Mono-shock and lowering...

Thinking of building a Z using a mono-shock. My concern here is that this bike will be used mostly at the strip maybe a few trips on the street. Not really worried about having a lot of clearance around corners so what I would like opinions, factual knowledge, etc. I see how you guys have built them as far as bolting the rear shock on but I do not need it to sit up like a normal streetbike does. I want to lower the bike down. So...if built normally can you just move the upper shock mount higher to get a lower ride height or would that mess up the geometry and/or shock movement arc? Would you have to nount normally and need to use lowering links? If I wanted to lower bike say 3" would I just move upper shock mount 3" higher or does the linkage set-up work in such a way that that idea isn't the way it would need to be done? Anyone know how this would work or need to be done?

find a middle ground with a + or - 1" adjustment on the top shock mount.

then make or buy adjustable lowering links

it will change some things but nothing that can't be dialed in with test and tune

I lowered mine a little with the initial setup by welding my mount a little higher.
now if i were to lower it anymore I would use a lowering link or build an adjustable
one.

when building one for the drag stip you have to remembeer that normal street rding geometry doesn't come into play. There is a ton of geometry in hooking one up you will have a alot of rear end squat
which is lost HP (tranferring hp to the ground) Ideally you would want a strut rearend for drag racing.

I am sure that alot of guys will have better info. The height of the rearend isn't as important as gettin the hp transfer to the pavement

This bike will used in the streetbike class so it will be running a street tire. So it will need a shock. It could be run with a strut but being street tires have a stiffer sidewall, you need a shock so it will squat. A strut would work but it would be either spin or hook... A slick has a soft sidewall and will flex so a strut works there but on a street tire, a shock is best to compensate for the stiffer sidewall. It looking to be at least 68" wheelbase and I want it down low to help keep front-end down so the lower the better. I think I can go as low a 3" ground clearance. I need it shorter then most also beings I have short legs. How did you guys determine where you put the top mount...What amount of squat do you have on your mono-shock's? That would figure in where to put the top mount also/

had to stiffen my shock up today cut my Shinko by bottoming out I'm 180lbs my ol lady 140lbs riding 2 up I built mine on the jack stuck the swingarm in with wheel and lowered the jack ti; I had the
ride height close.

my original shock was a 2" shorter than stock shock I put the top in and noticed the bottom hole was nearly exact to the slider mount of my new swingarm (about where shock mount would go)

I measured and welded from there knowing the final product would be a little lower depending on the stiffness of my shock



most of the pic's of the mount are in my build

Lets see, street tire, 68" w.b., you gonna play with the fast kids huh?
What I know on them is they seem to use most of the shock travel and they rework the crap out of the shocks plus use a different style lower link that changes geometry. Now don't hold me to this information as gospel, everybody has different ways of skinning a cat so to speak. Alot of this is why I was playing with the geometry on the turbo bike, I wanted to be able to tune a street setup or strip just by moving a single bolt.

Les

I'll add to this since I'm building my 900 to do what you are thinking of doing as far as purpose goes. Some of what I'm about to say you may already know but I'll put it out there for those that don't.

A long time ago when AMA/Prostar was still around Brock Davidson was running a big-blocked Suzuki Bandit in the Super Street Bike class capable of dipping into the 7's. Sometime around there he wrote some articles for the long defunct Motorcycle Performance or a publication close to that name. Anyways he wrote an article covering suspension set-up which I still have a copy of. In it he states, "First and foremost, you must have properly functioning front and rear suspension." Later in the article he reveals, "I set my bike up with the same suspension geometry as a 1991-92 Gsxr1100 and use a 550lb spring. This works well for most applications and represents a good starting point for nearly all."

If you've looked into my build thread, you've probably noticed that I'm using the suspension from a 89-92 Gsxr750 which has the same geometry as the 1100. You'll also notice that I went with a CBR600RR shock. Why not the Gsxr750 or 1100 shock? Because the CBR shock is the same length as the Gsxr unit (keeping the same geometry as the Gsxr shock would) but runs a 550lb spring from the factory and has the correct valving for the higher rate spring. Sure I could have ran a Gsxr shock with a stiffer spring but chances are I would have needed it revalved. I may still need to tweak the valving on the CBR shock but I'll be at least in the ball park.

Again going back to the article, "I generally set up my Unlimited machines at four inches to compensate for squat. Dynamically, when the machine squats on takeoff, you get the improved traction, but also a lower CG to offset wheelies. Additionally, you receive the added benefit of the bike raising while moving down the track, which results in more traction at the top end" he mentions. I'm planning on running lowering links instead of moving the mounts around and losing the factory geometry that a suspension engineer has already figured out for me. I'm gong to set the bike up a little high and see how it handles.

Another thing you may want to think about is the shock travel. You don't want to make it so low that the tire hits the rear frame rail. That's part of the reason why I hacked off my subframe and made a longer one. At the length I wanted to run, the tire would have most likely hit the rear of the frame before I ran out of suspension travel.

To sum it up....there are as many variables as there are solutions but I took out as many variables as I possibly could by sticking with what the suspension engineers took a long time to figure out for me already.

Later, Doug

Some of those guys don't look like they squat that much but a guy I know on a GS based bike squats what looks like 6" or more. Those guys spend lots of $$$ on their shocks too. I won't be as involved as those guys beings this will be something to have fun on...no intention of trying to run with the big boys but fast enough to make it interesting. Don't know anything about special lower links but it wouldn't surprise me any. Just didn't know if simply raising the top mount would change the shock angle enough to make the idea a bad one. Sounds simple enough but I know how that works at times. lol