Yesterday I found a link to instructions for changing the oil in the Fast Ace forks used by Zero on their bikes. I have changed the oil in a lot of forks, including cartridge forks, and this looks to be more difficult and involved than anything that I have worked on. Plus, the forks only seem to use between 75 and 100ccs of oil. Most modern forks that I have worked on usually have as much as 500ccs of oil in them. The small amount of oil in the Fast Ace forks would indicate to me that the fork lubricant should be changed at least every few thousand miles of riding to control internal wear and the dampening function of the oil.
Anyway, what I did was to take the instructions that I found on the internet and rewrite them to correct the spelling, grammar and formatting to come up with something more understandable (if only I had photos). Until someone gets a hold of a workshop service manual, or does the work themselves, here are the dis-assembly and oil change instructions:
HOW TO SERVICE FAST ACE MALE-SLIDER FRONT FORKS
Tools you will need:
6mm Allen wrench
5mm Allen wrench
(2) 17mm open end wrenches
15/16 low socket
Plastic bucket
Metric measuring container
Fork siphon or syringe
Name-brand 20wt synthetic fork oil, or 80wt gear oil with anti-shear additives (which has the same consistency as 20wt fork oil)
Here we Go:
(1) Start off by removing only one of your fork legs at a time. This because some may get confused regarding which is the left and right fork and it will help when setting the proper fork height alignment when reinstalling.
(2) With the fork leg removed and in a vertical position:
(3) Remove the top cap with a 15/16 standard short socket carefully, while it is still vertical. With this done and the top cap off, slowly pull the cap up until about 6 inches of the spring is visible and let gravity drain the oil into a plastic bucket. You can pour a flushing compound, like kerosene, into the fork and flush them out a couple of times to get all the contaminants out that might cling inside. Then let the fork tube hang for a while to be sure that no residual oil is left inside.
(4) After a few minutes, take a clean rag and wipe off the two nuts below the cap and draw a mark on both nuts across from each other. This is done to ensure that you get the correct height adjustment of the metering rod (dampening rod) back to the original position.
(5) Now take the two 17mm wrenches and unscrew the top cap from the spring assembly (counting the number of turns you made past the marks on the nuts) and slowly separate the assembly (making sure not to bend or damage the dampening rod):
(6) Completely remove the rod and set it aside and (again do not drop or bend the rod) and let the rest of the fork assembly gravity drain into the plastic bucket for 5 min or so. Now take the fork leg while over the bucket and slowly pump the fork tube in and out and you will notice (where the dampening rod goes in) that the oil will drain out of both it and also the lower fork tube. Do this many many times until no more oil comes out. ( Don’t worry about the spring assembly falling out as its attached to the lower leg with an Allen bolt.)
The next step is to pour (between 75cc and 100cc of 20wt fork oil – for riders weighing between 150 and 200 pounds) the fork oil into the measuring cup, suck it out of the cup with the syringe and slowly squirt the oil into the fork as detailed below.
(7) Now with 99.9% of the used fork oil drained and the fork tube in the collapsed position and standing vertical. Fill the fork (siphon/syringe) and start adding fork oil to dampening rod tube. Continue this till all 75cc----150cc of fork oil is used. This might take 3 or 4 times squirting with the syringe (DO THIS VERY SLOWLY AS NOT TO GET IT ALL OVER THE PLACE OR IN YOUR EYES):
(
Now with the fork tube assembly still vertical, let the oil settle for a few minutes and it will partially bleed itself of air bubbles ( not completely). Now carefully wipe down the dampening rod and cap assembly and insert it slowly down the dampening tube. Then thread it back together counting the number of turns from dis-assembly and tighten the cap back to the marks you made on the two nuts until they are opposite from each other. Finally, carefully use the 15/16 shallow socket to screw the top cap back into the fork tube so it looks like it did before you started. Taking photos before you start and during the dis-assembly process will help with re-assembly.
That sure sounds like a lot of work to me.
Author
Topic: Suspension oil change (Read 1163 times)