Front fork top caps

[Dizerens5]

I've started the job of changing oil in the fork legs. Also found has been a big loss of oil on one side so time to change seals as well. However I can't match the forks of my 79 with the Haynes book. The Allen filler plug is there ok, but what should be a big hex-head screw-in top cap only has two flats (19 mm size) and both of them just spin freely along with the Allen filler, without screwing either in or out. See attach photo. How can these free-turning caps hold the springs? Don't understand. What will happen if I remove the Allen fillers?

[Barry]

It's normal that the top cap rotates. We've all been there wondering how the damn things come out

The top caps are held in with a wire circlip.  Push down hard on the cap against the spring pressure and you will see the circlip that sits in a groove in the stanchion. Press down on one side of the circlip with a small screw driver to tilt it in the bore then fish it out before releasing the top cap.

It can be a two man job the first time you do this but it's not hard to develop a technique to do this single handed. My method is to fit an allen key in the screw then press down on the top cap with a large flat screw driver. When I think I've compressed the spring enough I rotate the allen key until it jambs under the handle bars. I then tie it in place so it doesn't slip. Fishing out the circlip is then easy with two hands free.  

If you think this is an odd method of securing the main spring it does at least eliminate the hassle that can can occur with overtightened screw type caps.

The flats on the top cap are just there to hold it still while you undo the allen screw for adding oil.

[montmil]

Ring us up when you're ready to disassemble the fork lowers from the stanchions and replace those leaky seals. Not difficult but a couple tips ease the job.

[Bob_Roller]

If you are gong to replace the seals, the method I use, is to remove the fork tube from the bike, you only have two pinch bolts holding it in once you get everything else removed for the lower fork tube .

I use two pieces of wood contoured to fit the upper tube, and another set for the lower tube, put the fork and wood blocks in a tabletop vise and then disassemble them there .

[nhmaf]

The really tough part is getting the darn 3-piece newer-style damper valve assembly shoved back into the fork lower so refit the circlip down there - you don't need to go there if you are just replacing the usual fork seals.  That little 2-3" damper spring is a real bear!

[Barry]

The really tough part is getting the darn 3-piece newer-style damper valve assembly shoved back into the fork lower so refit the circlip down there - you don't need to go there if you are just replacing the usual fork seals.That little 2-3" damper spring is a real bear!

I imagine that spring really is a bear but unless it was retro-fitted (which would be a very good thing so I hope it turns out that it was) Constellations 79 won't have it. As far as I know 79 forks like mine had a solid full length damper valve body without even a shim to stop it rattling.

The sprung valve body was introduce a year or two into production but was also a recommended mod under a service bulletin so many of the early models may have been modified under warranty.

[Rob Valdez 79 R65]

The top caps are held in with a wire circlip.Push down hard on the cap against the spring pressure and you will see the circlip that sits in a groove in the stanchion. Press down on one side of the circlip with a small screw driver to tilt it in the bore then fish it out before releasing the top cap.

I "made" a tool for the job, using my impact screwdriver/reducer/short extension/allen driver.
I would post a picture, but I cannot.  Try following this link:
http://www.pbase.com/tomfarr/image/122139709/large

The weight of the impact driver makes a lot of difference in the effort involved.

If he is working on a '79, he may find these other pictures useful as well: http://www.pbase.com/tomfarr/forks

[Dizerens5]

Thanks guys! I'll try and print that lot. I'm going to refill forks with the correct amount of SAE 5 and see what comes out. If it's only slight seepage I can live with it. If a bad loss then I may decide to give the job of seal replacement to somebody who knows what he's doing as my mechanics ability is a bit limited!

[montmil]

The fork oil drain holes on the R65 (1979-85) are positioned such that the fork lowers are not completely emptied of fluid unless a complete disassembly is done.

Rebuild spec is for 190-200cc of fork oil.
Drain only and refill is 190cc.

Spec fork oil is 7.5wt but riders often experiment to find what they prefer.

Use caution and do not over-torque the small steel drain bolts going into the softer aluminum fork lower bodies. New crush washer if you got 'em.

[Johnster]

If someone is popping that circlip out of the top of their fork tube remember - circlips ALWAYS love to jump out of thier hole and run far away if you get them free - shade the tube with your hand, work under a rag or do something to keep that circlip from jumping scross the garage and getting lost.

-John

[Dizerens5]

I did try using finger pressure to push the caps down, as an experiment. They would not move although the wheel was off the ground. So I guess more stern measures are needed. I have an unpleasant vision that circlips would not be the only things flying around, probably bits of my fingers too!

[Barry]

You really have to push quite hard. After all you are compressing the main spring which is already under approx. 1" of pre-load.

[Luca]

I use a socket to press down on the cap at the top of the fork tube.  That way I have some room around it to pry out the ring (I use a pocket knife with a very thin blade).  If you have an extra set of hands, put an extension on the socket and have them push down while you pry.

It's much easier to do with the forks out of the bike, although for proper fork alignment you will have to re-install with the uppers clamped in the triple trees.  If you go to a shop, make sure they don't assemble the forks and then install them on the bike.  When I disassemble, I use two hands to push down the top cap via the socket, then, once it is down, hold it with my right thumb and pry with my left hand.

Also, fork oil weights are not measured to a standard like motor oil weights (such as SAE), so one manufacturers 5wt fork oil might not be the same as another's.  Any experimentation should be done with one brand of oil.

[nhmaf]

Fit a proper fitting Allen key bit into an extension on a ratchet wrench handle.   Leave bike on centerstand.  Get a friend - at least for the first time you do this, and have them ready with a small awl or small blade screwdriver that will reach 1-2" down into the fork tube.   You will tip the front end forward so the tire is on the pavement/garage floor, fit the bit into that Allen key bolt plug, put the ratchet wrench handle against your shoulder and grip the extension, pushing straight in/down along the axis of the fork tube.    You will find it pushes down, and once pushed down far enough, you will see around the inside of the tube the round retention ring that must be pried out whilst still holding down the plug cap below it.  

As mentioned earlier, it is best to push the ring clip downward out of its groove and get it to rotate so that one can reach in with long nosed pliers and pluck it out.   IT is possible for 1 reasonably strong man to do this with practice.   You will have to push downward with at least 50 pounds of force against the spring, assuming typical preload values.  It can be easier to do if one takes the fork tubes off and has a bench with a well padded vise to work with, but that also requires alot more disassembly.

You may find that once you've pushed the plug down far enough it is easier to hold in place if a little bit of side force is applied to cock it askew in the tube.   I rely on this so that I can free up 1 hand to pry out the clip when working alone- BUT DO NOT LET LOOSE OF THE WRENCH OR TAKE YOUR SHOULDER PRESSURE OFF IT AS THAT SUCKER CAN SPRING RIGHT BACK UP AT ANY INSTANT!   Might be a reasonable precaution to be wearing some sort of glasses - just in case you slip and things spring up out of the tube that you are peering in...

Work safe!

[nhmaf]

Darn forum software "bleeped" out my use of the word "c o c k" for pushing the plug slightly sideward in the tube so you aren't resisting the full spring force whilst holding it below the retention clip and prying it out...