Need more forward drive

[Modracer77]

I have an 08 GRT 4 bar car with the spring behind on the lr and in front of the rr. I'm really good on entry and going through I just can't get any drive off. I race on a pretty flat 3/8 mile track. We have the lr birdcage indexed into the spring 2 degrees. Springs areLf550Rf600Lr175Rr150Any help would be great thanks

[Egoracing]

Where is the left bottom bar on the chassis? What is your 5th coil spring and shock and it's location?

[JustAddDirt]

probably got a pullbar on it, and not a liftarm.

[Modracer77]

The bottom bar is 3 up from the bottom and we are on a pull bar. It's the bisquit one from quick car. GRT sold me a spacer to put in there so we only run 3 bisquits and they are all reds. Its 10 3/4 inches up from center and 2 inches forward.

[JustAddDirt]

what hole would you be in on the LR to have that bar level?
how much LR weight?
pullbar mounted in center of rearend?
rear weight %?

[andy29]

use a 1050 spring adjust preload to get 1 1/2 inches of travel

[Modracer77]

Pullbar is in the center and we have 45 lbs of lr and about 57.5% rear thought about taking some rebound out of the rf to help the weight transfer a little easier

[Egoracing]

Lowering the left bottom bar on the chassis adds drive from the center out while on the gas if it birdcage is floated. Adding angle by moving it up on the frame removes drive. I would also think about moving the bar to the left of centerline.

[Confused?]

Adding LLB angle increases wheel loading, which increases drive. However, it also icreases roll steer which makes the car feel looser. The car will want to crab down the straight with more LLB angle.

[4bangerhotrod]

the rear steer far outweights any drive raising the LLb adds. lowering the bar adds drive reduces rear steer and makes the car drive much straighter, it indexs the birdcage into the spring more when the car is on the bars.

[Confused?]

When you start think and understanding thrust angles, then you will see how adding angle increases drive. Lowering the LLB DECREASES drive. Indexing does increase which increases the initial bite but not once the car is up on the bars. There is a point of diminishing return though. Just like any adjustment. Depending on the chassis, one or two holes should be enough to change a cars handling without having too many adverse reactions.

Lowering the LLB to a flat position lowers the thrust angle of the LR. This unloads the LR tire. Sure the indexing will load the spring more, but it's short lived. As the car starts to climb the bars, the top of the spring is moving away from the bottom faster than the indexing can keep up with.

This does not work for every driver. Some "feel" way to loose when they are not. If you don't like it, don't use it. How much angle is used also depends on the track. Is it a tight 1/4 mile or a sweeping 1/2 mile. Less angle would be needed for the 1/2 mile.

[MiddleMan]

Try increasing angle and length of LLB. Increase in angle will increase drive, increase in length will take rear steer out, in turn tightening overall handling. May need to increase RF spring rate to loosen entry when doing so.

[4bangerhotrod]

if your just wanting to add drive off the corner raise the LRT rod one hole. sure raising the LRB rod will add thrust angle but also adds rear steer which loosens the car more than the added drive tightens it up and lowering does add instant drive till the bars take over an the car gets off the spring, once the car is off the spring it still keeps the car straighter because of the reduced rearsteer. the top rod over rides the lower rod, if your just wanting to tighten exit lower the bottom rod, if your wanting to loosen exit raise bottom rod. but if you want to add drive an tighten up exit raise the top rod.

[setup479point2]

Tend to agree with 4banger , my drivers in crate and emods all agree lowering LRL adds drive and makes car come off corner harder and straighter.

[charcoal01]

hey 4banger, your inbox is full.