Visit The Dirt Forum for More Information

Author Topic:   spring rate change
Dirt Freak

Total posts: 402
posted September 27, 2005 12:47 PM  
I have a 3 link mod with both springs behind on sliders, non-floated rear axle. I was thinking of trying to move the spring slider in front on the left rear to increase forward bite and tighten from mid corner off. (on the throttle)
I don't want to waste a whole night trying this so I thought I could build a bolt on bracket so the "on center" distance would be the same for the shock and slider. Since both are mounted to the overail and in diferent locations along the "Y" axis. I could change the whole thing with out disturbing the spring preload. I want to try this on the slick of the heat at my track then be able to change it between the heat and feature If I hate without having to rescale for LR bite at the track. I'm concerned that during axle wrap up wether the pull bar spring needs to be lighter because of the added slider weight trying to unload the axle? Is a spring change in the works or has this been tried before? Will moving the spring warrent a rate change? Will the car tighten up on entry with the axle wrap unloading the LR?

Dirt Full Roller

Total posts: 64
posted September 27, 2005 02:33 PM  
Should loosen the car on entry. It will dewedge the car under braking making it looser. Should only tighten when you are on the throttle when the pinion tries to climb up putting more pressure on the LR spring and unloading the RR spring that is mounted on the back.

Dirt Forum Champ
Total posts: 2007
posted September 28, 2005 06:32 AM  
typically with springs clamped in front you can run a softer pullbar spring because your clamped up spring is also resisting the axle rotation. If you get too stiff you wont get any axle rotation which means you dont get any LR wedge added.

It will prob tighten the car all around. Especially from middle off. We used to run this on a 2 link and it reallly made the car tight on the gas, driver complained about the RR not doing anything when on the gas, so you have to make sure you get the car turned before getting ont he gas or somehow make it turn on the gas. We ended up running 0 LR bite most of the time.

Moving the spring to the front, you might need to stiffen it 25# or so but youcould try it the way it is first. As for having to rescale it. If you let the car sit at ride height and measure from the ground to a point on the frame and then move the spring to the front or change the spring then adjust only the preload up or down on that corner to get that measurement back when the car is on the ground after your changes, then you wont change you scale % any appreciable amount. Or you can do it in the shop on the scales, find out what you have to put in or take out of the LR when you move it then you'll know when your at the track what needs to be done.

Dirt Freak

Total posts: 402
posted September 28, 2005 07:20 AM  
That's the info I was looking for!

I wasn't sure wether to consider the pull bar spring and LR spring to be in parrell or in series.

While measuring distances to acheive the correct corner weight is a good idea, I can engineer a bolt on bracket that weighs 1 pound from s**** aluminum. My spring and shock are located on the overrail itself and aren't the same distance from the axle as most manufactured cars are so th reason for a bolt on bracket. I should be able to change it by myself with enough time left over to watch the next heat.

Dirt Full Roller

Total posts: 31
posted September 29, 2005 12:41 AM  
i think you should $h!tcan the slider's for coilover's or..good old weight jack's and run your bar's off of the center of housing or get w/ the greater population of the faster car's and go w/ 4/z z/z and such but don't get me wrong 3 link's are fast but not much for forward bite on dryslick stuff.we ran 3 link until this year quite well to 3 track championships! just my #45 cents,brad

Back to the Archives