83 GPZ 550 shock options

I got my new to me 83 running well, but I noticed a ton of slop in the rear suspension, mostly coming from the lower shock mount.

The shock will need bushings and sleeves, and the bump stop crumbed to dust and fell out,.

Does anyone here recondition these shocks, or does anyone have any good ideas / options for me?

Thanks!

And I should add I have access to mills / lathes and enough fab skills to do basic modifications, plus I work with real machinists who can make about anything if I can find a shock that is a good starting point. I'm hoping that with a bit of milling, grinding, or other tweaking I can make a shock off something newer and more common fit.

Why not just buy a pair?
Steve

83 is the monoshock. I've been digging through this chart:

www.worksperformance.com/pdf/app_guide/street.pdf

And there are a few newer bikes with the same length (or close) shocks, but so many have piggy back resevoirs and there is no room for that. The 01-05 bandit is close, but i'd have to remake the brackets that mount it to the swing arm as the bandit has a clevis on that end. There is plenty of room there, wide open under the swingarm. Those shocks are thick on ebay too, and cheap.

I'll keep exploring my options.

After further scouring of the list I found a CBR900RR shock is also very close, and lo and behold I have one of them laying around.
I stuck it in there and it will require 2 things - the remote reservoir hose needs to be turned about 120 degrees, which will require a spacer, and I'll have to remake the bottom brackets under the swing arm. I'll post up some pics as I start the work.

So the top mount is good? There's a GPZ 550 unitrak on the net that's using a cbr900 rear shock and he mentions having to modify one of the mounts but dosnt go into any detail other than that.

The top mount is close but will require a couple shim washers and I'll have to sleeve the upper frame holes 2mm (10mm bolt on the cbr shock, 12mm on the GPZ)... so that is the easy part.

While the CBR900RR shock is very close in overall length, turns out it has about 40% of the stroke of the GPZ shock. So, I scrapped that plan.

I took the "easy" way out for now, and refurbished the stock shock mounting points. The upper sleeve was made new to be a nice slip fit in the plastic bushing. Its made from 4140. I got extremely lucky and found the right length fine thread M12 grade 8 bolt at work, and the ID of the new sleeve was made to be a nice slip fit onto that.

For the lower mounts, which were all wallowed out and out of round, I reamed both the brackets and the stock bushing oversize (.531") and then had made a custom 4140 bolt that is about .002" undersize. I had the ends threaded 7/16-20 because it was a good match, and I had plated nylocks in that size.

This will get me by for a while, and was relatively easy.

Buy a new shock. I know that will cost a bit but the shock you have is 33 years old! Pensky, Works and Race-Tech will make you a custom shock with the latest technologies and materials.

I put it back together yesterday. When I started, I had an easy 1/2" of up down slop in the rear wheel, and after reassembly the slop was zero or so small I couldn't feel it. Had an unseasonably nice Feb day here yesterday, so I went for a 20 mile ride and I was surprised that the shock actually felt pretty decent. It felt as good as the forks anyway, which maybe isn't saying a lot (they need seals). But, regardless, I was very pleased with how the old girl ran and felt.

I''ll leave it alone for now. Any shock options I've seen cost more than the bike did, which isn't very appealing for a low buck project. I have other, newer bikes to ride too, so this one will remain low budget for the time being.