Member Contributer Dutchy Posted July 3, 2016 Member Contributer Share Posted July 3, 2016 4th gen OEM front end (with Wilbers springs) 100,000km Not ready yet to fork out $700 for a set of Jamie Daugherty internals just yet (I need to find a new job 1st..), I started taking the forks apart and clean the parts. Yuck Better The new SKF fork seals are sourced, but now I come to an area I am not even an magician's apprentice... I read and hear about shimstack, but what knowledge/advise can you dispense on next steps? what (and where do I source) parts to improve? Or is it a matter of cleaning and bolt up agian? Here the bits that sit on the damper rod; will take the other section apart next: Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted July 3, 2016 Member Contributer Share Posted July 3, 2016 An easy solution would be to buy a set of Race Tech Gold Valves, which replace the parts you have laid out on the paper towel in the pic above. The specific number and thickness of the shims you use controls how fast the fork fluid is allowed to pass through the valve. The Gold Valve also has different size and shape orfices to make this control more accurate. In theory, a competent suspension guy could modify the OEM valve to flow better and select shims (they are available separately) to accomplish much of the same thing as the Race Tech kit does. Somewhere I have a set of old forks that had been re-valved by Lindemann in California, and I've always wondered what he actually did to them. The evidence should be clear--provided I ever take the forks apart. More recently, I acquired a set of SP2 forks that had been fettled by KAI'S in the UK, and I can definitely say that they did something, because the "oil lock piece" has been removed from both damper rods (though the top-out springs seem to not have been shortened--a common mod for these forks). I haven't taken the valve bodies apart, though, and I wasn't planning on doing so until I had a chance to ride a bike with these forks. Race Tech Gold Valves cost about £80-90 in the UK (or they did the last time I looked--prior to Brexit). Your Wilbers springs are progressive, so not ideal for use with Gold Valves, which were designed for use with stiffer straight-rate springs. The result from fitting Gold Valves with progressive springs would be too hit-and-miss for me to bother. Unfortunately, there are plenty of stories on the 'Net about people saying that the Race Tech online spring rate calculator results in too-stiff springs, so you could end up with the wrong springs for your weight. I have a couple of sets of fork springs you could borrow if you wanted to try them. I think I have 1.0 and 1.1, but should also have some in the .95 range. (But I'd need them back!) If you're not ready to mess with the valves and springs (or new JD cartridges), the only thing you can really do is thoroughly clean the forks and replace the fork oil--and then go ride! Ciao, Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 3, 2016 Author Member Contributer Share Posted July 3, 2016 Looking at the parts in the UK https://www.amazon.co.uk/Race-Tech-Gold-Valve-Fork/dp/B000GV2C4U https://www.amazon.co.uk/Race-Tech-Rebound-Gold-Valve/dp/B000GV2D76/ref=sr_1_2?s=automotive&ie=UTF8&qid=1467545598&sr=1-2&keywords=frgv+s02 it woud be ~UKP250 around Euro 325 ("unfortunately", the "halt" to BJ has not led to a complete BOHIC to the UKP exhange rate......) Methink a good clean will be the order of the day.... But looking at the parts in the OEM versus the # of shimms in (the picture of) the RT kit, there seems to be a difference for sure Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted July 3, 2016 Member Contributer Share Posted July 3, 2016 Hi Dutchy, Here's what I did to mine about a year ago to take it up to Summer Summit 3. The standard complaint about our 4th gen's forks are the compression is to harsh and way to much fork dive on braking because of the lack of rebound damping. The stock 3 port valves flow almost as much as the Race Tech ones so the shim stacks are where "all the magic happens". By no means am I any kind of suspension guru BUT I do have a 2 inch thick binder of research on this and what I came up with has worked out pretty good for me. It's not perfect but a LOT better than stock. I weigh 135 lbs. in running gear so I'm a light weight. I stayed with the stock springs, went with Silkolene 2.5 weight fork oil 130 mm from the top of the collapsed forks (prior to installing springs). I think this raising of the fork oil level was the biggest contribution to getting rid of the fork dive on hard braking. The stock shim stack is one 17mm x .15mm shim and two 17mm x .10mm shims. I think the initial harshness on encountering bumps was caused by that .15mm thick shim, it being 3.4 times STIFFER than the .10mm thick shims. SO, I replaced the single .15 mm thick shim with three .10mm thick 17mm shims. Not quite as stiff as the single .15mm shim but the fact that there are now 3 shims instead of one they flex sooner being thinner and in a more controlled fashion because there are 3. So now I have five 17mm x .10mm shims with the stock clamp shims in my COMPRESSION shim stack. Next time I take the forks apart I'll try a tapered stack (17mm, 15mm, 13mm, 11mm and 9mm, all .10mm thick - keeping it at 5 total shims). For rebound, the stock shim stack is two 17mm x .15mm and three 17mm x .10mm shims (w/clamp shims). Because the stock 3 port valves flow so much this is not near enough damping SO I went with five 17mm x .15mm shims and one 10mm x .10mm shim with the stock clamping shims. This change combined with the raised fluid level got rid of the excessive dive and the rebound recovery is very controlled. Next time I take the forks apart I won't touch this rebound set up, it works great. IF I was to mess with it I'd try the 5th gen rebound valves which are the more restrictive 4 port HMAS style. If you are a normal weight human (i.e heavier than me!) You may want to add a shim or two on the compression and/or MAYBE go with a heavier fork fluid. Good luck. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 3, 2016 Author Member Contributer Share Posted July 3, 2016 Cheers Rangemaster, I have raised the oil level already form the Wilbers recommended 170mm to 150mm, I will try with the 130mm airpocket next upon assembly next (will most likely be in a few weeks since family holiday 2 weeks coming up) Let's see if I understood.... :-) The COMPRESSION Shim stack assembly is this one: And the "offending one .15" is right? I will measure the lot tomorrow, just had a pizza with a few beers so that is me for the evening...... I weigh 87kilo in the buff so with full gear that will be 90+ So where does one source shims? Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted July 3, 2016 Member Contributer Share Posted July 3, 2016 Dutchy, your arrow is pointing to the correct shim. As far as sourcing shims, I went to a local motorcycle shop and asked if they had any. The owner, a super nice guy, brought out 3 shoeboxes each half filled with every shim imaginable. I picked out a bunch of different sizes (at least 50 shims-took me about a half hour) and asked him what I owed him. Considering that a lot of places charge around a dollar a piece, I thought his "A six pack of Marble IPA." was a steal. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 3, 2016 Author Member Contributer Share Posted July 3, 2016 Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted July 4, 2016 Member Contributer Share Posted July 4, 2016 Oh. I wouldn't buy that sort of part on Amazon, but Ebay prices have also soared... Race Tech also sells packs of shims. By the way, Race Tech didn't sell a rebound Gold Valve kit for the VFR for many years. They always said it was not necessary to re-valve the rebound valves. But customers kept insisting, so they eventually started selling rebound Gold Valves. I bet Paul Thede's view about the efficacy of rebound Gold Valves on conventional Showa forks has not changed--but his view of the gullibility of his customers probably has! Speaking of gullible customers, I realised that I did have the Lindemann "re-valved" compression valves from my FL in my garage, so I pulled it apart yesterday. I didn't measure the shims, but I can say with some degree of certainty that the valve itself does not appear to have been altered in any way. The ex-gullible part of me thinks that the shims are also OEM... (Note that these forks were re-done sometime in the early 1990s, before Rob Lindemann died and the business of the same same passed on to Ed Sorbo.) I do have some FP forks I could take apart to compare shim stacks, but I don't have the time to do that right now. [Picture of FL compression valve, disassembled, which I thought I took goes here...] Ciao, Link to comment Share on other sites More sharing options...
Member Contributer VFROZ Posted July 4, 2016 Member Contributer Share Posted July 4, 2016 Nothing wrong witht them pistons, they are as good as gold valves, even the compression. The shim you're pointing to is a check valve, not a damping shim. It definetly needs to be straight and stiff. You can definetly do a much better stack for both, but you probably need new linear springs. I believe the 4th gen has 0.7kg/mm springs, which are a very soft. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 4, 2016 Author Member Contributer Share Posted July 4, 2016 tok 'm apart once more and hey!!!! there's another shim!!! :-) They sure gel well!! So any stackers that have been tried and tested? For the compression one tip is replace the one with the blue arrow with 3 .1mm's " Next time I take the forks apart I'll try a tapered stack (17mm, 15mm, 13mm, 11mm and 9mm, all .10mm thick - keeping it at 5 total shims). " So in what sequence/position left/right of the actual valve? " For rebound, the stock shim stack is two 17mm x .15mm and three 17mm x .10mm shims (w/clamp shims). Because the stock 3 port valves flow so much this is not near enough damping SO I went with five 17mm x .15mm shims and one 10mm x .10mm shim with the stock clamping shims." so same question, where would I position the 5 17mm .15 ones? I will gladly test this, no liability or law suit on you!!! :-) Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted July 4, 2016 Member Contributer Share Posted July 4, 2016 Hey Dutchy, VFROZ is absolutely correct-that is the check valve shim, should only be one on that side the valve. Your pic threw me with the 3 shims showing. I was outside working and coming in to take a break from the heat. And yes, they do have a tendency to stick together. Do you have micrometer? That's how I keep track of the thickness. OR, you can gently flex them with your fingers, the .15mm thick one is quite a bit stiffer than the .10mm ones. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 5, 2016 Author Member Contributer Share Posted July 5, 2016 Yes I have a micrometer and will put stuff in labelled ziplock baggies :-) Next installment will we late July since family holiday time will start before the shims come in.... Link to comment Share on other sites More sharing options...
Member Contributer VFROZ Posted July 9, 2016 Member Contributer Share Posted July 9, 2016 4th and 5th gen cartdriges are the same, but the OEM pistons on the 5th gen are a lot more restrictive. I have high flow pistons that are much more open than the ones you have for both compression and rebound. They are also a tiny bit bigger on diameter of the ports. Keep in mind that I have 0.95kg/mm springs, so you need to find out what weight your Wilbers springs are. My compression stack is: 3 x 18-0.15. 15-0.1, 13-0.1, 12-0.1, 11-0.1, 10-0.1, 9-0.1 I also have a 1.3mm bleed hole drilled into the piston for slow speed damping, not sure if you will be able to do this to the standard piston. My rebound stack is : 1 x 18-0.1, 8 x 18-0.15, 15-0.1, 12-0.1, 9-0.1, a lot more than yours. I'm also using cSt24@40 oil at a height of 135mm It took a lot of experimentation to get to this, and it is now miles better than stock. It has a lot of feel, better control specially on high frequency bumps mid corner, it doesn't bottom out or dive and it is also more comfortable. The compression stack goes from bottom, smallest to largest then piston and check valve then bolt. For rebound it goes nut, then smallest to largest, then pisto then check valve. Link to comment Share on other sites More sharing options...
Member Contributer rhoderage Posted July 9, 2016 Member Contributer Share Posted July 9, 2016 Dutchy - whether or not you are ready to spend on the JD parts, he is a great guy and I am confident that if you emailed and asked him these same questions he would point you in the right direction for reusing stock parts or swapping shims... no doubt he has done a lot of testing of different parts to figure out his preferred setup. He spent a lot of time talking to me about suspension, helping me understand the options before I finally committed and upgraded! Link to comment Share on other sites More sharing options...
Member Contributer RC36Rider Posted July 10, 2016 Member Contributer Share Posted July 10, 2016 Don't drill the stock pistons just yet. The low speed bleed is probably effected by means of tiny undercuts in the piston face. I cannot be 100% sure because your pics do not show the compression side of the pistons but these undercuts are visible on the rebound pistons. If you drill an additional hole you will end up with way too little low speed damping. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 10, 2016 Author Member Contributer Share Posted July 10, 2016 Cheers guys, all good info. Am on summer vacation with the family so am trying to restrict time "online" :-) Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted July 10, 2016 Member Contributer Share Posted July 10, 2016 16 hours ago, RC36Rider said: Don't drill the stock pistons just yet. The low speed bleed is probably effected by means of tiny undercuts in the piston face. I cannot be 100% sure because your pics do not show the compression side of the pistons but these undercuts are visible on the rebound pistons. If you drill an additional hole you will end up with way too little low speed damping. You are correct sir. I didn't do anything to the low speed bleed on the face of my pistons. I know some people file them off and then drill a bleed hole but I was kind of doing the 'one thing at a time' drill so I could guage each change for better or worse. Dutchy I hope you are enjoying your family vacation. Enjoy it while you can-kids grow up fast. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted July 11, 2016 Author Member Contributer Share Posted July 11, 2016 Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted August 31, 2016 Author Member Contributer Share Posted August 31, 2016 Well, Jamie Daugherty's one-off kit (compression valves+ships and rebound shims) didnot arrive prior to me setting off on my trip. So I will post them in the classifieds as I won't me replacing/rebuilding redslut with another RC36. Realizing he has done me a favor, I checked this with him first. He's ok but will not be in a position to coach/guide a prospective buyer; fitting is pretty straightforward though (it requires disassembly of the forks). Scrap that, will keep the parts. Dont need money..... :-) Link to comment Share on other sites More sharing options...
keny Posted September 1, 2016 Share Posted September 1, 2016 19 hours ago, Dutchy said: I won't me replacing/rebuilding redslut with another RC36. So you made up your mind. I can see why, because a other 4th gen will never be "the redslut" even how much work you do to it. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted September 1, 2016 Author Member Contributer Share Posted September 1, 2016 Yes I did..... Jamie did come back and told me the valves are pretty universal and WOULD fit a RC51 . it is by no means sure I will go for The Beast come spring Link to comment Share on other sites More sharing options...
Alhazred Posted September 2, 2016 Share Posted September 2, 2016 How did you get him to make you a custom set of valves and shims? He just told me a few weeks ago that they don't do that. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted September 4, 2016 Author Member Contributer Share Posted September 4, 2016 cannot lock this topic, only hide or delete? Anyway, decided to keep the parts for a possible 2nd bike net year Link to comment Share on other sites More sharing options...
VFR4Lee Posted September 4, 2016 Share Posted September 4, 2016 Don't you know? The magic happens at Disneyland! Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted September 5, 2016 Author Member Contributer Share Posted September 5, 2016 Ok I will go look for Gretchen and Nancy then, NFL not my cup of tea... :-) Link to comment Share on other sites More sharing options...
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