ATC200M front fork rebuild - writeup

[BarnBoy]

Rebuilding the front forks on my '84 200M. Decided to take pics and try and provide some info on the process for those who may need it. Will update as I progress.

First, I recommend you download the factory service manual and print out the section on the front end.

Once the forks are on the bench, you need to loosen the Allen bolt in the bottom of the fork. This is what keeps the damper and fork assembly together. Mine were.stuck and corroded, before I touched them I soaked them for about 2 or 3 weeks in Hagens brew (50/50 mix of diesel fuel or ATF and Acetone). A small impact carefully applied with a 6mm allen socket is useful to break them loose. Loosen but do not remove.

Next step is to depress the inner fork cap and remove the circlip. This will allow the inner springs to come out. This is most easily accomplished by the use of a hydraulic press to compress the spring **JUST ENOUGH** to where the clip is visible. Sometimes some penetrating oil can help free the cap up, they get stuck with grime and age. The clip can then be removed with a pick.

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Once the cap is off, the springs can easily be removed. I suggest a clean drain pan be used to dump the springs into so as not to loose pieces. Pay attention to the thrust washer between the 2 springs.

Picture below shows all the components on the bench,, and tools required for the job.

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Updates to follow as I progress......

[ATC King]

The big question is, organic ATF or synthetic. :naughty:

[BarnBoy]

The big question is, organic ATF or synthetic. :naughty:

Well I went with organic ATF, if its worked for 30 yrs I suppose it won't stop today ;)

Finally found this thread again, I plan to update soon with more pics of the parts and reassembly.

[BarnBoy]

I cleaned and polished my lower fork legs. Used progressive grits of sand paper up to 1500 grit, along with Mothers Mag polish and a cotton wheel and by hand with a rag. They aren't perfect but for a rider, I think they'll look great.

If you have any pits or chips in your chromed for tubes, take some 2000 grit wet dry sand paper, and carefully biff any high spots or rust off. Take care to only sand around the circumference of the tube, NOT longitudinally, up and down. Do this until you cannot feel any sort of lip with your finger nail, and when it won't catch any fibres from a cotton ball.

Next step is to clean any oil and grit off of the parts, I fomt have a parts washer so I just use a tub with gasoline. Then blow dry with and air compressor and wipe/rinse as needed. These are all the parts and supplies you will need for this project. OEM is the way to go IMO for these seals etc, they will last 20+ yrs and aren't very expensive. Ive got maybe $30 in seals and o rings per fork tube, @ $10 for a set of cheap fork boots off eBay, and $8 in a bottle of ATF.

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Part numbers

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A manual is essential for working on these bikes. If you work on your own 3 wheeler and don't have a manual for it, you're an idiot. Get one here: http://www.oscarmayer.net/atc/manuals/

Here is the section needed for this job.

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[BarnBoy]

Next step is to install your new seals into your lower hosing. First goes the main oil seal, as per manual it is installed with the lettering facing UP. Coat the seal in ATF, also a wipe inside the bore. Use a seal driver or socket or whatever is handy that allows a straight push on the seal. Be careful getting it started, and keep an eye on it as you drive it home. Don't get it all cockeyed in the bore, work your way around the edge and keep it straight.

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Then install your snap ring, and carefully drive in the dust seal. This goes in real easy, just keep er straight and go till it seats on the lip on the top of the lower leg housing.

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[BarnBoy]

Once your seals are installed, its time to prep the piston, rebound spring, and oil lock piece. I like to coat everything in ATF, just try not to get oil in the threads on the piston. Coat the bore of the fork tube in ATF. Then, clock your split rings on the piston 180° out from each other. Dont forget to do this. Then install the rebound spring on the piston, its the shortest spring you have.

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[BarnBoy]

Insert the piston and rebound spring into the fork tube, and push it down to the bottom with the long spring. You may have to do some finagling to get it through the tube but it should come out like this....

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Next, take your oil lock piece and insert it over the piston.

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[BarnBoy]

Next, insert your fork tube assembly into your lower fork legs, taking care passing it through the seal. A wipe of ATF will allow the 2 parts to slide together with no problems. Then, take your lower Allen cap screw and install your new copper sealing washer. Apply a bit of blue loctite to the threads and screw it into your fork piston. Place the assembly in a vice with soft jaws or a towel, and torque the lower bolt (11-18 ft lbs). You may have to install the fork springs and cap to torque the bolt if it spins on you. I was able to torque it no problem without this, but I always double check once the unit is completely assembled together.

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I like to let the loctite cure for 20 mins or so before filling with oil. Thats where I'm at now, will update as I progress...

[BarnBoy]

Next thing you need to do is fill each fork with oil. It calls for 88 cc of ATF in the manual. (You do have a manual dont you? If not GET ONE! This is the kind of stuff thats important) Now, 1 cubic centimeter (cc) is equal to 1 milliliter (mL) in case you didn't know. Fill to the appropriate amount, then you're ready to move to the next step. The manual does say to measure the fluid level in the forks, I did and they are pretty close. As long as you put the same amount of fluid in each fork you shouldn't have to worry about it.

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Next, install your new O ring onto the fork cap.

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Coat your fork springs in just a thin film of ATF. Then install the long spring (spring B according to the manual) first. It does not appear to be direction specific, so either way should be fine.

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Then, take your thrust washer and spring A (medium length). Install the thrust washer on top of the long spring (spring B), and install the medium spring (spring B) on top of the thrust washer.

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[BarnBoy]

All that's left to do now is install the cap and circlip, then you're done! I used a hydraulic press, same as how I took them apart. Don't over compress the spring, just push it down enough to pop that clip in there.

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And you're done! Congrats! Hope this helps some of you with your own projects. Just take it slow, don't force anything, read the manual and git er done! Merry Christmas everyone.

[MrConcdid]

Awesome write up, thanks for taking the time to take the photos and post them.
this should be a sticky, I will certainly refer to it.

Thanks
MrC.

[BarnBoy]

Awesome write up, thanks for taking the time to take the photos and post them.
this should be a sticky, I will certainly refer to it.

Thanks
MrC.

Thank you sir, hope it helps!

[DREVS]

got to do this myself on some 200s forks, they appear to be the exact same forks, and must say I am worried about that Allen bolt and I am worried about the fact I need to buy a shop press. I did not see a new clip in the photo do you reuse the ring clip that you needed the shop press to help remove? Did you reuse the Allen bolt as well? Just curious since I need to obviously buy a shop press for this job would a Honda Dealer or Motorcycle shop be able to rebuild these for me and would it cost less than a shop press?

[BarnBoy]

You need to soak the Allen bolt in penetrating oil, or hagens brew and be careful trying to break it loose. Worst comes to worst the head could be drilled off and disassembled that way.

Yes, I reused the bolt and circlip etc. Doesent really matter, just didn't have new ones.

A shop press is cheap at Harbor Freight and can do a lot. Not 100% necessary for this job but it helped a lot. Just buy a press if you have room, it'll pay for itself down the road.

[DREVS]

yea thanks, I will study your write up many times before I attempt. My biggest fear of doing this kinda work is the fact i have never done this kinda work lol

[BarnBoy]

yea thanks, I will study your write up many times before I attempt. My biggest fear of doing this kinda work is the fact i have never done this kinda work lol

It's not rocket science, this was the first set of forks I rebuilt. Rule #1 is DONT FORCE ANYTHING!! Follow that and you'll be just fine....git er done!