Moving Rear Shock

[paul8899]

I've been thinking about how the exhausts will fit on my Tzr and I think that the shock lnkage will make things awkward when it comes to getting them made so I'm thinking of making a new top mount to lift the shock up a bit.

If I move the shock up but keep the original linkage will it affect its operation ?

[speedy sie]

the zx750r "n" has an almost linear linkage ill get the thing out and have a look might be wrong

[paul8899]

You're describing making the back end of the bike lower by effectively putting the linkage further into its' travel.

Unless you've got a linear or flat rate linkage on the bike, which no production bike does AFAIK, then you'll be putting the suspension further into the rising rate part of the linkages movement and, unless you fit a shorter stroke shock, you'll also be taking the linkage past its intended end of movement and into unknown territory where it might either go very steeply rising rate or even lock up.

How about if I move the frame pivot the same distance , would that keep the same ratio ?

[paul8899]

Suspension = white mans magic

It's positioned that way for a reason.

I'm ok on the hammers but not too good with linkage voodoo

[paul8899]

You'd have to move the swingarm pivot and linkage tie point up as well. BUT you're going to lower the back of the bike and rake the head angle out which will result in screwy handling.

Unless you recovered the head angle/read ride height by dropping the rear wheel adjuster slots in the swingarm.....

Would using shorter tie rods to compensate work ?

[kja.busa]

How about if I move the frame pivot the same distance , would that keep the same ratio ?

Don't even go there Paul, you'll screw the handling totally. The easy option by a country mile is make the expansion chambers fit the bike, not make the bike fit them, its a no-brainer in my book.

[vfiend]

Don't even go there Paul, you'll screw the handling totally. The easy option by a country mile is make the expansion chambers fit the bike, not make the bike fit them, its a no-brainer in my book.

[Mark/Foggy]

Paul, you're using enough software at the moment, why not get your head around the power of what it can do. Model the linkage in solid modelling progr and then you'll have to give some thought to how you set the constrains as you're building the model. You should be able to build what you've got and 'plot' the relationship between wheel travel and shock travel (compression).

If you fix the chassis mount as variable in 'y' and rotary as viewed on screen, fix the swing arm pivot as rotary, but ground and give the arms a variarble length; you can change everything pretty much to your hearts content until you get what you want.

Natch, never actually done this myself, but this is how I'd go about it.

Mike's got a good point here, you'd be better off heading towards a more linear linkage than the original that comes prest on the bike, it's designed to cope with roads and the occasional passenger.

[Kayla]

Don't even go there Paul, you'll screw the handling totally. The easy option by a country mile is make the expansion chambers fit the bike, not make the bike fit them, its a no-brainer in my book.

You could ask the pipe builder to consider a cross over at the headers, that should buy around 100mm or so to move stuff around under the bike. The left exhaust effectively exits on the right and the right exhaust can snake back on itself and under the left pipe like on this R1-Z-

[ricey3]

I've got some software that can model the linkage and shock set up and the changes. I used it when I made new linkages and rockers on the crf450 that I mono'd. Don't mind doing it for you but my advice would be to mod the pipes around it.