LR spring theory...

[dfhotlm33c]

So, I know this has been discussed ad nauseum, but I am trying to pinpoint the theory for my own application...

It seems as though the consensus here, and on Afco's tuning guide is that a softer LR spring will generate more traction...

Virtually every setup sheet (GRT, Rocket, Mastersbilt) recommends stiffer LR than RR...

The recommendations here seem to be split..

My analysis: A driver like myself, still somewhat green and not adept at trail braking on a track that slicks off and requires that you get all the way out of the throttle, would generally benefit from the stiffer LR..

Put another way..I have 200 LR, 225 RR as of last night...assuming the car was decent on a very slick track, what should I expect out of the car if I was to experiment with stiffer LR?

[Egoracing]

Less body lift which will result in less weight transfer and less side bite as a result of less leverage on the suspension.

[F22 RAPTOR]

There is a greater "Hike-Up" potential from a "SOFTER" Spring having more stored energy, because it compresses more to hold up the same weight as a "STIFFER" spring. A "STIFFER" spring can run out of height before you get done climbing the bars and bars alone don't generate the most "complete" traction. This is where the, "STACKED SPRING" setup came from, even greater stored energy is possible than with a single spring. When trying to increase forward traction ONLY, several factors in setup must work together, not just a spring change. Like Bite for instance or Rear/Left side percentage or RF spring rate... And on and on. Hope this helps.

[Matt49]

All good answers so far but let's be careful how we use the word "traction".
The softer LR allows the car to get up on the bars faster which does two things:
1) Transfers weight laterally to the RR and increases j-bar angle both of which increase side-bite
2) Increases 4-bar thrust angle which increases LR drive

The combination of these two things might be considered "traction" but I just don't like to think of it that way.

[lovinlatemodels]

Not gonna say that this thread is right or wrong but a 200 spring never gave our car more lift or traction infact we always had better luck on a 250 or 275 spring and always had plenty of lift on the LR to the point we weren't even on the spring it was all lift bar providing the traction. I perfer on tuning to the driver and not what everybody else is doing.

[Egoracing]

Not gonna say that this thread is right or wrong but a 200 spring never gave our car more lift or traction infact we always had better luck on a 250 or 275 spring and always had plenty of lift on the LR to the point we weren't even on the spring it was all lift bar providing the traction. I perfer on tuning to the driver and not what everybody else is doing.

IF your car is going to transfer 800 lbs to the right in the turn and you are on a 200 lb spring it is going to relax the spring (read that as raise the chassis) 4 inches. If you are running a 275lb spring it is going to relax 2.9 inches. The added movement is more bar angle AND it raises the chassis which used the center of gravity better. It is that simple, if you were not getting more movement then there was something wrong that was not allowing it to transfer. 99% of ALL 4 link cars are not on the LR spring once into the corner when setup right. It is how fast you can get on the gas and drive away from the car behind you where the better setup is faster.

[MasterSbilt_Racer]

Not gonna say that this thread is right or wrong but a 200 spring never gave our car more lift or traction infact we always had better luck on a 250 or 275 spring and always had plenty of lift on the LR to the point we weren't even on the spring it was all lift bar providing the traction. I perfer on tuning to the driver and not what everybody else is doing.

You may have been in a stop and go situation and didn't have enough initial wedge to get the car up on the bars.

How an adjustment effects the car depends on what it is doing before and after the change.

[dfhotlm33c]

Masters...I totally understand that concept...however, I am trying to understand why the disparity between "boots on the ground" like at this site, and the recommendations on virtually every setup sheet, book and adjustment guide I can find (Excluding Afco, which agrees with the theory that softer spring= more LR hike, better chance of remaining loaded and hence better traction) that usually recommend a stiffer LR to tighten car. The setup sheets for my car specifically recommend using stiffer spring for slicker track, as does Mastersbilt and GRT...and being a math/physics person, I understand the principles both use to explain what should happen

This is why I mentioned the relative inability to trail brake at this point and the type of track..wondering if someone that dumps the throttle would experience a different effect than someone who trail brakes with better success..

and now you bring the wedge concept into the picture...I lowered the wedge from 150 to 50 and experienced some success, the car actually didn't nose to the wall at throttle application...

Sorry for the length of posts and such...just trying to get a sense of what "should" happen with various changes so I can justify making changes at the track...still trying to dial in a car that is just moderately comfortable to drive..keep swinging from one end to the other..

[MasterSbilt_Racer]

Masters...I totally understand that concept...however, I am trying to understand why the disparity between "boots on the ground" like at this site, and the recommendations on virtually every setup sheet, book and adjustment guide I can find (Excluding Afco, which agrees with the theory that softer spring= more LR hike, better chance of remaining loaded and hence better traction) that usually recommend a stiffer LR to tighten car. The setup sheets for my car specifically recommend using stiffer spring for slicker track, as does Mastersbilt and GRT...and being a math/physics person, I understand the principles both use to explain what should happen

This is why I mentioned the relative inability to trail brake at this point and the type of track..wondering if someone that dumps the throttle would experience a different effect than someone who trail brakes with better success..

and now you bring the wedge concept into the picture...I lowered the wedge from 150 to 50 and experienced some success, the car actually didn't nose to the wall at throttle application...

Sorry for the length of posts and such...just trying to get a sense of what "should" happen with various changes so I can justify making changes at the track...still trying to dial in a car that is just moderately comfortable to drive..keep swinging from one end to the other..

It completely depends on what the car and driver are doing. If the car is near ride height when you gas up, a stiffer spring will aid drive. If you keep the car barred up, a softer spring will aid drive.

For a driver who is a friend of mine, one works for some tracks and the other approach works for the other tracks. You have to be able to see what the car is doing to make the correct adjustment. As I have said on here many times, there is no setup sheet out there that is right 100% of the time. It simply isn't possible.

[let-r-eat]

This could be a good thread. Some of these tuning guides IMO are taking LOTS of things that are important out of the equation. Brake pressure, throttle input, steering inputs......etc etc etc.Traction is matching the friction coefficient of the rubber and the surface. A stiffer spring can overload this earlier or the softer spring can dampen too much allowing slippage. The speed and amount of weight transferred plays a critical role as well.There is no clear cut answer to your question.