K2 / Proflex Riders Group

General => Tech Forum => Topic started by: Todd on November 17, 2003, 02:29:31 am

Title: Elastomer replacement ... try auto valve springs
Post by: Todd on November 17, 2003, 02:29:31 am
Hello all,

My wife has an old Proflex 455. We have gone through several sets of elastomers, even with storing the bike inside the house. The local bike shop gave me a tip that someone said they used an automotive valve spring as a replacement from a chevy big block engine. I went out and bought one and it works great. I bought it at CarQuest and they have it listed as manufacturer part number "fed vs-1581". Look like the fed is short for Federal Mogul. It appears to be used in Chevy and Ford 351 or larger engines. The spring consisted essentially of three springs in one. The outer main spring, and inner spring like piece that was welded to the outer spring, and a seperate spring inserted in the center that could removed if desired. I tested all three ways and had to use all three to avoid bottoming out. This actually works out very well and has a great feel to it. The spring is a bit tall, but I think this is actually a good thing as you can simply just torque it down until it gets to the proper size. Since you have to torque it down this also helps as it is also a bit narrower than the washers that hold the spring ... since it is torqued down it doesnt slide around. There is a wide variety of different valve springs out there so I assume you might be able to make this work on other bike models also. It cost me only $8 bucks. I have some pics if anyone is interested.
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: Simon on November 17, 2003, 03:19:33 am
How are you damping the spring ???
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: kiwi on November 17, 2003, 04:21:18 pm
hmmm yes the damping on the mcu equipped bikes relies on the friction between the mcu and the "damper shaft"..without it the ride would be pretty bouncy i would think!!
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: jimbo on November 17, 2003, 05:50:07 pm
Quote
hmmm yes the damping on the mcu equipped bikes relies on the friction between the mcu and the "damper shaft"..without it the ride would be pretty bouncy i would think!!


Curious, how was the spring dampen with the Speed Spring replacement?
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: Tom_A. on November 18, 2003, 03:02:18 am
Actually,  I good amount of the damping for the elastomer rear suspensions was in the friction of the pivot bushings....otherwise known as Coulomb damping.  In fact, part of the procedure for setting the swingarm torque was to tighten the screws until the swingarm "just" didn't fall under it's own weight.



The old Scott Unishock Forks were coil sprung/friction damped.



I think a valve spring might just work pretty well.  It may require a bit more friction at the pivot to add some damping back in.  I'll have to remember that for my 853 once the elastomers harden up again.

Title: Re: Elastomer replacement ... try auto valve sprin
Post by: Simon on November 18, 2003, 03:19:15 am
Quote


Curious, how was the spring dampen with the Speed Spring replacement?

Wasn't speed springs only for units with ods dampers ???
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: jimbo on November 18, 2003, 09:55:25 am
Quote

Wasn't speed springs only for units with ods dampers ???


I'm not familiar with the ODS units.  Does it have dampers on it?
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: kiwi on November 18, 2003, 08:14:54 pm
they are simple oil damper hence Oil Damped Sytem or ODS for short  ;)
Title: Re: Elastomer replacement ... try auto valve sprin
Post by: jimbo on November 19, 2003, 04:33:01 am
Quote
they are simple oil damper hence Oil Damped Sytem or ODS for short  ;)


Thanks.