RM 400

[Toolboy]

Thanks for the info...

I dont really understand the spacer fitment??

At the moment i have just pushed the fork tubes through and will get to the problem later.

I have a TM400 and a RM370 to play with and looking at shocks for those?

Any recomendations?

Tim

[vmx42]

Thanks for the info...

I dont really understand the spacer fitment??

Hey Tim,
A shock guy can open up the shocks, machine a spacer [15mm in your case] that sits under the piston to effectively shorten the length of the shock. You will loose 15mm of shock travel, but it will bring your suspension back to standard geometry.
thanks
VMX42

[Rossvickicampbell]

silly question Jeff - this may bring the travel to where it should be but if the shock body is too long that isn't going to change so the stance of the bike sitting there would still look like "arse up" wouldn't it?

[Toolboy]

Yes i now understand what your talking about.

I could be a very costly exercise.


Thanks for the info

Tim

[vmx42]

Hey Ross,
The original post said that the shocks were 15mm too long, so a 15mm internal spacer would restore the shocks to the correct length and thus to the original geometry.

But you would need to carefully measure the shocks and the resultant loss of travel to work out whether or not the reduction in wheel travel is acceptable. If the loss of wheel travel is too great, then you would have to do as Walter says and shorten both the shaft and body.

I would suggest a visit to an experienced suspension shop to work out which way to jump. If it comes down to cost then the spacers would probably be the cheapest…

In the end it's up to Tim as it is his bike, but I reckon if you rode it the way it is now you would have serious chain tension issues, and with the reputation these RMs have for throwing chains and destroying their crankcases I wouldn't risk it. But then again I am paranoid…  
VMX42

[Toolboy]

Either way of fitting spacers or cutting the shaft/body length will have issues with the springs and pre-load.

VMX42 - I have had the shocks fitted and raced with for the past 18 months and there has never been an issue of chain tension and never thrown a chain yet!!!!!
            I push the bike really hard as well..

Tim

[vmx42]

I have had the shocks fitted and raced with for the past 18 months and there has never been an issue of chain tension and never thrown a chain yet!!!!!

Good news 

Either way of fitting spacers or cutting the shaft/body length will have issues with the springs and pre-load.

Yes, you will have to take the new shock length into account and adjust your spring pre-load, but I don't think you will have any issues unless the primary springs are too long to actually fit the revised shocks. But I just had a look at the photo you posted and you might be right as you don't have much preload room left as it is.

All the more reason to consult a reputable suspension technician.

[Toolboy]

Wasp...If i go for a set of Promax shocks wont i have to get them revalved / sprung to my weight and ability??

I had these Ohlins revalved an sprung by SuspensionRus in Melbourne, but silly me was too naive at the time to have them shortened to length.

Tim

[Toolboy]

Yeah the bike did tip nose down so i pushed the fork tubes through and kept the power on

Wasp - The promax suspension come comp/rebound adjustment??

Tim

[SPRUCY 46]

Hey Ross,
The original post said that the shocks were 15mm too long, so a 15mm internal spacer would restore the shocks to the correct length and thus to the original geometry.

But you would need to carefully measure the shocks and the resultant loss of travel to work out whether or not the reduction in wheel travel is acceptable. If the loss of wheel travel is too great, then you would have to do as Walter says and shorten both the shaft and body.

I would suggest a visit to an experienced suspension shop to work out which way to jump. If it comes down to cost then the spacers would probably be the cheapest…

In the end it's up to Tim as it is his bike, but I reckon if you rode it the way it is now you would have serious chain tension issues, and with the reputation these RMs have for throwing chains and destroying their crankcases I wouldn't risk it. But then again I am paranoid…  
VMX42

Not challenging your experience VMX42, but I raced every big bore RM from 370 B to 500 F back then and continue to, and have NEVER thrown a chain. I think, from MY point of view, that's a pretty good record