I though I would just add some words about my home made spring compressor.
It's been in the outdoor shed for a few years, hence the surface rust. I've used it on Bandit1250S's VFR800 VTEC, TL1000R, all generations of SV650 and 1000 over many years where I had to add shim packing to adjust the preload a bit more or to fit custom springs I had made for me.
For what it's worth, I found for my then 100 KG of relaxed muscle that an 8% extra on spring tension was ideal. 10% way too much, and 5% not that much better than stock.
All the bits in the picture came from a local hardware outlet chain, Bunning's Australia.
The continuous threaded rod is 12 mm metric, 400 mm each side. I found a better length is 450 mm for when an unusually long shock is used. It's the uncompressed length that the unexpected worry when the hex runs out and there is still a bit of spring tension. It's getting it back together again !
The hex joiners are 12 mm to suit the rod, about 50 mm long.
They and the rod are used in slab concrete house construction to hold the timber roof trusses down to the slab for cyclone strength. The elliptical end plates are from the steel pipe fencing parts. 2" or 2.25 nominal pipe, I can't remember which, but I think it's 2 inch. Water pipe and fencing pipe, I think they have the same OD. In their normal use, say in a Factory, they would be dyna bolted to the concrete floor and the pipe just pushed in flush vertically as a fence upright with a pipe at the top.
The standard hole at the bottom plate is 60 mm and the size at the top is 65 mm. I hacksaw cut, ground and filed it from 60 out to 65 mm. It's the worst part of making this simple rig. Note at the bottom is a V groove (very important this) Stops the 10 mm holed head end from slipping sideways under the great pressures.
Don't under estimate the force as a 10 kg/mm spring depressed 15 mm is very dangerously powerful if it let's go at you in an instant of time.
The bottom hex's go into a vice, just for holding it at a nice working height and it allows you to tighten the top hex only as the bottom hex is locked tight with a nut on each rod and stops the natural twisting reaction.
The reason for the hex's over nuts is that it spreads the force over a longer threaded area so there is no fear of thread stripping or jamming. I deliberately did not use stainless steel hex or nuts as they are prone to galling at the thread faces and locking up, 100% undo able. The rod is a very low grade SS.
The shock goes in upside down into the jig relative how you see it sitting in the bike. In place of the top mounting bolt , I use a 10 mm steel rod from a tube spanner kit. The top plate compresses on the end of the coil spring. It doesn't touch evenly on some shocks. It pays to have the shock centered evenly as there is a lot of force in play.
The result of 20 years of use of the same parts has the top plate a little soft at the holes, so on stronger springs like the Bandit 1250, the rods bend in a bit and I slipped some thin wood between the rods and spring sides to heep it stable. You could make use of any number of rods to spread the load if you have access to a heavier plate for the bottom ellipse shaped plate that I used.
It could be 4 rods in a square say. It started use on the SV650 Series 1 which has a pretty soft spring around 6 kg/mm force.
Cutting the hole in thicker metal is a lot of work and off the shelf is easier to re manufacture at home. I have used it as needed with another type of shock the other way around too, as some shocks have an un screwable mounting clevis head adjuster (the SV650) which allows ride height adjustment at the expense of spring preload. The usual Suzuki cheap shock has the coil stopped in place by 2 semicircular washers that are best (safest) removed by a magnet on a rod, Next is a screwdriver and long nosed pliers. Just Don't use your fingers !!!!
Other springs have one circular washer and lock nuts on the chromed shaft.
The better ones, your on your own. Just don't unwind the rebound oil block part, that is not the way to go.
Last edited by Slower and Slower; 09-28-2018 at 04:42 PM.