KTM shock spring advice

[evo550]

Anyone had experience with a progressive wound shock spring on a KTM pds shock ?
I am currently running a straight rate spring that loves to buck and twitch through the rough under brakes.
Spring rate is right and static and race sag set right.
Any thoughts.

[admiral]

i run progressive wound springs on both my PDS KTM's. what year/model is your bike? most KTM shocks are set up pretty bad stock. the early PDS shocks ('98-'03) were too stiff then around '04-'07 they were too soft. my stock '99 380SX was a buckboard  and my stock '05 250SX bottomed so much it left skid marks under the fender. i attempted many revalves with the 380 and i could never make it better. i could make it feel different but it was different and just as bad. i finally threw in the towel and sent it to MX Tech in IL. when it came back there was a big zip-lock freezer bag in the box with all the stock guts in it. they replaced the internals with their own parts. the difference was amazing. when i bought the '05 250 SX i didn't even hesitate to send that shock off to them after a few rides and they replaced all the guts with their proprietary stuff and it's very good. what i'm getting at depending on your year/model a spring change might not do a whole lot.

[evo550]

I have a '08 250 sx, The suspension has been done by a highly reputable suspension company here in Australia, and they have done wonders with the front end, but there advice was to stick with a straight rate spring on the rear.
It works great under power, but under a trailing throttle at speed, get ready for anything.
My thoughts were that a progressive spring would deal with this situation better, as the suspension is unloaded and would be using the "light" part of the progressive coil to absorb the hits, instead of the stiff part of the straight rate spring.

[admiral]

with KTM PDS some tuners like the straight rate and some like the progressive. it is possible that a prog. spring might help but i would say the high speed comp. damping is the problem if you have the rebound set correctly. imo the shock set up on a bike affects the majority (70%) of the suspension setup good or bad. what you describe has been a typical KTM trait through the years. i couldn't revalve it out either. i have tried quite a few different tuner's setups on KTM's here in the states and it became clear to me that some have figured out the PDS shock and some were no better than i was at valving it.

[evo550]

Thanks Mate,

Something I'll have to live with I guess, it's happy when the powers on, just real nervous when the powers off and the rear has no load on it ie, braking bumps or lips on the take off ramp of jumps (it can get real interesting with the last one)
 

[graham472]

Got a Racetech progressive spring with a standard shock on my 08 144sx, she's luuvely. Before with the standard spring it was just like you described  evo, arse puckering, especially after riding RM's for years.
 

[evo550]

Graham,
I'm really tempted to buy a progressive spring just too try one out, I have ben speaking to some other supension shops and opinions are mixed on whats better straight or progressive.
There is a company in Australia making  "Tapered" spring for the pds units, not sure how they are different, might make some calls this week end and find out.
"Arse puckering"......love it

[admiral]

Evo, too bad you're not in the states as i have an extra progressive spring that you could test.