apart in the past and reassembled without new crush washers - and no leaks. I don't think it would hurt anything to use a little thread sealer. If that doesn't help, take 'em apart and inspect, then go back together with new crush washers (and a dab of thread sealer if you like).
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Old 12-06-2012, 12:34 PM   #3
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Renew the big copper crush washers-- they can re re-annealed by heating and reused, but that's iffy. There is also an internal aluminum sealing washer that goes between the shock rod and the bottom end cap that can be reused but typically leaks. In an anal-retentive world they should be replaced every fork oil change, but I do it every second or third change. I keep spares on hand and if I see leakage when I'm changing fork oil they get changed.

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Old 12-06-2012, 12:40 PM   #4
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+ 1 on what Bill says. I don't change my crush washers every time (please don't tell anyone). Charlie, I wonder if you've got some crud or something preventing the crush washer from sealing. You could loosen the damper rods and drop the sliders down a bit, let some oil drain to flush anything out, then tighten everything. If it still leaks, may be time for new crush washers - I buy 'em in bulk, have a lifetime supply.
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Old 12-06-2012, 02:05 PM   #5
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Quote:
Originally Posted by Bill Harris View Post
Renew the big copper crush washers-- they can re re-annealed by heating and reused, but that's iffy. There is also an internal aluminum sealing washer that goes between the shock rod and the bottom end cap that can be reused but typically leaks. In an anal-retentive world they should be replaced every fork oil change, but I do it every second or third change. I keep spares on hand and if I see leakage when I'm changing fork oil they get changed.

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Yes and no. There is a crush washer between the damper and the inside of the slider lower nut. It is the only thing sealing the slider nut from leaking. On the outside there is only a 8mm wave washer and a nut. Here are couple of things to be aware of.
1. If you over tighten the nut to try and stop the leak you will break off the end of the damper rod.
2. The only way to fix this problem correctly is to remove the fork slider and replace the crush washer.I also recommend a new 8mm wave washer.
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Old 12-06-2012, 02:44 PM   #6
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I rebuilt my forks last Winter. Like most other Winter projects on my bike I found extra stuff to do. I had to reshim the wheel bearing. I replaced the tubes and the lower triple. It all now checks out straight. It does seem to work better than it ever has since I flipped this bike about ten years ago.

I think I'll get some new washers and large O gaskets, I have some of this stuff already. And change the oil. Teflon tape on the threads? And don't break the damper stud.

Thankx
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Old 12-06-2012, 03:22 PM   #7
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Originally Posted by disston View Post
I rebuilt my forks last Winter. Like most other Winter projects on my bike I found extra stuff to do. I had to reshim the wheel bearing. I replaced the tubes and the lower triple. It all now checks out straight. It does seem to work better than it ever has since I flipped this bike about ten years ago.

I think I'll get some new washers and large O gaskets, I have some of this stuff already. And change the oil. Teflon tape on the threads? And don't break the damper stud.

Thankx
No Teflon tape.
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Old 12-06-2012, 03:54 PM   #8
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No Teflon tape.
Why? (not trying to be disrespectful but this condition is used in several other places too and I'd like to know the reason)
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Old 12-06-2012, 04:38 PM   #9
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I have had great luck putting a little silicon on the big copper crush washers. I wouldn't use tape there either. Most people do not tighten those bottom plugs enough but I find loose top nuts all the time too. I think it's 76ftlb?
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Old 12-06-2012, 04:45 PM   #10
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Why? (not trying to be disrespectful but this condition is used in several other places too and I'd like to know the reason)
I have had 100% success rate by just replacing the crush washer.
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Old 12-07-2012, 06:56 AM   #11
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Originally Posted by disston View Post
Why? (not trying to be disrespectful but this condition is used in several other places too and I'd like to know the reason)
Charlie, the threads on the damper rod don't seal anything. It's not like the threads on your oil pressure sending unit where a dab of sealer (your choice) helps to seal the threads. The only thing that keeps the fork oil from leaking at the damper rod is the CRUSH WASHER. I don't think teflon tape would hurt anything, but I doubt that it would seal any leaks.
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Old 12-07-2012, 08:58 AM   #12
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I have had 100% success rate by just replacing the crush washer.
I'm in the no goo or tape camp as well. My most recent fork rebuild (1971 R75) had a ton of both tape and silicon on every threaded surface in the forks, not to mention the steering neck was packed FULL of grease. PO truly believed that if something was worth doing it was worth over-doing. EVERYTHING was cleaned then new washers and all is fine and oil tight. Just like the rest of my bikes.
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Old 12-07-2012, 11:01 AM   #13
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I am definitely in the no goo or tape camp on the damper rod. No need for it whatsoever.
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Old 12-07-2012, 07:49 PM   #14
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I once worked on a bike that had the crush washer for the damper rod under the nut instead of inside the slider. This shouldn't work, but it did.

It's realy easy enough to pull the large plug out of the bottom of the slider and replace both the 8mm crush washer and the large one on the plug. While you're at it, you might replace the bottom bumper(s). At one point, BMW suggested Hylomar on the threads of the plug, and I still do.
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Old 12-07-2012, 08:10 PM   #15
disston OP
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Yeah. I was kinda planning on pulling the large plug to get to the small washer on the damper rod. I know I replaced both of these when I rebuilt my forks last Winter but the fork oil has been dripping constantly since then. The torque is pretty high on the large plug so I have tightened it several times and I think the damper nut is tight enough also but I get this sticky stuff on the bottoms of my fork sliders. So I gotta take it apart just to see if I put it together right in the first place or I can see anything else wrong.

Remember the small copper washers for the fork damper? They were many years ago. I don't see them anywhere any more. I have a couple. Maybe they seal better than the Aluminum ones?

The O-ring washers should be the sealing in the fork bottoms. Threads should not have anything to do with it.
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