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My new rear.......NO not like J lo

  • Thread starter Thread starter pan
  • Start date Start date
P

pan

Guest
It was a real pain to do but I like the way its starting to look :-)

DSCF0103.jpg
 
I like it Pan!
How much did you end up having to take off the front of the swingarm to get it between the frame rails?
 
Off the top of my head I think it was 8mm each side, but I fitted it into a spare frame first ( so I could keep the bike rolling ). I made it a nice tight fit but when I fitted it into the bike there was a 2mm gap that I needed to shim. so I would say that frames can vary by a few mm. The thing that I didn't expect was that that it would hit the back of the engine! there is a section milled out to clear the ZRX engine, so this had to be substantially extended and the lip taken off the rear of the crank cases!! lots of work for a swingarm swap :-(

Mark...
 
could you snap a few pics of what you are talking about, so we can have a record of what would need to be removed in the back by the engine if we were to do this mod.
 
first timer said:
could you snap a few pics of what you are talking about, so we can have a record of what would need to be removed in the back by the engine if we were to do this mod.
Click to expand...

Will do when I take it back out of the frame, where the 2 halves of the crank cases bolt together I have just removed the rough casting scar and that gave a little more clearance.
 
pan said:
Off the top of my head I think it was 8mm each side, but I fitted it into a spare frame first ( so I could keep the bike rolling ). I made it a nice tight fit but when I fitted it into the bike there was a 2mm gap that I needed to shim. so I would say that frames can vary by a few mm. The thing that I didn't expect was that that it would hit the back of the engine! there is a section milled out to clear the ZRX engine, so this had to be substantially extended and the lip taken off the rear of the crank cases!! lots of work for a swingarm swap :-(

Mark...
Click to expand...


8mm off each side....... So you narrowed it into the welds?

I have one of these swingarms and wanted it to work so badly, but was afraid that if I took off that much material it would affect the strength. The swingarm I have only has about 5mm on one side before I would have had to cut into a structural weld.
Did you run into this?
 
No I didn't cut into the welds at all, the 8mm included the spacers that protrude past the ends so not all the 8mm was taken from the arm tube. As I said the hard and unexpected part was the engine clearance problem.
 
Cool! That is good news. I would like to use that swingarm sometime. I'd really like to see photos.

Did cleaning up the cases solve your clearance issue?

Very cool project Pan! I look forward to watching your progress.
 
Ogri said:
Cool! That is good news. I would like to use that swingarm sometime. I'd really like to see photos.

Did cleaning up the cases solve your clearance issue?

Very cool project Pan! I look forward to watching your progress.
Click to expand...

Cleaning up the cases only gave a little clearance, nowhere near enough. Look at your swingarm and you will see it has a section milled from the front to clear the Kawasaki engine, this needs extending to the width of the GS engine. I wish I had taken a before picture as I'm sure it would be easier to grasp, could you take one of yours & post it on this thread for me?

Mark...
 
how about this, orgi you post a pic of your swing arm in the area pan is talking about and pan you take a picture of your swing arm, then you will have a before and after
 
Any shock problems with this modification?

Any shock problems with this modification?

Well guys...I've also got a '99 ZRX1100 Swingarm that I'm looking to hook'up to my '78 750. The pivot tube width and diameter looks solvable (ala Pan)...The overall length is in the same range as the alloy GS1100 arm that's i have currently fitted (about 2 inches longer than stock 750) But I'm a little concerned about the shock spacing on the Kawi arm. It looks like it's maybe 1-1.5 inches too wide.

Pan - How have you addressed this? Did you widen the rear of the frame...or compress the legs of the swingarm...or cant the swingarm shock mounts inward...

I'm ready to start hacking away at this thing - but I don't want to modify (aka ruin) a perfectly good swingarm if the shock mounting is going to be a deal-breaker.

BTW - if anyone is still interested in a pic of the factory cut-out on the pivot tube - I could post one...

-Pete
 
My swingarm has been away getting powdercoated hence the lack of progress :-( As for the shock mounts you can either cut them off the arm and have them re-welded further inward but this would need to be done in situ with a jig made up to line up the top & bottom mounts. I have opted for moving the top mounts outwards, I hope to have this completed over the weekend so will post some new pictures asap. GSChoppa if you can post a picture of your un-butchered arm then that would be useful ;-)

Mark...
 
Just found this picture on ebay. You can see that there is a small section milled out of the pivot tube, this needs to be extended to just a little wider than the rear of the engine.

zrxswing.jpg


More pictures of my arm / bike soon :-)
 
1999 ZRX1100 Swingarm Specifications

1999 ZRX1100 Swingarm Specifications

First Timer...Sorry about the delay! I can change a cam in a small block and rebuild a bank of GS carbs with my eyes closed - but posting a pic is a bit over my head (and I do pharmaceutical research for a living!)

(Hopefully) Here is a pic of my 1999 ZRX 1100 swingarm with some specifications that might be of interest.

Basically...you need to shave about 8mm (ZRX 236mm vs GS 220mm) off each end of the pivot tube (to fit between the frame rails) and fabricate a sleeve to increase the diameter of the GS pivot bolt (GS750=14mm GS1100=16mm I believe) to fit inside (20mm) the ZRX pivot tube. I was looking thru my vast stockpile of what the wife calls useless junk and actually found 2 perfectly sized sleeves from a late oil cooled GSXR 750 that fit the bill nicely. Shaving the ends of the pivot tube doesn't look to be a dealbreaker - One bearing is quite far inboard and the other is about 7mm inboard. I'm of the mindset that an extra mm or 2 on 1 side isn't going to make much difference on the flexi-frame GS. Responding to Ogri's concern about structural integrity, i don't believe you should have to grind any welds to fit the pivot between the frame rails. ...And Pan's right on the money when he says you have to do some mild grinding on the engine/pivot tube to get the arm to fit.

You will also notice that the axle is the identical diameter to early GS's - Bonus! The spacing between the legs is pretty close as well (ZRX 265mm vs GS 257mm)

The big issue I see is the distance between shock mounts (ZRX 324mm vs 285mm GS). I certainly repect Pan's plan to widen the rear frame to match the ZRX distance. I, however, am more seriously contemplating carefully grinding the welds that hold the shock mounts to the swingarm and relocating those mounts inboard (which looks very possible - the current mounts are perched way on the outside of the swingarm legs) OR ditching the current swingarm mounts entirely and fabricating/welding blocks to accomodate the clevis mount shocks that came stock. I have a local guy that does my aluminum welding - he's rea$onable and insanely competent. I figure if I make up a jig to rigidly hold the mounts in place all should work fine. My ulterior motive for messing with the arm rather than the frame is that I spent a ton of time making a custom seat for my bike and if I mess with the frame, I'll have to start all over with the seat!

I hope a few other intrepid souls try this swap - a few different viewpoints is always a good idea.

I guess I'd better start grinding...

Pete

http://picasaweb.google.com/GSChoppa/ZRXSwingarm
 
Let's Try That Pic Again...

Let's Try That Pic Again...

1999ZRX1100SA_Specs.JPG

Is this better?
 
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