replacing fork seals, need confirmation.

[whiterabbitt]

ok so I am replacing my fork seals and installing progressive springs, and all balls steering stem bearings.
I just wanted to confirm that on my 77 750 I install the seal before the inner fork tube, as clymer states. I would hate to have to buy another set of seals because I boogered them by incorrect assembly.
and any tips would be appreciated.

[Steve]

There might be something different about your bike, but it's apparently not like any other set of forks I have done.

I have always assembled the tubes, then slipped the seals over the top and set them into place.

The handiest tool I have found for setting fork seals is an 18" length of 1 1/2" PVC pipe. It's a rather snug fit, so cut a slit down the length so it can expand a bit. Make sure you leave one edge square, so it drives the seal in squarely.

.

[hampshirehog]

You can do them either way. Using Steve's method, sliding them down the tubes makes sure that you pop them in square - but you'll need that bit of pipe.

Before you assemble make sure that the insides of the fork bottoms are really smooth and smear a bit of grease on the outside of the seals. Make sure you get them right side up as well.

[cowboyup3371]

Steve is right but I also installed my seals first, lubed inside and slid tubes into place then tightned them down without a problem

[chuck hahn]

Yes the manual is correct. I get them started with my thumbs and as level as possible then flip the lower tube over and set the seal on a piece of plywood.. then a rubber mallet on the studs to drive the seal in till the rim touches..finish seating them with a piece of PVC. Put the retainer clips on and then reassemble them as normal.

[whiterabbitt]

thanks guys. now to find a machine shop for the steering stem mod.

[mike_of_bbg]

Some of the GSes have a lower guide bushing which wraps around the bottom of the inner fork tube, and has a larger diameter than the tube itself (and thus the seal). On those bikes you must have that lower bush and inners in before you pound in the seal. They also require the "slide hammer" technique to remove the upper bushes (and/or seal, I blow mine out with air first).

See part # 22 in the fiche for my model, which has the lower bushing:



You'd be kinda screwed if you pounded the seal in before installing the inner fork tube. Note no corresponding part for the 77 GS750, just a smooth inner tube:

[whiterabbitt]

ok so I got everything apart and cleaned, now I need some advice on the best way and materials to use to remove some small scratches and a pit on the inner tubes. the scratches for lack of a better word are perpendicular to the stroke and dont catch a fingernail but do a razorblade and are very small. the pit is a nail grabber but not deep, maybe just through the chrome.

your advice is much appreciated

[mike_of_bbg]

Are these in the travel area? You can try wet sanding with say 600 grit. Make sure there are no high spots. If they're outside the travel area you can leave them alone. I've heard tales told of filling in pits with either JB Weld or super-glue. One key to success with either seems to be to de-rust and de-grease the pits quite thoroughly before filling. Super-glue seems like the better way to go to me.

There's always Forking by Frank if you're willing to shell out the $200-250.

[whiterabbitt]

if I was gonna part with that much more change after buyin the progressives and machining the steering stem I think I would buy gsxr parts or something similar off a late model and just go full on upgrade. not tryin to do that though.

yeah they are right at the start of travel, under the dust cover. I will try the wet sanding of the small scratches and attempt to fill the pit...... I wonder if silver solder would hold up? any ideas?

[TheCafeKid]

You can fill them, but you need to be sure they're absolutely smooth after. If they're not, they'll distort the seal and it will leak anyway.
I've personally never tried filling them, I simply use a jewelers file and carefully get rid of any edges in the pit. The edges will cut the seal. If you can get rid of the edges, you may be ok just doing that. Yes, any pit is a potential place for oil to seep by, but it should be pretty minimal if at all.

If you find they're totally binned, lemme know, I have a set of decent 77 forks I may be willing to part with.

[whiterabbitt]

so can anyone tell me what the best brand/type atf is to use in the 50/50 mix for my forks? I plan on using rotella straight 30wt. just wondering about the atf.

if your wondering why, fork oil around here is $15-$18 a bottle and with the pit i have a feeling ill be back in them soon.

[whiterabbitt]

ooohhh boy...... so I was gonna put everything back together last night when after installing 1 seal I noticed that it sat considerably deeper (3 mil) than the ones that came out.
so I dug the old ones out of the trash to compare and what I found was that the old ones seem to have another layer to them. in the fiche above its number 10 I think. the old ones are bent from removing the seals and the rubber is coming off the metal anyway. I thought they were a part of the old seals to be honest

are they necessary? can I use a washer to make up the depth and run the seals I have since one is already installed?

[whiterabbitt]

well i am running the new fork seals without the spacer/wiper seal things, and a 50/50 dexIII and 30wt mix. After 140 miles I have no leaks and everything feels good. it feels like a whole different machine with the new springs and oil in the forks, little to no brake dive, no pumping at speed, a bit stiff on the cracks and expansion joints though. might try a different mix in the forks.

thanks TCK for the jewlers file tip, and thanks everyone else for your input that helped me reach a successful first fork rebuild.

oh and the new stem bearings are wonderful, I can no hand it without immediate fear of death. and no wobble at any speed, woo-hoo