In researching my purchase of a suspension for the 3-wheeled box (*sigh* -->$), a few shops have said that they will change the valving because I autox the car, rather than road race...

While that's sounds terrific, I'm forced to wonder whether they are really changing anything that can't be changed with the adjustment *****. (BTW, I'm talking about DAs.) And that's evidently different than valving them for a specific spring rate.

The differences, wrt to shocks, between autox and road racing are:
-typically lower spring rates
-more emphasis on low-speed
-faster, jerkier transitions
-?????

So what re-valving is done that can't be done with DA *****?

Andy

 

Sounds more like "re-fleecing" than revalving. It honestly sounds like they will revalve your shocks for a softer spring, which you may or may not be running. A stiffer valved shock can still damp a softer spring. JMHO.

 

I would still imagine that a shock should be valved for whatever spring it must control, at least in a non-stock class. With stock (= too soft) springs, different rules apply, I'm guessing.

BTW what's "re-fleecing"?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by madhatter &raquo;</TD></TR><TR><TD CLASS="quote">Sounds more like "re-fleecing" than revalving. It honestly sounds like they will revalve your shocks for a softer spring, which you may or may not be running. A stiffer valved shock can still damp a softer spring. JMHO.</TD></TR></TABLE>

This was supposedly separate from the "revalve due to spring rate".

A 400# spring in autox will have different shock valving than a 400# spring meant for road racing.

 

Lee is probably the one to answer this, and I hope he does so i can learn some more from him.

As Lee has said before, Springs are rated by how far they are compressed, but shocks are rated at a shaft speed. Because of faster transitions in autocross, vs longer "slower" movements on a roadcourse, you would need to change the valving for speed, and not just how stiff the shock might be.

Jon K
http://www.seat-time.com

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by maxQ &raquo;</TD></TR><TR><TD CLASS="quote">This was supposedly separate from the "revalve due to spring rate".

A 400# spring in autox will have different shock valving than a 400# spring meant for road racing. </TD></TR></TABLE>

I'll agree with that.

If you have the time to read it (not all of it is relevant) you can get a good idea of what they revalve shocks for. It pretty much tells you the criteria used to determine shock valving, so just work backwards .

http://www.penskeshocks.com/Ad...l.pdf

taken from: http://www.penskeshocks.com/technica.htm

Edit: or just PM CRX Lee

 

iirc, when i talked to lee at nationals he told me that the "roadrace" valving uses a lot more low speed compression and ignores any need for streetability. you don't want that for autocross because you need to be able to place the car within inches of something you aren't supposed to hit time and again on a really crappy surface. on a roadcourse it doesn't matter if you are off your apex by 3" or over your apex and in the grass by 3". your lap times might vary by a tenth or two. in autocross, being away from the cones by 3" will cost you at least .5 seconds, being 3" too close to the cones is multiple seconds and the course workers won't really like you for it.

nate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">iirc, when i talked to lee at nationals he told me that the "roadrace" valving uses a lot more low speed compression and ignores any need for streetability. </TD></TR></TABLE>

Low-speed compression/rebound being the only thing you can't adjust with the DA *****... I guess I should've guessed that...

GSpeedR- excellent link!! I'll read that tonight after work... and probably return with more questions in the morning. Thanks!

Andy

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by maxQ &raquo;</TD></TR><TR><TD CLASS="quote">

Low-speed compression/rebound being the only thing you can't adjust with the DA *****... I guess I should've guessed that...

GSpeedR- excellent link!! I'll read that tonight after work... and probably return with more questions in the morning. Thanks!

Andy</TD></TR></TABLE>

actually, low speed _is_ what you adjust on DA koni's. *deleted since it wasn't helping, just hurting. again, i apologize*

nate


Modified by solo-x at 11:53 AM 2/11/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote">

actually, low speed _is_ what you adjust on DA koni's. the baseline setting is different though, as well as the curve. i can't imagine a big difference in time on a roadcourse between the autocross valving and the roadcourse valving though, so it probably shouldn't be much of a concern for you, IMO.

nate</TD></TR></TABLE>

Ok, I'm back to being confused. If the baseline setting is what you're changing, then what's the difference between that and "a spring rate re-valve". And one of the vendors told me they won't change the curves just move them up and down.

Why shouldn't it be a concern for me if you just stated in the previous post that it WAS a big deal in autocross?

Andy

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by maxQ &raquo;</TD></TR><TR><TD CLASS="quote">

Ok, I'm back to being confused. If the baseline setting is what you're changing, then what's the difference between that and "a spring rate re-valve". And one of the vendors told me they won't change the curves just move them up and down.

Why shouldn't it be a concern for me if you just stated in the previous post that it WAS a big deal in autocross?

Andy
</TD></TR></TABLE>

oops. forgot you have roadrace valved shocks for autocross instead of the other way around. i'm going to defer to lee now, since you've exhausted my limited knowledge. sorry for adding to the confusion.

nate

 

now i REALLY wish i had read this before i sent my shocks in to be revalved.

 

Although there are some differences in the cornering activities involved between road racing and autocross, there really isn't that much of a functional change as far as valving in concerned that you are going to see.

In autocross, you are going to generally transition up to a higher peak g force and back down in shorter overall time and in a slalom situation you will definately go from left turn peak g to right turn peak g much, much faster. In road racing the transition will be more subtle into and out of a possibly lesser peak g but held over a longer amount of time and the car needs to be able to be consisitently held near that peak and kept there while the car is cornering at a higher speed. It is super rare that you would ever go from left or right turn peak g to the other in any really fast (for the suspension) situation.

Generally, you will find that for a given car with the same basic tires and similar surfaces, you might run more spring rate and more low speed damping in both rebound and compression for road racing but you are pretty much splitting hairs if the spring rates are correct. Autocross needs to be a bit more forgiving allowing varying surface qualities weekend to weekend so you may want to run a bit lower low speed compression if not a compression adjustable shock when the tires and car remain constant. The better maximum grip opportunty that the tires have (like a slick vs. DOT) or grip opportunity that the pavement has (non-bumpy and smooth textured vs. sealed asphalt or bumps), then the more low speed bump and potentially spring rate you can run. A Prepared class car on slicks will likely have a stiffer spring and more low speed damping than will a similar car on DOT tires but it will also be less likely to be accepting of rougher pavement surfaces.

Generally for similar tires cars that have the spring rates in similar but still appropriate ranges for the discipline, we are going to run a similar if not exactly the same valving. If the shock has a sufficient rebound adjustment range to cover the spring rates and you don't add just so much freakin' low speed damping that the tire can't grip the surface or the car can't turn in, then you'll be fine.

Typically we will add quite a bit of low speed and high speed rebound to both race and autocross valving when coming from a street valving and also add more low speed compression and check out the high previous high speed compression. The differences that we change between the two will be minimal if any if the tires remain consistent. A few cars might have issue with this based on other items (some BMWs rear don't want much low speed in autocross) so there are variables related to the rest of the car.

So do you need to send your shocks back in for an autocross valving vs. a road race valving? I submit that you don't unless the adjustments have little to no effect or unless the shock is so weak or internally basic that it really wasn't really well suited to the other discipline either. If it was really pretty good for one, it should be pretty good for the other especially if we are talking about production based cars that simply have a ton of other variables as well. Shock tuning is still pretty much fine tuning so all the other hairs need to be split and the other variables need to be covered before you have to worry about revalving from one discipline to the other.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by solo-x &raquo;</TD></TR><TR><TD CLASS="quote"> on a roadcourse it doesn't matter if you are off your apex by 3" or over your apex and in the grass by 3". </TD></TR></TABLE>

3 inches? how am i gonna pick up those quarters at the apex if i'm 3 inches off?

(in all seriousness, inches from apex and 1/10ths of seconds are quite important on a roadcourse as well)

 

Thanks for taking the time to write that up, Lee. Excellent info as usual!!

Andy