Spring table

[ZERO25]

Is the theory relevant to dlms?

[MasterSbilt_Racer]

Is the theory relevant to dlms?

Does the cg location, relative to where a beam axle applies it load to the chassis matter? Yes.

[ZERO25]

Its a term you dont see much discussion about. I know Bob Bolles used it in his roll angle software.

[MasterSbilt_Racer]

Its a term you dont see much discussion about. I know Bob Bolles used it in his roll angle software.

I guess it's kinda been forgotten. Everything kinda comes and goes in this sport. You can also get yourself in left field if you make a big change.

[north louisiana dirt]

I know this is a Late Model page, but the mod page seems dead at the moment....And I am no expert at all..... so as far as spring table is concerned... why would a Modified set up sheet call for a 13" RR spring ? To lower that spring table and get it over on the tire faster ? It just seems like, in this day of longer LR springs and extended load, a short RR spring's day might have passed...How about a longer/ softer spring to "keep it on the spring" longer like the LR? RR is in hike somewhat in this day and time if you want to maximize traction in the slick and control it with a Chain, Right ?

[MasterSbilt_Racer]

I know this is a Late Model page, but the mod page seems dead at the moment....And I am no expert at all..... so as far as spring table is concerned... why would a Modified set up sheet call for a 13" RR spring ? To lower that spring table and get it over on the tire faster ? It just seems like, in this day of longer LR springs and extended load, a short RR spring's day might have passed...How about a longer/ softer spring to "keep it on the spring" longer like the LR? RR is in hike somewhat in this day and time if you want to maximize traction in the slick and control it with a Chain, Right ?

Yes, short spring is about the spring table. Remember that same soft rr that stays loaded in hike won't load during compression.

[billetbirdcage]

I know this is a Late Model page, but the mod page seems dead at the moment....And I am no expert at all..... so as far as spring table is concerned... why would a Modified set up sheet call for a 13" RR spring ? To lower that spring table and get it over on the tire faster ? It just seems like, in this day of longer LR springs and extended load, a short RR spring's day might have passed...How about a longer/ softer spring to "keep it on the spring" longer like the LR? RR is in hike somewhat in this day and time if you want to maximize traction in the slick and control it with a Chain, Right ?

Keep in mind if the spring is on a coilover or slider, then the top pivot of that sets the spring table height not the length of the spring. You can put a 3" tall spring on the coilover or slider and not change the spring table. Now if your on a jack bolt and no slider then yes lowering the jack bolt will effect it.

[ZERO25]

Keep in mind if the spring is on a coilover or slider, then the top pivot of that sets the spring table height not the length of the spring. You can put a 3" tall spring on the coilover or slider and not change the spring table. Now if your on a jack bolt and no slider then yes lowering the jack bolt will effect it.

Interesting! Using Bolles software some 20 years ago, you had to measure from the top of the spring, at ride height, to the ground for one of the inputs.

[north louisiana dirt]

thanks Billet and MB Racer.... I almost confused myself as one Mod I help is on a slider and one is on a wedge bolt...(rules).... so on the slider... what is the advantage of running a 13"-175# on the RR instead of a slightly longer spring of the same rate as long as the slider had enough adjustment in it to get the car to ride height ? I always thought you didn't want the spring to completely unload and be up say 1.5 " and slam back down if you hit a slick spot or got off the Gas abruptly...

[MasterSbilt_Racer]

thanks Billet and MB Racer.... I almost confused myself as one Mod I help is on a slider and one is on a wedge bolt...(rules).... so on the slider... what is the advantage of running a 13"-175# on the RR instead of a slightly longer spring of the same rate as long as the slider had enough adjustment in it to get the car to ride height ? I always thought you didn't want the spring to completely unload and be up say 1.5 " and slam back down if you hit a slick spot or got off the Gas abruptly...

I'm glad Billet came back and cleaned up my comments. I was assuming Jack bolt, but that's kind of old, even for mods, these days.

"Where load is applied" covers it, but not that clear to everyone.

[billetbirdcage]

so on the slider... what is the advantage of running a 13"-175# on the RR instead of a slightly longer spring of the same rate as long as the slider had enough adjustment in it to get the car to ride height ?

Absolutely nothing different, besides being lighter in the pocket book from buying a different length spring. Now granted rarely do 2 different length springs have the exact same linearness (Is that a word, lol) as typically as the springs get close to coil bind they usually go up in rate, so having a 13" spring being compressed 2" is not likely to be anywhere close to coil bind and therefore likely very consistent on rate thru it's travel. But if you had a 6" tall spring, it's likely the rate would climb from it's rating when it nears the 2" travel mark. So my ABSOLUTELY nothing comment is based off the springs are exactly the same rate as each other thru the respected travels they see.


I always thought you didn't want the spring to completely unload and be up say 1.5 " and slam back down if you hit a slick spot or got off the Gas abruptly...

Ideally you don't but that isn't always possible. You need or want a certain rate from ride height down so if the RR raises a lot it's likely to unload the spring. The only way (besides something like cage indexing or something to alter the motion ration to make the spring non linear) to keep that from happening is to have a softer spring for more compression of it at ride height. If that ride load on the RR spring is say 300# and you need 2" of travel of compression at a 200# rate so your 2" compressed load is 700#. So the spring is compressed 1.5" at ride hieght and any lift over that and it will unload the spring. So unless your allowed to use spring rubbers, bumpstop, progressive RR spring or something to make the spring progressive in compression to allow a lighter rate but still go from 300# to 700# in 2" your not gonna be able to alter that 1.5" lift before it unloads the spring.

Racecars and set up's are just a big series of compromises due to rules, parts available, and etc.

[Ltemodel]

I did some experimenting with this years ago. I have some ideas, but no solid science to back it up.
On a shorter spring, the spring has less wire and would twist more to absorb the energy. Would this more stored anergy cause the spring to be more reactive over ripples in the track?
This would allow the tire to stay stretched and traction Ed up longer.

Second, I think everything needs to operate in the rear around the rolling arc of the reared. The height and width of the rr spring need to stay in that arc. If everything stays n that arc, it becomes more efficient.
It’s kind of tough because I think the rearend operates more like a pole vaulter than a roll.

As we started lowering the rr spring, sidebite improved and the car scotched up quicker and lasted longer.
The driver actually said the car felt better.

I’d love to hear some ideas about this.