1980 GS1100e Monoshock How-to

[johnnay]

This is a writeup of how I converted my GS to a late model GSXR swingarm and monoshock. I did a lot of searching and reading to do this mod, and while a lot of people have done it before, I didn't find a succinct write-up that laid it all out in black and white. This post will attempt to do that.

My bike is a 1980 GS1100e, and the swingarm is 225mm at the pivot. There are a few more modern swingarms that are narrower than this dimension, but I bought a 2004 GSXR 600 off of ebay because it looked cool and was a reasonable price, so that's what I used. It measured 233mm wide at the pivot and 545mm long, which is a little longer than the stocker at 530mm. To do the swap, you can spend lot's of money by getting nice bushings made and stuff like that, but I like finding more economical ways of doing things - mostly because I'm too impatient to wait for machining work to be done...! So, this was all done with a metal chop saw, a grinder, a MIG welder and regular hand tools. Enjoy...\\/

You will need:
2004 GSXR 600 rear end complete from pivot shaft back (other GSXR years/models will work but swingarm fitment method won't be exactly the same as what's in this writeup)
GSXR Rearsets (mine were 2005 GSXR 1100, but I believe the mounting dimensions are the same for several models)

[johnnay]

1. Grind off all the extraneous tabs on the frame (includes brake master cylinder mount if you're going to rearsets). Don't grind off the tabs that the footpeg brackets mount to - we'll reuse these for the rearset mounts.

[johnnay]

2. Mill (grind!) the swingarm to be 225mm wide at the pivot with the dust seals on. I just ground down to the edge of the bearing, which turned out to be the right width (you'll have to replace the bearings before reassembly of course!)

[johnnay]

3. Reduce the width of the two inner bearing sleeves from the GSXR swingarm from 35mm to 33.5mm (you can just reduce one to 32mm if you're lazy!). The stock one is on the right, the cut one on the left.

[johnnay]

4. Do the same as what you did in #3 to the stock GS inner bearing sleeves - shown below the GSXR sleeves from #3.

[johnnay]

5. Cut a 158mm piece out of the GSXR pivot bolt - this is hollow and will be used as the inner spacer..

[johnnay]

6. Paint/refinish the swingarm and reassemble it with the GS spacers inside the GSXR ones. Then mount it using the stock GS pivot bolt with spacers or washers on each side (you don't need the big footpeg brackets anymore because we'll be putting on rearsets a little later), or use the later year GS pivot shaft - apparently it's shorter. I just ground down the original footpeg brackets (sacrilege, I know) and used the stock swingarm bolt.

[johnnay]

Top Shock Mount:
7. Fabricate a crosspiece of sufficient strength (I used a piece of bent 1 5/8" tubing I had on hand) to hold your shock mount in the location specified below in #8

[johnnay]

8. This will probably vary depending on your shock, but for mine, I located the upper shock mount 105mm above the pivot shaft (center to center), and 70mm rearward of the downtube centerlines. My shock's top eye is 26mm wide, but obviously, measure yours before welding the tabs..! You'll need a 10mm bolt at least 45mm long

[johnnay]

Bottom Shock Mount:
9. Cut off part of the outer tabs of both center stand mounts, keeping the inner tabs and the rest of the outers as bracing

[johnnay]

10. Cut the lower shock linkage bushing from your new swingarm into two pieces 15mm wide. Weld on 2mm thick washers with an outer diameter big enough to butt against the lower shock linkage and stop it from sliding sideways. Drill out the centre stand mounts to 12mm and use a bolt at least 85mm long. Obviously you'll need to get a new lower pivot bushing before reassembly.

[johnnay]

Rearsets:
11. Enlarge the upper mounting hole to accept a 10mm bolt. Mount the upper mount of the rearset to the existing tab on the frame for the rear passenger footpeg bracket

[johnnay]

12. Weld a tab with an 8mm weldnut onto the frame for the lower rearset mount - you could probably reuse the brake master cylinder mount here (cut & bent properly). Spacers may be required to move the rearsets out a bit, but this added leverage may compromise the strength of the mounts - they may need to be braced a bit more.

[johnnay]

13. Done! Now you should be a happy camper like me in the picture... (I know, I look young for my age)

I hope to add a 530 chain conversion to this thread as well. Stay tuned....!

[crag antler]

Nice write up
Really thorough with pics\\/

Now you should be a happy camper like me in the picture... (I know, I look young for my age)

I was wondering how you were going to reach the handlebars