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Author Topic:   lift bar spring rate
showtime13
Dirt Full Roller

Total posts: 60
posted October 02, 2005 12:24 PM  
Do you get more traction with a stiffer spring on the lift bar when the track gets dry/slick?

rocket36
Dirt Freak

Total posts: 209
posted October 02, 2005 01:52 PM  
good question. hopefully go24, 2nd2none, sdhnc or one of the others with plenty of experience can answer this one.
i would have thought that a stiffer spring would not cushion the torque effect as much on a slick track which would allow for more wheel spin.

showtime13
Dirt Full Roller

Total posts: 60
posted October 02, 2005 07:50 PM  
That was kind of my thoughts too rocket36. I was thinking that putting preload in the spring would help but I was still to loose down the straights ive asked around in the pits and it seems that most guys are running a stiffer spring then us....i wonder if it makes a differents with how much wedge you have in the chassis as to how much spring rate you should use has somthing to do with it.

showtime13
Dirt Full Roller

Total posts: 60
posted October 02, 2005 07:54 PM  
I run a 4 link unclamped LR behind. When the track gets dry/slick will you get more traction with a stiffer spring on the lift bar? last night we was good in the turns but didnt have enough traction down the straight-a-ways. We have a 225lb. spring on it now. HELP!

lee browning
Dirt Roller

Total posts: 19
posted October 02, 2005 09:10 PM  
I have been runing a 350 coil in our car. now when it gets tacky I put a 400 in and move it back to 31" on my bar. the reason for that is because when it is tacky you don't need continious hook-up down the straight, it also allows the driver to get on the trottle harder and use the torque in the engine to pull you outof the corner. Now when it slicks over and gets dry I put less of a coil in ex:300 at 37" and believe it or not, that helps by adding more torque from the car to the ground. Softer spring softens the cusion between the torque-arm and the tire patch giving the car more foward drive. Also I have seen it where it helps transfer weight to the rear which helps with foward drive. I hope this information will help you.

rocket36
Dirt Freak

Total posts: 209
posted October 03, 2005 12:42 AM  
showtime, check your 5th coil shock travel, that should give you a good indication.
i've never tried different spring rates in the lift arm, just different lengths.
what lee has stated seems to make sense.
you could also try raising you left top rod at the frame or indexing on the birdcage.
we run the standard rocket setting 5th coil of 300lb. i have experimented with the length but the guys at rocket keep telling me just to leave it at 38".

GO 24
Dirt Freak

Total posts: 366
posted October 03, 2005 09:40 AM  
350-300lb will put you in the ballpark. Generally a stiffer spring will give you more initial bite BUT if you have a driver who's either all or nothing with the pedal he may have a tendency to spin the tires, a softer spring will hook up later in the straight away and should stay hooked up longer---IF you go to light you'll never get off the corner though.
We generally run a 350 all the way back with a couple turns of preload (this is after the pinion is set and the spring is seated)

GO 24
Dirt Freak

Total posts: 366
posted October 03, 2005 09:43 AM  
Oh and it's exactly the opposite, softer spring will give you more traction when it's dryslick BUT your way way to soft with that 225.

showtime13
Dirt Full Roller

Total posts: 60
posted October 03, 2005 02:36 PM  
Hey guys this is very good info. and I really appreciate it after reading your post it's no wonder I have been good for the heats but could never really get it to hook up come feature time. What I have on the lift bar is a 4 valve 50/50 shock on the bar and a 4 valve 50/50 shock on the top of the rear end. 225lb.spring is at 33" from center of axle. im geting about 2 1/4 in. on the shock travel sometimes 2 1/2". Oh and the pinion is at 8 degrees.
Last year we had a 250lb. spring on it and I thought that buy putting a softer spring would help me even more come feature time BUT obviously Im all ready way to soft to begin with. Because what you said GO 24 is exacly what im finding out is the car realy hooks up at the end of the straight a ways and I see my self driving in to the corners way lot faster then everyone else. Now Lee says he puts his spring towards the front for the feature now what do you think of that GO24? Thanks guys !!

showtime13
Dirt Full Roller

Total posts: 60
posted October 03, 2005 04:33 PM  
What about a progessive spring??

bullittwrench
Dirt Roller

Total posts: 5
posted October 03, 2005 05:30 PM  
I've had good luck with the progressive springs on a leaf car. On a 4-bar, they were great in the tacky but stunk on a dry slick. Played with all 3 rates that Afco has.

bullittwrench

showtime13
Dirt Full Roller

Total posts: 60
posted October 03, 2005 05:46 PM  
thanks bullitwrech...did you try moving it backwards and forward on the lift bar?

lee browning
Dirt Roller

Total posts: 19
posted October 03, 2005 10:27 PM  
After reading your post about the springs and more importantly the shocks, I would like to say that it would help your entry if you put a 3 compression 7 rebound on your 5th wiht a 350 and a 350 on your 6th and whatever prelaod that you use make sure that both coils have the same. then make your chain is set for whatever degree that your chassis calls for. Now the shock that your using on the top of your rear-end seems a little different to me. I have always used either a 90/10 regularly and if I want the car tighter on entry I put two 90/10's on a 5 degree uphill angle towards the chasis. Also if I want the car looser on entry try removing the shock completely. Another thing that I have done to get the car looser on entry is to remove your 6th and replace it with a straight chain, this allow's the chain to stop the movement of the rear-end on a dime. the reaction should be instantly loose of the throttle.

*Again I hope this information can help you.

rocket36
Dirt Freak

Total posts: 209
posted October 03, 2005 11:22 PM  
lee is right again. try running either a 3/7 or at least a straight 3 valve shock on your 5th coil. if you choose to run a axle dampening shock on top of the rear end, run a 90/10 (9/1). you should only require an axle dampener when the track is extremely slick and your REALLY loose going in, otherwise i would take it off. under the advice of the guys at rocket, and several rocket drivers, we removed ours and have never run one since. the rocket cars still have provisions to run one but very few do.
let us know what you do and how it all goes.

GO 24
Dirt Freak

Total posts: 366
posted October 04, 2005 08:32 AM  
I run the spring/shock all the way in/or toward the rearend...I'm sure this hurts us alittle bit when it's tacky but it's where I want it when it slicks off.
I've tried the progressive springs as well & they seem to be to inconsistent for my liking.
I agree with the other guys but forgot to mention it earlier, use a 3/7 shock on the 5th arm.
4 links are naturally too tight going in anyway so we've never used the 90/10 shock (most guys don't) but there again that's driver preference and driving style.

In your case I'd put in a 350 spring on a 3/7 shock at 34in, set your pinion and put in the preload...anywhere from 2-4 turns after the sprinmg is seated.

showtime13
Dirt Full Roller

Total posts: 60
posted October 04, 2005 03:56 PM  

 
Here is a aticle that i read from Carrera

showtime13
Dirt Full Roller

Total posts: 60
posted October 04, 2005 04:45 PM  
Can you read it? what is your opinion?

showtime13
Dirt Full Roller

Total posts: 60
posted October 04, 2005 05:05 PM  
**** I cant read it on here but this is what it says

The 90/10 gives mores "kick" when you stand on the gas, but it will usually break the tires lose about 1/2 second later. This will often produce slower lap times on all but Heavy Tracks (even though it may feel better).

The softer 50/50 valving doesn't give you that "kick in the **** ". But the tires don't break lose and it usually produces faster lap times on slick tracks.

If, with a horizontal 90/10, the car is lose going in, try putting two horizontal 90/10 shocks on. This tightens the car when you back off the gas. it made since to me so ive been trying this all season and I think it actualy has helped. Now I just cant wait to try this 350 spring. I really think that the idea by taking the 90/10 shock off sounds like a good idea too and putting the 3-7 on the bar.
Rocket36 my season is over for the summer but belive me when next season comes I will definately be making these changes to my chassis.
Thank again you guys your AWESOME!!
Im going to print this out and let my crew chief read this. You all have been a big help!
lee browning my name is Doug Browning...lol isnt that weird?

GO 24
Dirt Freak

Total posts: 366
posted October 05, 2005 08:02 AM  
Good luck to ya!
Mark www.fasttrakgraphics.com

showtime13
Dirt Full Roller

Total posts: 60
posted October 05, 2005 02:00 PM  
Sorry guys just 1 more question.....Does the amount of wedge in the car have anything to do with how much spring rate on the lift bar?

GO 24
Dirt Freak

Total posts: 366
posted October 05, 2005 02:19 PM  
Not really, 2 different things/2 different areas of the track that they effect.
LR behind spring should be somewhere between 225-275.

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