Front Fork spring replacement?

Hi All

I have replaced the fork seals on my project bike 1980 XJ 650, but now they seem spongy and dont seem to return all the way up. I reused the original springs checking the lengh of them against the workshop manual first. They were 2mm shorter than that in the book and did not think that this would make much differance. Could this be my problem (springs) or could it be something simply like not enough oil?

Regards Brian

 

Hey Brian,

Wouldn't be for lack of oil, those springs with the top cap off should push the long collar out the top of the fork tube. Sounds almost like something was missed on the re-assembly... Those aren't air assist are they?

 

Hi
No they are not air assist forks. Without taking them apart again im sure that everything went back togethet as is was. When the bike is on the main stand and you push down on the front they come back OK but when its off the stand and the full weight of the bike is on the forks they only seem to come back to within 1 inch of its full travel.

 

Thay're all done. Sagged out. No, 2MM isn't much off spec, but it tells you they've begun to collapse.

Cheap fix? Add an inch or so preload with a hunk of PVC pipe.

Best fix: Replace with a new set of Progressive Suspension or Works Performance springs.

 

might try preload for short term fix while I locate some new ones

Thanks all for help

 

When I replaced my fork seals, I used a cable winch to stretch the spring out a little to get them back to stock length and strength, it worked very well.
Just a thought...
On the rear shocks, I noticed some after market shocks use two springs instead of just one. I assume the lighter of the two soak up the smaller bumps, giving a smoother ride and the larger, stiffer springs take up the larger bumps so they don't bottom out, right?
So I'm thinking, I already cut 1" off the stock shocks to lower the rear of the bike with good results. I may cut off another 1" and install a short piece of lighter springs off of a smaller bike (same diameter) just using a large washer between the springs, tach welded in place. What'd ya think?
I have a couple pair of stock shocks to experiment with, so I may try it when I get the urge.

 

Ill see what some springs cost me here in Australia first if too dear will try to fix them some how. when you stretched them did you go over the stock length ? Will be interesting to see how your other idea pans out

 

When I stretched my springs, I first measured the length theywere. Then I stretched them approx. 3" to see if they ended up longer, which they did, by about an 3/4". I figured they would probably compress soon after installation, so I did it again and this time I stretched them a little further. I guess I must've ended up with them being about 1" longer.
The results were impressive and maybe too good. The front end is quite stiff now, maybe too stiff. Of course I have to take in consideration that I lowered the rear suspension, which takes weight off the front. And I also removed the Vetter fairing I had on at the time, and they put alot of weight on the front also, so that made a big difference .
I refilled the forks with Yamaha fork oil, which I think is 40 weight. I also blocked off the anti-dive units, which are a joke anyway.

 

Stacking springs like you're talking about has the same effect as a dual rate spring - softer until the lighter spring coil binds, then firmer for the heavier spring. Just what you described.

ATVs often stack 2 or even 3.

No need to weld the washer on, just stick it in the stack.

 

I think that using a large washer between the springs will cause them to scrape on the shock housing and make some weird noises if not tack welded onto the springs. Also, the washer needs to have a large enough hole in it so as not to make contact with the shock piston rod or it will scrape and ruin the shock eventually.
Another idea, ( I have ideas I haven't thought of yet!!) is to weld a couple tabs to the inside of the washers vertically, to keep the washers centered in the springs to keep them from moving around. That should work.

 

That sounds like a better idea than welding to springs.

 

Brian, you've got mail

 

I think if you were to put a tack weld, even a small one on a spring the results will be a broken spring where the weld is and either small pieces falling down inside or a loose washer with a chunk of spring attached moving around inside.
Don't weld on a spring, it'll wreck it.

 

After giving it some thought, welding to the spring isn't such a good idea I guess. The idea of using washers with shoulders welded on them will work alot better. It would keep them centered in the spring and keep them from moving side to side.
I'm heading out to the salvage yard soon to get a pile of springs and start cutting!