1982 KZ1000 to Fighter..

Was a great day today... been raining for the last two days, so what better time crank up the radio and work on the bike right!!!

After spending awhile this morning getting the bike leveled and the swing arm in proper stance position I was able to accurately evaluate the mount position of the lower linkage. Fortunately for me it lined up pretty nicely with the lower existing center mounts with just a little modification.

So what I did was cut off the two outside mounts and combined them with the two center mounts. This doubled the thickness of the mounts I would use. I then cut some 1" wide plates and made a top and bottom support plate.. Really turned out pretty good, and it should not be be going anywhere.

Here are some pics of the process..




First Pass..



Drilled test mounted..


Bottom Plate Installed..



Test Fit.


Top plate installed


Primed In..


Linkage angle

OK guys I need some advice here!!

Trying to figure out the top shop mount and mocked up a few things, but came up with this....



Don't pay attention to the mount, but the angle. I can make the mount work, but Im unsure of the angle and the stress that may be created on the top shock U bolt mount. I think I have seen one mounted at a complete 90deg but I can't find that reference at the moment.

So what does everyone think? Its a pretty stout mount, and the through bolt is 3/4". I THINK it will be just fine, but would really like some opinions on this one.

Here are a few more pics of the angle.




Thanks in advance,

Jack

Looks good!

lookin good man!! i got some catching up to do, i like how you doubled up the lower tabs, i was thinking of mounting the shock tab at a ninety too,or i might just fab one from steel, i know a guy that uses a program called solid works, he could enter the data of the shock mount and tell you how much force it would take to break it, but it seems like it would take quite a bit

How did the factory use that top shock bolt? That will tell you alot about the kind of forces is was designed to resist, whether is was straight compression, or there were some shear forces involved; like the ones you wish to subect it to in your mounting mock up. I know most guys use that top mount that you have, it give you easier mounting options. I did not have such a top mount, and made mine out of tubular steel and some plate for the tabs.




You will notice though, I have my mount angled about the same as you have your mockup

Im no design engineer but, it looks to me like you would want some bracing going uo from the top of the shock mount like porsches. appears shock load would be tranfered thru frame into backbone of frame?having that top bracket on your shock turned 60 degrees looks like it would wear the bushing at a weird angle?

I just had a peek at the rear suspension on the zx-10r which uses a similar rear shock upper mount. The clevis on that bike is much closer to vertical and I would imagine that when the suspension is compressed, that it is nearly vertical. Keep in mind that the bottom of the shock will swing rearward as the rear suspension is in compression.

Changing the angle of the clevis changes the way that the load is distributed on the connection. The more vertical the clevis, then the load is mostly compression on the base of the clevis to whatever mount you decide to use. The more horizontal, then the load becomes a shear load on the bolt itself. Generally, bolts are not well suited to take shear load. (They tend to shear off. ) In this case you would want the clevis to have a large base with possibly more fasteners that would create a lap joint. A lap joint will use the tension in the bolts to spread the load over the whole surface of the joint and that sliding friction is what prevents the bolt from bearing the load in shear.

My upper mount is probably the one that you are thinking about that is perfectly horizontal. It is, however, a heavier aluminum clevis that has four through bolts and a relatively large base. It is installed on the KZ in the exact same fashion as it was on the donor GSXR. I believe that this creates the lap joint that I am referring to.

You will notice that the clevis is attached to a 1/4" thick cross bar which later gets boxed in and also receives bracing on top to help transfer the load straight up the backbone of the frame.





I personally would prefer to see you use something more stout than 1/8" thick angle to support your upper shock mount. Keep in mind that, that one point will be supporting the entire weight of the rear of the bike plus any passengers and cargo. Under acceleration, up to 100% of the entire weight will be on the rear tire. That could be 800 lbs + on the rear suspension.

Thanks guys, that is exactly the feedback I needed. The mount on the donor is thru bolted straight up and it makes sense to go that way in its current configuration. If I removed the mount bolt and just fabbed a mount straight to the top shock mount I don't think it would be an issues.

Test, I think your mount is the one I was referring, but for some reason I thought I saw one that actually used the mount bolt itself. However I think you are dead on with the shear load.. In the back on my mind I think I know it. There is a reason I just didnt build it!!

I think you and porche have the right idea, and I need to get rid of that mount bolt and fabricate a direct support mount. The bolt would add some flexibility and maybe some slight adjust-ability, but unless I do a direct top center mount it may add more liability then its worth.

Don't worry about the 1/8" angle... that was strictly for mock up. Thats why I said don't look at the mount.. LOL But I appreciate you looking out. She will be heavy duty for sure, regardless of which way I go. Don't want my big ass riding on a half ass mount!!

Thanks guys I do appreciate the feed back. The main reason I wanted to document the build was to get some other eyes on it.. Keep it coming..

Im actually gonna to be putting my hands on a couple of different GSXR's today to get some measurements for purple_haze so I will take a good look at these mounts.

Thanks again,

Jack

Ok, guys check this out, just back from my parts pickup and got a change to examine several GSXR's today. Here is what I found. It appears that a couple different mounts have been used on all the models of GSXR's.

Here is a direct shock mount on a 750.



Here is a post mount on a 750 (same as 1000).


And here is a post mount on a 600..


So it appears that either mount type will work and has been used in production for some time. With that said.... I brought one of these home with me..


So, no sense in reinventing the wheel here, I am going to follow you guys lead and do the side mount.

Thanks again...

Update #2 for the day.

Picked up my ZX10R parts today and of course I had to do a quick mock up.. Nothing technical to report, just thought I would share the photos.

So here you go...















Jack

oh yeah!

that lil mock up there has got to get you feelin pretty good :evil: .

i really like the zx-10 wheels.

your bike is going to look pretty mean.

leon

Hell yeah! That J bodywork will look killer on this bike. Always wanted a J. Can't figure out why. :whistle:

The zx-10r wheels are awfully cool. I even have a set. Just like 'em too much when they are attached to the zx-10r. :evil:

Got a plan to re-gain the lost height from using the zx-10r forks? They're awfully short.