Gen 1 fork rebuild

[garyahouse]

HP:
...Yammie 10 wt. fork oil... I think it's BellRay, but I forget. Got 2 quarts. Thanks for the encouragement. In the past I haven't been real brave with this sort of thing but I'm committed. Ughhh, PVC tool? We haven't talked about that yet. How big? Do I recall someone saying 2 inch? Would that be regular "schedule 40" PVC? How long? I'm thinking like 6 inches?

(EDIT: WRONG OIL. DO NOT USE 10 WT. YOU'LL SEE LATER IN THE STORY THAT I HAD TO RETURN IT FOR THE RIGHT STUFF... 5 WT.)

Dave

What's the exact length needed? If I drop a 1/2 x 3 inch extension into the end of the 3/4 x 16" pipe, it will "use up" some of the available space meant to clear the damper rod. How much extra space to I have to work with? Machinists are used to working with tolerances. Help me out here. I'm thinking about just welding another socket on the top end... maybe a 3/4 inch... with the square hole facing up to receive the ratchet and during assembly, the torque wrench. However, I have more crummy used extensions than I do crummy used sockets.

Gary

 

[Fred W]

You'll want your 2" schedule 40 PVC seal driver (aka pipe) to be much longer than 6". Make it ~ 2' long so you'll be able to press down or tap on the top end of it without hitting the top of the inner fork tube (fully collapsed).

Be sure to cut the business end of the pipe as square as possible to drive the seal in evenly. Especially important if you'll be using it to drive the top bushing in (like I do). Ir you fit a cap on the opposite end (loosely) it will give you something to push or whack when using.

 

[MCRIDER007]

HP:Yammie 10 wt. fork oil... I think it's BellRay, but I forget. Got 2 quarts.

I"m not sure what wt. oil you are planning to use but it looks like its 10 wt. Belray. Yamaha used to recommend Yamaha 01 fork oil and then confused everyone when they called it a 10 wt. Its not, Yamaha 01 actually a 5 wt. and that is the wt. you should be using if you still have the OEM damping pistons in your forks. A lot of FJR owners use Honda SS-7 which costs $6.00 a pint (takes 3 pints) and whose viscosity is very close to Yamaha 01.

 

[HotRodZilla]

HP:Yammie 10 wt. fork oil... I think it's BellRay, but I forget. Got 2 quarts. Thanks for the encouragement. In the past I haven't been real brave with this sort of thing but I'm committed. Ughhh, PVC tool? We haven't talked about that yet. How big? Do I recall someone saying 2 inch? Would that be regular "schedule 40" PVC? How long? I'm thinking like 6 inches?

Gary, I remember Jeff Ashe talking about using a piece of pipe from a chain-link fence or something like that. Metal or PVC may not matter...I just remember that the first time I heard anyone talking about that "driver" they were using a metal pipe. Also, as Fred mentioned, I would not drive the seal with the end you cut unless you have a lathe or some way to ensure the cut is very straight. either pipe should come with square ends from the factory, so cut the other end, cap it, and drive it from the cut side.

 

[hppants]

I used the Honda SS-7 oil after I read a study done here comparing various oils. I don't remember why I chose it - but it works great.

Another tip - I used the old seal between my PVC driver and the new seal. It assures me that I'm driving straight. However, Fred's advice for cutting the PVC tool square is sound.

Be sure to inspect your upper fork tubes for any pits, corrosion, etc. where the fork seal rides. If you can see scratches, but can't feel them with your finger nail, you are fine - leave it alone. If you can feel it with your finger nail, I take some very fine (extremely fine) emery cloth (like 1000 grit) and VERY LIGHTLY sand the fork tube smooth. Don't worry, if you take 0.000002" off the tube, the spring in the new seal will make up for it.

Subscribed to this thread.

 

[garyahouse]

Hey Zilla,

Good to hear from ya. Thanks for weighing in on my project. Don't suppose you could swing by the house and give me a hand?? Hope you and the family are well.

Anyway, I stopped after work at Auto Zone and bought a 26mm socket. Ha - this is funny. It was so shiny and... perfect. I almost hated to grind off the chrome to prep it for welding. So here it minus one layer of chrome and ready to go...

Ted will probably be able to get everything welded in a couple days. Meanwhile, i'll check on the viscosity of that oil Yammie gave me, and pick up a 2 foot length of 2" pvc to be able to deal with the seals.

Gary

 

[08FJR4ME]

HP:Yammie 10 wt. fork oil... I think it's BellRay, but I forget. Got 2 quarts. Thanks for the encouragement. In the past I haven't been real brave with this sort of thing but I'm committed. Ughhh, PVC tool? We haven't talked about that yet. How big? Do I recall someone saying 2 inch? Would that be regular "schedule 40" PVC? How long? I'm thinking like 6 inches?

Dave

What's the exact length needed? If I drop a 1/2 x 3 inch extension into the end of the 3/4 x 16" pipe, it will "use up" some of the available space meant to clear the damper rod. How much extra space to I have to work with? Machinists are used to working with tolerances. Help me out here. I'm thinking about just welding another socket on the top end... maybe a 3/4 inch... with the square hole facing up to receive the ratchet and during assembly, the torque wrench. However, I have more crummy used extensions than I do crummy used sockets.

Gary

Here are some pic's of the tool. As you can see I used 1/2 x 18" long black pipe of which I purchased at sears. $4.00 I think. This stub adapter came from a 4 piece kit from auto zone also for $8.99. The pipe is still 18" long. I don't know why but I can't get the second picture to post up.

Also I think I mentioned this before I used Belray but it was one quart of 7 wt and one quart of 5 wt. When mixed this should give you the correct viscosity index as compared to the Yamaha oil. Based on the comparison charts of all the different fork oils out there.

 

[garyahouse]

18 inches?? The post I read here CLICKY said 16. Maybe I should make it 18 instead? Did you add a couple inches for extra clearance?

Now I'm worried about the oil Yammie sold me. I just checked the bottle, it's indeed Belray 10wt. So, I need to take it back and get something else? You're saying 6 weight is what I want? Ugggh.

 

[HotRodZilla]

Hey Zilla,Good to hear from ya. Thanks for weighing in on my project. Don't suppose you could swing by the house and give me a hand?? Hope you and the family are well.

Gary

Family is good. If I was 1000 miles closer, I'd run by tomorrow and stay until you finished up. I could add the colorful cuss words to the frustrating parts.

 

[MCRIDER007]

Now I'm worried about the oil Yammie sold me. I just checked the bottle, it's indeed Belray 10wt. So, I need to take it back and get something else? You're saying 6 weight is what I want? Ugggh.

The oil wt comparison I use from Peter Verdone's website shows Yamaha 01 as being 15.6cst@40C which is a light 5wt oil. That same comparison shows Belray 5wt at 17.0cst@40C and Belray 10wt at 33.0cst@40C. I would go with the straight Belray 5wt.

 

[Fred W]

Below is a linked copy of the aforementioned Peter Verdone suspension oil viscosity reference.

With the stock fork damper valves installed, you'll want an oil that is as close as possible to the Yamaha 01 fork oil's 40 degree C viscosity with the maximum cSt rating at 100 degree C (least thinning with temp increase). This would produce the least variation in damping with temperature changes during use. OTOH, forks don't really get all that hot inside, so that factor is a bit less important than getting the right 40 C viscosity.

The stock damper valves give too much high speed damping and too little low speed damping. Only the low speed is adjustable. So you might even think about putting a thinner oil in and cranking up the low speed adjusters. Only problem with that is that the Yamaha 01 is nearly the thinnest stuff out there. Maybe one of the 2 1/2 or 3 wt oils would work out. The risk is that you may not be able to get enough low speed damping, that the adjusters would run out of range if you go too thin.

 

[garyahouse]

Thanks for staying with me fellers. I don't feel so all alone on this project. I contacted Yammie and they're ordering 2 quarts of BelRay 5wt for me, should be in tomorrow. I'll just swap out the oil I bought for the new stuff. According to the chart above, it's pretty close to what I need. To be honest, I'm more concerned with clean oil than I am with EXACTLY the right viscosity... I don't ride the bike very hard and tend to keep it set up fairly soft as a smooth ride is more important than great handling to me. So, the 5wt BelRay shouldn't cause an issue.

Gotta stop at Home Depot tonight and pick up a 2ft. length of schedule 40 PVC.

Thanks and stay tuned.

Gary

 

[MCRIDER007]

To be honest, I'm more concerned with clean oil than I am with EXACTLY the right viscosity... I don't ride the bike very hard and tend to keep it set up fairly soft as a smooth ride is more important than great handling to me. So, the 5wt BelRay shouldn't cause an issue.

I can't add anything to what Fred said except that there is no such thing as EXACTLY the right viscosity because the viscosity changes with temperature and the fork oil's temperature is going to be effected by air temperature, riding style, and road conditions. Living in Florida your average riding temperatures are probably higher (maybe much higher) than most of the country so using a slightly higher viscosity oil (than Yamaha 01) may be the right viscosity for you. I think if you are within 10% of the Yamaha 01 you will get a very good result.

 

[Fred W]

Good point. I know my fork oil visosity at 0C (32F) is certainly a lot higher than Gary's will be at 40C (104F).

If it were a linear relationship (which I know it is not) the Yamaha 01 oil would flow at 23.7 cSt at 0C. Still that isn't as viscous as many (most) of 10W oils.

 

[hppants]

Fred - thanks for posting that chart. That is the reference I used for comparison and why I chose the Honda Showa 5wt (numbers are very close).

 

[garyahouse]

Fork tool has been completed. Ted gave it a torque twist test and it withstood 75 ft/lbs without any issues. That should be plenty strong enough. Planning to take the forks over to his house tomorrow to "blow" the seals out by filling them with oil and giving them a good squeeze. Wonder how much pressure that's going to take Hope it's easy enough to do...

So here's the end with the 26mm socket welded on. You'll notice my 2" PVC pipe in the background

And here's the other end with a 3/4" socket welded on backward, providing a convenient 3/8 square drive.

in between the two is 18 inches of 3/4 inch steel tubing. Learning as I go.

Gary

 

[Fred W]

Fork tool has been completed. Ted gave it a torque twist test and it withstood 75 ft/lbs without any issues. That should be plenty strong enough. Planning to take the forks over to his house tomorrow to "blow" the seals out by filling them with oil and giving them a good squeeze. Wonder how much pressure that's going to take Hope it's easy enough to do...
Learning as I go.

Gary

Noooo!

You don't need to do any of that. Once you release the cartridge the inner fork tub is used as a mini slide hammer to drive the upper bushing and seal out together.

PM sent

 

[garyahouse]

OH. Thanks for the input Fred. I've done so much reading, it seems. I thought there were two ways to do this, the slide hammer method and the "press" method. I just went, eeny-meanie-mynie-mo... and picked one. Seemed less "damaging." So, based on your advice, I'll do the slide hammer method. Once I slide hammer them out of there, and clean everything out with some brake cleaner spray, I've got new seals, bushings, and all that stuff ready to go. I've read that putting them back together might be a little difficult. Or was that the Gen II forks? Oh well. Still wondering about that.

ON ANOTHER NOTE, Today's the day I'll be tearing the forks apart. Tool is completed and waiting for me over at Ted's house. I'll be heading over there after our annual school Christmas party at a local restaurant. We'll be disassembling, cleaning and inspecting - as far as I know. Time will tell how this goes. I'll take lotsa pictures...

EDIT: THOUGHT I'D POST UP SOME OF THE PICTURES:

First I dumped out the oil and pulled the top washer and the spring. The oil seemed fairly clean at first, but got seriously yucky looking near the bottom. Pumped the tube on the outside and the damper rod on the inside several times and let 'em drain for a few minutes. Since I'm taking them apart, a longer drain period isn't necessary.

Back in the vice, and here I'm popping the dust seal off using a small flat head. Turned out it was in great shape and maybe could have been re-used, but I've already got new ones so it'll be replaced.

Came off pretty easy.

Next I fished out the end of the wire retaining ring with my little flat head.

And pop it out... easy enough -

I had my handy dandy damper removal tool ready to go, but when I put the air gun to the allen headed bolt (at the bottom of the fork leg), it came right out without any issues. Took all of 10 seconds. In addition to clamping the fork leg in the vise, I inserted the axle about half way in to give me something to hold on to prevent the fork tube from turning and potentially breaking of one of the tabs I had clamped into the vise. Below you can see the cap screw with its copper washer still attached.

Then the damper assy comes right out; I stuck the bolt & washer back into the end for now. Notice the large washer stuck on the right end of this assy. It was the washer that I attempted to pop off earlier with my magnetic pick up tool... which was impossible. Getting it off now is easy. However, getting it off while the forks were still assembled would have been a different story. One fella recommended removing it with a long coat hanger wire with a "hook" on the end of it.

Notice the left end above has a reduced diameter? That's where the this socket-shaped rascal (below) fits. I removed it from inside the lower fork leg after removing the damper assy. above.

Below: the socket shaped thingie is called an oil flow stopper. It just slid out. It just slides over the bottom of the damper assy.

Notice the large washer below?

It comes off, but takes a little persuading: the presence of this washer and the way it covers the 26mm nut just below it... makes it impossible to use the special tool I had welded up. Turns out I didn't need the tool, but if I did need it to remove the damper assy, this washer would have to be removed first. The forum recommended a coat hanger to get under it's outer edge and pull up on it to dislodge it from it's "seat." I never actually needed to do this. I did remove it (below) so I could properly torque the 26mm nut with my special tool when reinstalling the damper assy. In the pic above, I lightly tapped it a couple times with a hammer and it popped loose.

Time to remove the upper bushing and oil seal. I gripped the fork leg with some wood spacers in the vise jaws to protect the paint on the fork bottom, and used the chrome section like a slide hammer to gently remove the upper seal and bushing.

... and after about 15 light pulls, out it came. Here you'll see first the oil seal, next the spacer washer, then the upper bushing (copper colored), and directly underneath you'll see the lower bushing, which was still tightly attached around the bottom of the chrome slider tube. It's black on the outside. That's the teflon coating, which was still in remarkably good shape.

Now it's time to clean everything up.

Gary

 

[Fred W]

The only reason to use the hydraulic method of seal removal is if you do not intend to remove the cartridge or replace the bushings. When the seal pushes out you are going to have oil flying everywhere. What a mess!!

Once you have removed the cartridge you'll have a big open bolt hole in the bottom of the fork, so that hydraulic option goes out the window at that point.

On a first gen it is easy enough to get the bushing and seal off together (using the slide hammer technique) and just re-use the bushings if they look OK. If I was going through the bother of replacing the fork seals I'd also want to at least have a look at the bushings.

That alternate (hydraulic force) method is probably intended for all of those people that replace perfectly good seals prematurely because they've gotten a little dirty inside and start to leak or weep. Cleaning the seals occasionally with a seal mate (or a home made version of one) you should be able to get your fork seals to last as long as the bushings will.

 

[hppants]

I agree with Fred. The slide method worked very easy on my Gen I. I'm glad you are replacing the bushings. They have some kind of coating on them (prolly Teflon) and on my old ones, the coating was worn trough in places. I replaced the bushings with the seals and 40-ish K-miles and 2 1/2 years later, no leaks. Coincidentally, I'm planning to replace my fork oil this weekend as I'm putting on a new tire anyway.

Pay attention to the orientation of the spacer that goes in the lower fork. My first go round, I missed that and it took me a couple of hours (and a couple of beers) to figure it out for re-assembly.