KZ1000 is op rear shock mounts

Hey all, have a question. When doing a restomod on a KZ1000, why do the top rear shock mounts get moved?  Seems to me, if the triangle from the top mount to the swingarm pivot to the lower mount is the same dimensions as original, there would be no reason. Wouldn't the swingarm angle be the same and the shock angle same as stock? Any answers will be appreciated. 

Many race bikes of those days moved the top mounts forward to change the leverage, thus the handling of the bike. Keep in mind that different swingarm could have a different distance between the pivot and lower shock mounts.

I remember seeing a swingarm or two with lower mounts having multiple holes so the rider or mechanic could move the bottom of the shocks forward and backward a bit.

My understanding is as below, in the stock position the linear travel of the shock doesn't follow the "arc" the swingarm moves through so will create side loading in the shock (remember we are talking very small gains for racing, it's more a "replicate the factory racer look" on a street bike)  With the top mount moved forward the linear travel of the shock is better aligned to the "arc" the swingarm travels through

 

Thanks guys for the info. If I put a different swingarm on an locate the lower mount the same distance from the swingarm pivot and use stock length shocks would I need to move the upper mount?

WoodheadB2 wrote:

Thanks guys for the info. If I put a different swingarm on an locate the lower mount the same distance from the swingarm pivot and use stock length shocks would I need to move the upper mount?

No, this is a "superbike" racing mod and as explained any benefits for road riding would be minimal

I put a KZP swing arm on my Z1 that is 1 1/2" longer. That changed the angle of the shocks and lowered the bike. I had to do a fender extension so the tire wouldn't hit it. My shocks were 13" where stock is 14" so the bike was riding real low. One shock came apart at speed and I saw it in my mirror passing me at 70MPH.   Had to put on a cheap set of RFY shocks I had just to ride the bike again. Picked up a stripped down KZP and switched the shocks for a set of repop Z1 shocks and all is good. Turns out the bike is more stable at a ton and the angle is close to the one on the KZP. They moved the top mount forward on the frame but there is a place for a shock mount further forward that's not being used. 
What I'm trying to say is you change one thing it affects other things as well.   Not just plug and play.. 
Steve
rumble.com/v4rugm9-broken-shock.html

There are several different reasons and effects when laying down the shock angle depending on your intention.
As well as following the arc more closely which gives a more linear actuation you also gain more wheel travel for the same amount of damper stroke and like for like it will also apply more leverage to the suspension unit making it softer on the same settings for both compression and damping .
Once done you will most likely need to adjust the spring preload at the least to maintain the required sag and if using basic fixed damping shocks you may find the damping too soft and have to invest in some higher quality adjustable damping units.


 

Here's were I'm at. Where the shock is sitting on the swinger, it is 1 inch shorter than stock from the pivot to shock. I can't mount them stock dimension because I would have to weld the brackets half on the castings and the stock weld would get in the way. The  swinger is also 1 in longer than stock at half adjustment. I think with the 17 in wheel that would drop the axle about where it needs to be for the ride height to be close to stock. At that setting the swinger angle is right at 10 degrees. If ya look at the pic with the brackets close, you'll see a mark for the stock length from the pivot to the stock lower mount dimension. It's at the aft end of the brackets. So in yous guys expert opinion, do I need to move the top shock mount? By the way, I've been lurking on this site for a while and I really appreciate the way you guys try to help members without resorting to talking down to members with questions. Especially Wookie and zed1050. I've been on other forums and if I ask a question, all I got was an "elder" making sure that I knew that he was smarter than me. So thanks for your input, it's much appreciated. 

Upturned  Busa swinger and  5.5" rim Z750 wheel by the looks of it ???.
Once you have the stance you want i would move the top shock mount forward to at least match the original shock angle.
I made a drilling and welding jig for this very job which ensures both sides are exactly the same..

It's a Suzuki TL1000r swinger. ZX6 rear wheel. Man, I wasn't looking forward to moving the top shock mount, but I want it to be right. What did you use for the studs? I've seen them on different websites that cater to cafe racers, made of steel, but I need to get my shocks first (not going to use stock, looking at BikeTec reservoir type) so I can be sure of the eyelet size before committing myself. 

I made my own from mild steel bar.
I do this stuff regularly so have a lathe and mill but unless you are keeping the originals in situ "just in case" you could carefully disect them from the current position and re-use them.

I fixed your pics (next time click "insert all" before you upload. Love where you are going with this, don't forget the further you move the bottom mount in from the axle the greater the leverage will be so a stiffer spring will likely be required