Revalving a 5th gen fork for better rebound

I have a 2000 5th gen with Gold Valve compression valves and would like to utilize the stock rebound valves because I have too many other things I need to spend my money on, including a recent traffic award, and instead utilize the extra shims I already have. Having said that, can anyone suggest a shim stack for a 1.00 fork spring? I recently added 2 15x17 shims to the original stock shim stack and I'm thinking it's still to fast using Maxima 5wt oil. I'm considering adding 2 more to the stack but would like to minimize the amount of time I pull the forks and only do this once more. So, got any suggestions?

 

Take a look at the older GV instructions I have attached. They have instructions for revalving a stock rebound valve on the VFR750 which probably won't be too far off what you are looking for. Something like 5 or 6 0.15mm x 17mm shims as the main part of the stack sounds about right. All the GV rebounds that I have installed had that configuration as their stock recommendation.

 

Thanks Terry. The stock rebound valve came with the following shims:
valve
10x17
10x16
10x15
20x8.2
40x11.3

I'm proposing using the following shims to get where I think I want to be:
(2) 15x17
(3) 10x17
(3) 10x16
10x12
20x8.2
40x11.3

Got any thoughts on that? Seems like it might be close to Racetech's rH18-rH19 version of the shim stack but no way of knowing without running it through valve shim program or trying it out.

 

Did you know that a 0.15mm shim has a stiffness just over 3 x that of a 0.10mm shim? That means your 3 x 0.1 x 17mm shms are roughly equivalent to 1 x0.15 x 17mm shim. So your stack is still a bit on the light side compared to rH18, but you will have added a fair bit over the stock set-up. Try it and see.

 

I wasn't aware of that. Thank you again for your help!

 

Here's a link to the Racetech Suspension Bible. Don't tell the copyright police! Page 75 has the shim thickness:stiffness table.

https://www.dropbox.com/s/m76608uhz75k9xv/RACETECH SUSPENSION BIBLE.pdf?dl=0

 

I added a .10x15 shim into the stack and overall the setup above seems to feel really nice! Of course I question whether it could feel better and I may tear into it one more time in the future but I think I'll run with this as is for awhile.

Terry what do you make of the 2 thicker/smaller shims at the bottom of the stack? I question whether those really need to be in there and may take them out mostly because there's not a lot of meat left on the shaft for the nut to screw on to with all those shims. I only left them because they were part of the original stack.

 

The 8.2mm diameter shim is very important as it is the fulcrum on which the shims above are bending. I believe the 0.4 x 11.3mm is just a spacer and could be deleted it you need to; I assume there is also a 2.6mm thick valve base before the nut; you need it but at a pinch you could substitute a decent steel washer that was sufficiently thick but thinner to create some space.

This is not a problem I've encountered however. I would have used 0.15mm x 17 shims for the main part and then created a simple pyramid of one each 16, 15 and 12mm shims. I think your stack has 8 x 0.1mm shims and 2 x 0.15mm shims, so total thickness is 1.1mm. If you went with the 3 x 0.1mm (12,15,16) you would have room for 4 X 0.15mm shims for a total 0.9mm thickness, or 5 x 0.15 and a total 1.05mm. And that would have a lot more rebound than your stack.

 

My logic was thinking that same thing regarding the 8.2 shim along with the 11.3 shim simply being a spacer. I'm glad we're both in agreement. Yes, there is a very thick base 'washer' before the nut and I figured that was simply a spacer. Regarding the pyramid of shims, my logic was thinking very similarly to yours and I'll try something similar to what you suggested down the road. However, for now I'll ride this around for awhile in a variety of terrain and twisties and see how I feel about it. Again, I really appreciate your feedback and yellow VFR's rule!

 

So I got the preload set up and hit the twisties today.....ugh....it's just as bad as before, like a pogo stick. I can't help but to think that I added enough shims to slow the rebound but it's really hard to tell if it is slightly slower. I've been hesitant to add the same type and amount of shims as RT would have me add if I were using their valves with the bigger opening, but I think that's my next course of action.

 

Not to teach you to suck eggs or anything but...Are you sure the check valve is working properly? It is pretty easy for the shim to get caught on the edge of the sleeve during assembly and get jammed full open. When that happens you will have zero rebound. That will be quite obvious when you prime the cartridge during oil filling however. You should be able to move the check valve shim off the valve body with your finger and have it snap shut again.

 

Yeah, when I filled the cartridge with oil I was actually worried I'd have too slow of rebound with how it felt. Also, I did double check when putting it together that it was functioning properly, but since I've never gone this deep before- good thinking.

 

I finally had a chance to work on the forks this week and I think I finally found the right combo or damn close!

I added 3 more .10 x 17 shims as that's what I had on hand. So now I have this combo on the rebound side using the stock Honda valves:
(2) .15x17
(6) .10x17
(3) .10x16
(1) .10x15
(1) .10x12
(1) .20x8.2
oil is 130mm from the top

I took out the 40x11.3 as that was just a spacer that I didn't need. I also used a combo of Maxima 5wt and some Maxima 15wt in a 75%/25% combo as I had both on hand. I didn't measure accurately, AND I spilled some out on one fork so that is just what I was going for and may have something else at the moment. So after a 20 min ride tonight on bumpy pavement, my forks feel comparable to my Penske shock out back and the bike feels well balanced, smoother, and not nearly as bouncy up front as it was. Moreover, it feels better than the stock valving finally! I'm still going to try an official Maxima 7.5wt oil to make sure I'm using an honest 7.5 weight but I'm going to run this as is, for several months I think. I'll report back once I swap it out down the road.