fork springs differ by 1/4", use?

[mtiberio]

so I have a new set of fork springs for a mid 70's 35mm guzzi fork, and they differ in length by .25". If you have had the forks apart, you know adjusting preload is not easily done, so there is no real way to equalize them, and frankly I'd rather the assembled dampers and springs be the same length side to side anyway. This will leave one side with a bit more preload than the other. If we assume these springs are about 100 pounds per inch, we are talking a difference of 25 pounds in preload.

So should I use them or get a matched set?

[tiger_one]

Use them. 

The Ducati 696 has two different size springs in the forks, like over an 1" or 2" if I remember right.  When upping the rate by just a small amount, sometimes use an .85 in one side and .9 the other on a bike that had .85 in both.  Shim usually determines the preload, but like you say, tough to figure out before putting the forks back together.  In the 696 for my wife, I replaced the shim with a stiffer spring.  Worked perfect, but I admit was just guessing and it took many tries.

[Wayne Orwig]

I have no first hand info. But at the Blue Ridge rally this year I was talking to someone that had an issue with a bike being unstable at high speeds. He eventually traced it to uneven spring length.

[Stevex]

Last winter I took my (35mm) LM2 forks apart to re oil the standard dampers. I measured the long springs and found they were compressed from original by 15mm, not surprising when you remember they are 36 years old. I ordered some new springs from Gutsibits.
The two replacement springs that arrived differed in length by about 10mm! I thought, ffs, why spend money on new springs that haven't been made to a good enough quality standard that they are not even equal.
My solution was to get some spacers machined (Delrin if I remember correctly) to 15mm and fit them between the damper lower body and the top of the spring to re estabish the correct spring length and approximately the original pre load.
They work very well with the re oiled dampers, such that I've not gone down the Wirth / FAC route I was planning.

[mtiberio]

Since I'm trying to solve the handling problems on a Disc Brake Eldorado with a 'hands off the bars death wobble', I'll find a matched set. I currently have the short dampers and short springs in the forks, and if I remove my hands off the bars for even a second, the bike begins to tank slap. Yes, I have new steering head bearings. I suppose I should check the wheel bearings. Either way, I have a set of the long dampers, and just need a set of the long springs. I prefer the stockers to wirths as I like a supple front end. just my $0.02

[Stevex]

When I first went to look at the LM2 I eventually bought I gave it a quick road test and it wouldnt ride a straight line.
The bars gently wagged from side to side no matter what I tried to do. It was the crappy tyres that had been on the rims for the last god knows how many years. Just saying, it could be tyre related.

[mtiberio]

have new tires in my garage, want to do all the front end work at one time...

[Arizona Wayne]

Don't think I've ever had a MC that didn't have some head shake @ X coasting speed.  Find it to be normal.  MP3 doesn't do that tho.   

[johnr]

With forks on sport bikes being set up with rebound adjustments on one side and compression on the other, I can't see that a quarter of an inch would make much difference.  Use some washers, make a spacer, or something.  You should be fine.

That's assuming that they are the same spring rate and all other things are equal. They are obviously not a matched set so there is no surety of that.

If they are otherwise OK you would definitely want to equalise the pre load with a spacer, but I think I would try for a matched set myself.

[Aaron D.]

I've ridden bikes with a shake but never owned one.

[guzzista]

If you end up getting springs , these guys can get springs to your specs. Good bang for the buck also, IIRC http://www.sonicsprings.com/catalog/