Front end adjustment

[reg71]

Ok, as some of you know, I recently changed the front by adding Racetech internals to my 98. Now upon reassembly, I have been having some issues getting the steering back to how it was before. Right now it kind of feels heavy and harder to turn in that I remember. I'm sure this has to do with how far up I have the tubes and/or the clip on position. What I am wondering is where I should go, up or down to make the turn more responsive. should I move the clip ons also or just slide the tubes? I have heli bars so my ride was not quite stock before. I may even switch back to the stock clip ons to get the handling to feel better. Right now it just takes a lot of effort it seems.

[Bubba Zanetti]

Reg:

I'm not sure what to tell you. The 97 feels the exact opposite, or I should say it feels more "planted" so when I put in a quick steering imput she snaps over quick without feeling "spongy".

Sorry for the vague descriptions, but suspension talk is hard over the net.

Did you do the work, or did a shop do it?

BZ

[Lgn001]

If you raise the tubes in the triple clamps, that will tend to make it more responsive (decreases rake and trail). Have you checked the sag already? Too little sag will also slow response, all other things being equal, as it raises the bike in front. I'd set the sag first, and adjust the tube height second. Sorry for the brief reply; I'm at my "real" job...

[Bubba Zanetti]

Lgn001 is smarter than me! I just assumed sag had been set...I shouldn't assume.

[mello dude]

Reg- Lgn001 has got it right. Do the sag set exercise first. (Rear too.)Youll need a buddy to help. After that, first raise the fork tubes 5mm each for a data point. If you want some more, the Penske has a shock length adjustment.
Shoot for a 5mm taller setting for another data point. If you want even more go another 5 taller in the rear. (Mine is set definately taller than stock.)

Another tweak, once you have done above is the balance of spring stiffness front to rear. You can play with that from the rear shock to compare to the front. A bit stiffer in the rear will make the front bite a little more and a bit less will make the front bite a bit less. You can do the front the same way but its better to do this one to a lesser degree. (Set sag first!)

Your point on the helis is a good one too. With them you have less weight on the front wheel - you are more upright. If you go back to stock or even more you have more weight on the front allowing it to work

There is several good references on suspension setup out there - dig into one of those if you need more. I'm brain dead right now, cant think of names for the moment.

So for the moment - do the sag, play with ride heights first. BTW you can over do the rear - the center stand wont be of any use, the rear tire will still be on the ground.

MD

[Puma Cat]

Reg, if you increased the front spring rate, the front of the bike will sit higher (that is, the front ride height will be higher). The relationship between sag and the front ride height is due to spring rate. The higher the spring rate, the less the front will sink under the weight of the motorcycle. The preload will influence how much the front of the bike settles even more when you sit on it. A bike that sits higher at the front has more trail, and will feel slower and heavier-steering (this shows how much trail influences handling). I can give you sag figures for the front if you need them.

I don't know what MD means by raising the fork tubes 5mm for each data point, perhaps he can explain. When I talke to Dan about this last week, he said you should raise the forks in small increments, no more than 2mm at a time, until you feel the sweet spot of turn-in relative to stability. Personally, I would err on the side of conservatism and make smaller adjustments at a time. When I installed the .90 springs in my F4i, the front sat higher, and I had to raise the rear shock 5mm to get the front end geometry back to where it was originally.

Also, check the position of your forks after you reinstalled them. The stock position is 41 mm from the top of the fork bridge to the end of the fork tube (not the cap! the fork tube end; the cap adds about 2mm). Use an accurate gauge or micrometer to measure this accurately, millimeters matter!

Give me a call if you want to discuss on the phone 510-703-4727, call me after 7 pm if you want to chat.

[mello dude]

Yeah the stiffer springs will cause the front end to sit higher. I ended up on my ride with the fork tubes raised at 5mm and the rear up higher than stock. Cant vouch for a stock height in the rear - didnt measure. The bikes geometry is pretty conservative to start, so I wasnt over conserned. (My front spring is a 1.0)
- I did use a caliper to measure. Data point? Ride it, try it. Puma, I think we're on the same wavelength anyway.

MD

[Puma Cat]

Yeah, we are...

[RVFR]

Originally Posted by Puma Cat

Reg, if you increased the front spring rate, the front of the bike will sit higher (that is, the front ride height will be higher). The relationship between sag and the front ride height is due to spring rate. The higher the spring rate, the less the front will sink under the weight of the motorcycle. The preload will influence how much the front of the bike settles even more when you sit on it. A bike that sits higher at the front has more trail, and will feel slower and heavier-steering (this shows how much trail influences handling). I can give you sag figures for the front if you need them.

I don't know what MD means by raising the fork tubes 5mm for each data point, perhaps he can explain. When I talke to Dan about this last week, he said you should raise the forks in small increments, no more than 2mm at a time, until you feel the sweet spot of turn-in relative to stability. Personally, I would err on the side of conservatism and make smaller adjustments at a time. When I installed the .90 springs in my F4i, the front sat higher, and I had to raise the rear shock 5mm to get the front end geometry back to where it was originally.

Also, check the position of your forks after you reinstalled them. The stock position is 41 mm from the top of the fork bridge to the end of the fork tube (not the cap! the fork tube end; the cap adds about 2mm). Use an accurate gauge or micrometer to measure this accurately, millimeters matter!

Give me a call if you want to discuss on the phone 510-703-4727, call me after 7 pm if you want to chat.

There ya go Reg Good ole Steven will gets you in the right spot sooner or later.
Yep to what was said above, you should for the stock front fork tube placement is to see like 2mm above the clip-on, as on mine the top of the tube less the cap is set at 40mm above the upper triple clamp, other wise you will need to raise the rear to bring it back un less theres room for the helibars to give or take a few mms. Then again you may have gotten use to an ill handing machine and don't know what to expect. No I'm not picking on you, just know from past experiences what I've seen. but I'm thinking PC has the right stuff to get you through this ok. LOL on another note, now the tires will play into this too ;)

[reg71]

thanks for the pointers guys. I think I have the gist of it. Now I just have to find someone who knows what the hell they are doing to help me do it... I didn't even think about the front being higher from the stiff springs... it makes sense, though. I haven't even touched the back yet either... Once I get it dialed in, I won't change it again!