Rocket right rear spring question

[TeamRocket42]

I'm putting my 2014 rocket back together and going back with new shocks and springs. Question should I run stiffer rr spring or soft. I have read all the circle track articles and some post off here on stiff rr springs. A well known racer told me a few weeks ago that using too stiff of a rr spring will unload the rr under acceleration or axle wrap up. He says a soft right rear that is preloaded was a better choice. My question is how would you preload the right rear spring to equal a stiffer rate?

[Matt49]

With one of these:
https://pitstopusa.com/search.html?q=pre-loader
You can't change the rate of a spring by pre-loading it. These devices allow you to put static load into a corner of the car without changing ride height. It doesn't change the rate of the spring. Just how much weight it is storing.
Frankly, if you don't have a spring smasher, you're wasting your time because doing this stuff on the scales is about impossible. I'm finally breaking down and getting a smasher myself this year. Long overdue.

[Len72P]

Preloading the RR . If you normally run a 225 RR spring and when checked in your masher it reads 375 lbs. at ride height , 20"pin to pin. Then install a 175 spring on and mash it to the same 375 lbs. @ 20".Then add 100 lbs preload at 20" .When installed the RR corner will be up 1/2" from ride height, at 20.5". Using a right rear travel chain , pull the ride height down to 20". You are now at ride height with the 175 preloaded an extra 100 lbs. At 2 inch comp.(mid-corner) the spring load would be equal @825 lbs. Comparing to a std. 225 setup at 825 lbs.( 2" comp.) At 3" comp. it would be softer @1000 versus 1050. Of coarse there is no up travel on the RR , from ride height, because of the chain, but look at the dynamic state of any late model running at east bay and the only time they are against the chain( ride height)is during a tire change. ! Food for thought.

[TeamRocket42]

Thank you Matt. That preloader is what was described to me but I didn't understand how it worked. Now I understand. I guess if I'm going to do this I need to invest in a spring smasher. Like you said it will be hard to get it right without one. I would just like to know what rate you would start with. I guess its trial and error. Nobody wants to give out any spring rates to start with a preloader. This set-up would seem to keep the left front more planted as well on the throttle.

[billetbirdcage]

Thank you Matt. That preloader is what was described to me but I didn't understand how it worked. Now I understand. I guess if I'm going to do this I need to invest in a spring smasher. Like you said it will be hard to get it right without one. I would just like to know what rate you would start with. I guess its trial and error. Nobody wants to give out any spring rates to start with a preloader.

While it's hard to just give you one wheel number without knowing what your doing on the rest of the set-up but: If you want a general static load number then mid 300's to lower 400's is a basic starting point. I may change that number as much as 200# in a given night or from track to track so......

Also remember that using a cartridge that you can/may/will unload the RR spring load on the RR when the car raises above RR ride hieght: This may be positive or negative depending on what your after.

[TeamRocket42]

Thank you Billet. I guess its a balancing act of trying to get momentum and still keep forward drive. (Corner entry= rr is compressed and or loaded all the way thru center). (Corner exit on throttle= rr spring is decompressed and diagonal load decreases.) I was told the preloader somewhat keeps the rr loaded on throttle in an effort to keep all tires on the ground. My plan is to get a smasher and just make a start somewhere. Thank you guys for trying to give me an answer.

[wastingmoney]

Leave the spring you like in and use 1inch spring rubbers. that's what the professionals do.

[mickley.28]

Spring rubbers are an easy/quick way to change spring rates without affecting ride heights.

[MasterSbilt_Racer]

Leave the spring you like in and use 1inch spring rubbers. that's what the professionals do.

That is exactly the opposite of what the discussion is about.

[wastingmoney]

not really

[MasterSbilt_Racer]

not really

Progressive vs digressive. Those words are opposite.

[wastingmoney]

well that's what the Blue 1 car does seen it and done it at a test day with thrm and same as other XR1s

[Mr.Kennedy777]

While it's hard to just give you one wheel number without knowing what your doing on the rest of the set-up but: If you want a general static load number then mid 300's to lower 400's is a basic starting point. I may change that number as much as 200# in a given night or from track to track so......Also remember that using a cartridge that you can/may/will unload the RR spring load on the RR when the car raises above RR ride hieght: This may be positive or negative depending on what your after. So to help that situation out a bit, could you not stack a spring on top of the pre loader, so that it would be able to travel above ride height? Like a 225 and an 1800? I’m sure if a guy set it up right, the difference of the stacked rate at 200 and the rate when the pre loader locked out at 225, wouldn’t compromise the feel too bad? Or what?

[MasterSbilt_Racer]

well that's what the Blue 1 car does seen it and done it at a test day with thrm and same as other XR1s

That is or was the standard deal. You are right.