mechanical substitute for air pressure in front forks?

[pdxvmax5257]

I thought I had read in a back issue of a VBoost magazine that someone had substituted a mechanical "preload" in place of the stock air pressure fitting at the top of the front forks. I've gone back through them and cannot find it. Has anyone
a) heard of this?
b) know anything about it?
c) tried it?
Or maybe I'm insane, which is more likely.
Thanks.
pdxvmax

 

[GREEN light BLITZ]

Personally I cut mine off, welded the holes shut and stuck in new springs and emulators, so I dont even remember what that air thing was like cause it's only been a short while and I've already erased it from my mind because it's no comparison.

 

[4gasem]

I'm sure you could put a longer spacer on top of the stock spring, but your best bet is to get Race-Tech or Progressive springs which then means you no longer need air.


Sent from my iPad using special algorithms and data nodes.

 

[dannymax]

I believe the air is a dampening thing, the more it is compressed, the stiffer the dampening becomes. So any mechanical substitute would need to have those properties.....like a progressively wound spring.

 

[Miles Long]

I thought I had read in a back issue of a VBoost magazine that someone had substituted a mechanical "preload" in place of the stock air pressure fitting at the top of the front forks. I've gone back through them and cannot find it. Has anyone

a) heard of this?
b) know anything about it?
c) tried it?
Or maybe I'm insane, which is more likely.
Thanks.
pdxvmax

You still may be insane, but those voices in your head did not tell you about this modification.
Bob Bivona, V.O.M.A. #294, is credited with developing it.
It consists of an adjusting screw and locknut, in place of the top fork nut. No air is used. Preload is adjustable, and fork maintenance is a bit easier - just unscrew the adjuster completely to remove the preload, prior to removing the forks, changing the springs, etc. I believe that Bob once posted pics of this mod on the "vmaxtech" website.
Cheers, Miles

 

[Redbone]

I will have to look this up, is the mod for both the '85 to '92 and '93 to '07 forks?
Sounds like a worthwhile mod, reduce the preload a bit for long trips, tighten it up for playing in the twisties.

 

[4gasem]

Maybe Jedi could make us billet caps to achieve this...

This isn't something new. Cartridge forks, like on my SV have this option from the factory.

Chris

 

[jfeagins]

I think the forks on my 86 Venture Royale had 3 way preload adjusters built into the top from Mother Yamaha. You just had to pull a rubber top plug out of the way while on the center stand, apply a large, flat blade screwdriver down inside to turn it to which ever setting you chose.

Maybe a set of those would have the same thread pattern and interchange with Vmax forks?

 

[pdxvmax5257]

"Bob Bivona, V.O.M.A. #294, is credited with developing it.
It consists of an adjusting screw and locknut, in place of the top fork nut. No air is used. Preload is adjustable, and fork maintenance is a bit easier - just unscrew the adjuster completely to remove the preload, prior to removing the forks, changing the springs, etc. I believe that Bob once posted pics of this mod on the "vmaxtech" website.
Cheers, Miles"

Obviously I haven't figured the "quote" feature out yet....
Thanks a lot Miles, partly for putting my mind at ease concerning my memory. Point taken on the "I may still be insane........" LOL
I'll go look on that website, does anyone know how to get in touch with Bob? I'd offer to remunerate him if he'd make me a set!

 

[Rusty McNeil]

I believe the air is a dampening thing, the more it is compressed, the stiffer the dampening becomes. So any mechanical substitute would need to have those properties.....like a progressively wound spring.

I agreee mostly....Even without air pressure "put" into the forks, there is still some progressive action provided by the atmospheric air in the forks. This is why oil level in the forks is a tuning tool since it chages the volume of the air, versus the air pressure. The further the fork compresses, the stiffer the air becomes; It's juts not as noticeable as when you put a few PSI above atmospheric in there.

It also changes as the forks get hot and the air pressure increases above what you did or did not put in there. Even if you don't put anything in there go ride the fuck out of it in the twisties and then push the schraeder valve in and see what happens; there will be some pressure coming out...