[QUOTE=Billj747,Jul 31 2009, 08:32 PM] It does matter if you are bottoming out or slamming into the droop limit of the shock -upsetting the car and making it less compliant and comfortable. With the SRCs independantly adjustable spring perch and shock height, compression travel can be sacrificed for droop travel. Not much compression travel is needed with such high rates so the key is finding out how much comp travel you need and then set the shock body hight there for maximum droop travel.

 

Bottoming out won't possibly reduce grip, it will. You don't want to be "riding" the bump-stop as it is exponentilly stiffer in a short amount of travel to an infinite spring rate (bottomed out). Higher rates generally reduce grip and a bottomed out suspension will be very upsetting and losing grip. My 'secret'/point was is I set up the SRCs to have just as much bump travel as needed to give me as much droop travel as possible, something that most coilovers lack, short of KW or JRZ.

Text is a terrible means of communication and without a diagram of the internal design of the SRC, misunderstanding about what orifaces and valves will continue.

In response to a setup comment, turn-in can be improved by increasing rebound. Since the lowspeed compression has overlap with highspeed (increased damping to reduce body roll also increases damping over high-velocity bumps, which is harsh and upsetting) you might try lowering the compression to a comfortable level and try increasing rebound in the front to improve that response.

 

This conversation would be much better in person.
Hopefully we'll meet sometime


Actually I want to try one more time.

Since you're familiar with the SRC's, think about the stroke of the damper and then think about the length of the spring and now tell me why it is you want a longer stroke like the KW's.

 

Great conversation

I will try adjusting my SRCs the way Billj747 describes.
The more droop you have the longer your tire has contact to the ground, giving it stability IMHO.
How do you determine how much bump travel you need? Trial & error until you hit the bump stop

 

Yes it is mostly trial and error since I don't have acess to the SRC equipped cars I've worked on to tell you the perch heights.

There are still too many variables, KW even at the highest FXMD rates are still softer than SRC which means more steady-state cornering travel, which equates to a longer effective range than SRC. Even with this, wothout over-lowering either coilover, if the SRC is set up to not bottom out over the worst curbs, the droop limit is compromised compared to setting the SRC up to not bottom out under steady-state corners or small bumps. Either way theirs not enough travel in the SRC to avoid hitting either the bumpstop or droop limit unless you are on a billiard-table smooth track and don't have to deal with broken up city streets. The resulting compromise equals a lack of grip when hitting the limit of travel on the track or comfort on the street. Since we are dealing with a production car, bumpsteer and roll centers become an issue and while its easy to bandaid all of this by compromising with a lower-grip higher-spring rate, it is a compromise. Their is no one-answer for all and it depends on the tire, stagger, etc of a specific application, which is what FXMD specializes in, but that's another story.

Their is so much more to it than forum discussion, you're more than welcome to email me and exchange numbers if you want to talk sometime because text isn't the best means.

Billy

 

Thanks for the input.
I'm quite sure I know what you are talking about, since I've been racing R/C cars for many years (On- & Off-road) and dialing-in the suspension was one of my favorites.

Anyhow, I think that's the one of the key issues with the SRCs at least for my main application (Nuerburgring Nordschleife)
Maybe I have to settle for KW, but let's not get OT

 

For the record, I'm not saying or implying KW is a or the solution by any means. Afterall, we sell Tein products as well.

 

Did you even think about what I wrote here?

"Since you're familiar with the SRC's, think about the stroke of the damper and then think about the length of the spring and now tell me why it is you want a longer stroke like the KW's."


You have yet to realize what you're saying is wrong. If you took one second to think about what I wrote above you'd realize that.


Once the shock is past the effective spring range it doesn't matter if it extends more. My dampers are setup like Tein intended minus ride height which in this case has nothing to do with droop or bump. I only bottom out on extremely rare occasions and have yet to bottom out on the track. When my car is jacked up the spring is fully extended with roughly and inch of extra droop in the front and about 3/4 of an inch in the back. Anything beyond the spring fully extended is a waste of travel yet you somehow still beleive that more is better?
On the Teins the shock travel exceeds the effective spring range therefore having a longer stroke is pointless.

I hope this makes sense.

 

I don't think you quite understood what I said. I hate arguing on forums or try to make points through such a terrible form of communication.

We are dealing with the src which has an adjustable threaded body that can adjust the height of the shock within the lower and upper mounting points, thus the ability to change the position of the shock and the amount of compression travel at the cost of droop and vice versa. (Raise the body from the lower single perch which raises the ride height, then lower the 2 jam spring perches to get the desired ride height -thus reducing compression travel and increasing droop travel) by doing this you are taking out any 'preload' of the spring and at an extreme, the spring will 'float' around at full droop because the spring perch is now lower and further away from the upper spring perch.

The KW has a traditional stationary threaded body with one spring perch to adjust ride height. This shock body does not move so more compression travel is necessary to allow for additional lowering, this is why kw has a recommended range for ride height to take travel into consideration. Yes at a higher ride height, additional compression travel isn't being used. A separate concept I pointed out was softer springs result in more peak body roll and compression travel under steady-state cornering.

With the whole 'preload' craze going on and improper setting up of the damper, droop travel is extremely limited in many coilovers and hitting the droop limit can be achieved in cornering when the dampers are set up this way. By adjusting ride height and cranking in a bunch of preload like I see all to often, there isn't enough droop travel to be compliant on the street (slamming you into your belts over broken road) and a similar result on a bumpy track or when using apex curbing. Yes you don't need a whole lot of droop travel for pure cornering alone on a billiard table smooth track, its all of the other scenarios where additional droop travel beyond steady-state cornering droop is beneficial.

Like I said before, higher spring rates band-aid a lot of dynamic geometry problems and also don't need as much travel. I personally don't believe 3/4-1" of droop is enough for production cars, absolutely not for the street, and I don't see it much in saloon/production stock/etc... Type of racing.

Most sports cars and sedan racing utilize helper springs and excess droop travel beyond the unloading of the spring itself. I would disagree it is a waste. If you hit any significant bump on a track, the 3/4-1" of droop travel will get upset, be less predictable, 'skip', and have less grip than a setup with more droop travel.

 

I don't think you quite understood what I said. I hate arguing on forums or try to make points through such a terrible form of communication.

We are dealing with the src which has an adjustable threaded body that can adjust the height of the shock within the lower and upper mounting points, thus the ability to change the position of the shock and the amount of compression travel at the cost of droop and vice versa. (Raise the body from the lower single perch which raises the ride height, then lower the 2 jam spring perches to get the desired ride height -thus reducing compression travel and increasing droop travel) by doing this you are taking out any 'preload' of the spring and at an extreme, the spring will 'float' around at full droop because the spring perch is now lower and further away from the upper spring perch.

The KW has a traditional stationary threaded body with one spring perch to adjust ride height. This shock body does not move so more compression travel is necessary to allow for additional lowering, this is why kw has a recommended range for ride height to take travel into consideration. Yes at a higher ride height, additional compression travel isn't being used. A separate concept I pointed out was softer springs result in more peak body roll and compression travel under steady-state cornering.

With the whole 'preload' craze going on and improper setting up of the damper, droop travel is extremely limited in many coilovers and hitting the droop limit can be achieved in cornering when the dampers are set up this way. By adjusting ride height and cranking in a bunch of preload like I see all to often, there isn't enough droop travel to be compliant on the street (slamming you into your belts over broken road) and a similar result on a bumpy track or when using apex curbing. Yes you don't need a whole lot of droop travel for pure cornering alone on a billiard table smooth track, its all of the other scenarios where additional droop travel beyond steady-state cornering droop is beneficial.

Like I said before, higher spring rates band-aid a lot of dynamic geometry problems and also don't need as much travel. I personally don't believe 3/4-1" of droop is enough for production cars, absolutely not for the street, and I don't see it much in saloon/production stock/etc... Type of racing.

Most sports cars and sedan racing utilize helper springs and excess droop travel beyond the unloading of the spring itself. I would disagree it is a waste. If you hit any significant bump on a track, the 3/4-1" of droop travel will get upset, be less predictable, 'skip', and have less grip than a setup with more droop travel.

Please email and call me. I don't care much for trying to communicate and discuss this level of physics and vehicle setup through text.