Fork seals

[stryker1080]

Just finished up couple little mini projects on my bike and then last time i went riding my front right fork started leaking oil... Went out and bought new seals today and some oil, gona start taking apart forks tomo...

Couple questions first (1991 cr250):

1. Do i need any special tools. From different topics i get different answers... Im already planning on using pvc piping as a seal driver, what about the spacer u put on the bottom? I think ill just make my own. Also, do you need to take out the oil seal case out to replace the fork seals?

2. Does anyone have a section view of how the forks are assembled, like which parts (guide bushing, slider bushing, etc) are attached to the fork slider or the fork tube.

Any last tips, just reading over manual and some online guides ....

[kuritaro9]

the mx-tech website breaks it down very good...

[Virtus]

Here is a page about my experiences with a 98 CR250. Not sure how close a 91 is. I recommend finding a shop manual for the torque settings and exact procedure. The manual is pretty inexpensive.

Fork seal replacement

It was an adventure. There is also a link to the retainer tool plan (again for a 98 which may have a different diameter than a 91) and a few pictures. One of which is a blow up of the shock.

[stryker1080]

Its dumb how they designed the piston locknut at top, normal wrenches cant take it off... Gotta fabricate a homemade wrench thatll be able to do it tomo Grr i hope the rest of it doesnt require more homemade tools haha ?

[stryker1080]

Was gone for a little while but now im back and at it again... ANyways so i got the locknut and spring guide off... Poured all the old oil out (glad im changing that too, was contaminated with water... looked milky). Now im about to take the damper adjusting bolt out but i already turned it out like 20 turns and its still not out...

1.Is there some trick or is it alot of threading??

2.Is there anyways i can replace the seals without breaking apart the fork tube from fork slider?

[stryker1080]

I cant get the damping adjuster bolt out ? , The damping rod doesnt spin when im trying to losen it so it doesnt seem its connected to anything... From the exploded view in manual it looks like its just simply threaded in. Maybe its cross threaded

[hawaii500_1999]

i'm not sure which flavor of forks you have,

but if you post a picture i could help you figure it out.

[stryker1080]

Here is a pic of the damper bolt

Here is the assemlbly of the fork

... From the assemlby drawing it doesnt look like the bolt threads into the damping rod so it should come right out, i keep turning it in the "softer" direction or CC and it doesnt move at all....

[hawaii500_1999]

it is threaded into the damper.

you need to buy a damper rod holding tool.

or

before dissasembley you can put an inpact on the hex, (not the adjuster screw itself!) and hold pressure on the fork leg, (helps to use a bench vise to hold the lower part of the fork.) and zip it out.

this method i have used but it is not recommended by most fork builders. because of the chance of the shim stack lock nut coming loose.

You do not need to remove that to change the seals.

removing the fork seals.

-after removing the cap and spring.

-slide the dust seal down.

-you should see a clip under it. use a small screw driver to pop it out.

-now it's time to remove the oil seal. do this by pulling the lower and upper fork tubes apart from each other. slide them together a bit and slam them apart real hard. it may take a few wacks.

-after the tubes are seperated, remove the two slider bushings, being carful not to damage the teflon coatings. and then the seals.

installing the new seals.

-place a sandwhich bag over the end of the lower tube, or wrap plastic wrap around it. (sometimes i use the bags the seals came in.) and oil the plastic. this is so not to scare the new seals when putting them on.

-slide the dust seal on. then oil seal. then the washer and bushings.

(hopfully you paid attention to which way everything came off.)

-slide the upper tube over the lower tube.

this is a tricky part.

-use a tie down and suspend the fork upside down, place some folded rags under the upper fork tube on the shop floor. try to suspend it so that the necked down part of the lower leg is right in the working zone to get the second bushing pressed in.

-use a zip tie to hold the washer up out of the way. just wrap it around the tube under the washer.

-using a large flat tipped screw driver and a small hammer, gentley tap the bushing down in an even way. make sure that you have the lower tube inside the outer tube enough for the bushing to go all the way down.

(this will take some time so pull up a stool or something to sit on.)

-cut off zip tie. (carful not to scratch the fork tube.)

-drop washer on top of bushing.

-slide oil seal down and with a seal driver, slap her in.

-place retaining clip in over the oil seal.

-slide dust seal down and snap it into place.

-remove the tie down and flip the fork leg back upright.

-i think you know the rest.

[stryker1080]

Thank you I will try that tomo after work!! ?

[stryker1080]

THe dissasembly went without a hitch, but quick question for you guys... The manual says to replace the bushings if they show any copper, mine do BUT i dont think it matters:

On my slider bushing, the ID of it has teflon on it but the OD does not. Since slider bushing is fixed relative to top fork and only relative motion is between itself and fork slider (touching on ID), then theres no point in replacing that bushing correct?

Same thing with the guide bushing, the ID shows copper but OD still has teflon . THe guide bushing is fixed on the fork slider and only relative movement is on the OD between itself and fork tube.

Doesnt seem like there wuld be a reason to replace them no?

[factorymx]

try using a impact wrench

[hawaii500_1999]

THe dissasembly went without a hitch, but quick question for you guys... The manual says to replace the bushings if they show any copper, mine do BUT i dont think it matters:

On my slider bushing, the ID of it has teflon on it but the OD does not. Since slider bushing is fixed relative to top fork and only relative motion is between itself and fork slider (touching on ID), then theres no point in replacing that bushing correct?

Same thing with the guide bushing, the ID shows copper but OD still has teflon . THe guide bushing is fixed on the fork slider and only relative movement is on the OD between itself and fork tube.

Doesnt seem like there wuld be a reason to replace them no?

you are right.

they are only coated on one side.

[stryker1080]

Allright got working on it again today, i hate my work schedule never get a good chance to work on the bike but ill have all weekend....

Anyways, i got the stuff back together, oiled all new seals up and slid them on, got the guide and slider bushing in place, tapped it in... Now the oil seal!

I cannot get the damn oil seal in. I am so close, probably 1 mm deeper and ill be able to see the grove for the snap ring. I have made a lil driver out of a abs pipe connection and am pounding on it with a wooden block. Is there some trick to it? Should i pound hard or small taps and alternate?

I dont want to hit any harder cuz i think i seen a part of the oil seal tearing just a bit...

[hawaii500_1999]

are you sure you got that bushing all the way in?

you may need to pull the fork apart again and start over.

i usually hit it 2 to 3 times with the seal driver and it's in. and yes i hit it hard. i'm not sure exactly how your tool is, but the seal drivers i use have some good weight to them.

also 1mm isn't a whole lot, have you tried to clip the snap ring in? or were you just looking for the groove? i sometimes use a small screw driver and push the snap ring into it's groove. you might be there but it's just a snug fit.

[stryker1080]

I stopped hammering it, that way was not working for me... Instead i put the fork and my fork seal driver in a vice and sucked it in, rotated 90 degrees, sucked in , etc.... Worked first time ?