Shim stack, how do you build one ?

[SEBSPEED]

Still looking for a good shim stack to use in F4i forks on a VFR with stock Honda valves ? :beer:

<{POST_SNAPBACK}>

Have you by chance tried to contact a suspension shop for their input? Not trying to be an ass, just wondering if they were willing to help.

[Baileyrock]

Have you by chance tried to contact a suspension shop for their input? Not trying to be an ass, just wondering if they were willing to help.

Actually I did think about calling Phil at AfterShocks for his input, seeing how he just built my VFR forks. I would hope he would help me with some numbers, but it may be a secret ! Most places will say just send them out and we'll fix you up. I tried to get him just to build a shim stack for the VFR, but he wanted the whole fork assm. :joystick:

[R_Cote]

Thanks, if you end up needing some more stock honda valves let me know ! :thumbsup:

<{POST_SNAPBACK}>

Where did you get the valves? I may be interested. By the way I finally got mine all back together and got a chance to ride it for 35 miles. It is a good improvement over stock. I attribute it mostly to the proper strait rate springs I installed. (Race tech 1.0's )

The ride is much firmer but not harsh. Also the annoying brake diving is all gone. The front end just feels more planted. I rode some bumpy roads and hit some good size frost heaves and big dips in the road and it wasn't at all twitchy. No back and forth bar movement at all.I like it.

when I finished the short ride I checked how much travel was used up and found it still had 1" left that did not get used. This is also with a lower than stock oil height I believe. I set the oil level at 140mm. I think the manual only states to measure out a certain amount and fill it. Not sure if I should try 145-150mm (less oil more air) on the oil height. I'll have to ride it more and harder before I make any more changes.

Another thing that impressed me was it also eliminated the nagging bar jerk that was always associated with making a very slow ninety degree turn on an offcamber. Like pulling into my driveway there is a sort of step up speed bump, so to speak. Actually it's part of the old curb before I had my driveway paved, and my driveway is higher than the street. This always yanked the bars pretty hard and I had to be careful. This seems to be all gone. I tried it like 4 times and could'nt duplicate the problem. It made me laugh. Like I won a battle or something.

I'd also like to add that with these springs I had cut the spacers to 70mm which gives me minimal preload with the adjuster almost backed out all the way.

So far I'm loving this set up. But It's only been 35 miles.

[Baileyrock]

Where did you get the valves? I may be interested. By the way I finally got mine all back together and got a chance to ride it for 35 miles. It is a good improvement over stock. I attribute it mostly to the proper strait rate springs I installed. (Race tech 1.0's )

The ride is much firmer but not harsh. Also the annoying brake diving is all gone. The front end just feels more planted. I rode some bumpy roads and hit some good size frost heaves and big dips in the road and it wasn't at all twitchy. No back and forth bar movement at all.I like it.

  when I finished the short ride I checked how much travel was used up and found it still had 1" left that did not get used. This is also with a lower than stock oil height I believe. I set the oil level at 140mm. I think the manual only states to measure out a certain amount and fill it. Not sure if I should try 145-150mm (less oil more air) on the oil height. I'll have to ride it more and harder before I make any more changes.

Another thing that impressed me was it also eliminated the nagging bar jerk that was always associated with making a very slow ninety degree turn on an offcamber. Like pulling into my driveway there is a sort of step up speed bump, so to speak. Actually it's part of the old curb before I had my driveway paved, and my driveway is higher than the street. This always yanked the bars pretty hard and I had to be careful. This seems to be all gone. I tried it like 4 times and could'nt duplicate the problem. It made me laugh. Like I won a battle or something.

I'd also like to add that with these springs I had cut the spacers to 70mm which gives me minimal preload with the adjuster almost backed out all the way.

So far I'm loving this set up. But It's only been 35 miles.

Very cool !

I have several sets of bent forks, both VFR and F4 and all valves seem identical.

On your new set-up, did you increase the rear spring rate at all??? I'm running I think is a .95 fork springs and stock 15.3kg on a Ohlins rear and found that the front has a floaty feel to it under normal cruising(slight bouncing), but felt OK where pushing the bike. I called Phil at AfterShocks who did my forks an explained what I was experiencing and he said that the light(stock) rear spring was causing problems, throwing of the bikes balance.

Just looking at front rear spring balance, stock .74kg front/ 15.3kg rear. My bike with .95 front is like a 25% increase so I should increase the rear spring 25% to 19kg just to maintain Factory front/rear balance. You would need even more with 1.0 kg = 20 kg rear?

I was avoiding the heavier rear spring fearing a harsher ride, but without a heavier rear spring to front over powers the rear disrupting balance. I'll be buying a 18-19kg rear spring asap.

I plan to pass on the F4 front end swap until I balance the current set-up with a new rear spring. :thumbsup:

[R_Cote]

Baileyrock.

I have not touched the rear at all except to set the proper static sag. I was thinking of spending some attention to that next. I have owned this bike since March of 2002. I bought it from a friend with only 2,800 miles on it. To date it has just under 12,000 miles on it. So you can see I don't Ride much. After riding the thing for a couple years I realised I needed to spend some attention to detail in the suspension department. Most of my knowledge on this comes from my offroad experience. I have had great success with my KTM so I decided to play around with the Viffer. Plus working on forks is easy.

To the best of my knowledge, if you can achieve the proper static and race sag by not being way out at either end of the adjustmet then the spring rate is fine. I believe the VFR may be ok for me with the stock spring. I never mess with the rear shock valving as I don't have the capability to do it myself. I leave that to the professionals. Although this shock has never been off this bike it probably should be serviced.

I've never run her on a track and I do admit I'm pretty catious when I ride. I would like to try riding on a track someday but for now I'm satisfiied with just riding the twisties.

My chicken strips are very wide. LOL!

[Baileyrock]

Baileyrock.

To the best of my knowledge, if you can achieve the proper static and race sag by not being way out at either end of the adjustmet then the spring rate is fine. I believe the VFR may be ok for me with the stock spring.? I never mess with the rear shock valving as I don't have the capability to do it myself. I leave that to the professionals.? Although this shock has never been off this bike it probably should be serviced.

I've never run her on a track and I do admit I'm pretty catious when I ride.? I would like to try riding on a track someday but for now I'm satisfiied with just riding the twisties.

My chicken strips are very wide. LOL!

I thought along the same lines as you, but all suspension experts will tell us otherwise. I was able to set proper rear sag with the stock rate spring, but I can tell a loss of balance on the bike.

I bought my 02 with 200 miles on it and have almost 35,000 hard twisty miles on it and no chicken strips. I'll report results after my change, but at some point you will be much better off maintaining the bikes balance which you are no where near now. It may save your butt doing so ! Your only talking about spending $100 for a new spring for the stock shock.

Springs are the number 1 thing to get right first in suspension set-up from what I'm learning! :beer:

If you have a balanced bike or car and increase spring rate only on one end you will no longer be in balance and either the front or rear will be loosing traction at some point and that is something you don't want to happen on a bike ! :unsure:

[fallzboater]

Just looking at front rear spring balance, stock .74kg front/ 15.3kg rear. My bike with .95 front is like a 25% increase so I should increase the rear spring 25% to 19kg just to maintain Factory front/rear balance.  You would need even more with 1.0 kg = 20 kg rear?

I was avoiding the heavier rear spring fearing a harsher ride, but without a heavier rear spring to front over powers the rear disrupting balance. I'll be buying a 18-19kg rear spring asap.

<{POST_SNAPBACK}>

I wouldn't blindly try to retain the factory front/rear spring rate ratio, there's no reason to expect that it was close to optimal. I think the stock rear spring is closer to being correct for most riders than the stock front springs (way too light for anyone, really).

What I believe you want is to have the same amount of suspension movement front/rear over a given bump. If the damping is also correctly set up, that will keep the chassis level over bumps, and while loaded up through corners. To do that, you want to have the spring rate measured at each axle (axle rate) to have the same ratio as the weight distribution. So, if the weight distribution (with rider) is 45/55 front/rear, and you have two 0.95 kg/mm front springs (1.9 kg/mm total), then your rear axle rate should be 2.3 kg/mm. If the swingarm and linkage has a ratio of 6:1 (I have no idea what it really is, and it may be progressive. Anyone want to measure?) between rear axle movement and shock movement, your rear spring rate should be 13.9 kg/mm. There may be certain dynamic handling characteristics that could be enhanced by diverging from that balance, but I think it's a good starting point. Any suspension experts want to elaborate?

[Baileyrock]

I wouldn't blindly try to retain the factory front/rear spring rate ratio, there's no reason to expect that it was close to optimal.? I think the stock rear spring is closer to being correct for most riders than the stock front springs (way too light for anyone, really).

What I believe you want is to have the same amount of suspension movement front/rear over a given bump.? If the damping is also correctly set up, that will keep the chassis level over bumps, and while loaded up through corners.? To do that, you want to have the spring rate measured at each axle (axle rate) to have the same ratio as the weight distribution.? So, if the weight distribution (with rider) is 45/55 front/rear, and you have two 0.95 kg/mm front springs (1.9 kg/mm total), then your rear axle rate should be 2.3 kg/mm.? If the swingarm and linkage has a ratio of 6:1 (I have no idea what it really is, and it may be progressive.? Anyone want to measure?) between rear axle movement and shock movement, your rear spring rate should be 13.9 kg/mm.? There may be certain dynamic handling characteristics that could be enhanced by diverging from that balance, but I think it's a good starting point.? Any suspension experts want to elaborate?

Nothing blind here period ! <_<

My info is from suspension experts, like Aftershocks and Ohlins which both recommend lighter spring rates than Race tech. I used there recommended rates to determine the %.

As far as being close to balanced from Honda, I'm sure they spend some time considering that and must be very close if the experts are saying to basically match it with very similar % increases front/rear.

[Guest]

Just a comment about changing the rear spring picked up from a suspension clinic [Cycle Improvements] last weekend.

Honda's OEM spring for the Gen5 is 15.3 Kg/mm (Gen6 too, IIRC). Given that the manufacturing tolerances are in the +/- 10% range this means that the spring is somewhere in a range of 13.8 to 16.8 Kg/mm range.

Checking out what is available from Race Tech, for example, they supply a maximum spring rate of 16.1 Kg/mm spring for the VFR. [The 10% range is 14.5 to 17.7 Kg/mm.] In other words, by buying the "stiffest" Race Tech rear spring it is possible that you will have a softer - more sagging - rear suspension!

Please take care. In this one specific case, you may be further ahead going to a suspension shop. A shop with a spring rate tester may be able to improve (increase) your spring rate by simply swapping out other similar rated VFR springs.

Remember it is not the cost of the initial improvement, but the cost of replacing the bargain that hurts....

[ULEWZ]

If you guys are going to replace the valves with RT gold valves, might I recommend a couple of different brands that are more durable:

GP Suspension Valves

Or Ohlins internals:

Ohlins internals

[Baileyrock]

If you guys are going to replace the valves with RT gold valves, might I recommend a couple of different brands that are more durable:

GP Suspension Valves

Or Ohlins internals:

Ohlins internals

They both look good, if I do another set I may try the Ohlins 20mm kit ! :thumbsup:

[Guest]

(1).1x17

(2).1x16

(2).1x15

(1).1x11

©.2x8

F4 fork stock shim stack on the rebound valve. The 17mm shim is against the valve side if you are unfamiliar with this stuff. I am in the middle of a swap right now on my VFR750 and am revalving/rebuilding/respringing before the F4 front end goes on. My basic goal is to get a little bit more plush on compression by running a little thinner oil (motorex 5w) while increasing rebound to act with the heavier springs. Suspension valving is pretty much trade secret for the businesses that do it so they won't be willing to recommend a stack for you...you have to try stuff out yourself. I installed a 0.15mm base shim and an additional .1x16 shim in the stack. Fork swap isn't done yet, but we'll find out how it works for me this season. Good place to buy shims if you need to http://www.mx-tech.com/?id=products&subcat=152

[Chev]

As far as being close to balanced from Honda, I'm sure they spend some time considering that and must be very close if the experts are saying to basically match it with very similar % increases front/rear.

For what it is worth, Honda does use a Progressive linkage on the rear suspension. This "could" prove to be very difficult in the balance aspect of your search.

The plus side is that you are setting sag at 30-35? mm on each end. If they are both the same, and your spring rate is correct (sorry no insight here, I just leave that to the suspension experts), at the instant that you inpact a bump the reaction force will be the same. Shortly after, everything will be out of balance and you will have to trust the valving to do it's thing.

I used to hang out a a dirtbike board and just read posts on valving. I'd be no help, since I have never actually seen fork valves, but the people at Dirtrider.net can talk about valve stacks all day long. You might peek in and see who you can round up to help.

[Motor_Ref]

Sorry to have driven you so far off topic...

<{POST_SNAPBACK}>

Yah, where's my shin stack ? :lol:

Somewhere between your knee and your ankle. :goofy: