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ZRX front fork oil change time

B

bobct

Member
Member
It's time to at least change the fork fluid in the ZRX forks on my C10, 7+ years and about 30k miles since installed with the Cog seller (gfinca, if I remember correctly) of the forks installing new fluid.
Reading up on ZRX forum for disassembly to change seals and bushings, no leaking seals.
Curious what you guys use for fluid weight in ZRX forks and any insight/tips on rebuild.
 
Well, ended up with a leaky fork seal before I got around to changing the fork oil. Ordered bushing and fork seal kits from all balls, fast delivery.
Fork seals and bushing kits fit all year 1100 and 1200 ZRX forks, not sure about the last two production years of the 1200 ZRX which have non rebuildable fork cartridges.
I didn't have a 1/2"impact driver and just got the bottom of the fork allen cap screws that holds in the dampening rod assy loose enough just to spin. Tried fabbing up something to hold the square portion of the dampening rod assy but no luck. Took the forks to my friends house and zipped them out with his impact gun easily.

I went with the 10w fork oil as was mostly recommended for the ZRX.
Springs were straight springs, no tighter wound ends. Spacer seemed to be stock, I wish I measured the length of the spacer for future reference.
Some ZRX members are making longer or shimming the spacers on the frugel side and others are installing emulators. Most ZRX owners find the OEM forks anemic for sport riding. Still better than the C10 stock front suspension.

The tip I read on here pertaining to any fork cap assembling, is while the spring is out of the fork fit the cap on the fork tube and mark the fork tube and cap inline with where the cap threads start engaging the fork threads was used and was invaluable,
I had about 1" of preload travel when installing the caps under pressure.
 
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Bob, for your buddies that want to add spacers;
I suggest that they remove 2" of the existing spring and make the spacer 2" {or mebbee 2 1/2"} longer.

Explanation;
If you install a longer spacer;
,, You will increase pre load, (and the bike will set a bit taller), but the spring rate does not change. {so amount of dive will be almost unchanged when braking}.
If you cut the spring, and increase the spacer {the same amount as the amount removed from the spring},
,, The spring rate increases, and make's the spring stiffer.
,, result will be; bike sets slightly taller, and you will have less dive when braking.
If you cut the spring, (and increase the spacer as little as 1/2" more than the amount of spring removed),
,, The spring rate increases, and make's the spring stiffer. and your adding 1/2" of preload.
,, result will be; bike sets even taller, and you will have less dive when braking.

Many may not understand that by cutting the spring, the spring becomes stiffer.
,, "because you have fewer spring coils to deflect as the spring is compressed".
The mod costs nothing, and works to stiffen any set of fork springs.
NOTE: Springs can be easily cut with an abrasive cut off from Harbor freight.

Ride safe, Ted
 
Hi Ted,
Thanks for the spring lesson. I gathered the info on longer spacers from perusing the ZRX forum, they were adding fractions of inches to the spcer length. I knew the C10 frugal mod was to cut the spring and add that in spacer length. I just wasn't sure why I did not see reports of cutting the springs on their forum, I dont think they were adding inches of spacers that I found in my limited searching of their forum.
They are going with Ohlin or progressive springs and emulators, some are going to older ZX9 era upside down forks or there is a mod for purchasing triples that fit the ZX/ZG1400 forks. They are looking for older ZRX forks too, pre 2004 because the 2004 and 2005 forks cant be modified for emulators (different cartridges?).

Those ZRXs are holding their value pretty well for a 16+ year old bike with 1990s tech. A friend of mine traded in his stock pristine ZRX1200 about 4-5 years back and didn't really get much for it, I wish I knew beforehand that he was trading it in.

Take care Ted,
Bob
 
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I was only talking about spring force.
My point was; removing spring coils, accomplishes more than adding a spacer {to increase pre load}.

Ride safe, Ted
 
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