Jump to content
Sign in to follow this  

pressure springs question

Recommended Posts

Hello, I have been researching new springs for my bike's forks ('07 Suzuki rmz450) and have learned that there are two sets of springs in each fork tube. There is of course the normal springs, but there is also the smaller "pressure" springs. I have seen these for sale in rates from 1.0kg to 2.2kg. It seems the stockers in my forks now are 1.9kg. How much do these springs affect ride quality? According to race tech's site:

"Race Tech's Dual-Chamber Pressure Springs improve overall plushness on braking and square egde bumps. Also can help to reduce mid-stroke harshness. Our Pressure Springs fit both Showa and KYB."

Just curious what you guys think about this, is it something I should worry about while I'm trying to improve the plushness of my forks?

Thanks for any responses.

Share this post


Link to post
Share on other sites

According to most that are knowledgable in revalving and fork tuning, the pressure spring will make a significant difference in your forks.

I changed my pressure springs and revalved base shim stack as well on my mid valve shim stack and the combination made my frorks very plush and forgiving. This was done to my 06 CRF 250R.

I went from a 2.2 pressure spring to a 1.6 pressure spring.

Share this post


Link to post
Share on other sites

Thanks for the response. What exactly does the pressure spring do? Is it involved in the first few inches of suspension compression, or is it making a difference through the entire stroke? How critical is it compared to getting the right regular springs? Thanks again for any info.

Share this post


Link to post
Share on other sites

The pressure spring applies pressure to the oil within the fork cartridge.

The amount of pressure the spring applies depends on the spring rate, spring preload (if any, as most are not.....except the SPI EPNP), and the distance the spring is compressed.

So a change in spring pressure is rather significant to the forks performance and what you would feel. The pressure spring aplies pressure directly to the chamber of oil above the Base Valve.

I have tried the stock pressure spring and revalving the fork.

Also the SPI EPNP (Early Pressure, Non Progressive), which preloads the spring and revalving the fork.

After a lot of testing I am going to try the stock pressure spring setup again. While the idea of a preloaded "light" rate pressure spring sounds great in theory. I am thinking that introducing more pressure to the fork cartridge initially hurts the forks performance more than helps certain aspects.

I was thinking that the EPNP unit would allow for stiffer MVc setups without cavitation, but recently realized that a well configured Base Valve Compression Stack (BVc) and Base Vavle Sub Valve stack can provide more than sufficient pressure and also help pressure balance the fork.

And yeah I got slightly off topic.

Share this post


Link to post
Share on other sites

Thanks for the response, it gives me an idea of what the pressure spring is all about. You said you tried the stock pressure spring, and the SPI EPNP, but have you tried a lighter rate pressure spring? Am I correct in thinking a lighter rate pressure spring would have the cartridge oil under less pressure, and provide a plusher ride, or would it just make the clickers adjustments less noticeable or useful? Thanks again for any info.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×