constant rate vs progressive springs

[grannyknot]

I have a set of /92 FJ front forks coming in the mail soon to install on the 84 FJ 1100 so have started doing some research in the files on upgrading them. Previous owner proudly told me before buying the bike that it had a new set of progressive springs in the front forks, but from the archives I'm getting that constant rate springs are better and maybe I should install spacers too and emulators.

I'm not a racer but I can hold my own in the middle of the pack in a group ride with everyone trying to show how good they are. But most the time I don't push it much.
Any recommendations would be appreciated.
Thanks,
Chris

[FJmonkey]

Progressive rate springs are good if you do more touring. If you like the corners then they are too soft. I hate my progressive (soft as warm shit) springs.

[racerman_27410]

I have run both kinds of front springs and i HIGHLY recommend getting straight rate springs from a reputable source.

the progressive springs for the FJ are a generic one size fits all type of springs..... they are also what comes stock on the FJ.

the top end of the spring is so soft the FJ just plows on thru that part with the preload necessary to hold the suspension up in it's stroke... leaving the harsh end of the spring to ride on.

the straight rate springs (in the correct rate from .95 to 1.10kg depending on your weight) will hold the FJ up with minimal preload and give you a much more supple and controlled ride.


KOokaloo!

[bugboy]

My PO was also proud of the fact that he put in progressive springs.  He was a big gentleman (300 lbs.) whereas I am about 165 lbs.  My front forks seem to have very little travel/ability to soak up bumps.  I've hit some bumps that feel like the front end hits them and rather than the forks compressing it feels like the front end just "hops up" and over.  I have not taken the front forks apart yet, as it seemed like there was "another day of good riding weather" just around the corner. 

It seems that the group opinoin is to go with some RaceTech in .95.  I have not found suitable long term employment and the military pension does not allow for emulators at this time but I can probably afford the springs.

[andyb]

Have you measured sag on them? That sounds like more of a damping problem rather than spring rate.  A progressive spring should be pretty plush until you start loading it hard with cornering forces, at which point it'll want to run the front lower in its travel in the more stiff portion.

If the prior owner set the damping for his weight, then you'll feel that things are not as responsive as they could be, but should feel best on really hot days (when the fluid is at its least thick).  On the other hand, if it's got progressive springs with heavy spacers to make up the preload, then the prior owner was a moron and a spring swap is very much in the cards for you.

[Arnie]

Bugboy,

Before you go to the expense of new springs, make sure you check and set the "sag" and renew the fork oil.
You may find that you don't need new springs at all, just that preload has been set EXTRA HARD to compensate for the PO's extra bulk.
Also, the fork oil may be over-filled and you're running into hydraulic lock.

There are a number of threads about setting front suspension on here, use the SEARCH.

Cheers,
Arnie

[racerman_27410]

the whole problem with progressive springs is that they are usually generic springs IE one size fits all.

I believe at one time we checked and a set of progressive springs listed for the FJ were the exact same springs listed for an old Honda 650 (a much lighter bike)

SO with the weight of the FJ the "plush" portion of the spring is swallowed up just trying to hold the bike up in the suspension stroke which they normally cannot do without the use of extra preload spacers which in turn mash the springs down even further.

what you wind up with is a very harsh ride as when the bike hits a bump the coils of the spring are so close together there is no place for them to go ... BAM.

next thing you know someone is tired of the harsh ride and decides to try heavier fork oil..... this just slows the forks action down even more though most get the impression it actually helps since the forks dont really bottom out any more they just hydraulic lock as the thicker oil has a harder time moving thru the fixed holes in the damper rod.

proper rate springs hold the bike up in the suspension stroke without the need for extra preload.... they allow the suspension to move thru it's entire stroke.

the oil controls the action of the springs.... if you hit a bump and the fork doesnt extend (rebound) in time to hit the next bump then your fork oil is too heavy..... ideally you should run the lightest weight oil you can that will allow the fork to extend quickly without bouncing back off the top.

with the proper spring rate for the supported load including rider,passenger and luggage and some light weight fork oil the stock FJ forks can be made to perform as well as damper rod forks can.

remember

Springs hold up the bike

fork oil controls the movement of the springs.

KOokaloo!

[axiom-r]

I have a set of /92 FJ front forks coming in the mail soon to install on the 84 FJ 1100 so have started doing some research in the files on upgrading them. Previous owner proudly told me before buying the bike that it had a new set of progressive springs in the front forks, but from the archives I'm getting that constant rate springs are better and maybe I should install spacers too and emulators.

I'm not a racer but I can hold my own in the middle of the pack in a group ride with everyone trying to show how good they are. But most the time I don't push it much.
Any recommendations would be appreciated.
Thanks,
Chris

Chris, If I am proud about something its the mods I did that allowed me to sell those forks. I followed a path close to the one racerman describes- tried a bunch of stuff to stiffen up the front end.  In the end I was dissatisfied with the forks and the springs so I wouldn't say there was any pride there...  The parts are in good shape you should buy new springs properly rated for your weight and riding style that way you know what you got.

cheers~!

tim

[Mike Ramos]

I have never been involved with discussions about modifications and I am hesitant to do so now; however regarding the front suspension on the FJ 1200.
What works well for me is nothing very exotic: simply heavy duty progressive rate springs with 15 wt. oil filled to standard specifications.
Hot or cold (?!) temperatures are academic. I have never bottomed out in the harshest road conditions and the ride is acceptable under all around conditions. Review the "California Cruise" video if you want to see the forks work acceptably well over a really beat up road.
Fork performance during cross country rides is also acceptable.
Mike.

[grannyknot]

I have a set of /92 FJ front forks coming in the mail soon to install on the 84 FJ 1100 so have started doing some research in the files on upgrading them. Previous owner proudly told me before buying the bike that it had a new set of progressive springs in the front forks, but from the archives I'm getting that constant rate springs are better and maybe I should install spacers too and emulators.

I'm not a racer but I can hold my own in the middle of the pack in a group ride with everyone trying to show how good they are. But most the time I don't push it much.
Any recommendations would be appreciated.
Thanks,
Chris

Chris, If I am proud about something its the mods I did that allowed me to sell those forks. I followed a path close to the one racerman describes- tried a bunch of stuff to stiffen up the front end.  In the end I was dissatisfied with the forks and the springs so I wouldn't say there was any pride there...  The parts are in good shape you should buy new springs properly rated for your weight and riding style that way you know what you got.

cheers~!

tim

Tim, I was refering to the guy I bought my 84 FJ1100 from, not you. The PO of my bike told me he had installed heavy duty progressive springs and I would love them. Now that I have taken apart those shocks and the ones I bought from you I can see this guy was totally full of BS. His look like they came out of a ball point pen compared to yours, yours truly are HD and will be the ones I use when I reassemble everything.
I just re-read my post and I worded badly, I am completely happy with the stuff from you.
Have a good Xmas.

[hein]

   Chris, spend the extra dollars and buy the Race Tech straight rate springs and the emulators. For me at 200 lbs. the 1. kg springs work well. The sag is easy to adjust with the lenght of the provided spacers.
By using the emulators you end up with a poor man's version of cartridge forks. The spring preload adjustor on the emulator allows you to adjust the compression damping and the oil viscosity now controls the rebound damping.
    While not as easy to adjust as modern cartridge forks with external adjustors this system can still be adjusted without fork disassembly.
Hein.