Some thoughts for PDS Shocks

[DEANSFASTWAY]

Thanks Jeremy for the list . I never saw a piston blowout but Ive replaced many bladders from seals leaking and rubbing the shock bodies , mostly Showas , mostly newer Showas , KX 65s too . Only time Ive ever seen something really go bad with a piston setup was with an ATV AXIS shock (quality stuff) Penske type , like an Ohlins . Whoever built the shock(brand new) must have overfilled it with oil and had the piston too deep in the reservoir body and when the Racer hit a G out hard the piston or Nitro pressure blew out the end cap and split and like flared out the rezzy body clip area . The kid DNFed at a National . I guess in that respect there must be more care taken to position the piston correctly but no big deal if youre competent . Shed : whats a through rod ? Am I missing something ? (besides some hair)? Let us know . Thanks DEAN

 

[shed]

A through rod damper is one where the piston rod protrudes through the top of the damper body. The significance of this is that when the damper is compressed, the rod volume inside the body remains the same, so there is no net fluid displacement, no need for a gas spring, no fluid compression, and more consistent damping characteristics. If I find a good wesite with a picture, I'll post a link.

 

[shed]

bugger, ive got a picture of a penske through shaft damper, but I dont know how to attach it!

 

[Jeremy Wilkey]

Shed,
Drop me it in an e-mail.. I'll put it up for you..

BR,
Jer

 

[DEANSFASTWAY]

Oh yeah i got ya I just couldnt picture it at first .

 

[KiwiBird]

Click here for article and pics of Penske through shock

Check out the first pic with the very trick roller thrust bearing to deal with spring rotation under compression.

 

[marcusgunby]

where have all the guys who put up posts like these gone??????
SVI ?? shed etc???? where are you??

 

[DEANSFASTWAY]

probably working

 

[marcusgunby]

LOL not fair-tell them to come and play;)

 

[Jeff Howe]

For what it's worth, I would like to see all shocks using piston style reservoir's. They don't need to be as complicated as Ohlins or PDS and a schraeder valve is simple to deal with. My Penske shock is much easier to work with then the others and you don't have to worry about a blown bladder causing problems. Imagine something as simple as a blown shock bladder costing a top National rider a win (and maybe a championship) and it really doesn't make much sense. I would also think a piston style rezzy would be more efficient at convection. Seems to me that rubber bladder could hold heat inside the shock better, which we don't want. I love my Penske and it's a damn shame they quit making them for MX bikes.

 

[DEANSFASTWAY]

See Jeff Emigat Southwick 94 or was it Dowd or Henry , cant remember but one of them rode the moto out on a bouncer. When the Yamahas just turned blue. it was hot out. I like schraeder valves too and I put them on KTMs quite a bit ,youve just got to make sure they clear the exhaustpipe.

 

[Scott Senatore]

The question I have to ask is can a properly set up PDS perform as well as a properly set up linkage set up?

 

[marcusgunby]

Ive not rode one yet-not saying it cant be done however.

 

[DEANSFASTWAY]

I think so . Mike lafferty sure makes it look good.

 

[velosapiens]

seems like bladder/friction and bladder/area are the same thing, but maybe you mean something besides the swept seal area which creates the friction.

i have an 02 with the piston (EE revalve) and an 04 with a bladder (PRS revalve, in lehi utah). the 04 dogs up the 02 and any other bike i have ever ridden. i have no idea how much of that is the bladder. danny morgan of prs feels the bladder helps small-bump compliance by just being easier to get it started moving. i believe this, but i know people have had excellent results with the piston as well.

bottom line for me, it seems that both can be made to work well.

 

[husqy510]

bladders /piston

the only two things i see that support the bladder setup are 1)the actual friction of the piston aginst the resivior adds to heat ..probably not a lot ,but still some . 2) in a quick hit the hydralic presure could deform the o- ring enough to cause some additional stiction .
the drawback of the bladder is if you scew up bleeding the system and have air left in the system you will be stretching the bladder beyond its normal shape everytime the shock is fully extended .it will fail in short order

 

[Scott Senatore]

Does anyone have pictures of what the internal workings of the PDS look like?

 

[terry hay]

Husqy
That is simply logic gone wild. You are siting lack of competentcy in assembly as a reason to promote the piston. I would tend to promote the performance capability of the bladder when things are as they should be. Appr. 30% of our PDS customers have the bladder installed with a high proportion track testing straight after. Its not hard to guage the happier of the two. I don't have a lot of time for things that don't work. I have worked with Australia's top Enduro rider for several years now and he simply won't have a shock without one.
Terry

 

[georgieboy]

wld lowering the nitrogen pressure have any benfits regarding the initinal friction of the piston/o-ring?

 

[Jeremy Wilkey]

This is why I left internet forums for a while. Guys Its simple.. They don't work any differently. Your chasing a waste of time.. Friction is not an issue. Its real, its measurable.. But its not a factor due to its small effect.. The effect of improvements with the bladder come down to differences in build.. If you do them the same and right the shocks work the same, till the gas leaks out of the bladder which does happen BTW.

Want in on the secret? Bladders are used because they are cheaper, and some suspension tuners are to cheap as to not by the right tools to build the shock properly..


BR,
Jer

 

[Scott Senatore]

Hi Jeremy,
In the KTM Hard Parts Catalog under suspension they have a new PDS 2 single piston PDS shock. Have you seen this single piston set up before?

 

[Jeremy Wilkey]

Rick#3,
I've read the same thing.. I can only pray to God its not 1.) a single piston! 2.) a Ohlins clone..

I used a single piston set up for a while.. What a waste!

Jer

I'm writing a article on needle stuff.. More soon!

 

[Scott Senatore]

thanks Jer, if you ever get some free time could you talk about your single piston experiments some more?

 

[Scott Senatore]

Hi Jer,
Did you find out anymore information on this?

"Rick#3,
I've read the same thing.. I can only pray to God its not 1.) a single piston! 2.) a Ohlins clone.. "

 

[Jeremy Wilkey]

The results are in..

I hope you guys enjoy this!