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Author Topic:   LS weight ?
3kids
Dirt Roller

Total posts: 20
posted August 07, 2005 11:20 AM  
Can not enough left side weight make a car loose off the corner when it gets extremely dry slick? Car enters and rolls the middle good but has no drive off. 4 bar-Z link with spring in front on LS clamped an spring on top RS. 80LBS of bite in Lr. Bars on LS at 20 degrees top and 10 bottom. Z link bars are at about level. 1200LB pull bar. Short panhard bar in front of housing at 23 degrees.
Has 60 percent tail at the beginning of the race and 50.9 percent left side without driver. Stagger is at 1". in the rear.
We have been trying different offsets to get more RS weight to help with sidebite. Would you be better off having a wider front end or 2" wheels on both sides or having the RF wheel in for RS or more sidebite? And does moving the RS wheel in help pin the RF better to help the car turn?

toslow2day
Dirt Roller

Total posts: 5
posted August 07, 2005 11:30 AM  
spring rates, shocks, what type of track other info needed.

3kids
Dirt Roller

Total posts: 20
posted August 07, 2005 11:57 AM  
LF- 650
RF-700
LR-200
RR-225
Bilsteins
LF 50-30
RF 45-45
LR 20-70
RR 30-30
Axle dampner 90/10 carrera
We run a 1/2 and 3/8 with big sweeping corners.

WPP
Dirt Freak

Total posts: 451
posted August 07, 2005 04:22 PM  
Soften preload on the the pullbar if car is loose off go to a 200 on rr spring also lower the left lower bar level or 3 degrees below level

3kids
Dirt Roller

Total posts: 20
posted August 07, 2005 07:47 PM  
Wouldn't lowering the bottom bar only work for indexing the birdcage if spring was behind and floated?
When it gets dry slick do you want to take out roll steer or add more roll steer.
Also if you lower the left lower bar won't that take roll steer out and at the same time take away drive because the bars are not angled up?
This is what has really stumped me with this 4 bar setup that we have.
Thanks for the input, we really could use a different opinion on this or waht others have tryed.

37mod
Dirt Full Roller

Total posts: 36
posted August 08, 2005 03:51 PM  
Try running the 45/45 shock on the LF and a 30/50 on the RF. This will let the RF lift a little sooner than the LF, transfering more bite to the LR, out of the corner.

JMillerJr76
Dirt Maniac

Total posts: 128
posted August 08, 2005 04:39 PM  
For the most part, on a 4bar car, the lower left arm just controls roll steer, the upper bar will give you bite.

Kromulous
Dirt Forum Champ
Total posts: 796
posted August 08, 2005 04:50 PM  
Lack of LS weight, can cause the car to have to much roll, and side bite on the right side.

A few ideas, progressive pull bar spring, get some angle in the Z-Link bars, swap the rear springs, more LR bar angle (upper bar). Might try moving the spring on the RR to infront on the cage, for indexing.

At 80lbs bite with a clamped up LR the thing should plow like tractor, so something tells me that the pull bar is not moving enough. Check it to make sure its not all bound up and make sure you are getting 2 to 3 inches travel, 3 to 3.5" being optimum.

You have to remember that with a LR clamped in front set up, you need the axle housing to index back to create more bite, via the clamp bracket on the front.

That or the RR is out driving the LR, but it doesnt sound that way since you say the RR Z-link bars are flat.


Check the pull bar, and the travel.

[This message has been edited by Kromulous (edited August 08, 2005).]

3kids
Dirt Roller

Total posts: 20
posted August 09, 2005 07:01 PM  
Thanks for the input guys! Really has helped me on what to do next. I know now what the bars will do on the LR.
Kromulous, what rate progressive do you recommend for the pull bar? We are already getting 21/2" to 3" of travel with the 1200LBS spring, so do you think that I have used up all the travel before the exit of the corner? If so can I slow this down with a differnt shock on the LR? Like maybe a 3-8 or a 4-8?
Or possibly a stiffer axle dampner shock?
Thanks again for the help!!
Also if I move my LR top bar up to the next hole it will be at 28 degrees of angle, does that seem like a lot and wouldn't that almost make the cage go over center? Then if I move the LR bottom bar down it would be worse yet for going over center.
Is anybody taking the LR back when it gets dry slick or just leave the rearend square? If so how much do you move it?
Thanks:

Kromulous
Dirt Forum Champ
Total posts: 796
posted August 10, 2005 07:29 AM  
28* on a Mod is not to much, to me it aint.

The pull bar could be traveling to far to fast, thats a good insight. You may try some various preloads, like 1/4" then go from there. Most Pierce drivers use that 600 to 1200lb Hypercoil progressive, and with some preload on a 4Z set up.

2 to 3" of travel should be good travel wise thou.

The LR, you might want to try a little stiffer spring, maybe a 225. That or just swap the rears.

Does it push in, in the center, off? where is it loose and when does it begin to lack drive?

3kids
Dirt Roller

Total posts: 20
posted August 10, 2005 11:33 AM  
When the track gets dry we have been taking angle out of the Z-link bars and then it gets a small push in the middle. So I think I need to keep the angle in those bars to keep the steer in the car.
Also I notice that it when I keep a greater amount of angle in the RS bars it is worse at exit of the corner, but when you begin to take angle out it starts to get that mid corner push.
The car is real good at entry and through middle with angle in the z-link bars, and is still good in when you take angle out but starts that little push in the middle and then gets loose off. The loose off seems to be about the same no matter where the angles are on the RS.
It starts to loose traction right after the apex till corner exit then when it is staight, look out because it will pull the LF up and get all kinds of drive, and keep that drive till entry.
Should you use the front or rear z-link bars for adjustment and what bar would make the most difference?
I have one of those springs form a few years ago, so I think we will try that or first might try more preload and change rear springs around.
Hope this info helps because your info has given me some new perspective on things.
Thanks again!!

dluna
Dirt Freak

Total posts: 334
posted August 10, 2005 12:29 PM  
Have you tried taking the angle out of the z-link, then adding some static RR trail to help with the mid corner push?

I think when you add more angle to the upper LR bar, you are going to see that mid corner push even more (throttle). Maybe you can fix that with the LR lower buy adding a little more steer in conjunction with the added angle of the upper.

Kromulous
Dirt Forum Champ
Total posts: 796
posted August 10, 2005 01:50 PM  
I hardly ever move the FWD bar on a Z-Link, i think of it as my traction bar, and the rear bar as my control bar.

If that lower bar is not pointing up hill at all, you basicly took alot of FWD traction away from the right side. Unless i am thinking wrong about this. Someone correct me if i am.

Try bringing both LR bars up one, bring the RR FWD bar up one, and leave the rear bar flat. If its tight lower the RR rear bar down one.

What springs are you running on the rear?

At 60% rear, and 80lbs LR bite on a clamped up LR set up, this thing should push like tractor. Something has to be binding or somthing.

avenger 11
Dirt Forum Racer

Total posts: 88
posted August 10, 2005 04:06 PM  
How much left rear bite should be ran with the 4-bar clamped set-up?


3kids
Dirt Roller

Total posts: 20
posted August 11, 2005 08:41 PM  
dluna, we have put RR trail in the car and it did help but shouldn't you take that out when it gets dyr slick?
KromuIous, I will try more bar angle in the LR the next time we run to see if that works. Springs right now are LR 200 and RR225, but we are going to change them around for the next night.
I know of some Skyrocket cars that are at 130lbs. Lr bite and are bad a$$ fast on any type of track condition or size.
Thanks again for the input, if you have more ideas keep them coming!!
One other thing Kromulous, how much angle do you have in your RR lower z-link bar and what is your length is that bar, mine area around 21" I know that skyrocket cars are 16 1/4" long. Does the length matter or does the longer bars on react slower?

Kromulous
Dirt Forum Champ
Total posts: 796
posted August 12, 2005 06:52 AM  
I run a swing arm / Z-Link, and its an 18" one, with a short rear link, 16" long. Usually about 5* up on the angle, nothing to extreme here, but it has some angle. I find it helps getting the car to loosen up in, while we run a high wedge type setup.

21" versus a 18" would be slightly slower in reaction, and the 21" would produce more roll steer, but slower. Because the longer arm needs more time to come into its radius.

If you run it flat at ride height it will get tighter with body roll going into the turn. I'm surprized the car turns very well. Plus it will take more body roll to gain any traction thru bar angle.

Swapping the rear springs will help a bunch. Are you sure the car is not tight in? do you have to throttle steer it to get the back end to come around? or do you drive it real straight.

Remember, its always a give and take deal on these cars. If you want more coming out, your gonna have to give alittle else where. See if you can stand the car to be alittle more loose in, and that will help coming out.

130lbs LR Bite? with a clamped up infront 4 bar? Wow...

3kids
Dirt Roller

Total posts: 20
posted August 12, 2005 04:41 PM  
I do have to use the throttle to get the car to turn when I move the bars on the RR when it gets dry.
So does this mean that the car is to tight with Lr bite or just leave the bars alone and keep the steer the same as when we run our heats and try it that way for the feature?
The car never feel like the back end is going around on entry.
At the 1/2 mile track we run, I can get off the gas for a split second, the car kind of turns in with a little brake help, then get on the gas and does fine till just past the apex then looses forward drive.

dluna
Dirt Freak

Total posts: 334
posted August 12, 2005 06:38 PM  
Since your explanation sounds really similar to what was happening with my car, I couldn’t past sharing this story. I’m SURE you have already checked the whole car for binds, however…this is what happened to me:

About a year ago, we welded on a bracket to the rear of the axle tube on the LR. The bracket pointed straight out towards the back of the car from the axle tube about 4 inches. I was running the LR on a slider. The slider broke, so I went to a coil-over, which instantly gave me more travel on the LR (slider was limiting the travel the whole time). The car was great on entry up until just before exit…then I would loose forward bite and the rear would want to slide up the track. I found that the bracket was now making contact with the underslug because of the extra travel I was getting. So the RR was still driving hard and the chassis was still lifting in the rear, which in turn was lifting up on the LR axle tube…taking weight off that wheel when I needed it most. I made just about every spring change you could imagine until I found this. Car was night and day difference on exit. Now if I could figure out this whole thing they call driving, we’d be good to go.

fireman
Dirt Newbie

Total posts: 1
posted August 14, 2005 03:51 PM  
go 600 -1200 progressive, hyperco best, next afco, take that bottom lr to level, remember, bottoms get you in, tops get you out, try leaving the top lr alone set it about 20 degrees, if still loose, take stagger out, put soft lr rf shocks on, or split valve, try making adjustments to rr now, like top z link bar to level, not much more.

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted August 15, 2005 08:25 AM  
If it was me i would flip flop the rear springs, put bottom 4-link at 2.5 degrees, put 50lbs on left side above axle high as possible and start with 40-50lbs of bite. JMO you might not agree. Just remember more left side will loosen car on entry, and 10 degrees in that bottom bar is giving you a lot of rear steer coming out of corner.

hope this helps.

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