nath981

[QUOTE=RK1;I weigh same as you and same .85 Race Techs- cut the spacer to 70mm and raised tubes 11mm.

FWIW, I had been running 4mm worth of spacer over the shock and it felt really stiff. I just took out 2mm of it and the rear feels way more compliant. I don't really understand why that is but it seems to have made a real difference.[/QUOTE]

Please let me ask some questions here since you mention your specs:

I have the 85 RT, cut the spacer to equal OEM combined length. Exactly how much does this raise the front end? I feel my front is way high(from floor to middle of chin spoiler bolt is 9 1/2" or 241.3mm from floor free standing/no rider---and this is with 11mm raised forks). Other threads seem to suggest 170mm distance to this bolt is more appropriate and mine's 2" higher. Does the 70mm spacer cut correspond to oem combined spring/spacer length since i don't remember my spacer length?

Relative to the rear, I have 6mm over shock and feel like I can't my body get far enough forward and have to be constantly keeping pressure on the pegs to feel planted in high speed turns with road irregularities to mitigate the harshness. This seems to be congruent with others' comments that when the front end gets new springs, it serves to highlight the inadequate rear suspension.

thanks, Nathan

gboezio

Nathan, if you have RT springs and stock lenght spacers, your front SAG should be quite high, try measure your static SAG (bike up no rider) then measure your riding SAG (with your weight on standing on a toe)
You can use a tie rap or a marker.
And yes when you start getting the front right, the rear shock feels closer to a 2x4

Tweety

I'm fairly sure the 2x4 is more forgiving and comfy than the stock shock...

nath981

gbo,

diff between rider sag and static sag is 1 9/16" or 39.7mm

thanks, Nathan

Hawkrider

Whoa! Really? Something's wrong there. You should be shooting for an unladen sag measurement of about 15mm. Laden (rider) sag should be about 30-35mm. This is how you choose your spring rate. The big delta you have indicate you have springs that are too soft. As a matter of fact those sound similar to stock numbers with the squishy progressive springs.

JamieDaugherty

Isn't that a little high for the static sag? I usually measure 5-7mm static and 30mm rider. This because there is preload on the spring at full extension.

nath981

Analyze this Doctor:


.85 springs, rider weight 175, spacer/spring cut to match OEM length, 15oz 7.5 wgt oil.
no preload adjusted in yet

all measurements from triple clamp :

fully compressed, no oil=41mm(to metal rim at fork seal)
fully extended, no oil=152mm(to metal rim at fork seal)
static sag(bike standing on its own weight=127mm
rider sag=87mm

127-87mm=40mm

I guess this means I should start dialing in some preload? or?

thanks, nathan

JamieDaugherty

Your rider sag should be calculated as:

152-87 = 65mm

Yes, you need to dial in some preload. I'd shoot for something in the 45mm range to start with.

Hawkrider

Jamie, I usually shoot for ~15mm unladen sag for the street. 10mm is in the ballpark. Any more than that I think you need more internal preload.

For newer forks 45mm laden is the upper limit for sag. Our forks work a little better in the 30mm range for rider sag (street setting).

(Edited for clarity)

gboezio

So 25mm static and 65mm rider SAG
It needs like 20-18mm more preload, it will bring static SAG to 5-7 mm and to get that rider SAG lower, you could use some even stiffer springs.
Since all springs are not equal, it's nice to measure, washer, spring length and desired preload (around 20mm), substract from the fully extended fork inside measurement (substracting the cap thickness since it sits lower that the end of the tube), this is the shim length.
I like to cut them longer since it's easier to cut some more than to remove some, but finding some thin pipe like this is quite easy to cut another.

I'm surprised that with .85 and 175 lbs rider that you get a 40mm drop.
To get an accurate rider SAG measurement, some people let the bike drop slowly to SAG and take measurement, then they will ask someone to press down the front of the bike and let it rise slowly, and write down this second measurement, then they will take the midway point as true rider SAG, since telescopic forks tend to drag a lot and friction should be equal going up and down, this take the friction out of the equation.
If the friction is high (bigger difference between the two measurements), this may point some other fork problems and will provide sloppy measurements.
This can be done to measure static as well.

JamieDaugherty

Let me break it down for you this way:

Typical spring rate = 1000lb/in
Typical spring installed compression = 14mm/.550in
Spring preload = 550lb

Assuming a leverage ratio of 3:1 that means it takes 183lb of rear force to overcome this preload. The VTR is ~400lb, assuming 50/50 distribution that's 200lb per end. If 183lb of that takes up the spring preload then there is only 17lb left to generate the static sag. Going backwards to the spring then back to the wheel:

Load = 17lb
Ratio = 3:1
Spring load = 51lb
Spring rate = 1000lb/in
Spring compression = .051in/1.3mm
Ratio = 3:1
Wheel travel = 3.8mm

If you are getting 15mm then something is really wrong. I'd say this is an indication that your spring rate is too low, or something else is going on all together.

nath981

[QUOTE=gboezio;203678]So 25mm static and 65mm rider SAG


Hell, I thought I was doing a good job takin all those measurements. made me feel like I was doing something scientific, but, sounds like I need to go to sag school,huh!! I'm goin to dial in some preload and see what happens.
I'll post shortly.

thanks all, Nathan

nath981

based on info below, i need to add more preload still?

.85 springs, rider weight 175, spacer/spring cut to match OEM length, 15oz 7.5 wgt oil.

4 lines showing preload adjusted in

all measurements from triple clamp :

fully compressed, no oil=41mm(to metal rim at fork seal)
fully extended, no oil=152mm(to metal rim at fork seal)
static sag(bike standing on its own weight=111mm
rider sag=95mm

152-95mm=57mm sag

I guess this means I should start dialing in some preload? or?

thanks, nathan[/QUOTE]

RCVTR

Nathan,
I think it will start making more sense (everybody will be speaking the same language) if you measure from fully extended, not fully compressed.

Lift the front of the bike and measure the fully extended length. Then set it down, compress the forks a bit and let them return to their rest position and measure the length again. It should be about 15 mm shorter, with the preload adjuster in the middle of it's range. If not, adjust the length of the spacer by the amount of the difference.

The bike should then sag another 15mm or so when you get on it with your riding gear on, if the spring rate is correct, for you rider weight.

nath981

It's pretty hard to describe these procedures as everyone thinks so differently.

I only did fully extended and fully compressed once before adding oil. When I checked the static sag(wo rider) I pushed it down a couple times and then let settle, then pulled up on bars and let settle and averaged the two. I'm going to crank the preload all the way and measure again just to see what I get. I'll post results.

thanks, Nathan

nath981

1 line showing preload adjusted in

all measurements from bottom triple clamp :

fully compressed, no oil=41mm(to metal rim at fork seal)
fully extended, no oil=152mm(to metal rim at fork seal)
static sag(bike standing on its own weight=114mm
rider sag=105mm

152-mm=47mm sag

.85 springs, rider weight 175, spacer/spring cut to match OEM length, 15oz 7.5 wgt oil.

what's this look like??

thanks, Nathan

JamieDaugherty

I'm concerned about your 152 fully extended versus the 114 static measurement. That seems like way too much. More preload for sure. Did you compare the free length of the new springs to your stock parts? Cutting the spacers to the same length as stock only works only if the springs are both the same length. They normally are different.

If you use a front end stand that helps a lot. I'd also suggest that you use a tie-wrap around the fork tube. As the fork compresses it will push the tie wrap up. That will give you a good point to measure to when you put the bike back up on the stand. If you are careful you can actually do this by yourself. For the rear you need a helper.

nath981

the 152mm is the max the fork could be extended and it was done before oil. I'll go measure extension by jacking the front end off the ground and see what I get.

I laid the stock spring and spacer alongside the RT spring and cut the new spacer to match the OEM overall length.


I am using ties for measurement.

thanks, Nathan

nath981

I think you hit on something Jamie. 152mm is the extension I began with before I dropped the front end 11mm. I thought this measurement wouldn't change once taken, but........ah oh!

I jacked the front off the floor and discovered my mistake. The full extension is actually 143mm now. Seems like it should be 141mm since I dropped the front 11mm. but it ain't.

Daaaammmmm!!!just when i was starting to feel like I was doing something scientific taking all these measurements and doing these calculations. what a dumb ***! anyway, glad you picked up on it.

143mm full extension
105 rider sag

143-105=38mm sag with 1 line showing.



114mm static w/o rider
105mm with rider

9mm difference

now how are we looking?

thanks, nathan

Hawkrider

Holy jeezus. I think you're talking shocks and I'm talking forks. Let's get on the same page before we confuse anyone else! I edited my post that you quoted for clarification.

Hawkrider

Nathan,

You only have about 10mm adjustablility on preload. Since you have the adjuster full in and you don't have good sag numbers yet this indicates to me that you need a longer spacer, specifically 13mm longer. That's

38mm (what you've got now)
- 30mm (what you're shooting for)
= 8mm

PLUS

50% of the adjustable preload range which is 5mm.

That will give you a unladen sag of 143 - 114 - 13 = 16mm, which is almost exactly where you want to be.

And this will ultimately get you at 30mm laden sag with +/- 5mm of adjustability.

RK1

Some of you guys know this stuff way better than me, maybe I'm missing something, somehow this doesn't make sense to me.

Here's why;

I happen to have the same .85 RT springs with the same spring/spacer OAL as stock, same as Nathan is reporting.

My sag measured about 28-29mm, and that's with 4 lines showing on the preload adjusters.

Nathan is measuring 38mm sag with one line showing- his adjusters are cranked down 3 lines- about 6mm more than mine. Difference of 15-16mm. He's got about 20 lbs. on me but I don't see how that could make such a difference.

Nathan; I just now noticed your questions in post #61.

I'm not sure what you mean by "chin spoiler bolt". If I remember correctly it is 168 or 170mm from the floor to the bolt head at the base of the oil filter. That's with the chin fairing removed. If you are anything like 2" higher there, something is very wrong.

Yes, cutting the RT spacer to 70mm gave me the same spring+spacer OAL as stock. You might want to pull them and double check.

gboezio

My RT springs were quite taller than the stockers so I cut 25mm from the spacers, I'm in the ballpark, but I would give an extra 5mm so 80mm long. Maybe they someone mixed springs somewhere, I think they are 92 Gixxer springs after all, they don't make customs, they simply use what's already made that fits, easy money.
It's easier to mesaure from the fork seal, push the tie rap by sitting or standing the bike then set on the stand and push the handles up to extend and measure, so easy

RK1

80mm spacers wouldn't work for me. I've got the sag where I want it with 70mm. With 80s I'd have too little sag even with the adjusters backed way off.

Also I've pulled up the fork tubes 11mm, about as far as I'd want to go. Another 10mm on the spacers my front end would be too high for my taste.

RK1

Yeah, maybe they sent him the wrong springs. When mine came I checked the weight stamp on them and measured them so I know they were the right ones, but the washers which came in the box wouldn't fit in the fork tubes. I'm guessing they were for 43mm tubes instead of 41s.

nath981

thanks gentlemen,

I should have ordered .90k fork springs instead of going through all this ****. So much for the RT weight calculator. There may be a lesson here for others: that is, order one size above your weight and just back off the preload.
well for me, I'll cut new spacers 13mm longer and see what the measurements do to the sag numbers.

Report back later today.

thanks, Nathan

Hawkrider

Don't think that your springs are the wrong weight. The weight is selected based on you and your bike's combined weight. Once you make your spacers longer you should be exactly where you want to be with 16mm unladen and 30mm laden. It doesn't get much better than that for the street. Track duty is a little different and you do want stiffer springs if you're fast.

RK1

Yeah there's nothing wrong with RT spring weight recommendations. I was just wondering if it was possible that they shipped him lighter springs than the .85s he ordered or something else is wrong.

If he's using the same springs and spacer length as I am would his slightly higher weight result in 16mm more sag? Maybe I'm wrong but it doesn't seem plausible to me. Hope the longer spacers fix it up right in any case.

RCVTR

A couple of things.

Nathan are you measuring sag on the fork stanchions or the chin fairing? These are definitely not the same thing. Measure sag on the fork tubes.

Also, you mentioned that 11 mm on the preload adjuster was not 11 mm sag. I will be slghtly different because you are compressing the air in the top of the fork, which changes the effective spring rate.

nath981

greg,

cut spacers 13mm longer. 70 +13=83mm

full extension = 137mm

static sag(w/o rider)= 124mm

sag (w rider)= 101mm

137 -101= 36mm sag

all measurements from bottom side triple clamp; no preload, no rebound adjusted in.

thanks, nathan