1980 GS1100e Front end swap

[80GS1000]

Nice work. Takes a bit of deliberation before taking a grinder to your baby, doesn't it? Might I suggest using a Dremel with a metal cutting wheel for fine tuning the remaining metal/welds you want to remove as there's a lot of precision available with that tool, then filing the rest smooth by hand with a metal file. You doing any other frame mods?

[johnnay]

haha, I'm usually in too much of a hurry for precision...8-[

All the tabs are gone, and a sanding wheel on the grinder took care of smoothing them all down. Should look nice after painting. I also got the GSXR swingarm mocked up and started scoping out the shock mount. I had to cut away the rear battery tray crossbar mount to make room for the shock.

Not sure whether the center stand mount will result in wonky geometry or not - anyone have any real world experience using it? I know swanny started to, but then redid it in a little different position. I also have to do some more thinking about shock length - the one I have now is from a honda CBR600RR.

I'll post some more pics later today.

[80GS1000]

Not sure whether the center stand mount will result in wonky geometry or not - anyone have any real world experience using it? I know swanny started to, but then redid it in a little different position. I also have to do some more thinking about shock length - the one I have now is from a honda CBR600RR.

YoshiJohnny used the centerstand mount to mount the lower pivot of the shock. He reports great handling and no issues with it. From mocking up the shock and swingarm on my bike, the angles all look right. Next part of fabrication for me is have a VERY strong bolt (think 10.9 rated or stronger, 36,000 lb shear strength at 10 mm diameter) that will hold on the lower pivot of the shock linkage to the centerstand brackets along with some new spacers and nuts, and a locking system.

How are you planning on holding on the upper part of the shock?

[johnnay]

Well from my initial look, the top shock mount will need to be somewhere right in the middle of the engine cradle tubes and the subframe tubes (for lack of a better description). Therefore I'm thinking a kind of an arrangement of tubes like an "H" with two centre bars:

Front of bike
__________
____|_|____

With the shock mounting between the two centre tubes. the long tubes would join each side of the frame. Make sense?

[johnnay]

With the tank & tail back on to see how it looks with the new swingarm.. I likee!

[johnnay]

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???

[80GS1000]

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....

[johnnay]

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..

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.

[80GS1000]

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..

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.

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.

Probably would be easier and less expensive to buy a Gixxer or 'Busa than respring the CBR shock.

[johnnay]

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...!

[monte]

What an effort for a two valve!!! Monte

[johnnay]

What an effort for a two valve!!! Monte

Huh??? It's a 4 valve...

[rufus]

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

[johnnay]

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, 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!

[rufus]

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.