Race Tech Fork Spring Settings

[TahoeBound]

I've got at least 500 miles on new RT fork springs. I've been up and down the range as far as external adjustments go at what seems every possible combination in 1-click increments of Preload, Rebound & Compression. Countless hours of online research. Overall the ride is good, but I think the ride @ 70mph on So Cal freeway slabs should be MUCH better than it is. Probably the best thing I've done is put on a new front tire 1/2 way through the process and now I feel like I'm getting accurate feedback.

Symptom - it is NOT harsh and it is NOT plush, but seems very busy (opposite of an old Cadillac) on the freeway slabs. From what I gather, that indicates too much rebound. At this point rebound is dialed completely out at 32 clicks (arrived there by 1-click increments). Seems like the best setting so far but doesn't sit well with me logically & the ride is not where it should be IMO.

Fix - I thought with no more external adjustment I'd go internal & decrease oil height to 130mm (from 110mm, coincidentally Traxxion rec. 150-160mm !). Louie at RT says this will have little affect. He recommends increasing preload which will speed up the spring action & make it feel "softer." I thought increasing preload makes it firmer? I also understand that if you "increase" preload, you will have to increase rebound and I know increasing rebound makes the ride firmer. He's says that they've had good results with rider sag @ 35mm too. Most what I've heard on this forum (and Traxxion) is 38mm-45mm.

Question - now what? Is Louie correct, do I need to start again with more preload? Should sag be @ 35mm?

Particulars -

42-45mm rider (dynamic) sag (equates to 3rd - 4th line of preload)

110mm oil level from top

US-1 2.5-5wt oil

.90 spring @ 175 lbs

Compression set at 16 clicks out seems good without excess dive (most rec. 12-15 out)

TIA

Tahoe

 

[RaYzerman19]

From what all I've read, you probably want less sag, say 35 mm. Kinda thinking the 2.5-5 wt oil is a little light, the damping settings are to be dialed in later. I don't know that oil level will make a huge difference either, maybe a bit. BUT, start with less sag and try it. It should have a noticeable effect right away. You'll dial in the damping to suit your preferences, maybe you'll go a little more given the lighter oil. You might be good right there. If you're not happy, try a bit more oil. If you're still not happy, go 10 wt. oil. Yep, it's a bit time consuming to get things dialed in. And then few thousand miles from now, check the sag again in case the springs have "settled".

I am about to put the RT springs and gold valves, but I can't dial mine in until next spring.

 

[TahoeBound]

I've been eying the Gold Valves since my '04, but just can't pull the trigger!

Yes, adding preload/reducing sag has helped a lot. I need to measure but it should now be around 39mm (2nd line showing). I reset rebound to 20 clicks out (of 32). Compression still @ 16 out (of 22). The bike is riding the best its been since putting the RTs in. The one negative is it doesn't seem to turn in as easy.

I'd like to add more preload (1st line) which will max out the external adjuster & bring sag down to 36mm & see if that helps even more. My question now is should I add spacers internally to increase the preload? Is there a way to increase preload without decreasing sag/increasing ride height...does that suggest heavier springs?

Tahoe

 

[McRide]

I have been tweaking my suspension as well and have managed get it dialed in. I have a penske rear/ 850# spring and traxxion 1.1 front springs with 10wt oil. I was out last weekend doing the click by click adjustments and did find the sweet spot for freeway and twisties. PM me if you want to swing by (I'm in San Diego).

 

[MCRIDER007]

Yes, adding preload/reducing sag has helped a lot. I need to measure but it should now be around 39mm (2nd line showing). I reset rebound to 20 clicks out (of 32). Compression still @ 16 out (of 22). The bike is riding the best its been since putting the RTs in. The one negative is it doesn't seem to turn in as easy.......Is there a way to increase preload without decreasing sag/increasing ride height...does that suggest heavier springs?

The reason you have preload is to keep your steering geometry consistent with different weight loads. When you used preload to reduce sag you raised the height of the front end, increased trail, and slowed the steering rate. I think you are going down the wrong path in reducing sag that far but if that is what you want and you to want to keep your "turn in" the same, you are going to have to raise the forks in the triple clamps to compensate for the reduced sag (and no, there isn't any way to increase preload without decreasing sag/increasing ride height and using heavier springs will give you the same change in sag/ride height).

 

[BentAero]

Remember, spring rate is spring rate, you can't change that. Preload mearly changes the amount of force that it takes to begin compression of a given spring. MCrider007 is correct. Adding (or reducing) preload is a fine tuning adjustment, not a substitute for a rate change.

 

[not2shabby]

If you just changed to heavier springs, they are overpowering your rebound damping ability. By 'busy', do you mean the front end kind of pogo's down the road? Try turning the rebound adjusters all the way in. I recently went with .95 springs and reb/comp gold valves. I have the preload at 2 lines showing, comp about 13 clicks out and reb at 3 clicks out and the ride is much better than stock. I'm about 185 lbs.

 

[TahoeBound]

Thanks for all the replies. This has certainly been a learning experience. I've replaced springs several times in the past on different bikes without issue (including an '04 FJR), but not this time!

...I think you are going down the wrong path in reducing sag that far but if that is what you want and you to want to keep your "turn in" the same, you are going to have to raise the forks in the triple clamps ...

Because increasing the preload really helped, I thought I'd try Race Tech's recommendation's ~35mm and then know I can always go back. I must admit I have no confidence in RT as far as a specific-FJR setup goes though.

Questions - if I reduce sag another 3mm, would I have to move the forks 3mm up to keep handling "even?" Is there a max safe fork height? Eg. no more than 10mm above triples.

...By 'busy', do you mean the front end kind of pogo's down the road? ...

"Busy" meaning opposite of an old Cadillac. Lots of fast movements. RT recommended more preload to speed up the spring action and make the ride "softer." That still doesn't make sense to me but it did work and they are the experts!

I'm thinking all this is indicating the RT spring is slightly light @ .90/175lbs (though recommended by RT). Next time I'll round up instead of down. .95 would likely have been better.

 

[MCRIDER007]

...I think you are going down the wrong path in reducing sag that far but if that is what you want and you to want to keep your "turn in" the same, you are going to have to raise the forks in the triple clamps ...

Because increasing the preload really helped, I thought I'd try Race Tech's recommendation's ~35mm and then know I can always go back. I must admit I have no confidence in RT as far as a specific-FJR setup goes though.

Questions - if I reduce sag another 3mm, would I have to move the forks 3mm up to keep handling "even?" Is there a max safe fork height? Eg. no more than 10mm above triples.

...By 'busy', do you mean the front end kind of pogo's down the road? ...

"Busy" meaning opposite of an old Cadillac. Lots of fast movements. RT recommended more preload to speed up the spring action and make the ride "softer." That still doesn't make sense to me but it did work and they are the experts!

Yes, everything on the front end is a 1:1 change, if you add 3mm of preload you reduce sag by 3mm and can compensate by raising the forks 3mm. How far can you raise the forks? I think you are going to be limited by clearance, clearance between the rebound damping adjustments and the handlebars, clearance between the faring and front fender under full compression of the suspension.

Question...if you do not have any confidence RT's recommendations then why are you following them? So far the only thing that RT has told you that makes sense is that oil height is not going to help your problem. A 35mm preload might work good if you were taking your FJR to the track but 45mm is a better street setting but regardless of which preload you use, it is not going to effect the ride quality because you are still using the same spring and you are still using the same portion of the spring when you are riding. If you feel you have too many fast movements in the fork then you probably need more damping, especially compression damping. You do not want to speed up the spring action, you want to slow it down so the forks do not overreact to every bump.

If you start with a balanced system (spring rate, rebound and compression damping) and add a heavier spring, you need to increase rebound damping but decrease compression damping. Pretty simple if the oil weight stays the same, but if you change springs and oil at the same time it becomes more complicated because you don't have any way to know if the new oil is the same weight as the old oil and how to compensate for the new oil (oil effects rebound and compression damping in the same direction, if you lighten the oil you need to increase both the damping adjustments to compensate). Finally, on the FJR, changing the rebound damping also changes the compression damping (in the same direction) so you need to set the rebound damping before you adjust the compression damping.

 

[TahoeBound]

Hmmm...very interesting. So, I'm out re-measuring sag & the numbers are substantially different than when I originally measured 500-1000 miles ago. Now, 1st line preload is 45mm rider sag!! WHAT?! Well, seems to confirm a couple of my thoughts over the last month or two, that the spring is too soft (or maybe I'm too heavy ). Anyway, when I originally measured, 45mm sag was at the 4th line!

Maybe now, I can actually dial in damping. The down side is I'll probably have to add spacers internally, because 45mm @ the 1st line means I will not be able to adjust for extra weight (eg. passenger, tank bag or the holidays )

Onward.

 

[HaulinAshe]

At 175 lbs. (assuming you mean rider weight), the .90 RT springs are a good choice for you in a solo environment.

If you want a similar effect to increased spring rate (without changing springs), raise your oil level from 120mm to 100mm.

Rebound (assuming stock/OEM valves & US-1 fluid) will need to be in the 8-12 click range, depending on how you want to balance plush ride to performance.

Compression should be somewhere in the 10-15 click range.

Preload is very deceptive on the FJR forks, and is in fact more of a ride height adjuster than a true preload adjust. Preload is actually controlled by the spacer length installed when the fork is assembled.

Assuming you are using RT .90 springs that are 273mm in length, I recommend a spacer length of 137mm (stock is 150mm). This will give you roughly 20mm of actual PRELOAD when the fork is assembled and the adjuster set to three segments visible.

Be VERY careful about spring length. RT lists all their FJR fork spring options at 310mm length. However, it has been my experience that only the .95 springs are 310mm, while the other rates vary significantly from 273 on up. Make sure and KNOW what spring length is being installed and exactly how much the free length of the spring is actually being compressed/shortened once the fork is completely assembled and the adjuster placed in "position-X".

One last note about rider sag. If you are using the stock/OEM shock, you will probably be much happier with a front end that settles between 45-50mm. Above 45mm and the bike pushes in turns. The extremely soft OEM shock setup allows the rear to settle a bit too much and matching it to a lower 45-50mm rider sag, keeps the geometry balanced and turn-in quicker.

If you are using an aftermarket shock where preload and/or ride height are adjustable, you can possibly raise the rear rider sag and get good turn-in response with a higher (40-45mm) front sag. Of course, your legs have to be longer or you'll spend more time on your tippy-toes like me!

 

[HaulinAshe]

...(from 110mm, coincidentally Traxxion rec. 150-160mm !).

THAT recommendation is IMHO a very dangerous one for the FJR. It would result in exposing the top of the cartridge and I have personally seen that cause significant wear on the upper cartridge cap bushing. I STRONGLY recommend against FJR fork oil heights below (greater than) 120mm. My personal experience and recommendation is keep your oil height 120-90mm. If you need adjustment outside of that range, change springs!!!

 

[MCRIDER007]

Assuming you are using RT .90 springs that are 273mm in length, I recommend a spacer length of 137mm (stock is 150mm). This will give you roughly 20mm of actual PRELOAD when the fork is assembled and the adjuster set to three segments visible.

This post is a really good response but I don't understand why (at this point) you are recommending a reduction in spacer length. What ever the actual length of the RT springs and the internal spacer, both are currently installed in the forks and the measured sag (if done correctly) is 45mm with only one line of external preload showing. If the OP wants more external adjustment, perhaps three lines of external preload showing, then he needs to lengthen the internal spacer.

 

[HaulinAshe]

This post is a really good response but I don't understand why (at this point) you are recommending a reduction in spacer length. What ever the actual length of the RT springs and the internal spacer, both are currently installed in the forks and the measured sag (if done correctly) is 45mm with only one line of external preload showing. If the OP wants more external adjustment, perhaps three lines of external preload showing, then he needs to lengthen the internal spacer.

You are absolutely correct, IF all other factors are correct and unfortunately several of them are unknown at this point.

I don't know if I'm recommending a reduction or increase in spacer length. He never stated (that I can find) exactly what his spacer length actually is. Whoever did the RT spring install should have, and probably did alter the spacer length from the Yamaha/OEM/stock length of 150mm. My recommendation, and RaceTech's, is for 20.0 mm spring preload, which is best measured with the adjusters flush to the fork cap bottom, and is established by the spacer length, not the adjuster position.

Personally, I prefer to establish 20mm preload with two segments visible on the adjuster. That keeps the rebound adjuster knobs low and out of the way. It's a significant factor for those using Helibar triple clamps, because the hoses and cables are pulled so tight.

Spring preload on FJR forks is difficult to measure accurately, because you must consider how much the springs are compressed when the fork cap is tightened down with the adjuster at the "target setting". The fork springs are compressed during final assembly as the damping rod and springs are pulled upward against the top-out spring. The final amount of "squishing" that occurs as the fork cap is tightened is the actual spring preload measurement referenced in standard suspension lingo. Often times the initial assembly with the fork cap not in place, results in the springs sitting loose and able to freely move up/down on the damping rod by 5-10mm.

The main point I am attempting to make is the adjuster on the FJR forks is not the way to truly set preload. Spacer length is the initial and key setting.

To regurgitate some published specs on Gen-II FJR from the Yamaha service manual...

Fork Spring Free Length = 262.0 mm

Collar length = 149.5 mm

Installed Length = 251.0 mm

... which means Yamaha applies 11.0 mm of preload on the stock springs using the stock spacer (COLLAR as they call it), WHEN the adjuster is set flush to the bottom of the fork cap. (four(4) segments visible)

Here's the math as I see it...

* Assuming the installed RT spring is 273.0 mm free length, that's 11.0 mm longer than stock, which would result in 22.0 mm preload if we leave the spacer at stock length (150 mm roughly). I don't worry about the 1/2 mm.

* As stated above, I prefer to run the adjuster with two segments visible, which is roughly 10 mm LOWER than flush. That now puts us at 32.0 mm of preload using stock spacers.

* The typical RT spring setup also includes a rather thick flat washer (2.0 mm) added under the stock/OEM washer at the top end of the spring. Now we are up to 34.0 mm preload when using stock length spacers.

* In order to have 20.0 mm of preload, we need to shorten the stock spacer/collar from 149.5 mm by 14.0 mm, which equals 135.5 mm. I said 137.0 originally because that's based on actual, real-life measurements that incorporates some minor variables such as the type of support system used for the bottom of the spring, play/slop/tolerance in the top-out spring support etc.

Math summary:

+ 262.0 stock free spring length

+ 149.5 stock spacer/collar length

= 411.5 total length of stock components resulting in 11.0 mm preload setting

+ 273.0 RaceTech .90 free spring length (assumed)

+ 135.5 calculated spacer/collar length

+ 2.0 RaceTech added flat washer

+ 10.0 targeted adjuster (re)positioning

= 420.5 total length of new components resulting in 19.5 mm preload with adjuster showing two(2) segments visible.

As stated above, my experience is there's about 1.0 mm of "other factors" in the typical install that results in the need for a 137 mm spacer. IMO, Better to start out long and cut it twice.

Clear as mud???

 

[MCRIDER007]

I don't know if I'm recommending a reduction or increase in spacer length. He never stated (that I can find) exactly what his spacer length actually is. Whoever did the RT spring install should have, and probably did alter the spacer length from the Yamaha/OEM/stock length of 150mm. My recommendation is for 20mm spring preload, which is best measured with the adjusters flush to the fork cap bottom, and is established by the spacer length, not the adjuster position.

Personally, I prefer to establish 20mm preload with two segments visible on the adjuster. That keeps the rebound adjuster knobs low and out of the way. It's a significant factor for those using Helibar triple clamps, because the hoses and cables are pulled so tight.

The main point I am attempting to make is the adjuster on the FJR forks is not the way to truly set preload. Spacer length is the initial key setting.

Clear as mud???

A bit clearer than mud. I understand exactly what you are saying and agree with you...if the springs have yet to be installed. Your method is a logical way to determine the correct spacer length on the first try...but that horse has already left the barn. Once the springs are installed and actual sag is determined, it really doesn't matter what spring or spacer lengths are, the only thing left to do is to change the spacer length to get the desired result.....

and my advice to TahoeBound at this point would be leave the springs and spacers where they are and move on to getting the damping correct. His sag is right where it should be and adding a passenger or other weight in the back of the bike will have a minimal effect on sag, if anything it will probably make the front end lighter which will reduce sag.

 

[TahoeBound]

More great info & advice. Thank-you both. I'm learning slowly but surely. I’ve printed and added this thread to my “FJR Notebook!” I've changed several fork springs in the past, including my '04 FJR, without problems. This time though has been another story. I am looking forward to getting my ’08 correct.

On advice from RT, originally I cut my spacers 50mm - simply measuring the difference of the old stock spring I pulled versus the new RT. But, I do not know if the RT was 273mm or 310mm, just that it was SUPPOSE to be a .90. As mentioned above, I believe in order to have more adjustment range I'll have to add spacer length or maybe use the extra RT washers. However, as MC7 points out, the sag (using the Paul Thede L1/L2/L3 formula) is in range & perhaps better to just get the damping dialed in and enjoy the bike again.

Jeff, I'll use your listed numbers to start but a question here:

“Rebound (assuming stock/OEM valves & US-1 fluid) will need to be in the 8-12 click range”

With my setup, rebound range has increased to 32 total clicks (I believe stock is 17). Is 8-12 still what you’d start with?

 

[HaulinAshe]

Jeff, I'll use your listed numbers to start but a question here:

“Rebound (assuming stock/OEM valves & US-1 fluid) will need to be in the 8-12 click range”

With my setup, rebound range has increased to 32 total clicks (I believe stock is 17). Is 8-12 still what you’d start with?

Sorry, but I still don't know if you have RT Gold Valves or stock/OEM valves.

The RT Gold Valve setup can be/has been notorious for excessive rebound damping. At 32 clicks you are well past adjusting rebound and it's been wide open since roughly 24 clicks. Once the rebound control rod backs away from the control needle far enough to allow the needle to completely clear the valve orifice, further adjustment has no effect. That happens at roughly 24-clicks (3.0 turns CCW) of the rebound clicker.

Be aware that unlike the brass OEM control needle, the RT needle is steel and is MUCH easier to stick/lodge in the valve orifice. The clicker will still operate and feel perfectly normal. But the valve can be stuck completely shut. You must be extremely careful when installing the rebound control rod with RT Gold Valves, and make sure to GENTLY insert the rebound control rod. If you drop it dry into the damping rod, it can easily slam the control needle and stick the rebound valve closed.

If you want some help improving the RT rebound setup, send me email and I'll share. haulinashe at gmail dot com.

IMO, cutting the stock spacers by 50mm was just plain wrong, unless the springs are indeed 310mm free length. I can understand how that mistake could easily be made, because RaceTech's own web site lists ALL their FJR spring rates as 310mm free length, when in fact, their free lengths vary greatly through the .90 to 1.05 rates.

As for sag being correct...

Fork preload doesn't work like shock preload. The bike tends to settle to a given point based on the bike/rider weight and how that relates to the specific spring values. Minor changes (5-10mm) in preload will NOT affect rider sag, because the spring will settle "X" to achieve balance with load "X". The preload does however, significantly affect the behavior of the forks across smooth roads and small/quick bumps where the fork is acting in the upper limits of travel.

Think of it this way. If you preload a spring by say... 10 mm, and that causes the spring to exert 50 lbs. of static force against the rod holding it 10 mm short, then you set a 20 lb. weight on the end of the spring, the spring will not compress/shorten any further until the applied weight reaches 51 lbs.

If you apply 300 lbs. of static weight to spring "X", it will compress to the same length whether it has been preloaded or not.

That's why the adjuster mechanism on the FJR forks is so useful. It allows you to set the sag to a specific value without changing spring values, as long as your spring rate allows sag to settle into the available adjuster range.

 

[TahoeBound]

I have: stock/OEM valves & US-1 fluid.

Best I can figure, I'm about 6mm too short on my spacers - with 6mm more that would give me 45mm sag @ 3rd line exposed so I'd have room for adjustment. Next time in, perhaps I'll add washers or is it better to buy & re-cut spacers?

BTW - ride in to work today the bike is substantially improved: 45 mm sag, 110mm oil level, 12 rebound clicks out & 12 compression clicks out. With a little more tweaking I should be right there.

Thanks!

 

[gumba]

I have gp springs and penske shock. Got them all installed with fresh rubber and the scooter felt like shit. I had the 45 mph head shake and the forks felt harsh. Tried to dial it out with adjustments to no improvement. To cut to the chase, I had misaligned the floating fork tube on axel. The trick is to get all the sticion out of the front end. Then you can get some place. My front axel is rcessed .020 from the flat. The book calls for flush. Torque the pinch bolts down with the front end jacked up.