variable pitch spring
Posted July 09, 2000 - 01:04 PM
i had the .42 springs changed for .46 & was impressed first time out at a motocross practice last sunday. far less work to keep it going over the bumps, far less work full stop.
the old set up took my zip tie to 10mm from the base but after two weekends on this set up i haven't used the last 1" so i'm presuming that i'm bottoming out without noticing it & the gold valves don't sink as far?
today i did a hare & hounds & it can't handle impact bumps smoothly still. compression clickers are anti clockwise to the max & rebound are halfway. anybody with experience of this?
has anybody tried the variable pitch springs?
if so what is your weight, skill level & terrain; & the spring weight used? Taffy
Posted July 09, 2000 - 08:09 PM
Time to change the valving. If you are saying that you have gold valves, then add a cross over shim to the stack as is commonly shown in the charts. If you have none, then add 1. If you have 1 then add a second(the charts I,ve seen don't show this).
Posted July 09, 2000 - 09:46 PM
tell me more, i want more ammo to talk to the English Co that have the franchise. before he got the forks he waxed lyrical, as soon as they were ready the smelly stuff started.
does anyone know about the slight loss of travel? is that how they all turn out?
he kept the rubber grommets that fit the base of the legs saying everyone throws them away! so i'm even guessing that it's anti-clockwise for softening the compression damping.
Posted July 10, 2000 - 07:53 PM
-If you didn't set the valving up, whoever did should stand up and revalve it to your satisfaction. Gold valves should be less harsh on the impact bumps if they are square edged. When the compression adjuster is backed out you should be using more travel. The oil level should be checked also, too much oil could be reducing travel. The springs might be too stiff but that doesn't explain your harshness. The bottoming stops shouldn't make a difference if you aren't using full travel.
Posted July 11, 2000 - 01:37 PM
can i get these charts because i got nothing with the forks, is this what you would get in the states?
as i suspected today he said i should try turning the screws in coz it was too soft on the comp adjusters, i thought this was quite comical but he did say that you REMOVE shims to soften the forks which took the wind out of my sails somewhat.
Posted July 11, 2000 - 10:25 PM
i mailed them at about 4pm your time so we'll see.
Posted July 18, 2000 - 01:37 PM
Have you gotten the shim stack info from Race Tech?
BASICALLY---The shim stack is a pile of very thin spring steel washers that cover the compression or rebound valve ports in the shock or fork. They flex as oil is forced thru the valve and close in the reverse direction. They are SPEED sensitive and not position sensitive. Your fork springs are position sensitive. The faster the fork compresses, the more the shims flex to let the oil pass.
The stack looks like leaf springs on a truck. The biggest ones are closest to the valve and progressively smaller ones are stacked further from the valve. There is usually a very small washer after the first few to make it a 2 stage stackup, like overload springs.
The shims closest to the valve are the first stage and are for slow speeds, along with your adjuster screw which bypasses the valve. Then comes the small "crossover shim", followed by the second stage - high speed stack. These are sometimes thicker and much stiffer. The very last thin shim is the important clamping shim, it is the foundation for the pyramid and will stiffen the whole high speed stack.
-Small clamping shims make it softer. More high speed shims make it stiffer and fewer make it softer. Thinner shims make it softer. Adding another small crossover shim sets the stiffer second stack further back and allows more oil to flow at high speeds(for harsh square edges). You have to be sure the nut is still clamping down on the stack when removing shims and that it doesn't run out of threads and bottom out.
Here is an example fork stackup from my CR250- (thickness x diameter) (Gold Valve)
.15 x 21 - first stage
.15 x 21
.10 x 12 - crossover
.10 x 21 - second stage
.10 x 17
.10 x 14
.10 x 13
.10 x 12
.10 x 11
.10 x 9 - clamping shim
Valving is extremely subjective. Rider skill, style, conditions, weight, power, 2st/4stroke,etc... all enter into the factors of what works best for you. Cartridge rod diameter and fork type are big factors too.
- Use your current settings and carefully think it through before rearranging. Extra shims removed can be put behind the clamping shim as spacers if they are bigger in diameter.
- Extreme caution must be used removing the factory swaging with a grinder. Loctite is used on reassembly. Torque precision is critical, as the valve body has aluminum threads easily stripped. Race Tech has a video to help in a step by step procedure. Stock valves have alot of potential so don't everybody automatically think you need a Gold Valve. I was pleased with the one on the CR. The WR stock valving is better than most MX models with it's stock valving.
Hope that was informative,
Posted July 18, 2000 - 02:09 PM
right on the edge of my minds eye but i was there with you. clear & concise as usual.
today i phoned the guy who has a reset my rear shock. he's about 30 miles from me.
he said that the RT guy is a complete rogue & gave me 3 (hairy) tales about him. he's got my money & that's it. with the school holidays starting next week & tons of work on, i'm gong to be lucky to ride the bike to try one last setting before i send them back.
he said that race tech were keen to get a dealer in the UK & they picked him. he's done three Race Tech jobs in the last month where people have wanted to put them back to Yamaha gear.
it has to be pointed out that this is a UK dealer & not race tech USA. i've posted race tech USA twice-no response. i don't want to knock race tech. it has to be seen through to it's conclusion first.
i'm not prepared to pull the legs apart & do it myself. i was told to check the oil level due to losing an inch of travel, this i'll try to do.
the loo-kl (fen accent folks) bloke who has a good following/reputation etc said that the yam forks are excellent & that there is very little that can't be done with them. he described RT as a gimmick.
the kind of thing i fell for when i was 19 but i hoped at 39....! the only thing he did say was that the yam set up could be better in the compression valving but that he would work on it this winter.
in anglia that usually means get the drill out!
Posted July 18, 2000 - 06:49 PM
Here's a trick. When I need to revalve several times to dial in a fork, I don't tear down the fork at all! Pull them off the bike and turn them upside down. Take one and put the axle in. Put the top end on a pad on the floor so you don't damage it and push down on the axle to preload the spring. This will hold the internal cartridge in place while you unscrew the compression valve - leaving the oil and everything else intact!! It may take an impact wrench to get it started, be very careful not to spin it fast and damage threads or the O-ring. When the valve is out you can restack it and then put it back in in the reverse order. KEEP EVERYTHING CLEAN. Dirt will get in the shims and mess up the valving.
- Many mechanics will cringe at this, but it works quick and easy. Just be careful with the aluminum threads.