Progressive Springs??

So I am rebuilding a set of forks for my XJ700X and was planing on upgrading to Progressive Fork springs to match the new progressive 412's I've got for the rear. Well when taking apart the fork I found that the spring in there was wound progressively. Are the stock springs progresive from the factory or do I already have an aftermarket spring in there.

 

Well according to chacal, the stock springs are dual rate. Which means one spring rate until the tighter coils bind, then a second stiffer rate after that.

This is accomplished by making the distance between the coils in two sections different. Every coil compresses by the same amount when loaded, but the shorter coils run out of room first.

A progressive spring varies the size of the coils continuously, so there aren't two sections, but are instead many small changes in the distance between coils, such that a section doesn't bind all at once, but instead binds "progressively."

Interestingly enough, I have a RaceTech Suspension book that argues that progressive spring rate is not the answer to a plush suspension that doesn't bottom out, because the air pressure in the fork acts like a progressive spring. Their solution focuses on damping, by changing the valving of the fork, and they retrofit older forks with "cartridge emulators" to give more dampening adjustability.

 

Thanks for the info. I have stock springs. Racetech suggests cartridge emulators for the older style shock but they don't have a listing for the Maxim X. Any idea which ones would be a match?

 

You'd have to ask them. They also generally advise a different spring rate, fork oil viscosity, and preload too.

I haven't gone this way yet, but I was thinking about delving into it next year as I finish off my turbo seca.

 

Interesting topic. I have been asking myself the same question about my springs on the xJ as well as the RD350LC.

I had thought that I had progressive springs as well, as the coils are wider apart and only the top end are close up. so by this explanation, I have dual action springs.

Question or any one with Progressive springs...uncompressed, are they the same height as the standard springs?

 

gday pmjydnl, i can tell you what i did to my LC, i put new hagon progressive srings in mine and what a difference, they work well, but they were longer and stuck out the top around an inch and a half, boy did they take some getting in, i used a sash clamp and a few other things, with my xj i went to put in a set of progressive progressive springs, these were around 1 inch from the top of the staunchon and from memory i had to add a 1 and a half inch spacer, havent done it yet though . ken

 

My Progressive Suspension fork springs were longer than OEM, but the previous posts have merit. Many high-end suspension shops advocate using straight-rate springs (with a rating for the total weight you intend on carrying - which is much more than the OEM springs) and modified internal valving to control damping. Gold Valve emulators are one popular way, but so are Ricor Intiminators Ricor, and there is much less work fitting them in a set of forks. The problem is that the smallest one they make is for a 39mm (KLR 650) fork tube. Not to say that they wouldn't make some for a 36mm XJ fork tube if there was enough demand 8)

 

cool zap, I was wondering what other options were on the market, since racetech can't be the only ones with an internal valving concept. Although I found their explanation a little less straight forward compared to RaceTech (and it seemed like the concept was the same).

What's the difference in fitting them to the forks? Is it just the drilling out of the damper rod (which seemed like a good idea to allow a wider range of fork oils and reduction in cavitation).

 

Let me just chime in with some personal experience.

I replaced the fork springs in one of my 550 Secas with a new set from Progressive Suspension. The forks are otherwise stock, rebuilt units.

I used the original (7K miles only) springs from that bike to replace the measurably sagged-out springs (27K miles) in my '81 when I rebuilt its forks.

This gives me the opportunity to compare, side-by-side, the performance of the Progressive Suspension fork springs against the stock springs with all other factors being relatively equal.

The improvement over stock is immediately noticeable; the most surprising being an increase in BRAKING effectiveness as the front wheel is kept in better contact with the road.

The stock fork, thus improved, and with 15W oil, is quite good; especially compared to original. Unless you're racing, I don't think you really need emulator cartridges. Just a rebuild and a set of good springs along with slightly heavier fork oil.

 

Thanks a lot for the info guys, it certainly open up the options and also removes some doubts.

Well if only I had read the posts earlier, I would have been a little wiser. Took the said forks to the shop and have now replaced both sets of forks with the original items . In some respects, i am not too fussed as one bike (my son's) is going down the Cafe racer route...and believe you me the standard XJ springs and front end is about 10 time stiffer than the original fork that came out. So while by XJ standard, it may be ordinary, I am certain that it will show some improvement

The RD350LC is being rebuilt for Club Rego and could have gone with the upgrade (as Ken Suggested) and may still do so in the very near future. But for now, it will have to do. I have come across some major drama with that rebuild that will cost a fair bit to get around.

My XJ750R, I think that I will go for progressive springs as I intend to ride that a lot more frequently and doing some distance as well, so there is a better need to have a good and reliable set up.

Cheers

Phil

 

Springs are an inexpensive, pretty much "drop in" upgrade if and when you decide to go for it. I'm going to replace the "good" stock springs in the other bike too, the improvement is well worth it.

You wouldn't think springs that look so similar could be so different.

 

You are quite right...cheap way to improve the handling and braking situation.
The rear set up are a little more expensive though.

 

haha exactly what i thought, when i replaced mine, i was like "hmph. silliest 70 bucks i ever spent" but then when i got them in and the bike on the road, the improvement is substantial, a VERY worthwhile upgrade.

I replaced the stock units with progressive suspension 11-1107 springs.

Bought from here - great service might i add -

http://www.jcmotors.com/p-27149-progres ... J86hY54HBw

 

Thanks. From what I'm hearing I'm just going to get springs and leave the emulators alone. It is a cruiser after all With the progressive's on the rear it should be nicely matched I'm assuming.

 

Jcmotors, that mr crazy above mentioned, has a November Sale going on, got the progressive springs for the fork and new 14 series dampers and springs for the rear, ended up at ~200USD. quite a good deal if you ask me. At least compared to the ~400USD I would have to pay at the local dealer.

(Now I just hope that it slips through the customs, but oddly enough even if I have to pay the taxes and customs it was cheaper to order over seas.)

 

My impression was that the Intiminators were MUCH more easy to install - basically dump the old oil, drop them in, reduce the preload spacer and switch to 5w Amsoil (included with kit). The reduced weight oil runs right through the OEM damper holes so all damping is performed by the drop-in. Well received by the Suzuki SV and DL crowd :wink:

To the OP - good decision sticking with OEM forks/PS springs. Probably best compromise in performance/cost available to the XJs.

 

Maybe I missed the details? With the Progressive Springs (which I ordered after hearing about the jcmotors deal) What fork oil weight is being used?

I read the thread about the stock fork oil levels and weights, but chacal specifically mentions that the information is for stock springs only.

Those that have done Progressive springs, what's the oil w and measurment?

thanks

 

I'm using 15W instead of the Yamaha-recommended 10W.

As for amount, my bikes are 550s so it wouldn't apply here.

 

i used 15w 5 3/4 inches from the top

 

I put my .80 straight wound, Sonic springs today. I used 3/4" preload and 15wt Maxima oil at 130mm from top WO springs at fully compressed.
Much better, more compliment.

 

In which forks? Doesn't the resurrected racer have an FJ/FZ front end?

 

Yes 1992 FZR600 forks.

 

Thanks guys, 15w.
measurement still sort of up in the air? One said 150mm another 130mm.

I'll measure 140mm and split it. See what that does. Springs should come in this next week and i'll do all the work and see how it feels.