FJR Rear Suspension Adjustment

[Goodman4]

Well I’ve decided to go on the quest for adjusting my suspension correctly. I never had a lot to complain about, I guess cause I didn’t know better, but after an hour of training in the Lee Parks class I was convinced there was too much I didn’t know about my bike.

At the class they usually mess with everybody’s suspension at the end of the day, but by then it was pouring down rain and most people wanted to get on the road instead of playing with theirs. I also think the main instructor didn’t want to get too wet. The local guy who runs that facility was game for looking at my bike but he wasn’t familiar with FJRs and wasn’t sure which setting did what. He said my front was really squishy and made some adjustments to both shocks. I didn’t like it very much and it felt rough even on the interstate home. I should add that my FJR is a 2007 that I’ve had a little over a year. It had about 7K when I bought it and now I’ve got a little over 20K.

Since the class I’ve been reading and now I fairly well understand the FJR adjustments. I decided to go with Jeff Ashe’s settings and at first I thought it was great. It seemed to have more control, but then I noticed how sore my butt was getting. The wife and I went on a ride last week and half way through an average day of riding she asked me if the Russell seats had wore out and lost their cushion. I explained it was the suspension, but she still is unconvinced. I didn’t want to adjust it on the trip so I just made one click of adjustment in the rear and one click on the front rebound dampening. I didn’t notice anything so I went back to the drawing board tonight on the rear shock.

When I check my measurements (at the level of my understanding) on the back shock, I measure the sag by putting the bike on the center stand and measuring the distance from a fixed point on the wheel hub to a fixed point above the wheel. It is 320 mm. I weigh 220 and have the top case on but the side cases off right now. When I take it off the stand and sit on it with my wife and I pushing down hard and letting it come back to my sitting weight, it measures 273 mm which gives me 47 mm of sag. When I take stiction into account by then pulling weight off by standing and sitting back down easily, I get pretty much the same 237 mm, which says I have virtually no stiction. Am I doing that right? Our measuring process was not that accurate, but I’m sure it was accurate to 2 or 3 mm. Do this mean I have a problem? Also this sag is a little much without the wife and luggage, right? But nothing I can do about that other than a new spring?

I then tried it on the soft setting and got very little difference as well.

The Jeff Ashe settings are 6 clicks on the rear. I have gone all the way up to the 15 which it says is standard and pushed hard on the back and it doesn’t feel to me like it pogos at all. I dialed it back to a smaller change to make it 10 clicks. I’m going to try it to see if I notice a difference in the butt soreness.

Any thoughts on what I need to do differently other than getting better shocks? I’m not ready for that investment. I’ll probably be happy when I get the rear back to the original settings once I get close to where it was. I have no idea where it was since they played with it and I had never touched it.

 

[Fred W]

When I check my measurements (at the level of my understanding) on the back shock, I measure the sag by putting the bike on the center stand and measuring the distance from a fixed point on the wheel hub to a fixed point above the wheel. It is 320 mm. I weigh 220 and have the top case on but the side cases off right now. When I take it off the stand and sit on it with my wife and I pushing down hard and letting it come back to my sitting weight, it measures 273 mm which gives me 47 mm of sag. When I take stiction into account by then pulling weight off by standing and sitting back down easily, I get pretty much the same 237 mm, which says I have virtually no stiction. Am I doing that right?

Yes, you are measuring correctly.

Our measuring process was not that accurate, but I’m sure it was accurate to 2 or 3 mm. Do this mean I have a problem? Also this sag is a little much without the wife and luggage, right? But nothing I can do about that other than a new spring?
I then tried it on the soft setting and got very little difference as well.

Yeah, that sag is a bit excessive for just you, so will be even more so with your passenger. The rear wheel total travel is 125mm. You want your loaded sag to be about 1/3rd of total travel, so 41mm. You aren't that far off for solo riding, but when you add your wife on the back the sag will be even bigger.

There should have been a difference between soft and hard, but hard was already too soft for just you.

The Jeff Ashe settings are 6 clicks on the rear. I have gone all the way up to the 15 which it says is standard and pushed hard on the back and it doesn’t feel to me like it pogos at all. I dialed it back to a smaller change to make it 10 clicks. I’m going to try it to see if I notice a difference in the butt soreness.
Any thoughts on what I need to do differently other than getting better shocks? I’m not ready for that investment. I’ll probably be happy when I get the rear back to the original settings once I get close to where it was. I have no idea where it was since they played with it and I had never touched it.

Using someone else's "recommended number of clicks" is not a valid way of adjusting your suspension, IMO. There are far too many variables, even between stock bikes, to get even close to what you need doing that.

I recently answered another poster that had questions about how to dial in his stock suspension here. Try adjusting yours following those guidelines and you should be able to get both ends as good as they can be with the stock suspenders.

I'll bet that if you follow my advice in that post for adjusting the rear rebound you'll see that your bike does oscillate at the top with minimum damping dialed in. Then the question is: can you get the bouncing to stop by adding damping. If you can't, the damper is shot and it's time to break open the wallet.

My adjustment procedure is also available by clicking on the little NERD in my sig-line

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[Auburn]

Keep an eye out this winter. There should be a group buy from gp suspension. The best thing you can do is upgrade the stock suspension.

 

[RavFJR]

Keep an eye out this winter. There should be a group buy from gp suspension. The best thing you can do is upgrade the stock suspension.

+1 on this... Upgrade the stock suspension. I wasn't as radical as most and upgraded my bike with just the Hyperpro front and rear spring kit for now. When my rear shock wears out (which is soon) I'll upgrade it as well. I found that attempting to 'dial in' the stock suspension, the front and rear never really complemented each other... Just my 2 cents.

 

[Fred W]

One follow up on just replacing the springs. This is an option to get the bike's sag correct and therefore the ride height and steering angles corrected, but you will probably end up with messed up damping for the new stiffer rear spring.

Rebound damping requirement is directly proportional to the spring weight. A stiffer spring will require increased rebound to keep the bike from oscillating. Conversely, an increased spring weight will require decreased compression damping as the spring is supporting more of the weight during compression. These can be adjusted independently on the front fork, but not so on the OEM rear shock. The one adjuster at the bottom of the shock primarily varies the rebound, but also compression damping to a lesser extent in the same direction (stiffer or softer).

So, if you just slap a heavier spring onto the stock shock, and then crank in a bunch of extra needed rebound to compensate, you are likely to end up with too much compression damping, which would give you a stiff, harsh ride and lack of rear suspension compliance.

In summary, for those with a tight budget, it's OK to just replace the springs in the forks (and then adjust the dampers to match) but doing that on the rear might not be such a great idea. Better to replace the entire shock with one that at least has dual adjustability so you can match your customized spring weight.

As always, YMMV

 

[MCRIDER007]

One follow up on just replacing the springs. This is an option to get the bike's sag correct and therefore the ride height and steering angles corrected, but you will probably end up with messed up damping for the new stiffer rear spring.
Rebound damping requirement is directly proportional to the spring weight. A stiffer spring will require increased rebound to keep the bike from oscillating. Conversely, an increased spring weight will require decreased compression damping as the spring is supporting more of the weight during compression. These can be adjusted independently on the front fork, but not so on the OEM rear shock. The one adjuster at the bottom of the shock primarily varies the rebound, but also compression damping to a lesser extent in the same direction (stiffer or softer).

So, if you just slap a heavier spring onto the stock shock, and then crank in a bunch of extra needed rebound to compensate, you are likely to end up with too much compression damping, which would give you a stiff, harsh ride and lack of rear suspension compliance.

Just to add a little additional background for others considering replacing the shock's springs, the FJR OEM shock has 2 springs which result in 2 completely different spring rates. Yamaha calls the Soft/Hard lever a preload adjustment but technically that is not correct, you are actually switching between 2 spring rates, and each rate will have a different, non-adjustable sag. Each spring rate will require different rebound/compression damping rates to work properly and my experience has been that the damping rates seem to be set up (at least for the solo rider) for the soft spring rate, thus giving the hard spring rate too much compression damping and a harsh ride. However, the 2013 OEM shock has new spring and damping rates and when I test rode the 2013 it appeared that the damping was set up for the hard rate giving the best of both worlds, heavier springs and better damping.....but not as good as a Penske I compared it to.

 

[RavFJR]

...it's OK to just replace the springs in the forks (and then adjust the dampers to match) but doing that on the rear might not be such a great idea. Better to replace the entire shock with one that at least has dual adjustability so you can match your customized spring weight.

As always, YMMV

Though I agree that a more precision rear shock over OEM would be the rage, I've been fairly satisfied with the stock shock and the HyperPro spring combo. The HyperPro rep took my weight, my driving habits and if I was going to use the OEM shock. The bike feels a lot more balanced now than with the stock suspension. Mind you, I primarily use the bike to commute to work, so if riding the twisties is your forte, then go with an upgraded rear shock.

 

[Chuck35]

My adjustment procedure is also available by clicking on the little NERD in my sig-line

There is other great stuff there as well. Thanks for taking the time! esp the GPS info...Garmin newbie here

My courser is trapped in a Fred quote box

 

[majicmaker]

My adjustment procedure is also available by clicking on the little NERD in my sig-line

There is other great stuff there as well. Thanks for taking the time! esp the GPS info...Garmin newbie here

My courser is trapped in a Fred quote box

That's Funny! )

 

[Dutch]

One thing to consider - the way a progressive suspension works is the shock speeds up as you use up travel.

When you start out with too much sag, the suspension is in the place that works the shock faster = harder ride.

 

[Fred W]

My adjustment procedure is also available by clicking on the little NERD in my sig-line

There is other great stuff there as well. Thanks for taking the time! esp the GPS info...Garmin newbie here

My courser is trapped in a Fred quote box

To get out of my (or anyone else's) quote box, try pressing "insert" then "enter" a few times. Sometimes that works.

Otherwise use the little light switch in the extreme left side of the reply icon bar and it will switch from wysiwyg to full text mode. In full text mode getting things to show up where they should be is much easier. Then you can switch back to wysiwyg to see how it will look

 

[RiderX]

Keep an eye out this winter. There should be a group buy from gp suspension. The best thing you can do is upgrade the stock suspension.

And/or there's a RaceTech deal going on right now if you want to send your forks off and get a shock built just for you! Best money I've spent

 

[Goodman4]

Thanks for the advice! I put new Pirelli Angel GTs on this morning and spent the afternoon doing Fred's suspension process. My sag is still too much on the rear shock for my fat butt. Just to see, I tested it with the wife in the driver seat and me off. The sag is on the light side of 35 mm, so basically she needs to learn to ride and I give her the bike to ride without me. Not sure that's gonna happen. I know, I need a new shock in the rear, but again, that's not likely right now.

I set the front sag correct for the first time ever and it is almost all the way tightened down (no lines showing) which means I have it behaving ok, but would probably benefit from new springs. I set the front preload as directed but struggled a bit cause I don't notice the rebound bouncing when doing the brake test, but it was still bouncy on the road. I think it's ok now, too.

I set the back rebound/compression damping with the same bounce method, and I think that is ok now.

For the front compression, I found a spot in our neighborhood which has a few light road spots and then a couple potholes as well as a smooth section. I kept circling and adjusting, and I was pretty sure I felt where the light spots and even the smooth part got a little too reactive and I "felt" the road. Then I backed it off. I didn't notice a big change in the larger potholes. That is correct due to the purpose of compression damping, right? It just would be more ready for a second one (or not).

Anyway, I took the wife for a short ride on several road surfaces and we both thought it was smooth again. It seemed like it might be still a touch squishy, but that may be because I have gotten used to the firm setup I had for the last few weeks. I'm going to probably tweak down the front rebound a bit more to see if it gets better or worse.

I put the extra detail here for multiple purposes. First I wanted to give you guys the opportunity to tell me I'm missing something or doing something wrong. Second, I want Fred and the rest of you to know that I appreciate the help and am taking your advice where the dollars allow.

I want to stay on Fred's good side so I don't get trapped in his quote box, too.

 

[Fred W]

Goodman4, you are a... erm... good man to report back your results.

But I am going to throw a curveball at you.

By setting the front fork sag "correctly" but being unable to achieve the right rear sag, you will be running front end high, rear end low (think chopper as the extreme examp0le) which means that your steering will be pretty slow (though highly stable) and may be contributing to your mushy feel, especially during cornering.

You may want to experiment with backing off on the front preload (and readjusting the front damping to match) to balance the front more with the stock rear shock, at least until you can find the scratch for a new rear shock.

If a new rear shock comes into budget, get new springs for the front and that setup may be all that you need.

PS - My quote box isn't that bad of a place really.

 

[Goodman4]

By setting the front fork sag "correctly" but being unable to achieve the right rear sag, you will be running front end high, rear end low (think chopper as the extreme examp0le) which means that your steering will be pretty slow (though highly stable) and may be contributing to your mushy feel, especially during cornering.
You may want to experiment with backing off on the front preload (and readjusting the front damping to match) to balance the front more with the stock rear shock, at least until you can find the scratch for a new rear shock.

That does make sense to me, unfortunate though it may be. I hadn't hit any corners hard yet since the tires were brand new so we'll see. I have my first track day on the FJR in a month, so this could get interesting. If I understand right, with this setup it won't fall in the corner quite as easy, but other than having to countersteer a little more to turn, it will still handle ok? I will be taking it easy in the novice group, as this is a stretch for me. Advice appreciated.

 

[Fred W]

Yes, exactly.

There is one other thing that I have noticed, but never read any theories on specifically, and that has to go with balancing the front and rear suspensions. If, for instance, you replaced the fork springs with the "correct" rate springs but left the rear shock stock, the front end will feel harsh even though everything is set correctly. Likewise, the opposite seems true. An upgraded uprated rear shock and spring with the stock weight front spring makes the rear seem too stiff, even though it is technically correctly set. The two ends of the bike work together in suspending the bike off the ground. It only comes into "resonance" (for lack of a better word) when both ends are sprung correctly, or at least be similar.

That is part of why I'd recommend actually backing off a bit on the fork preload in your current situation, (to less than text book optimum) to help compensate for the softer stock rear spring.

Try this: Measure your rear sag (you've already done this). Now calculate that sag distance as a percentage of the total rear wheel travel. Note: The FJR rear wheel travel is 125mm.

Now calculate the same percentage of the front wheel travel's distance (135mm on 1st and 2nd gens) and use that as your target for front sag preload adjustment. This should put both ends at similar spring preloads and the chassis and steering angles at the correct attitude, although it will be on softer springs than is optimum for sporty handling.

Of course you'll need to adjust the fork damping a little to compensate for the decreased fork spring preload if you adjust it, which should a little less rebound , and a little more compression.

 

[Goodman4]

Thanks, Fred. I had time to play with suspension this afternoon, so I backed off the preload on the front as you suggested, about one full bar. It was probably at 0.5 bars right near the top (no lines visible) and I've got it right between 1 and two lines now.

I went back through the process again and felt a little more comfortable with my ability to notice the point at which the rebound gets right. I still am pretty unsure with what to feel for on setting the compression dampening, though. I got confused once between the manual and your notes, so I better double check this:

From the manual:

To increase the compression damping force and thereby harden the compression damping, turn the adjusting screw on each fork leg in direction (a) [clockwise – tightening]
To decrease the compression damping force and thereby soften the compression damping, turn the adjusting screw on each fork leg in direction (b ) [counterclockwise – loosening]
Compression damping setting:
Minimum (soft): 21 clicks in direction (b )
Standard: 12 clicks in direction (b )
Maximum (hard): 1 click in direction (b )
[with the adjusting screw fully turned in direction (a) [screwed in]
From your instructions you refer to increasing the compression until you feel the road. This goes from zero. This is different than the click setting number in the manual, right? Because 1 clicks is very hard and more clicks are softer. I think you are just using zero from all the way loose and the manual is using zero as all the way hard. Am I getting that right?

So you loosen the screw all the way and tighten the screw (increasing compression) until you feel the road too much.

I'm pretty sure I've got that straight, but thought I'd double check and clarify for myself and others. I have more trouble getting the feel on setting the compression and deciding what "feeling the road" really means. I think I understand the purpose and mechanics of compression dampening, but knowing what difference it makes to different situations is still a little foreign to me. I convinced myself I felt it the first time, but it was still very subtle. When I did it today, I was on a different road and I thought I felt it, backed off two, and was happy. But then I got on the Interstate and I thought it felt kind of bumpy again.

What should significantly too much compression feel like? Which surface would you notice it on? I think it should make the shock be unwilling to react to small quick movements because it won't let the oil move through quick enough for it to react. So it would be too bumpy on a semi-smooth road?

What does significantly too little compression feel like? Which surface would you notice it on? I think the big thing is it would overreact to quick movements that would allow it to be too far off center when there is a second bump in quick succession, causing you to potentially bottom out. Right?

And for both of these extremes, what does adding the pillion and luggage weight do, assuming that you don't (can't) adjust the sag. I know it decreases the amount of bump you can handle because the sag would be greater, but I can't help that. But should I leave the compression dampening alone once I get it set or find the settings that I would need to dial in for it loaded up and write it down, adjusting it when we ride two up?


I don't know whether this is fun or just a pain in the butt, but I feel like I found a new science project.

- Paul

 

[Fred W]

Paul,

Sounds like you are on the right track. My description may have been lacking some details.

Yes, in my method the "starting point" for adjusting that damping should always be minimum damping and then you increment the damping adjuster in the CW direction to find the happy place. It is just easier to do that way. What I didn't mention is that to find the minimum damping position you need to first screw the adjuster all the way in to "lightly seated" and then unscrew it the maximum number of clicks.

When you look at what the fork compression dampening adjusters are actually doing, they are just (normally CW threaded) needle screws that block off progressively more of an oil orifice. When you screw the adjusters in clockwise you are blocking more of that oil passageway and restricting the flow more.

The reason I start with minimum damping is that it is easier for me to see or feel the "change" that takes place when you have gone just enough (rebound), or too far (compression). It makes it easier to visually adjust the rebound (by bouncing the bike) and see the point where the bike stops oscillating, and it is easier for me to feel when I have gone "too far" (too stiff) on the compression adjuster when I have just recently felt what "compliant" feels like.

Which segues to your question on how to know where to set the forks compression damping.

Theoretically the compression damping adjuster on the bottom of the forks is only for "low speed" damping. When we are talking low speed vs high speed we are talking about the rate that the suspension is being compressed, not the ground speed of the bike, though going faster on the bike will make any bump in the road a higher speed impact.

There are flexible shim stacks built into in the compression valves at the bottom of the cartridges that are designed to release oil when a (hard enough) higher speed impact occurs (like hitting sharp bumps in the road). Those shim stacks and their orifices are fixed values selected by the engineers. The only way you have of tuning the high speed compression circuit response is by changing the fork oil viscosity or replacing the stock valves with ones with different sized orifices and flexible shims.

The orifices that the adjusters work on are primarily a passage for "slower" suspension movements that have not managed to push open the high speed shim stacks. This would be like the weighting of the front end during cornering and braking, as well as slowly occurring (rolling) road irregularities. Obviously, there is a great deal of overlap between what is high speed and what is low speed. And the low speed orifices are "always open" so they actually do have an effect on the high speed articulation.

The ideal suspension would not compress at all over low speed irregularities, so there would be no compression of the fork during cornering and no front end dive when braking. But the high speed damping would allow it to freely articulate when you hit any bumps in the road thereby allowing the tire to follow the road imperfections and maintain full contact (and traction) with the road surface at all times.

As is true in all things in life, what we end up with is a compromise. The idea here is to increase the (slow speed) compression damping adjuster to the maximum level until it begins to negatively impact the high speed responsiveness of the fork. You will feel that as the front fork transmitting "too much" of the road bumps up to the bike and rider. When that is happening the tire is no longer following the road irregularities as well and you are losing traction as well as being less comfortable and enjoyable.

Of course "too much" is entirely subjective. What is too much compression damping to me (riding the rough roads of New England) may be perfectly fine for someone else riding the smoother roads of the (frost free) south land, or another guy riding on a smooth race track.

To get an idea of what you are tying to achieve, just take a ride with the compression damping at the minimum as a reference. Feel how much the front end compresses when cornering. Brake dive is even easier to sense . Also take notice of how nicely the suspension absorbs all of the bumps in the road. If you have the rebound damping correctly dialed in already (as you should) it should be very comfortable going over any road irregularities at this point. Cornering will feel mushy and somewhat vague as the front suspension moves around mid-turn.

Now crank in the maximum compression damping and go for another ride. At this extreme you'll notice that the front end feels stiffer as if the springs themselves were stiffer. Less front end dive during heavy braking and less fork compression during cornering, which makes it maintain steering geometry and corner like it's on rails. Until you hit any kind of a bump, then you'll feel as if the forks aren't even there and all of the road irregularities are transmitted up through the bars and to you. Be careful cornering hard in this test as the tire may actually skitter across the road if you hit bumps mid corner.

So back to my adjustment technique: Go back to the minimum amount of damping, ride the bike a while and then stop and increment the adjuster a couple of clicks. Ride and feel. If it's still compliant repeat the adjustment and test until you feel that you have gone too far and are feeling too much of the road surface. When you have gone too far, just back off the adjuster a little and that is the best you can do in the compromise with the suspension components that you have.

Hope that helps

 

[Goodman4]

Great explanation, Fred. First, thanks for clarifying the starting point. I doubt most people have any confusion with your instructions. I didn't until I second guessed myself from the manual.

But the extent to which you answered my question was unexpected and hugely helpful. This is exactly what I was looking for. I almost feel I should be expecting a well-deserved consulting bill.

I'll do more experimenting soon.