Fork maintenance failure

[RadioHowie]

Oh yea, and this week we are working on moving kiddo from his glide bike to a big boy bike.

WORST example of ATGATT EVAH!!!!

I can already see the knee, elbow and palms-of-hands scars.

DADDY needs a jimmykick!!!

 

[Redfish Hunter]

Yes my vertically challenged friend, I deserve a kick or two. Next time I see you I owe you a lunch so you might want to wait until after I pay to kick me.

 

[gixxerjasen]

Nah, that's when I'll take your wallet and pay for everyone's lunch.

 

[Redfish Hunter]

There will never be enough money in that wallet to pay for "everyone's" lunch. Did you forget that I am married and therefore have no extra money?

 

[RadioHowie]

There will never be enough money in that wallet to pay for "everyone's" lunch. Did you forget that I am married and therefore have no extra money?

Fixed it for ya, 'fish...........at least based on MY life!

 

[gixxerjasen]

Lower fork stanchion arrived today. Now just waiting on the uppers.

 

[dcarver]

GJ - great to see the stiff upper lip.
When KrZy8's engine went South, for about 1 second I wondered about another platform.

..No!

But please DO take up Yamafitter's request - Inquiring minds do want to know.

 

[gixxerjasen]

Yea, but then you have to realize "What other platform is problem free?" Granted, this combined with my AE issues has had that nagging thought in the back of my mind.

One way or another we'll get em apart. Might not be very quick though.

 

[Redfish Hunter]

Yea, but then you have to realize "What other platform is problem free?" Granted, this combined with my AE issues has had that nagging thought in the back of my mind.

An excellent point. If it can be built, it can be broken. If it floats, flies, f***s, or it's fast, it is going to cost you money. So far I don't see any difference in reliability or long term concerns between my Honda ST1300 and Dad's FJR.

I am hoping the new '14 FJR color does not cost me dearly.

 

[ionbeam]

...I am hoping the new '14 FJR color does not cost me dearly.

Looks like a good fit to me Redfish Hunter, what could be better than a bike painted to match your 'name'.

 

[gixxerjasen]

Uppers arrived. They are heavy. Hong Kong to my desk in three days for $30? That's pretty darn good!

No wrenching this weekend though. My mom is coming to Austin for the weekend so we will be driving down so my kiddo can spend some time with his "Gungie" this weekend. Too bad though, with the rain all weekend it looks like a good wrenching opportunity. But alas, some things take precedence and I don't get to see mom very often as my folks live in Tampa Florida.

If I could swing it, that red 2014 would replace my "Problematic" 2007.

 

[HotRodZilla]

No one's gonna buy it with those broken forks!!

Ducking and running for cover.................

 

[not2shabby]

I can just about garrantee this is your problem

https://i1194.photobucket.com/albums/aa370/not2shabby/bushings.jpg

Notice the deformed edge on the 3rd one from the right? It slid under the upper bushing when I was doing the slide hammer bit to separate the tubes. I had quite a time getting them apart. I'd say yours is probably worse.

As an aside; the next time I change fork oil I may remove the middle bushing to see if it makes any difference in handling/stiction/compliance. I installed RT gold valves, both compression and rebound and straight rate springs when I replaced the bushing/seals and oil and while it was an improvement, I still find the forks to be on the harsh side on sharp edged bumps. Road feel and handling was markedly improved though. It could be the shim stacks need to be adjusted for less high speed damping.

 

[Fred W]

I can just about garrantee this is your problemhttps://i1194.photobucket.com/albums/aa370/not2shabby/bushings.jpg

Notice the deformed edge on the 3rd one from the right? It slid under the upper bushing when I was doing the slide hammer bit to separate the tubes. I had quite a time getting them apart. I'd say yours is probably worse.

Considering that these bushings are intended to be removed this way, a person would think the design engineers would have made the difference in diameters and thicknesses overlap more so that **** like this didn't happen. I'm still somewhat anxiously waiting to see what has happened inside Jasen's fork leg.

As an aside; the next time I change fork oil I may remove the middle bushing to see if it makes any difference in handling/stiction/compliance. I installed RT gold valves, both compression and rebound and straight rate springs when I replaced the bushing/seals and oil and while it was an improvement, I still find the forks to be on the harsh side on sharp edged bumps. Road feel and handling was markedly improved though. It could be the shim stacks need to be adjusted for less high speed damping.

Something else that you can try between now and then is to go with a thinner fork oil. That will reduce both high and low speed damping and then you can just crank in the adjusters to get your low speed damping back again.

What oil did you use last time. We can look up the actual viscosity of it and see if there is anything available that would be considerably thinner.

 

[not2shabby]

I went by the 'Peter Vergone'(sp) post about fork oils and used Motorex 2.5 because it most closely matched the Yamaha fork oil, but a little lighter. I'd be afraid to go much thinner because that might put my clickers outside the usable range. I have a bunch of shims that came with the gold valves so I'm going to research how to lighten up the high speed damping w/o affecting the low speed...if that's possible. I think by doing that and eliminating the middle bushing, I can get the desired result.

Oh, and +1000 on the bushing design! Pretty stupid that they can even come close to binding like that! I wonder how many others have had this happen? I'm anxious to see what Jasen's look like!

Off topic here but related...kinda, I just changed fluid and seals on my WR250f due to a leaking oil seal and used the same fluid and it is/was harsh over square edged bumps also. Why the $#@& do they dial in so much high speed compression damping on Jap bikes to begin with? Every bike I've owned has been like that, some worse that others and from each mfgr of the big four. You'd think a bike designed for off road would be more compliant over rocks, ruts and logs, but it's like riding a jackhammer! My SIL left me for dead riding the 20 yo DR350 on the trail!

 

[08FJR4ME]

I can just about garrantee this is your problemhttps://i1194.photobucket.com/albums/aa370/not2shabby/bushings.jpg

Notice the deformed edge on the 3rd one from the right? It slid under the upper bushing when I was doing the slide hammer bit to separate the tubes. I had quite a time getting them apart. I'd say yours is probably worse.

As an aside; the next time I change fork oil I may remove the middle bushing to see if it makes any difference in handling/stiction/compliance. I installed RT gold valves, both compression and rebound and straight rate springs when I replaced the bushing/seals and oil and while it was an improvement, I still find the forks to be on the harsh side on sharp edged bumps. Road feel and handling was markedly improved though. It could be the shim stacks need to be adjusted for less high speed damping.

Wow!!!! You have way much more wear than I ever had. I could have gone to 100K after looking at your pic's.

Dave

 

[MCRIDER007]

I went by the 'Peter Vergone'(sp) post about fork oils and used Motorex 2.5 because it most closely matched the Yamaha fork oil, but a little lighter. I'd be afraid to go much thinner because that might put my clickers outside the usable range. I have a bunch of shims that came with the gold valves so I'm going to research how to lighten up the high speed damping w/o affecting the low speed...if that's possible. I think by doing that and eliminating the middle bushing, I can get the desired result.

I'm with Fred on trying lighter oil, unless your rebound adjustment is already close to being fully closed you should be able to go to a lighter oil. Its hard to give advise about shim changes without knowing what design Racetech uses to achieve the high speed compression circuit, but the large shims are the ones that actually flex and allow oil to flow past them so you can increase that oil flow by using fewer or thinner large shims. Changing the shim stack will not have any effect on the low speed compression circuit. Eliminating the middle bushing converts the GEN2 forks to GEN1.....which I think is not a good idea....but either way it probably will not result in any improvement to the harsh ride you are describing. The Big 4 from Japan have a long history of suspension that is undersprung with too much compression damping. I don't know if they are clueless about suspension or that is their attempt to have one size fit all.

 

[not2shabby]

Are you sure changing the stack has no effect on the low speed damping? I just looked at the chart that came with the valves and right now I should have 3 big shims close to the valve. I may try taking one of those out and see if it helps.

What's your objection to removing the middle bushing? Too much flex?

 

[MCRIDER007]

Are you sure changing the stack has no effect on the low speed damping? I just looked at the chart that came with the valves and right now I should have 3 big shims close to the valve. I may try taking one of those out and see if it helps.
What's your objection to removing the middle bushing? Too much flex?

The low speed compression damping circuit does not use a shim stack (and even if it did, the oil flow is adjustable). If you are going to change a shim stack you need to make sure you are changing the high speed compression circuit stack, it normally is in the upper damping piston but I have seen designs where it is on the lower piston. The large shims will be against the (piston's) valve and bend towards the smaller shims as oil flows through the valve and applies pressure to the large shims. Therefore, the compression stack will have the piston's valve and large shims closest to the compression chamber which is the lower chamber between the two pistons.

The usefulness of the middle bushing has been a subject of debate, I think it adds rigidity to the fork and improves both handling and ride, Fred thinks it useless, just adds stiction, and increases the wear rate on the lower bushing. Whether the middle bushing is in or out, I don't think it is going to cause the harsh ride you are describing but I do think a worn out bottom bushing can result in what feels like a choppy ride on smooth surfaces.

Its fairly easy to remove the cartridge and change the shim stacks and all its going to cost you is time and a oil change. Removing the middle bushing probably means you are going to have to replace the seals and most likely the bushings as well.

 

[not2shabby]

Hmmm, I don't have that many miles on the bushings yet, maybe I'll just mod the shim stack and change the oil first and see how it feels. Probably wait till they start salting the roads!

Hey Jasen, got those tubes apart yet?