Steering Geometry .... Has anyone tried this one yet!



45 replies to this topic
  • WR400_Jay

Posted June 13, 2000 - 05:01 PM

#1

I've come to the conclusion that no matter what I do I'm still not satisfied with the quickness and response of the steering on my 00' WR400 even after running the forks up and reducing the sag.

I was out in the tight woods with two friends one with and XR400 and one with a new DRZ400. We all traded bikes and came up with the same conclusion. Wr great power turns like a truck in the tight woods, XR great handling easy turning but has no nuts, DRZ400 good tractable power and good turning but soft suspension.

What I would like to do is change the head angle of my bike by machining a new lower clamp and relocating the position of the pressed in steering post farther forward in the bottom clamp and change the amount of rake in front end hopefully making the bike react faster.

Does anyone have rake and trail numbers for theses bikes? Will this work? I'm open for Ideas :) Help me out. Thanks!

------------------
00'WR400 75'Yamaha 250 enduro
White e-Series S-bend 12 discs, Yz timed, rejetted to Clark specs, throttle stop cut, lid removed, Topar Racing top clamp, Tag Metals T2 bars, Scotts damper, Devol disc guard and frame guards, lights removed, Cr routed Fastline brakeline, Acerbis Rally pro hand guards fastened to the top clamp, Gel grips Live in Southwest Ohio

  • MotoGreg

Posted June 13, 2000 - 06:09 PM

#2

You cannot change rake with triple clamps. Scotts sells a triple clamp set to change the trail by 5mm and this is supposed to make a big difference. I have my bike with the forks 13mm above the triple clamp (I experimented and came to this setting only to later find out later that Jimmy Button runs the same 13mm setting). I also have taken one link out of my chain to shorten my wheelbase. Also, you said you've "reduced the sag" I hope you mean front and not rear or else you've gone the wrong direction. You want to run 90-100mm rear sag and no more. The more the rear sags the less steep the steering head angle is and the slower the steering is. This makes a huge difference and the wr rear spring is softer than the yz spring. Preloading the spring is not the same thing as a stiffer spring rate. The wr spring is much softer than the yz spring. My riding buddy who has a well set-up xr400 loves how quick/nimble my bike is, it feels NOTHING like the wr400 that I started out with.

------------------
'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at www.insanespeed.com

  • Mitch_from_Oz

Posted June 13, 2000 - 06:39 PM

#3

Hey Jay,
Do you have the YZ seat and tank? That makes an incredible difference.

For tight woods, 10mm above the triple clamps with YZ seat and tank is more than sufficient. Any more than that and the bike could kick out from under you in rutted areas.

Trust me, I have tried it. Jimmy Button is a professional, dont go by what he has set. Try 5mm, 7mm, 9mm and judge for yourself.

Mitch

  • James_Dean

Posted June 13, 2000 - 08:07 PM

#4

Points made are right on the mark. Another factor is increased fork rebound will hold the front down and a little less fork compression too, but not so much that it becomes loose or bottoms. Keeping rear rebound a little firm helps precision in the really tight stuff too. There will be tradeoffs when the trails get faster and you will have to decide the best balance for yourself.

  • Matt_Porritt

Posted June 13, 2000 - 09:19 PM

#5

Yip.. the Scotts clamp set does make a difference.
I can do them at a better price than retail if you want some.. email me porrittm@anet.co.nz and I'll give you some prices if needed.

------------------
--
**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

  • MotoGreg

Posted June 14, 2000 - 05:39 AM

#6

Jimmy Button is a professional, dont go by what he has set


Of course I'm not suggesting for him to try something because a pro uses that. What I said was that I've tried everything and have settled on that setting probably a good six months ago. Last week a magazine came out with Jimmy's bike and said he runs the exact same setting which caught my attention. That doesn't mean that it is ideal for everyone of course but atleast now I know that my seat of the pants testing is in the ballpark.

------------------
'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at www.insanespeed.com

  • jj

Posted June 14, 2000 - 08:10 AM

#7

Question.

Motogreg you posted that the Scotts clamp changes the trail by 5mm. What is the trail?
I've got the upper clamp and I was under the impression that the advantage of this clamp was that it moves the bar postion forward 5mm. Are we talking about the same thing?

Thanks!

JJ

  • Taffy

Posted June 14, 2000 - 02:39 PM

#8

in roadracing you can get yokes/triple clamps in which the fork holding part is seperate from the post. by putting in carefully machined plates the forks come back or go forward. other plates are slightly wedge shaped & that tilts the forks up or down. were talking +/- 1 or 1 1/2 degrees. you've got to worry about how to fit your bars (clip-ons for RR). the other one is the space centre to centre of the forks. within 5mm or so & you could space the wheel on the spindle. fork diameters the same i should think. i would imagine the post size & height would be similar but none of this is insurmountable!!!

gewon ba be the first!

  • WR400_Jay

Posted June 14, 2000 - 03:44 PM

#9

Cool :) Thanks for the feedback guys. Lets answer some questions. Mitch I do have the YZ seat/tank combo on and it made a huge difference. I'm stuck with only being able to move my forks up to about 6-7mm because my bars are located directly above my fork tubes.
James Dean I just tried increasing the fork rebound this past weekend and it made a definite difference in turning. I'm going to experiment some more with this until I find the best settings.
Matt and MotoGreg I think the Scotts clamp set is what I'm looking for but one problem I have a Topar Racing billet top clamp that I bought a couple of months ago. I like Taffy's idea about the adjustability of the units that are put on road race bikes but I don't know if the clamp can be made strong enough to with stand the stress of jumps and hard landings.

I think first things first. I'll have to make a taller set of bar saddles to raise the bars above the clamps to allow the forks to be slid up in the clamps. MotoGreg do you think that changing the trail by 5mm was too much or could you use more? I have access to unlimited maching capability as well as every CAD/CAM software package on the market to adjust for any changes I need in the final design. I'm a CNC service technician for a large machine tool company. The machines I work on have probably made or made the mold for something you guys have in your home or garage. Possibilities are limitless. What should I do?

------------------
00'WR400 75'Yamaha 250 enduro
White e-Series S-bend 12 discs, Yz timed, rejetted to Clark specs, throttle stop cut, lid removed, Topar Racing top clamp, Tag Metals T2 bars, Scotts damper, Devol disc guard and frame guards, lights removed, Cr routed Fastline brakeline, Acerbis Rally pro hand guards fastened to the top clamp, Gel grips Live in Southwest Ohio

  • MotoGreg

Posted June 14, 2000 - 04:01 PM

#10

This is hard to describe without a drawing... maybe you can make a quick sketch. Imagine a line going down through the steering head to the ground. Now another line that is straight up vertical from the ground through the center of the front axle. Now, see where the first angled line hits the ground in front of second vertical line? The distance between the two is the trail measurement. Now imagine you had the Scotts clamps that move the forks back 5mm closer to the steering head, and see how the front line is furthur from the vertical line? The trail measurement is changed and the steering will be quicker with the trade off being less of a self centering (stable) front wheel. Ever jump off your bicycle and it keeps on rolling along staight? That's because the more trail it has the more self centering the front wheel will have. Trail is similar to the caster measurement on a car.

Do not confuse trail with rake. Rake is the angle of the steering head and that cannot be changed without cutting the steering head from the frame and re-welding it back on at a different angle... or running head on into a wall... or having super trick offset ground steering head bearing races like the factory teams use on SX bikes...

------------------
'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at www.insanespeed.com

[This message has been edited by MotoGreg (edited 06-14-2000).]

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  • Clark_Mason

Posted June 14, 2000 - 05:06 PM

#11

I have the complete Scotts front end setup on my 99WR. This pulls the complete front end back 5mm, basiclly shortening the wheel base by 5mm. The 00WR already has the wheelbase shortened by 5mm in the stock condition. The Scotts front end pull back was made for the 98 and 99's to make them more represenative of the 00 bikes and to also improve steering performance.

My 99WR handles excellent and is set up as follows: IMS seat and tank, Scotts complete tripple clamp stack including protapers and dampener, Bike lowered by approx 1" (forks 20mm shorter and shock 8mm shorter), chain shortened further shortening the wheelbase, forks raised about 4mm in the tripple clamps, Michelin Enduro Competition III front tire and either a Dunlop 606, 756 or 739AT depending on conditions.

Clark

  • jj

Posted June 14, 2000 - 07:50 PM

#12

I'm confused Motogreg, too move the forks back 5mm you would have to have the top and the bottom clamp....I've only go the top. If all this is correct then just having the top clamp would mean the the forks aren't fitting in the clamps straight...help!

JJ

  • MotoGreg

Posted June 14, 2000 - 08:49 PM

#13

Yes, of course you have to have both clamps. The center hole for the steering stem will be 5mm closer to the two big holes for the fork legs.

In your previous post you said you have a top clamp that moves the BAR forward by 5mm. That is basically a stock replacement clamp that lets you change bar position. The stock clamp has the bar mounts as one piece with the top clamp so you can't change the bar position, that's why there are so many aftermarket top clamps available like the one you have now.

------------------
'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at www.insanespeed.com

  • jj

Posted June 14, 2000 - 08:53 PM

#14

Moto, I'vr got the Scotts top clamp and the stock lower. Am I doing damage? I have it all apart right now for stearing head and fork seal maintance. I've just put the forks back and everything lines up just fine, what am I missing?

Thanks,

JJ

  • Mitch_from_Oz

Posted June 14, 2000 - 09:00 PM

#15

Correct me if I am wrong, but...

1. The upper clamp is primarily there for improved bar positioning and for different bar mounts.
2. To change the rake/trail by 5mm, then you certainly need the upper and lowers. They come in a kit. Otherwise, how can this be acheived without "bending" something.

Like I said, correct me if I am wrong.. :)

Mitch

  • MotoGreg

Posted June 14, 2000 - 09:20 PM

#16

You guys are making this too hard...

1. JJ, you have a Scotts top clamp that changes the HANDLEBAR location only, everything else is the same. Your clamp is meant to work with your stock lower clamp. You are fine. The DIFFERENT Scotts clamps we are talking about come in a set of two, like Mitch just said.

2. Mitch you are correct, JJ is just trying to confuse us all!

3. Rake and trail are two different things. Rake is the angle of the steering head and you cannot change that.

------------------
'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at www.insanespeed.com

  • Mitch_from_Oz

Posted June 14, 2000 - 09:36 PM

#17

Hey MotoGreg, thanks for sorting this all out... :)

3. You can actually change the Rake. Some tripple clamps (upper nand lowers) are designed to change the steering angle.

Anyway, good luck... :D

  • Taffy

Posted June 15, 2000 - 02:24 AM

#18

if you have the 00 bike that is 5mm shorter in the frame (presumably around the steering head) & then get the 5mm shorter scotts clamps you now have a 10 mm shorter bike than the 98/99 models placing more weight over the front.

shortening the wheelbase by moving the rear wheel forward is fine but it just shoves more of your body weight backwards.

do the above two & your starting to talk cos the balance is still right of the bike.

change the way you ride the bike. try braking harder on the rear brake. try different skills ad nauseum.

personally i think the bike is just heavy & most of all bloody top heavy.

the wheelbase was measured at 2 1/2" longer than my mates KLX & his sits lovely & low. you can grab the bars on a KTM & shake the bike bloody hard from left to right but not with the WR!

i'd love to see someone try these offset yo.. i mean triple clamps. your right they don't change the rake. but it has the effect of it.

as far as not being strong enough, well the two parts of each clamp usually have M12 bolts coming in from the front of the bike.

someone out there in gp land has used/is using them. the proof will already be out there as to wether they are up to it.

  • jj

Posted June 15, 2000 - 08:17 AM

#19

Sorry guys, I guess that I should have asked if they made more than one clamp. See what happens when you ASS-U-ME!
So what you all are saying is that Scott makes two styles of triple clamp one to be used with the stock lower that only moves the bar postion forward and one that is as a set, upper and lower, and changes the trial. Correct?

JJ

  • Guest_Guest_*

Posted June 15, 2000 - 01:34 PM

#20

Yea JJ you got it. (What a mess!)

I've had the Scotts upper and lower triple clamps and the Scotts damper for about 4 months on my '99 and love the combo. Turns tighter and has greatly enhanced stability with the damper.




 
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