Topic: Are air assist forks impossible to rebuild?

[jwhazel]

By a regular Joe mechanic that is? I have what appears to be '81 650c air assist forks on my bike. I've basically dissassembled them down to just the slider and the lower case. Unfortunately the slider does not seem to want to just come right out. It will come all the way up to the top, but then clanks as if something is blocking it. All I'm trying to do is replace the seals and soak the forks to clean all the old oil out.

A few hours of searching and reading through this forum and others have brought this question up a few times, but there seems to be two trains of thought. One: you can't replace the seals yourself, you have to take them to Honda. Or two: you can and it's easy (sometimes this method involves a press for some reason). Unfortunatley the thread usually peters out before a definitive answer is reached on whether they are servicible and if so, how?

For posterity, heres a fische of what I believe my fork look like. I really can't see what would be blocking the slider. I mean, the bottom of the case is sealed off, so it has to go in there somehow. http://www.powersportspro.com/images/newfiche/Honda/Motorcycle/CB650C_650_CUSTOM/1980_1981/(F__0802)_FRONT_FORK___CB650C__81_small.gif

Any help is greatly appreciated.

[dusterdude]

on the other sohc bikes there is a screw at the bottom of the lower leg you have to take out to remove the tube,perhaps yours has that as well.if it does shove a broom handle or something like that into the tube and press down hard while turning the screw to hold the bolt it is attached to from turning.good luck.

[jwhazel]

Whoops, I should have mentioned that I have taken the bottom allen screw out. It holds the dampener rod in place and, I would (or did) assume, keeps the slider from traveling all the way up and out of the case. Taking the screw off will allow the damperner to fall out of the slider, yet the slider still refuses to come out of the case.

[pyro139]

i have a 81 cb650c when have chance can scan the fork rebuild section of the clymer manual.

[jwhazel]

That would be fantastic pyro. If scanning is to much trouble, just the blurb about what to do after the dampener is taken out would suffice. Thanks so much.

[cb650]

I think the book says take forks to dealer.   Havent done any 81's.




                      Terry

[scunny]

air assist forks can be done according to Haynes
once you remove the damper rod bolt, carefully lever the dust seal out of the top of the lower leg and remove the circlip and washer. the stanchion can then be removed from the lower leg.
 

[mrbreeze]

I think the book says take forks to dealer.   Havent done any 81's.




                      Terry

Yeah?......well I say FU#* the dealer!!! It isn't a big deal and can be done at home very easily.Save the cash for parts instead of paying them for screwing off all day!!! (Hey man.....its yer cash!!!!....do with it what you think is right!!!)

[pyro139]

ya clymer says go to dealer cause need hydrolic press, well if haynes is giving instructions on how to do it your self, id get a haynes manual then.

[jwhazel]

Yeah?......well I say FU#* the dealer!!!

I truely am glad to see someone else here with my mentality. I was kind of afraid I would be lambasted with "if you want it done right, take it to the dealer". I'm sure that they would do a great job, but according to other messages on here, its a $200 job. More than half of what I paid for the bike and pretty much $180 more than what a seal change should cost. Not to mention these things need cleaned badly on the inside after dissassembly, something I doubt the dealer would do.

once you remove the damper rod bolt, carefully lever the dust seal out of the top of the lower leg and remove the circlip and washer. the stanchion can then be removed from the lower leg.

Aha! So thats whats blocking the slider from coming out. I originally started taking off the dust seal but decided against it for fear of gouging. Will have another go at it, this time much much more carefully. Thanks so much for this tidbit of info.

ya clymer says go to dealer cause need hydrolic press

Once I get this torn down I'll take a look to see what all is involved. If I can at least get everything apart in pieces, I can see whats involved with the press. Surely Honda does not possess magical presses that an ordinary machine shop would not have. If things go smoothly, I'll write up a tutorial for it.

[tomkimberly]

The air assist forks come apart just like most forks, remove the cap, remove spring(s), spacers, remove rubber dust seat and remove the retaining clip, use a broom handle to hold the pistion and remove the allen screw, now just pull them apart (be strong, it will take a good amount of force). Then remove the seal and replace. When putting them back together use a piece of PVC pipe to install the seal and bushings (install the bushings first and then the seal).

Tom

[cb650]

I think the book says take forks to dealer.   Havent done any 81's.




                      Terry

Yeah?......well I say FU#* the dealer!!! It isn't a big deal and can be done at home very easily.Save the cash for parts instead of paying them for screwing off all day!!! (Hey man.....its yer cash!!!!....do with it what you think is right!!!)

Never said I took any in did I ?    It is my cash and I will do what I want with it.




                                         Terry

[CBJoe]

Sorry to restart a dead thread  , but I'm curious if anyone can chime in about the need for a hydraulic press in this process.

I'm pulling apart the forks from my '81 CB650 parts bike to rebuild and use on my '80 CB650C.   I liked the lower front end stance of the '81 standard.

Where in the process is the press needed??  Why do all my manuals say to take the air forks to the dealer??

Does the fork seal need a press to remove and replace??


cheers....joe

[jwhazel]

It's kind of funny that I haven't logged on in months and when I do, I see a thread I started along time ago all the way at the top.

So anyways, rebuilding the air assist forks are just as easy as rebuilding any other forks from this era. The only special tools or machinery needed is a pair of angled circlip pliers and a piece of pvc pipe (2" ID IIRC) for tamping the seal down in place. The main things to replace are the seals and the dust jackets. The things to keep an eye on and think about replacing are the o-rings at very top of the forks when you unscrew the caps, the various o-rings used in the air fitting, and the washers used on the drain plugs and the hex screws on the very bottom. Whole thing takes about an hour or two for the first timer.

For the record, I never figured out what the deal with the press is or why you would need to take these to the dealer to have them done. IIRC, when you finally pull the stanchion out of the fork leg, theres a small collet wrapped around the bottom of it. This is probably the piece that needs a press to install/remove. I really have no idea what its purpose is, but I could tell that it didn't have anything to do with keeping oil in the fork or dirt out of it. It doesn't seem to be a part that would "wear out" either. So therefore I didn't bother with it. Rebuilt my forks just fine.

[tomkimberly]

Joe, read my reply two lines up. These forks come apart just like all the others, just make sure you remove the bottom allen bolt and the retaining ring holding the seal in place and pull apart, it will take a few trys but you can do it.

Tom

[CBJoe]

Thanks all for the replys.....I just wondered what the final word was on the press. 

many thanks... Joe

[paulages]

by the way, i don't know what all of you guys are doing with that broom handle  , but the allen bolt comes right out if you remove it while the spring is still pressing on the damper. an impact wrench makes it a breeze.

[CBJoe]

I see what you guys mean by not being afraid to use force when separating them I almost threw the fork leg across the room when they separated.

I'm taking the fork legs and dampers from the '81 CB650C and the Tubes and springs from the '81 standard.  I want the shorter front end stance from the standard and the dual disk setup from the custom. 

I've read a lot about the air forks vs standard forks on the forum, but I am left with one question.

Would I gain that much of a benefit from using progressive springs in the air forks over sticking with the original springs

cheers...Joe

[tomkimberly]

Glad you got them apart. Yes it does take a little force to seperate them. Make sure you install the plastic bushings before you install the new seals. Use a piece of plastic pipe as a tool.

The air forks kinda sorta work however replacing the springs and using spacers is the way to go. If you pressurise the forks too much they just start leaking.

Tom

[dfoxengr]

There was a good thread I found earlier today about this, with pics.

http://forums.sohc4.net/index.php?topic=59475.0

[Retro Rocket]

There was a good thread I found earlier today about this, with pics.

http://forums.sohc4.net/index.php?topic=59475.0

This thread has been dead for 4 years....

[dfoxengr]

I know that, but info on this topic is somewhat scarce, so I wanted to add the link for people's reference so that when they find this page on google they can be redirected to the helpful picture thread.