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1980 GS1100e Front end swap

  • Thread starter Thread starter johnnay
  • Start date Start date
From the back - it's hard to tell, but sometimes I think the swingarm might be bent - twisted actually. How do I tell for sure???
 
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Looking good! Looks like that CBR shock goes pretty much vertical from the pivot, no? Just as a cautionary note, you sure that shock is stiff enough to carry the weight of you and your bike without bottoming? The CBR600RR is 412 pounds with all fluids, gas, and oil. 'Busa or Gixxer 1000 rear shocks may be a better option IMHO for that reason.

As for swingarm alignment, do you have it fully mocked up, ie wheel spacers on, axle tightened, disc inside the caliper, substitute pivot bolt, screwdriver or something else long and straight through the lower shock pivot and the centerstand bracket holes? Was the swingarm from a wrecked bike, does it show any visible damage?

What kind of rear wheel are you using? Following your progress with interest.... :D
 
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The CBR shock is just in there because that's the only one I have - I bought a CBR swingarm that is just too trick for words, but unfortunately it would require seriously modding the frame to fit it..:cry:

I'll get either a busa or Gixxer shock soon, if only for the colour - I could always put a stiffer spring on the CBR one. The wheel is the same as the swingarm - 04 gixxer 600.

Didn't have everything tightened up on the swingarm, but it does have one of the spool mounts bent - I could buy another, but it's always such a crapshoot with ebay. Damn that CBR swingarm is fine...wish I could figure out a way to use it.
 
johnnay said:
The CBR shock is just in there because that's the only one I have - I bought a CBR swingarm that is just too trick for words, but unfortunately it would require seriously modding the frame to fit it..:cry:

I'll get either a busa or Gixxer shock soon, if only for the colour - I could always put a stiffer spring on the CBR one. The wheel is the same as the swingarm - 04 gixxer 600.

Didn't have everything tightened up on the swingarm, but it does have one of the spool mounts bent - I could buy another, but it's always such a crapshoot with ebay. Damn that CBR swingarm is fine...wish I could figure out a way to use it.
Click to expand...

Hrm, spool mounts seem to get bent when the donor bike lands on the swingarm spool, so it may in fact be bent/twisted. What is preventing you from using that CBR swinger? Its dimensions? Anything's possible. ;) :D

Probably would be easier and less expensive to buy a Gixxer or 'Busa than respring the CBR shock.
 
The CBR swingarm is too wide by over an inch, so cutting it down would make the two pivots dangerously small. I could weld a tube in between the two pivots, I suppose, but now we're talking a LOT more work than the gixxer arm. Plus, I'd have to monkey around at the wheel axle end with shims and stuff, since the gixxer wheel and honda swingarm axles aren't the same size. too much work...!
 
On the topic of the frontend, how difficult was the swap? On a lot of car forums I'm on people will often do a DIY on each to detail the process. Is there anything like that you've done? I have an 82 GS750E and I'd REALLY like to follow this process...

Thanks!

:-D
 
rufus said:
On the topic of the frontend, how difficult was the swap? On a lot of car forums I'm on people will often do a DIY on each to detail the process. Is there anything like that you've done? I have an 82 GS750E and I'd REALLY like to follow this process...

Thanks!

:-D
Click to expand...

Rufus, I hear you - I wondered the same thing when I started into this. Had to look all over this forum and others for good information. I've been collecting info and bookmarking good posts, but the problem is that I just don't have the time for a good write up right now. I'd love to do one, but I wouldn't hold your breath...

for now, the easiest method for the front end is to use a 90 - 94 GSXR 1000 front end - it's a straight bolt-on affair with no modifications other than filing/removing the ignition lock tab on the frame. Otherwise, read 80GS1000's post for the how-to on later model GSXR front ends.

Good luck!
 
Thanks,

I hear ya. His seems pretty easy using the modified bearing... may go that route as I LOVE the look of those gold forks...

It's the rearend I'm worried about doing now.
 
So I made a little more progress this weekend - fabbed up the crosspiece that I'll weld the shock mount to. Fits like a glove, and should look pretty trick once it's done - as long as I don't farg up the welds..[-o<

For those of you following this thread, I know it's slow going, but you should see my car project - 5 years now and all I've got is a rolling frame..:-D

On a positive note, the underground power line from my house to my garage is finally in, so I'll have real power today!! (I've been doing all this via extension cords up until now).
 
Looking good Johnnay! Are you going to brace the top shock mounting frame member? What's your plan on how to attach the top of the shock to the new frame piece?
 
The crosspiece is 1 5/8", with only a 10 1/2" span, so it's plenty strong as it is. I'll just weld two braced tabs to it that sandwich the shock eye, like on the centerstand crosspiece. I could weld a braced horizontal tab to the crosspiece and use one of the GSXR upper shock mount bolts like runrx02 did, but my method keeps the whole assembly lower, leaving more room for battery/electronics etc.
 
So, how exactly did you make a top shock mount for you rearend?? I'm doing the same thing on the same bike, but I haven't decided what to do about the upper mount. Please post some more pictures....great job so far!!
 
Ok, 80GS1000 isn't around to fill my fix of looking at other people's progress, so I had to go out and do some work on my bike..:oops:

Here's a pic of the shock mount welded in - geometry is (theoretically) good, and the bike's stance looks good, insomuch as I can determine it without the seat and tank, and with the lift in the way. Can't wait to ride it, but I have a few things left to do...

Rearset mounts
refinish swingarm
530 Chain & sprockets
36mm GSXR carbs
paint tank, side panels & tail
seat pan fabrication & upholstery

hope to have it back together by the end of May...
 
Looking good Johnnay! From the picture it looks like you already welded on a couple of tabs for your rearset mounts?
 
Thanks, I was pretty happy to get that in there. As for the tabs, those were already there, for the big aluminum passenger footpeg thingys (the 1100's equivalent of the passenger footpeg frame extension that you cut off) - I just have to weld on a couple more for the lower rearset bolts. I think (hope) they'll work out well for positioning, since they seem to work well for the shift lever, although I'll probably have to use some spacers to move the rearsets out a bit. Probably won't be able to tell for sure until I get the seat made, but if worst comes to worst, I can just fab a plate and mount the rearsets to that.
 
What did your final geometry numbers wind up being? Also, how much static sag is there in the shock now that the bike's weight is on it, and with you sitting on it?
 
My numbers look like this:

24 Fork Angle (Castor) in degrees
3.94 Trail in inches
54.42 Rear axle centerline to centerline top of fork tubes, inches
59.5 Rear axle centerline to front axle centerline, inches
39.16 Top of fork tube centerline to ground, inches

I set it up so that it's pretty conservative (not much choice with such a long wheelbase), but so I can shorten the dogbones to steepen the rake and shorten the wheelbase a bit if need be.

Not sure what static & loaded sag are yet - had to quit working on it right after welding in the crosspiece... will try to measure today.
 
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