Replacement fork springs

Hi
So I am replaceming my fork springs ....thought it would be easy ... pick a brand and just exchange for the originals ... but so many different lengths
Manual states 382mm ... wanted a set of Ohlins but these are now discontinued
Any suggestions please don't really want to be cutting extra spacers if possible
YSS do a progressive set but are 390mm

speed-

 

You do not have to match the length, the only difference is the total length plus the length of the spacer you need. You can go a bit shorter perhaps 3/4 of what you have. RaceTech or Sonic are fine, you'll want straight rate and a spring rate of about 0.95 -1.0 kg/mm if you're around 180-200 lbs., or use RaceTech spring rate calculator for fork springs (I don't recommend their rear shock calculator, too hard. Use Penske's for that).

 

Hi

Thanks for the reply
So if the springs are say 30mm shorter I can use a 30mm longer spacer to make up the difference ?

Speed-

 

Absolutely. 30mm is nothing. RaceTech, and I suspect others will have instructions on how to calculate the new spacer length and a certain amount of preload, along with a recommended new fork oil level.

 

Hi
Will the spacers come with the springs ( sorry not used to anything but a straight spring swap ... like for like)

Speed-

 

Depending on the kit, they may provide you with some 1" dia aluminum tubing and some washers. Typical thing is to use some 1" dia PVC pipe, EZ and cheap. What you want (with preload adjuster backed out to zero) is about 15mm preload, so spring in, washer as spring seat, fork tube extended, measure top of spring (and washer) to top of fork tube, minus any further washer..... add 15mm, install top fork cap and it should take you 15mm to compress the spring to get the fork cap back on........ RaceTech's instructions are similar to that. IF the springs are longer than stock, then you can cut your existing spacer to suit, or make a new one.
If later you find you need more preload than the adjuster provides, then use an extra washer or cut a new spacer.

 

Hi thanks for the reply

Not too difficult really ....

Speed-

 

This is all correct except you also need to make allowance for the fork cap/locknut/washer coming down into the leg when the cap is installed.
Leg extended, springs and washers installed, measure to top of leg, subtract the depth of the cap/locknut/curved washer (set preload at about the mid point), add 15mm, and you're there. PVC tube is easily cut with a hacksaw, but needs to be as square as you can. Make sure to deburr the ends so the swarf doesn't end up where you don't want it.

 

I'm looking at hyperpro springs for mine.
Hyperpro Progressive Front Fork Spring Kit VFR800 Fi 98-01 | eBay

 

What Terry says too.... I use a chop saw for the spacers, always square. Deburr, absolutely.
I'd use straight rate springs, not progressive like Hyperpro. I could not get those guys to tell me what their spring rates really were.

 

I figure they got to be a big improvement on the 20 year old oem springs.

 

The problem with a progressive spring is that the rate is constantly changing, not good when trying to dial in suspension settings.

 

Hi. I've just ordered k-tech linear 85 n/mm springs, 375 mm long. I'm leaving dampers stock still, lets see how that works.

Lähetetty minun SM-A750FN laitteesta Tapatalkilla

 

Hi what weight are you? do you carry a pillion or panniers top,box sometimes? I'll be interested to see how those springs work for you, what weight fork oil you going to use? you have a 5th gen?

 

Hi, yes 5th gen. And I weigh 80kg, 176 lbs, with a backpack sometimes. I did the maintenance front, and changed the oil to 10w, and I wasn’t thinking about changing the springs then. We now have winter, and the driving season may begin in April. I try to change the springs in the spring. I asked Brooks if 85n / mm is suitable before ordering, they think these are ok, let's see. I have't got them yet.

Lähetetty minun SM-A750FN laitteesta Tapatalkilla

 

For your weight those springs are fine. You can always add some preload with the adjuster if need be, and if you run out of adjustment, just add a washer or two or cut new spacers a bit longer. I fully expect they will be fine as is.

 

What spring rate would I need at 255 lbs say 110kg, plus luggage and gear?

 

Just checked racetech and for my weight they rec the stiffest spring they have I think, SK SPRING 8.0 x 2.25" 21.4kg

 

Caution, that is for Rear Shock spring, and I can tell you from experience, RaceTech tends to be too hard for their shock springs. A better rear spring calculation can be had from Penske for rear shocks.
For the fork springs, they recommend 0.99, or 1.0 for your weight. I'd say you could up that to 1.1 or 1.2, it's only a slight difference being the springs are so long, but, since we have preload adjusters, 1.0 should work. Again you can always add washers to increase preload if need be, but I think you'd be happy with 1.0.

 

Thanks, I read it wrong. this is what they recommend when I put my weight in,

FRONT FORK SPRINGS
Recommended Front Spring Rate: 1.01 kg/mm (Use closest available)
Stock Front Spring Rate: 0.74 kg/mm (stock)

The spring would be a different length to the stock one so I'd need a different spacer?