Replacing fork bushings

[Constant Mesh]

After 88K miles I have a fork oil leak. I got the Yamaha seal kit including two oil seals and two dust seals. I didn't get the inner and outer tube bushings.

Should the bushings be replaced or could they be OK?

How do you remove the oil seals if you don't remove the inner tube, etc.?

 

[hppants]

I believe you should replace the bushings. The coating (perhaps Teflon???) will undoubtedly be worn off and without new bushings, you run the risk of scoring your fork tube and cutting into your new seals.

You cannot replace the fork seals without separating the fork tube from the lower.

There is a wonderful how-to thread on doing this job somewhere on this forum. Search and ye shall find.....

 

[RossKean]

This was the beautifully done thread by FJRed. This applies to Gen II forks which are more difficult (middle bushing that is a ***** to set without a special tool). I'm not sure how much translates to Gen I?

https://www.fjrforum.com/forum//index.php/topic/140923-fork-seal-bushing-replacement/?hl=+fork++seal

 

[Constant Mesh]

Thanks for the info.

After a bit more research I found some info on removing/replacing the seals without removing the inner tube. They extended the inner tube to its maximum height and then added some generic oil to fill the tube close to the top. Then, threaded the cap on and pushed the inner tube back down, reducing the volume inside the tubes. The added oil pushed the seal out as the internal volume decreased.

https://www.motorcyclecruiser.com/how-to-replace-motorcycle-fork-seals

A little messy but the seal is liberated with the inner tube intact.

But, new bushings are probably a good expenditure after 88K miles.

 

[SLK50]

FWIW, my bushings were completely worn out at 65K.

 

[RossKean]

FWIW, my bushings were completely worn out at 65K.

The polymer coating on mine was trashed at that mileage as well but, to tell the truth, I didn't notice much difference after they were changed - other than the fact that the seals no longer leaked! The bushings themselves didn't look particularly worn.

 

[Fred W]

OP has a gen 1. Gen 1 bushings do not wear out fast like the Gen 2s do. All of the people saying the bushings will be shot have Gen 2s. When I rebuilt my Gen 1 forks (to put in upgraded valving from GP) the bushings were still fine. This was at around 65k miles. Ive also disassembled the forks on two friends' high mile 1st Gens and the teflon on theirs was fine also. I credit the lack of wear to them having only two ( not three) bushings in each leg.

Yes you can push the seals out hydraulically, but what a mess. On a Gen 1 the bushing and seal comes out pretty easily using the normal slide hammer disassembly technique. The bushings will not get damaged like they sometimes do on 2nd Gens, and can then be inspected and reinstalled. It's actually easier to do this than to push the seal out with oil, IMO.

 

[Auburn]

OP has a gen 1. Gen 1 bushings do not wear out fast like the Gen 2s do. All of the people saying the bushings will be shot have Gen 2s. When I rebuilt my Gen 1 forks (to put in upgraded valving from GP) the bushings were still fine. This was at around 65k miles. Ive also disassembled the forks on two friends' high mile 1st Gens and the teflon on theirs was fine also. I credit the lack of wear to them having only two ( not three) bushings in each leg.
Yes you can push the seals out hydraulically, but what a mess. On a Gen 1 the bushing and seal comes out pretty easily using the normal slide hammer disassembly technique. The bushings will not get damaged like they sometimes do on 2nd Gens, and can then be inspected and reinstalled. It's actually easier to do this than to push the seal out with oil, IMO.

The forks we have done at the tech meets over the years, generally the Gen 1 fork bushings are in good shape. But some have had wear similar to the Gen II. I'll try to get some pictures and post this weekend of the tools

One thin of caution for Constant Mesh: you do need a special tool (either make it or buy one) for disassemble/reassemble the forks. It is a 26mm socket that you need to hold the nut on the inside of the fork tube. I built mine with a 24" piece of 1/2" tubing welded to the top of the nut, and an 3/8 inch extension welded to the top so you can attach a torque wrench. Second, NEVER reassemble using an impact gun, you will gaul the threads. A piece of (IIRC) 2" exhaust pipe is thin enough to fit over the inner tube to use as a slide hammer to drive the bushings into place. Then I use a 24" piece of 2" ABS pipe with a cap on one end to drive the oil seal and dust cap back into place.

Don't be afraid to use a MAPP gas torch to put some heat on the lower fork tube in the area of the upper bushing to expand the tube slightly. Then you can use the inner tube as a slide hammer to pull the bushing out. If you get the inner tub out and the bushing stays behind, use the smallest wood chisel you have (1/4") and drive it in behind the bushing where is it split to bend the bushing inward. then you can grab it with a pair of needle nose pliers and twist inward which will make the diameter of the bushing smaller so you can remove. Only had this happen one time in the 50 some odd pairs of forks we have rebuilt at the tech meets.

As far as replacing bushings, they are relatively cheap, and since I have them disassembled, I recommend changing them. Chalk it up to routine maintenance and peace of mind. Usually the dust seals, snap rings, and the washer don't need to be replace, but I do have extras around just in case they are needed.

 

[Constant Mesh]

Thanks for the info.

As Fred mentioned I have a Gen 1 which has two bushings per fork.

I don't have the 26 mm tool. I was assuming that if I threadlock the damper rod bolt after tightening it firmly it would be adequate without measuring the torque. However, I don't know if I get the threads clean enough for the threadlocker to set properly.

The fork tube has an OD of 48 mm (1.89"). The flat portion of the seal has an outer D of 60 mm (2.36") and an inner D of 55 mm (2.17"). So there's a ring 5 mm wide on the seal where one can apply force to drive it home.

2 inch schedule 40 PVC pipe has an OD of 2.375" and an ID of 2.067".

2 inch schedule 80 PVC pipe has an OD of 2.375" and an ID of 1.939"

As you mentioned the schedule 40 pipe works adequately for installing the seal if it's centered properly about the tube. It would seem that schedule 80 pipe with its smaller ID would work adequately for installing the upper bushing. Its ID is about 2.6% larger than the tube OD so it should impact nicely against the bushing.

It will be a learning experience. Maybe I can do an adequate effort without the special tool. If not, I'll make a run to the local dealer and get them to torque the bolts properly.

Don't know if I can find a scrap chunk of schedule 80 pipe. Lots of schedule 40 bits available but schedule 80? Maybe not required anyway.

 

[hppants]

Schedule 80 PVC is available anywhere.

My gen 1 bushings were worn. The Teflon coating on the upper bushing was clearly worn on the tube that was leaking. I don't know if the slide hammer technique made it worse. I changed the bushings. FWIW - I didn't have the 26mm socket. I used some heat on the lower bolt and an impact wrench to disassemble. Then I put some blue locktight on it going back together. I trade the bike with at least 30K on the replaced seals. No problems.

 

[Auburn]

Thanks for the info.
As Fred mentioned I have a Gen 1 which has two bushings per fork.

I don't have the 26 mm tool. I was assuming that if I threadlock the damper rod bolt after tightening it firmly it would be adequate without measuring the torque. However, I don't know if I get the threads clean enough for the threadlocker to set properly.

The fork tube has an OD of 48 mm (1.89"). The flat portion of the seal has an outer D of 60 mm (2.36") and an inner D of 55 mm (2.17"). So there's a ring 5 mm wide on the seal where one can apply force to drive it home.

2 inch schedule 40 PVC pipe has an OD of 2.375" and an ID of 2.067".

2 inch schedule 80 PVC pipe has an OD of 2.375" and an ID of 1.939"

As you mentioned the schedule 40 pipe works adequately for installing the seal if it's centered properly about the tube. It would seem that schedule 80 pipe with its smaller ID would work adequately for installing the upper bushing. Its ID is about 2.6% larger than the tube OD so it should impact nicely against the bushing.

It will be a learning experience. Maybe I can do an adequate effort without the special tool. If not, I'll make a run to the local dealer and get them to torque the bolts properly.

Don't know if I can find a scrap chunk of schedule 80 pipe. Lots of schedule 40 bits available but schedule 80? Maybe not required anyway.

You won't be able to get the bolt tight enough without holding the nut inside the tube. And you don't ever want to use thread lock on these bolts. You have dissimilar metals and have a very good chance of galling the threads when you try to remove it the next time.

The upper bushing is in the same place on a gen I and that was the one I was referring to for the issue of getting it out if there is a problem. schedule 40 ABS or PVC conduit should work just fine for the seal and dust cap only. But you need the thinness of the exhaust pipe tubing to drive the seal home because it sits lower than the seal and you don't have the diameter to allow sch 40 or 80 pipe to seat the bushing far enough down to have it in the proper location. You should be able to buy a 2' piece at and auto shop, or go to a muffler shop and buy a piece of scrap. You probably will have to take a round file to the seam where the pipe is welded near each end of it.

I'll get some pics for you.

the 26 mm socket can be purchased on line for a few $.

Schedule 80 PVC is available anywhere.
My gen 1 bushings were worn. The Teflon coating on the upper bushing was clearly worn on the tube that was leaking. I don't know if the slide hammer technique made it worse. I changed the bushings. FWIW - I didn't have the 26mm socket. I used some heat on the lower bolt and an impact wrench to disassemble. Then I put some blue locktight on it going back together. I trade the bike with at least 30K on the replaced seals. No problems.

the problem comes the next time you go to take apart. The locktite can cause the threads to gall if you try to undo with an impact wrench again.

 

[Auburn]

Here are the special tools that I made to do forks with: Anyone can make these or have someone weld them.

all three together

26 mm socket welded onto 1/2" x 20" tube with a small 3/8" socket extension welded to the other end. spray painted black

I believe this is what I have: 26 MM socket from Lowes

End view of muffler pipe 2" by 14" (can be longer - need one end to be cut straight across) it is thin enough to drive the bushing into place and not hit lower fork tube.

2" ABS pipe with 2" cap( I put the cap on it so I can use a dead blow hammer to drive the into place and the pipe is wide enough to spread the load over the seal so it won't get damaged.

 

[Niehart]

^^^ Like ^^^

 

[hppants]

I guess my stupidity didn't think about the dissimilar metals. Of course I never had another seal leak, so it's somebody else's problem now.

I don't have a welder, or easy access to one. I suppose if my Gen 3 seals leak, I'll have to figure out something else. Thanks for the info.

 

[Fred W]

I've never heard that using loctite causes problems with dissimilar metals. If anything, the loctite would insulate the dissimilar metals from corrosion and galling. I'm curious where this info came from.

 

[Auburn]

I've never heard that using loctite causes problems with dissimilar metals. If anything, the loctite would insulate the dissimilar metals from corrosion and galling. I'm curious where this info came from.

I have seen it happen on brake caliper bolts where the stainless steel bolt was locktite (red) and galled the threads of the fork leg when trying to take then bolt out. I was told it was due to the dissimilar metal of ALU and SS. I was told it is better to use an antiseize and torque to the proper torque. The person who told me is a good friend who was a former GP mechanic (before it became MotoGP), and AMA superbike mechanic.

 

[Donal]

I've never heard that using loctite causes problems with dissimilar metals. If anything, the loctite would insulate the dissimilar metals from corrosion and galling. I'm curious where this info came from.

I have seen it happen on brake caliper bolts where the stainless steel bolt was locktite (red) and galled the threads of the fork leg when trying to take then bolt out. I was told it was due to the dissimilar metal of ALU and SS. I was told it is better to use an antiseize and torque to the proper torque. The person who told me is a good friend who was a former GP mechanic (before it became MotoGP), and AMA superbike mechanic.

Just remember that the 'proper torque' needs to be reduced to account for the loss of friction, otherwise you risk stripping threads.

Normally, recommended torque is for new, dry, bolts and assumes a significant part of the rotary torque will be used to overcome friction in the threads and between the bolt head and surface.

 

[Fred W]

Thanks, Auburn. I'll keep that in mind in the future.

I know that the red is pretty tenacious stuff, and that you have to use heat to release it. I try not to use the red stuff on anything that isn't a permanent connection, that I want to disassemble nondestructively in the future.

Plus I've never got in the habit if just slathering everything with loctite, just because. If it doesn't specifically call for it in the service manual I don't use it. And as you pointed out, it doesn't call for it on the Allen bolt that holds the cartridge in the lower fork leg.

 

[Constant Mesh]

The threadlocker symbol is shown on the fork internal parts diagram in both the '03 and '06 Yamaha Service Manuals that I have.

An arrow from the symbol is pointing to the damper rod bolt.

Maybe it's an error but it appeared in at least two manuals three years apart.