Getting Twin Chambers apart!

[mconnell]

I've done lots of fork seals over the years, but I seem to have the most trouble with twin chambers. Specifically, when I try to slide hammer the tubes apart, the inner bushing wants to wedge under the outer bushing. This makes the process very slow and difficult.

Has anyone else had this problem? Any bright ideas on how to get them apart easier? I've tried heat, but I can't see any difference with or without.

 

[marcusgunby]

Ive heard of forks doing this sometimes but ive never seen it-once it gets under and tries to expand the outer bush it gets very hard.I think the heat does help but maybe not enough.

 

[bclapham]

i had exactly that problem. Lots of heat, lots of patience and then new bushings and two new washers i am afraid!

good luck.

 

[KiwiBird]

More heat. Short, sharp tugs. I agree they do suck.

 

[bclapham]

also, when you put them back together, use a PROPER fork seal driver. i tried the PVC tube method and its hard to get the bushings and seals in totally straight....thats why i ended up having to go through all of that again 3 weeks later when the seals went.

 

[dbrace]

Its allways best to get the seal area REAL hot, i use a hot plate. As soon as they jam once they are a pain and the bushings will be toasted. Allways get the seals real hot before you even try to hammer them apart.

 

[mxneagle]

I've never had this problem on showa forks, I have had it on KYB's of late 90's vintage though.

 

[mconnell]

dbrace - I used a torch on the seal area, but that was after it jammed on me a few times. You're probably right, maybe if I had put heat on it first, I could have avoided the jamming.

I've had this problem several times on the late '90's CR250 forks, but the worst I've encountered was a pair of '99 RM250 forks a few days ago. It was a horror show, and the bushings were ruined.

 

[bclapham]

yep: mine were 02rm125 showas, when i first took them apart they were easy to do. but then i put them back together with the PVC pipe driver and had a terrible time getting them in. no surprise that after 3 rides the seals were shot and it was a nightmare getting them apart again.

i went and bought the proper tool after that and when they went back together the second time it was done in less than a minute.

btw- save money by running the CR250 seal and wiper kit (try service honda too), i got the inner bushing from honda too, but the outer bushing has to be from suzuki- on the 48mm forks, the outer bushing is 12mm tall vs 15mm tall on the honda showas.

 

[mconnell]

The 99RM250 uses 49mm seals, whereas the CR's are all 47. As luck would have it, I don't have any seal drivers that large, so I had to fabricate some in a pinch. I have new ones on order now!

 

[mop]

I have also encountered this problem, mostly with KYB forks. The fact that the inner tube bushing is "wedging" itself under the outer tube bushing is self-defeating: as it wedges under the outer bushing, it gets tighter and more resistant to breaking loose. Heating the area where the bushing is seated is a good idea, but on KYB forks there is an O-RING between the outer tube and the "seal casing" which is swedged on, so too much heat can melt this rubber O-RING and basically scrap the fork leg. Something that must be taken into consideration is the fact that the flat washer between the oil seal and slide bushing is always deformed (conically bent) once disassembly is achieved. What does this indicate? I would say that it indicates that the OIL SEAL tightness may be providing the resistance that prevents easy slide hammer disassembly. I mean, if the bushing was doing all of the resistance, much greater than the oil seal, wouldn't the washer be un-damaged? Wouldn't it be flat?
So with this in mind, it would make sense to remove the oil seal FIRST, then slide hammer the bushing out. HOW THE HELL CAN YOU DO THIS!?!?! Well, it can be messy, but it can be done: As soon as you detect this problem, (the inner and outer tube wedge solid when slide hammering it apart), stop banging on them. With the fork spring out, fill the fork with oil at about half stroke, re-install the fork cap with as little air space inside as possible. Now you have a SOLID fork (from half stroke, if you want you can fill it at full stroke, but it takes more oil). Remove the dust seal, remove the circlip. Now put the fork tube in a hydraulic press and compress it. The hydraulic power of the oil inside will force the fork seal up and out as long as it doesn't have a horrendous leak. Once it pops up, oil should not blow all over you and the shop unless you left a huge air pocket inside before you screwed on the cap. Once the oil seal is out, try slide hammering the bushings out again. They should come out a lot easier.

 

[marcusgunby]

that sounds like a really good plan mop-thanks for that.

 

[Dan105]

I just did a fork seal and changed the oil in both legs on my 01 honda twin chambers. Went very smooth. I used a hair dryer to warm the bottom of the upper leg around the seal and bushing area. I am know also using Mobil 1 ATF for suspension fluid. Someone told me thats what jeremy uses. I dont know how I will like it though. I was used to 5wt oil and I think this stuff is more like 7wt

 

[marcusgunby]

I use boiling water to heat the tubes.

 

[dbrace]

Marcus, do you really use water?? Do you pour it onto the tube or seal. I really couldn't see that working. Are you serious? Maybe it's so cold there ......

 

[marcusgunby]

Yes been using water for years-safer than a naked flame and less likely to damage the o ring under the housing where the seals sits.I boil up a kettle and pour it slowly over the seal area on both legs till i run out of water.Trust me the area is too hot to hold in your bare hands.I just did a set of KYBs and old showas and neither had any damage to the bushes using this method. ie the tubes were hot enough to expand and not hold onto the bushes.

 

[mconnell]

mop - you have a good point on getting out the seals first but I don't think this is the cure. As I was struggling to the forks apart, I noticed I was moving the seal a little bit each time I tried to slide-hammer them apart. Once I had them out about 1/8", I used a spring puller and slid it under the seal lip and pulled the seal out. But, even with the seal and washer out, further difficult slide-hammering was necessary to get the bushings out.

Like you said, I did bend the washers into a cone shape, so that proves the seal was tight.

I like the idea of the hot water.

 

[marcusgunby]

mconnell i think the problem you had is due to not using heat at the very start-once the bushes try to ride under each other you are in trouble.Heat and short sharp yanks is the way to go every time.

 

[dbrace]

Marcus, what does a short sharp yank look like, sorry i have a funny way of reading things sometimes, lol.

 

[KiwiBird]

Sometimes Brits substitute jerks for yanks, depends on the moment............

 

[marcusgunby]

LOL

 

[bclapham]

as long as marcus has a plentyfull supply of boiling water to make my cup of tea when i got back over in october, then everything should be fine!:)