Doing a RaceTech (.95) spring install on the Vtec. The manual specs a 100mm oil level. Has anyone experimented to see if a slightly higher or lower level has anything to offer?
Should keep the same oil level as that will just change the spring rate even more, adding more oil give you a smaller air pocket and it will increase the spring rate, adding less will reduce the spring rate. The air trapped in the top of the fork acts as another spring, but only its not linear like the steel spring. I would stay with what you know.
some people who change out fork oil dont realize its not so much the amount of oil by volume that counts its the volume of air pocket that counts, thats why you measure the oil hieght per the manual rather than the volume of fork oil. by checking the oil level in relation to the top of the fork you are ensureing the air pocket volume to spec.
HispanicSlammer, Jan 23 2007, 03:38 PMShould keep the same oil level as that will just change the spring rate even more, adding more oil give you a smaller air pocket and it will increase the spring rate, adding less will reduce the spring rate. The air trapped in the top of the fork acts as another spring, but only its not linear like the steel spring. I would stay with what you know.
some people who change out fork oil dont realize its not so much the amount of oil by volume that counts its the volume of air pocket that counts, thats why you measure the oil hieght per the manual rather than the volume of fork oil. by checking the oil level in relation to the top of the fork you are ensureing the air pocket volume to spec.
Thanks Miguel. Yeah, in past I've juggled oil levels to compensate for spring shortcomings. Higher levels > smaller air volumn > more progressive fork action and vice versa. One of the things I was musing about with these was the possibility that given the wire diameter (I haven't measure it) and number of windings in the RaceTech springs, there may be more (or less) spring metal in the oil with these springs than with the stockers which would affect (although probably not by much) the oil level in the finally assembled fork tube.
Do a write up for us? I am likely going to do this upgrade soon and I am a bit ashamed to admit after all these years of tinkering, I never got into the forks. Should be straight forward right? Photos too if you can!
My last VTEC had them on it and I liked the handling. The new one is fully stock and I am guessing I won't like it compared to my full Traxxion front end on the track bike and the previous progressive sprung VTEC.
I think most suspension shops would say if you've put the appropriate spring rates in over stock you can reduce the stock oil level. Stock forks have to handle many size riders and stock oil levels are high to prevent bottoming for heavier riders. Correct spring rates should take away the need for this compensation.
Traxxion Dynamics recommended a level of 125 mm spring out, fork collapsed for my 6th gen when I swapped out springs. It works for me. I have not had any issues with bottoming.
roadpupp, Jan 23 2007, 08:24 PMDo a write up for us? I am likely going to do this upgrade soon and I am a bit ashamed to admit after all these years of tinkering, I never got into the forks. Should be straight forward right? Photos too if you can!
My last VTEC had them on it and I liked the handling. The new one is fully stock and I am guessing I won't like it compared to my full Traxxion front end on the track bike and the previous progressive sprung VTEC.
Good luck.
did that already in the modifications > featured mods fourm
VFRFun, Jan 24 2007, 12:05 AMI think most suspension shops would say if you've put the appropriate spring rates in over stock you can reduce the stock oil level. Stock forks have to handle many size riders and stock oil levels are high to prevent bottoming for heavier riders. Correct spring rates should take away the need for this compensation.
Traxxion Dynamics recommended a level of 125 mm spring out, fork collapsed for my 6th gen when I swapped out springs. It works for me. I have not had any issues with bottoming.
Jim, I'm just pondering this myself. My forks are draining into buckets tonight, and I'm wondering about what my new fork oil level should be.
Concerning the level of oil - The new .90 spring is a straight wound Racetech part. The stock spring is progressive, and about .850" longer than the Racetech. The coil spring diameter appears to be close, but if I put in the new springs it will take more oil to fill to the recommended 100mm mark.
Or, do I want to add the recommended volume of fluid, and then just check to make sure the levels in both forks are the same, which will leave a larger air pocket?
SEBSPEED, Sep 15 2007, 09:55 PMJim, I'm just pondering this myself. My forks are draining into buckets tonight, and I'm wondering about what my new fork oil level should be.
Concerning the level of oil - The new .90 spring is a straight wound Racetech part. The stock spring is progressive, and about .850" longer than the Racetech. The coil spring diameter appears to be close, but if I put in the new springs it will take more oil to fill to the recommended 100mm mark.
Or, do I want to add the recommended volume of fluid, and then just check to make sure the levels in both forks are the same, which will leave a larger air pocket?
Check the level by using the dipstick method, and make it the correct level, regardless the actual amount of oil.
SEBSPEED, Sep 15 2007, 09:55 PMJim, I'm just pondering this myself. My forks are draining into buckets tonight, and I'm wondering about what my new fork oil level should be.
Concerning the level of oil - The new .90 spring is a straight wound Racetech part. The stock spring is progressive, and about .850" longer than the Racetech. The coil spring diameter appears to be close, but if I put in the new springs it will take more oil to fill to the recommended 100mm mark.
Or, do I want to add the recommended volume of fluid, and then just check to make sure the levels in both forks are the same, which will leave a larger air pocket?
Check the level by using the dipstick method, and make it the correct level, regardless the actual amount of oil.
So I'm sticking with the same air pocket for a different spring rate?
About the spacers; if I cut them to match the old spacers(3.940") + the difference between the two springs(.850", = 4.790"), how will that affect my preload adjusters? I read in an old thread that Turtlecreek did what I mentioned, and didn't have much if any preload left to dial out(soften).
If that's the case, how much should I adjust the length of the new spacer(for my .90 springs).
I have some notes around here somewhere from that project. If memory serves I set the oil level at 120mm and cut spacers to set the preload at 8 to 10 mm with the adjusters all the way out (pretty much what racetech recommended I think).
I'll try to dig up the notes and get back to you.
jim
edit: I followed Racetech's instruction sheet to calculate the new spacer length. Depending on your weight that may work well for you. My feeling is I could have dialed in another couple of mm of preload. As it is I get 30mm of sag with the adjusters about 2/3 of the way in. If you simply add the difference in spring length to the new spacer you'll probably cut them too long. Remember the first couple of inches of the stock spring is at a .74 rate. They have to be heavily preloaded to get the sag right. You probably (almost certainly) don't need that with a straight .90.
Again, working from an aging memory, I think Phil at Aftershocks recommended a 125mm oil level. I waffled and settled on 120.
SEBSPEED, Sep 15 2007, 09:55 PMJim, I'm just pondering this myself. My forks are draining into buckets tonight, and I'm wondering about what my new fork oil level should be.
Concerning the level of oil - The new .90 spring is a straight wound Racetech part. The stock spring is progressive, and about .850" longer than the Racetech. The coil spring diameter appears to be close, but if I put in the new springs it will take more oil to fill to the recommended 100mm mark.
Or, do I want to add the recommended volume of fluid, and then just check to make sure the levels in both forks are the same, which will leave a larger air pocket?
Check the level by using the dipstick method, and make it the correct level, regardless the actual amount of oil.
So I'm sticking with the same air pocket for a different spring rate?
SEBSPEED, Sep 15 2007, 10:12 PMAbout the spacers; if I cut them to match the old spacers(3.940") + the difference between the two springs(.850", = 4.790"), how will that affect my preload adjusters? I read in an old thread that Turtlecreek did what I mentioned, and didn't have much if any preload left to dial out(soften).
If that's the case, how much should I adjust the length of the new spacer(for my .90 springs).
Cut them to match the old spacers + the difference in OAL of the new springs.
SEBSPEED, Sep 15 2007, 10:12 PMAbout the spacers; if I cut them to match the old spacers(3.940") + the difference between the two springs(.850", = 4.790"), how will that affect my preload adjusters? I read in an old thread that Turtlecreek did what I mentioned, and didn't have much if any preload left to dial out(soften).
If that's the case, how much should I adjust the length of the new spacer(for my .90 springs).
Cut them to match the old spacers + the difference in OAL of the new springs.
I think that's going to give me too much preload and not enough room to soften up if I wanted to. If the new spring were shorter and the same rate as stock, then your solution would be perfectly correct. With the stiffer spring, the new spacer should be a bit shorter.
Edit:
from Turtlecreek's thread, in response to vfrjim:
i cut my spacers so that the total length was the same with 2 washers as the old spring, spacer washer combo. this was a mistake as the preload is out to minimum at this point, thus sticking up almost an inch. i will open it up and cut down the spacer some time in the future. oops, to answer, i don't know the length...sorry. i think it was 120mm, but not positive. that seems to match the numbers you show. I need to cut it down about 10mm which would put me almost exactly were you are.
I am doing the same thing roght now - I got .90 springs and I think we weigh the same, Seb (around 195?). So, how long was your spacer after all and what would you recommend?
SEBSPEED, Sep 16 2007, 11:03 AMWell, Racetech included a bag of washers in the box, so I'll measure the thickness of two of them, and subtract that from Jeremy's suggestion.
This way, Jeremy, if you're right, I can pull the caps off and add the washers in for more preload...
I'm heading out to the garage to get this done in a bit, anyone with a better idea speak now or forever hold your peace... goofy.gif
Rice, Dec 21 2007, 07:26 PMI'm heading out to the garage to get this done in a bit, anyone with a better idea speak now or forever hold your peace... goofy.gif
Congrats on getting around to that, Dmitry. Early Christmas present? warranty.gif
I cut the new spacers to match the length of the old spacers, plus the difference between the springs(as Jeremy suggested). It's been working great. beer.gif
Rice, Dec 21 2007, 07:26 PMI'm heading out to the garage to get this done in a bit, anyone with a better idea speak now or forever hold your peace... goofy.gif
Congrats on getting around to that, Dmitry. Early Christmas present? warranty.gif
I cut the new spacers to match the length of the old spacers, plus the difference between the springs(as Jeremy suggested). It's been working great. beer.gif
it would be nice if someone made the right spring for the VFR, instead of having to cut tubes to make generic springs works. On offroad bikes Honda normally offers and Optional heavier spring, they ought to do it for street bikes too.
spud786, Dec 22 2007, 12:04 AMit would be nice if someone made the right spring for the VFR, instead of having to cut tubes to make generic springs works. On offroad bikes Honda normally offers and Optional heavier spring, they ought to do it for street bikes too.
Meh. If it was just a heavier progressive spring it would be an improvement, but a truly correct straight rate spring is much better. Better to have to make spacers and pay $130 for springs rather than having to pay 3-5 times as much for a dozen or so straight rate custom size springs to be produced.
Ive had aftermarket springs and Honda Optional springs, Honda Optionals that I've seen and used are of very good precision quality . I've yet to see that level of precision in an aftermarket spring. The cost is higher but Its not like a wear item where its going to be an ongoing issue.
spud786, Dec 22 2007, 12:40 AMIve had aftermarket springs and Honda Optional springs, Honda Optionals that I've seen and used are of very good precision quality . I've yet to see that level of precision in an aftermarket spring. The cost is higher but Its not like a wear item where its going to be an ongoing issue.
Are they progressive or straight rate springs?
My stock springs needed to be replaced at 14k miles when I purchased my VFR. I could not get proper sag with the adjusters turned all the way in (weight 180lb). I measured them and they were below the service limit listed in the service manual. I have not measured my racetechs since installing them, but I have not changed my preload settings and get the same sag numbers for the past 50k+ miles with them.
I think BLS has posted before about the springs that Honda uses, the type of steel they use wears out quickly, something like that.
SEBSPEED, Dec 21 2007, 11:55 PMCongrats on getting around to that, Dmitry. Early Christmas present? warranty.gif
I cut the new spacers to match the length of the old spacers, plus the difference between the springs(as Jeremy suggested). It's been working great. beer.gif
Yeah, Christmas came a little early this year beer.gif
I didn't have the patience to wait for your response, so I cut the spacers about 1/4" shorter than the OAL of the stock setup. I did add an extra shim, good for an 1/8th or so, so we'll see how that will work out. If I need to I can always add a few extra shims to fine tune the setup.
BTW, I also send the FOX shock to Jamie for rebuild and to install the Ohlins spring (from the infamous $20 deal rolleyes.gif ) That spring is about 1100lb and should match the .90 springs almost perfectly. I made a little upgrade calculator for myself to make sure that front and back get stiffened about the same % as compared to stock.
[image: gallery_9588_2477_8878.jpg]
BTW, .95 front matches 1100 rear perfectly as far as % %ncrease goes:
[image: gallery_9588_2477_2198.jpg]
If anyone is interested, I can provide formulas.
I am hoping to have a different beast next season, because it was completely out of whack until now. I really felt that on the "Baby Gap"
Can't wait for the riding season to begin.
P.S. Another question. Oil level should be 100mm from the top with the spring in and fork tupe fully extended, right?
spud786, Dec 22 2007, 12:40 AMIve had aftermarket springs and Honda Optional springs, Honda Optionals that I've seen and used are of very good precision quality . I've yet to see that level of precision in an aftermarket spring. The cost is higher but Its not like a wear item where its going to be an ongoing issue.
Are they progressive or straight rate springs?
My stock springs needed to be replaced at 14k miles when I purchased my VFR. I could not get proper sag with the adjusters turned all the way in (weight 180lb). I measured them and they were below the service limit listed in the service manual. I have not measured my racetechs since installing them, but I have not changed my preload settings and get the same sag numbers for the past 50k+ miles with them.
I think BLS has posted before about the springs that Honda uses, the type of steel they use wears out quickly, something like that.
my vfr was bottoming right off the floor, im like 195, pop a wheelie bottom hard, brake into squared adge hole bottom hard. i ran alot of addtional preload to make it functional. Right now i'm runnin 90mm oil height with stock spring was able to back way off the preload since about 15,000 mile(now at 31,000), i could probably use heavier spring , but its adequate enough for the street and doesnt have the brake dive and bottoming issues.
I didnt have any sag set issues, just bottoming and brake dive issues, it was just blowing through the travel too easy with stock oil height, 90mm is about max though. They were border line too stiff initially after a couple thousand the oil detiorated enough and they were good enough. But' Im definitely border line on the spring rate.
My last set of Eibochs(single rate), once spring was longer than the other, but Id say Ohlins would have good tolerences for aftermarket.
doesnt really matter cause there's no optional for the vfr from Honda, if there was I'd probably already have it.
One quart of RaceTech oil was not enough... Now I have to order another quart just to add a few more ml.
On the bright side, if anyone in the area is in the same situation, you are welcome to it.
I compared the "new" fork with the old one by compressing them by hand side by side. The new one requires significantly more force to be compressed and rebound is significantly faster. I used 5Wt oil as per Racetech recommendation. Can't wait to take it out for a test ride... In a few month...
Rice, Dec 22 2007, 02:17 PM
jeremy556, Dec 22 2007, 01:53 PM
Rice, Dec 22 2007, 11:18 AMP.S. Another question. Oil level should be 100mm from the top with the spring in and fork tupe fully extended, right?
Spring and all spacers out, and the fork fully compressed. You will not like the results if you do it extended. wink.gif
Thanks a bunch Jeremy! Saved me a lot of headache fing02.gif
Rice, Dec 24 2007, 10:21 AMOne quart of RaceTech oil was not enough... Now I have to order another quart just to add a few more ml.
I would just go buy a quart of Bel Ray or something locally instead of waiting.
Unfortunately, waiting is not the issue - I will not be riding for another 3 month at least pissed.gif
I will take this opportunity to turn disadvantage into an advantage. I will buy another Qrt from Racetech, but 10Wt this time. If the current rebound damping proves to be inadequate, I will mix in 5Wt and 10Wt 50/50 to get 7Wt...
The 2-3 ml of 10Wt in a 1/2 Qrt of 5 wt should not make any diff me thinks.
Actually Oil level is a tool used to tune the last inch or so of travel. Once you have the correct spring rate, any valving changes and correct oil weight in the forks, oil level itself will have little effect on fork action (as long as the Min. level is met). The air gap as mentioned by HS does act as a secondary spring, but usually only at or near the last part of travel (bottoming). Once your forks are set-up you can increase oil level(raise level= less air) to help prevent bottoming on severe hits or loads. Add changes of 10mm per leg (above min. level to reduce air volume) oil volume to fine tune the last inch or so of travel to suit, mostly to prevent bottoming. fing02.gif
I've been heavily involved with offroad forks for many years, these generally have 12 inches of travel, oil height will effect the whole fork but has the greatest effect in the last 4 inches of the stroke.
Now a vfr has only 4 to 5inches of travel so oil height has and even greater effect, and I would agree that oil height is the greatest effect in the last 1 1/2 inch , but to say it only effects that area would be less than accurate.
10mm oil height stiffened my vfr forks dramatically, everywhere, espeicially in the last inch and 1/2 . as mentioned I was able to back way off the preload with the additional oil.
Forks generally have a 10mm min /max level on both side of the original spec
End of thread · 31 posts recoveredWayback Machine snapshot 13 Mar 2008