Traction Shock Question

[Ghopper]

drtrkr244 -

I think you should explain your procedure for testing race conditions on scales. fyi - this thread is discussing dampers, which have few near static qualities (stick/slip of seals, rod pressure).


Again, I believe you are learning sometime but there are many holes in not including the lateral and londitudinal forces. For example: the increase in LR load from the j-bar contributions.


Ghopper

[drtrkr244]

drtrkr244 -

I think you should explain your procedure for testing race conditions on scales. fyi - this thread is discussing dampers, which have few near static qualities (stick/slip of seals, rod pressure).


Again, I believe you are learning sometime but there are many holes in not including the lateral and londitudinal forces. For example: the increase in LR load from the j-bar contributions.


Ghopper

Like i said in an earlier post, you cant totally simulate race conditions. You can get an idea of weight transfer by using simple formulas found in varios books.You definitely cant simulate the lr or j-bar load changes.I generally use heavy duty ratchet straps to compress the right side springs and then add the corresponding weight transfer to each corner.I do not take the springs and shocks off.Its not an exact science but it gave me trends to go by when making changes at the track.

[fastford]

What I found out,basically, was a correlation between the loads on each tire and what the moment center was doing in the dynamic state. When I put the car on the scales at various dynamic ride heights and input that info with what my 3d moment center software showed. Most racers dont have a clue what weight transfers where during one circuit around a track. Thats the missing link you have to find out about your car . Only then, can u make accurate adjustments for the ever changing dirt track conditions!

i have to agree with grasshopper on this one, there is no way to simulate the true dynamic conditions that exist on a dlm sitting on the scales or any thing else, way to many variables that exist in its true dynamic state, im not saying you cant learn something but your also making a lot of assumptions, like a car dewedgeing when up on the bars, pure logic tells me this cant happen, jmo

[Ghopper]

fastford - most physical lab tests are missing something from the physical track test.

There are high-end, high-cost simulation programs (30k-150k) that can account for more track phenomena than the lab test, but the parameters needed to be really accurate are not easy for most of us to obtain. There are some programs (5-10k) that clear state to tune lumped parameters to match test data, because the actual information is not available.....but the sensitivity of your study may be lost in that lumping process.



Ghopper

[drtrkr244]

i have to agree with grasshopper on this one, there is no way to simulate the true dynamic conditions that exist on a dlm sitting on the scales or any thing else, way to many variables that exist in its true dynamic state, im not saying you cant learn something but your also making a lot of assumptions, like a car dewedgeing when up on the bars, pure logic tells me this cant happen, jmo

I dont profess to be an engineer, but ive been blessed with an analytical mind and excellent math skills. Maybe Im wrong on the de-wedging part, but my common sense tells me the unloading of the rf,soft spring setups, far outweighs the forward thrust generated by the bar angle of the lr. I wish some of these CUP sponsored teams would do more testing and let our shock gurus adjust accordingly.My theory has been supported by some of these shock guys.I dont do any different adj. at the track than anyone else, i just know what i learned on the scales pertains to the car im working on with their particular setup., and what adj. gives me the most bang for the buck.

[fastford]

here is something to consider, with the soft rt frt spring set up you lose wedge getting in the turn, but when you hit the bump stop or if using the stacked set up and you hit the stiff point, the dynamic wedge is incredible, the hardest thing i had to overcome when i got on this set up was overcoming a throttle push an doing this without disturbing the gains i made getting on the soft spring to begin with. i personally like to keep my rear square so i slitly adjusted bar angle, decreased static wedge, played with shock valving on all 4 corners as well as 5th coil untill i finally found the sweet spot, now understand it took minor changes to all this to reach my objective, but it was worth it,now my car goes thru the turn better than anything ive ever drove and will run strait down the straitaway because of the rear remaining square, i dont think i could have achieved these results any other way but on the track, maybe im still old school but thats my opinion

[drtrkr244]

here is something to consider, with the soft rt frt spring set up you lose wedge getting in the turn, but when you hit the bump stop or if using the stacked set up and you hit the stiff point, the dynamic wedge is incredible, the hardest thing i had to overcome when i got on this set up was overcoming a throttle push an doing this without disturbing the gains i made getting on the soft spring to begin with. i personally like to keep my rear square so i slitly adjusted bar angle, decreased static wedge, played with shock valving on all 4 corners as well as 5th coil untill i finally found the sweet spot, now understand it took minor changes to all this to reach my objective, but it was worth it,now my car goes thru the turn better than anything ive ever drove and will run strait down the straitaway because of the rear remaining square, i dont think i could have achieved these results any other way but on the track, maybe im still old school but thats my opinion

What forced me to start playing with the car,dynamically, on scales is exactly what u posted.We wanted to experiment on our Mastersbilt with a bumpstop. My driver loved the fact he could drive the car anywhere from turn entry to the center, but once he gave it throttle , he lost all drive.This was my first use of a bumpstop,ie. i started exp. on the scales.As most of u know, Mastersbilts are designed to be on the free side.They were built for the tracks in the midwest.Most tracks we race on are the sand/clay type which generally get looser and looser.After months of trial and error, we finally were getting it right. Luckily i was friends with their house car driver and after discussing this we realized we were doing the same adj to each of our cars.This is how i came to the theory that lr bar angle did not outweigh the loss of wedge from the rf.BTW, im old and old school, but i will experiment to get faster!

[fastford]

what he was probably doing was making the car loose because it had to much left rear bite when it hit the bump stop and he had to break the rear loose so it would turn, you will loose rt rear drive some what on this set up, this is where the 5th shock is VERY important also move the lift arm as far toward the rt wheel as possible, im not going into any more detail on here about what im doing because some people i race with are on here, if you have a question drtrkr244 you can pm me.

[drtrkr244]

We had it set so it just would touch the bump on compression.We raced on several different tracks ,and most would get too rough to allow the shock to hit the bump too hard.At first, i thought it maybe was the driver too, but i would get in the infield close to the track and watch the steering angle of the front tires.Most of it just came from the design of the car itself.Since then, our sponsor bought us a new Barry Wright.Its definitely a much tighter racecar. It doesnt take near the adj to get it tight enough for our type of tracks. I would like to look at a Gen X car to see if there built the same way.