6-speed Transmission Swap Instructions

Thanks for this,been very helpful.I am builing a 750 together with 750 LTD engine cases and zephyr 750 crank,pistons,cylinder and cylinder head.I started with a GPZ 600 gearbox,now have a Z 550 and GPZ 550(ZX550) too.As the LTD engine cases only fit in the older z's I'll use the 550 output shafts,guess the 600/zephyr 550(same part number on kawasaki.com)would be better with wider back tyre.I'm using your idea with the clutch basket,a friend of mine is machining the clutch basket.Just got zhe plastigage to check the crank bearings in the LTD engine cases,so sometime in the not too distant future it might be together,have to do some other stuff first,like head and foot gasket on a gt 550(european version of 550 spectre).

ac4 - It sounds like you are well on your way.
Please keep us up to date with your project, so we know how the trans swap works for you or if you have any issues.

Thanks again!Quick question,is there any reason not to decide later to use a zephyr/zr //Zx750 style clutch with the bearing cup fitted with the pushrod type clutch?I can't think of any ,have both options open then..

ac4 - You have to decide which clutch release mechanism you are going to use before installation of the transmission. The pushrod style uses the bearing roller cup with the hole in the end for the pushrod as where the zr550/zx550/zx600 transmission uses a bearing cup with no hole in the end.
YOU CANNOT USE THE PUSHROD BEARING CUP WITH A PULL STYLE CLUTCH RELEASE!
The hollow center of the transmission shaft is "pressurized" with oil in order to lubricate the clutch release plunger and ball bearing (or puller in a pull type) If the push rod bearing cap is used with the puller style, then oil will pour out the end of the bearing cup instead of pressurizing the transmission shaft and lubricating the clutch release mechanism. You would also have a jet of oil squirting out of your engine case as well....not good.
If you do decide to use the pull style clutch release, then take note of the following issue that was discovered....
A member (Fishrider) over at the Zephyr-Zone forum is currently doing a 6-speed swap in his Zephyr 750. He identified a possible issue that I will to explain.
It is know that the 550 input shaft is shorter than the 750 shaft, hence having to machine the clutch basket in order to make it full bolt on. But it was found that the shorter shaft may not fully support the pull style release mechanism (plunger/pusher). There is roughly ~6mm less shaft for the plunger to ride in, which under normal driving conditions should be fine. But, when the clutch lever is pulled then the plunger is pulled even farther out of the transmission shaft.
There is however, no risk of the plunger being pulled completely out of the transmission shaft!!

The pusher/ puller only moves about 5mm to release the pressure plate. So at full extension, that leaves roughly 13mm of the plunger still riding in the transmission shaft. And the more I have thought about this.....when the clutch is activated, the plunger/puller stops free wheeling and becomes stationary, which means it is then no longer being supported by the transmission shaft anyway. So as long as the plunger dosen't get pulled completely out the shaft (which I am almost 99% certain it cannot) then when the clutch is released, it will slide back into the transmission shaft and become supported again. I am attaching photos to help illustrate what I mean.

Difference in length of input shafts and how it relates to the pull style release plunger


The difference in the amount of support between the 750 and 5500/600 shafts. Picture courtesy of Fishrider


So in summary, I don't think using the pull type clutch release mechanism with the shorter 550/600 6-speed transmission is an issue at all.
But as of me writing this, I do not have definitive proof that it is not an issue. So to whomever installs a puller style clutch release, please double check the clutch release action to ensure that every thing works as it should. And then please let me/us know your results.

Motor is together,just need a frame to build it into:)I went for the pushrod clutch.Motor is turning nicely on the crank and the gears are all selecting nicely...Incidentally the GPZ 550 final drive cover is the same as the older 750 cover,and that has the later style clutch,so no problems with oil coming out of the final drive cover.(I also got the GT550 back on the road,running much better with grinding the valves)
I was looking at various parts,I wonder if the later 600s have a longer clutch shaft,so it wouldn't be necessary to machine the clutch basket.I think I mentioned I used the GPZ 600 clutch and 550 output shaft.
Will let you know when it's running in a bike:)
Thinking about building a 650 now too:)
cheers,andy
 

Howdy, just wanna contribute a little to this thread - I've put a 550 shaft transmission into my 750N1 and it works fine, same bevel gears. Once I break in the engine I'll get some numbers for RPM at various speeds in various gears. Thanks for the guide, Daftrusty!

Did anyone solve the issue of the pull type mechanism?  I put a 550 Zephyr transmission in my 1992 750C Zephyr.  You can see in the pics what I did to keep the clutch pin from falling into the shaft.  That is a 5.5mm hard nylon bushing.  You can see a short video here with the bushing in:    Personally, I think this should work, but I have had issues.  My clutch rod slips off the pin causing damage to the clutch rod and pin.  I had to replace my clutch rod, pin, and cover.  You can see what happened here while the engine was running:   www.zephyr-zone.com/zz/viewtopic.php?f=10&t=281&p=4818#p4786

I feel like the tension between the rod and the pin is good.  I don't think there is any extra deflection of the pin side to side when the pin gets pulled out by the rod.  However, when I test this system, the rod definitely slips off.  You can see the minor damage on the new clutch rod.  I just want to be able to put this bike back together.  The motor runs and I am confident the gears shift.  But without solving this issue I can't get it on the road.  Any thoughts?  This is the only thread that has seemed to get any play with this particular modification.  TIA

-Mike

The main problem is your clutch pull rod is to far out off the working angle of the clutch accutator rod, the clutch pull rod get bent and snaps of the mechanism. I would try to put a thicker washer (2-3 mm) under the needle bearing washer if possible and remove the nylon bushing to back off to a proper accutator rod working angle. 



or you have to under/back cut this pull rod collison area. 

 

Damn, thank you so much for the quick reply.  I have been pulling my hair out.  I will do what you suggested, but I am still confused how my bushing is causing the angle to be off.  are you saying that the clutch pin is too far out and needs to sit closer in to the clutch operating plate? The reason I tried the bushing in the first place was only to keep the pin from falling in too far when installing the pin.  The bushing was 5-6mm because that was the distance lost to the 550 transmission shaft.  I would have thought that adding back that space would have placed the pin in the correct position for the rod.  Putting an extra washer where you suggest would cause the pin to ride in even further in and have the end of the pin closer to the clutch operating plate. 

Fishrider….I apologize as I completely missed your update on the Zephyr Zone. I’m incredibly puzzled by this as well. 
I have been thinking about this issue all day at work and here are my thoughts and questions:
1.  Adding the spacer under the needle bearing race would simply sink the clutch release rod further into the basket and make it almost impossible for the actuator rod to grab onto it. 
2.  Your current spacer and position  would have zero impact on the installed length of the clutch rod. What does affect the installed length of the clutch release rod is the basket and this the the pressure plate. So I’m wondering if that’s where the issue lies. 
3.  Could the proper races and shims behind the clutch basket been left out??? If so, the basket would fit too close the the engine case, thus making the pressure plate too far in, making the release rod to far in for the release pawl to grab it properly. 
4. Did they leave a clutch steel or friction plate out?? That would make the pressure plate sit too far in, one again making the release rod to far away from the release pawl. 
5. Did they use an aftermarket clutch cable, or did they adjust it so poorly, that the release lever/pawl is indexed wrong and can’t properly grab the release rod. 
6.  Did they use a crazy thick aftermarket   clutch cover gasket? That would move the release rod too far away from the clutch release rod. 

In summary….if I am understanding the spacer and position of said spacer you used, it should have zero effect on anything and I believe the issue resides elsewhere. 
  Let me know if this makes any sense of if you have any questions. 
 

Thank you, for the reply.

I have not removed the clutch basket to check that it was installed correctly.  As far as I can tell the nut on the shaft sits where it is supposed to be. The nut is flush with the end of the shaft.  Which is where I would expect it to be if the shims and spacers were in correctly.  I believe they used OEM gaskets. Plates are all accounted for. The only other thing you mentioned was the clutch cable.  I made new cables from Venhill parts before I gave them the bike.  As far as I know the cable works fine and places enough tension on the release pin.  But maybe I am wrong.  Interestingly, I did install the pin without the bushing and hooked up the clutch rod and cable.  It felt pretty good this go around.  It wasn't squishy like before, and after many pulls on the clutch lever the rod and pin held.  Now, unfortunately, I have no way of testing it without buttoning everything up adding oil and giving it a go.  Last thing I want is to destroy some more parts testing it.  I suppose I can test it, and then drop the cover after a few pulls to see if any damage is being done.  Assuming, the rod holds on the pin.  

I believe you are correct that the bushing would not cause an issue but  Scirocco thought otherwise.  One of the things I wanted to determine was where the pin sits in the 750 without the modification.  That might help me see if my setup is off somehow.  I guess I should pull the basket as well just to be sure the shims and spacers are all in place.  Edit: Took off basket.  all spacers and shims correctly installed.  You can see a quick video of the release pin in place with the nylon bushing here:  www.facebook.com/1181929050/videos/1194897440915088/   

Thinking out loud.  I took a look at the only picture I had to see if the clutch lever was indexed wrong when the mechanics gave the bike to me.  From the pic it is hard to tell.  That line on the shaft looks like it might be the dot, but I am not sure.  However, You can see that the long threaded adjuster in the pic is set pretty far back.  If the clutch cable was long that might make sense, but, if anything, the clutch cable is short.  When I hook it up, the adjuster is pushed all the way through the holder.  The complete opposite you see in the pic.  If the lever was indexed incorrectly, then there may not be enough tension on the release rod.  Allowing the rod to spin against the clutch shaft when it was not engaged.  I assume the needle bearing should keep the release rod from spinning, but I would think that only applies if the rod is under pressure.  If, I remember, correctly indexing the lever on the shaft was always somewhat difficult even with the stock cable. If the lever was indexed correctly, and there was too much pressure being applied, then all that would happen is that the plates would not be engaged, effectively putting the clutch into permanent neutral.  It's also possible I had already moved the screw on the adjuster before taking the pic, as I was out of my mind when the damage happened.  That is just me second guessing the order of things that day.  I still don't think the bushing caused the issue.

I was able to get the shaft to slip off the rod the first time I hooked it up after receiving the new parts.  However, it is possible I had the lever indexed incorrectly.  As I remember that I sort of punted on getting the lever seated correctly because I was having a hard time aligning the dot and line.  All that being said, I assume that:  

1. With no bushing I just have to make sure the shaft engages the rod when I install it.  The bushing was only there to keep the rod from falling into the output shaft on installation.
2. As long as the shaft is in the correct position relative to the clutch plate, (which I believe it is), then:
3. If the lever is indexed correctly, only two things can happen.
4. Either there is too much tension and the plates are always disengaged.
5. OR there is not enough tension and the plates will not disengage.  

How in the bleeding hell did the rod get bent, burn through the shaft, break, and then get shot like a bullet into the cover, regardless of the how the lever and shaft were set.  The mechanics said they just could not get the shaft to stay on the rod.  They said it kept slipping.  Personally, I think the damage was already done when they gave it to me.  If I had just taken the cover off before running the bike I would have seen the bent pin or damage to the shaft.   The fact that I was able to replicate the problem, may have been me causing my own unrelated issue by not setting the lever correctly and conflating the problem with the bushing.  Let me know if you think my little forensic analysis is off.  I think all I can do is put it back together the way I think it should be (maybe without the bushing), and run it again. Do a number of pulls on the clutch and see if it holds.  If it doesn't hold then back to square one, or If it does hold, pull the cover off again, and see if there is any damage.  If yes, then back to square one.  If no damage, then, the next step would be to ride it, and see if everything actually works.  Then pull the cover again, and check.  What a pain.  Not to mention the fact, that I will always have this nagging feeling that something is off.