Terrible push getting in

[dirttrackrocker]

Heres what I have. I have an older 2002-2003 GRT Metric 4 bar LR swingarm RR

Springs

LF 700 RF 750

LR 200 RR 275 0n the swing arm

Shocks

LF 5/3 RF 3/7

LR 5/3 RR 35 LR Spring behind shock in front RR spring and shock on Swing arm

51.1% Left
57% Rear
40 lbs bite in LR

J bar even with pinion and 7" rake

Leading LR by 1/4

LR top bar 23% Bottom Bar 10%


The car has a terrible push getting in the corner. The only way I can turn it is to let off the gas and stab the throttle, if I touch the brakes it wont turn at all. I turned the right front off (even though were not allowed to) to try to cure this and it helped a little but not much.

Any suggestions on how to loosen it up getting in??

[washeduptoo]

Where is you jbar on the pinion?

[dirttrackrocker]

Even with pinion..

[washeduptoo]

Have you tried lowering the rake in jbar or up above pinion, I'm guessing its a 9in rear end? What about raising the rr bar on frame? I just saw in your 1st post you said even with pinion, sorry.

[dirttrackrocker]

Haven't tried that. What will that do?? Sorry, I'm new to these cars.

[dualdj1]

Generally speaking when a car doesn't turn in, lower RR bar for more rear steer (will loosen off as well), add rear stagger, soften LF spring, stiffen RF spring.

It sounds like you've got too much drive, which comes from rear % and bar settings. So you can lower rear % if possible, or if you want to keep it then soften up that LF spring and add stagger/lower RR bar.

Being a 4 bar LR though, you may have your 4 bar settings off which is creating too much drive, and I can't help with the 4 bar adjustments.

[dirttrackrocker]

Well, not sure how it could be too much drive. I'm talking about totally off the gas and on the brake. I've got it dialed all the way to the rear (brakes). My buddy says it doesn't look like the car is transfering weight to right front.

[1cln_sdime]

What r your wheels weights?

[dirttrackrocker]

LF 539 RF 519

LR 709 RR 660

Im at work now the rears I know are true, I'm pretty close on the fronts.

[washeduptoo]

Try lowering the jbar on the frame an inch and see how you like it, it will lower your roll center. Sometimes you can get too much rake and not let the car work properly, you have to find what rake works best for your car/driver/track.

[dirttrackrocker]

Thanks I will try that..

[dualdj1]

Yeah drive was not the right term i was looking for, but the adjustments I listed should still be correct for your condition. RR bar, stagger, LF spring. Jbar rake as mentioned will help too.

how did you decide on your front spring rates? Did they just come with the car that way?

GRT setup sheet:
LF 550 RF 600
LR 225 RR 225

also for your reference:
http://www.teamgrt.com/GRT_RACE_CARS_ADJUSTMENT_GUIDE.pdf

[dirttrackrocker]

Thats what was in it when I bought it. The spring rates you have are for a Chevelle clip. I have a metric clip. Just found a set up sheet for older metric cars and it says springs should be 750 LF and 850 RF. I think I'll try that.

[dualdj1]

cool deal, that's all i could find but was guessing it wasn't correct. their setup adjustment sheet will still hold true with your changes though, so know as you go stiffer RF you'll tighten exit as well. LF will only effect entry. So if you're happy with the way it's coming out of the corner, I'd just soften the LF, OR adjustyour j-bar.

[dirttrackrocker]

cool, thanks...

[js11]

seems like too much RR sping. Try running the rear springs at equal rates (or within 20 lbs) and put 50/50 shocks on the LF and RR corners. That will loosen you up going in and might give you more drive coming out.

[dirttrackrocker]

Thats kinda what Im doing. the 275 on the RR comes out to 190 on the swingarm. I have had guys tell me not to go by that and just go with what I would put on if it was on the Bird cage. I dropped to a 200 on the RR and I'm going to drop the J bar on the frame side and see what that does. If that doesn't work I might go up to an 800 on the RF

[washeduptoo]

Are your lower A-arms metric or nova? Mr. Adams(Lighning chassis) in another thread explained the motion ratio and how it works, you might be right, need heavier front springs. I think he recommend 900lf and 1050 rf. Let us know how things go and best of luck.

[Flyin Iowan]

left side weight seems low

[dirttrackrocker]

Thats because I weigh 270... They said for someone 250 + you should be between 51 and 51.5

[js11]

OK. I assumed the spring was on the axle tube (hence 200 or 225 rate suggestion). You probably don't want the same rate on the swing arm as you would have on the birdcage (way too stiff). I've run anything from a 375, to 400, to 425 lb spring on the swing arm on the RR (at 43% of advertised rate is 162, 172, 182 lbs on a 15" swing arm mounted/z-link) with a four bar LR (spring front or behind). Of course that calculation is based on how far away from the bird cage the spring is mounted.

I also think 51% leftside is light. If you could scale the car while sitting in it, try 53 or 54% that might help. Also, your offset wheel choices on the RF and LR might help.

[dirttrackrocker]

I have a 16" swing arm and the spring is mounted 11" from chassis mounting point. I had a 275 on there which according to the calculator on the dirt forum it was 190. I dropped down to a 250. I also put an 850 in the RF and dropped J bar on frame. Wheel offsets are what GRT recommends, 2" everywhere except RR which is 3". Left side with me in it is 53.7. LR is 4 bar spring behind shock in front. I found a problem while making these changes. The Eliminator on the LR was binding where it mounted to the birdcage, it actually bent the bird cage. I replaced the birdcage and put a clevis mount on it so it doesn't bind. Hopefully all these changes fix the problem. Thanks for all the help, I'll post the results after this weekend. IF the weather doesn't put a damper on things...

[dualdj1]

yeah bent birdcage could cause all kinds or probs. Best of luck, I think you'll be in good shape (or at least loose instead of tight)

[js11]

Yup. That sounds like it could be a culprit. Good Luck.

[HEAVY DUTY]

The dirt forum calculator isnt right.They left out a step.Whatever the percentage is you have to square it (times it by itself)Like JS11 said it should be about 43% of the spring on a 15" swingarm which means you need a 400 to 450 RR spring.A swing arm is also digressive in rate because the front of the swingarm moves down(away from the spring) as the rear moves up into the spring.

[28m]

A bunch of good suggestions above. Let me add and confirm a couple.

When you said it gets tighter when you hit the brakes...you have issues up front. I am guessing your ride heights up front are off. Triple check to make sure you have the correct angles in the uppers on both sides. Again, Im guessing you dont have enough angle in the upper RF a arms OR you are too low and it is bottoming our or binding. Try lowering your front ride hights like 4 turns. Hot lap it and stab the brake getting in and see if it is worse or better. If not better, try the opposite...go up 8 turns (4 to get back where you were). From my experience, what you are describing when you hit the brakes is all up front.

I think your left side is too light as well.

You can increase your LR bite to loosen the car getting in OFF THE GAS.

The next test is to play with your entry to see if it tight on the gas getting in and or if it is tight off the gas getting in. Each adjustment you make REALLY depends on how you get in...on the gas or off the gas. Each adjustment is exactly the opposite depending on your entry style.

LOL, no one said this was easy :)

[dirttrackrocker]

I agree it's a front end problem. I made sure my ride heights are where GRT says. Last week I lowered RF 4 turns to see if it helped. It didn't. Didn't try going up. Put it back where it was for this week and went to an 850 in RF. I'm thinking that, coupled with fixing the bind in the LR suspension will at least be a step forward. I think after reading the suggestions above, I am gonna go back to the heavier spring that I had in the RR.

[28m]

A heavier RR spring will loosen you up getting in ON THE GAS but tighten you up coasting in or on the brakes. I think it might make it worse for you to tell you the truth. Stay focused on the front. That is likely where the problem is. Bad shock...something.

I had a Dirt Works years ago that needed a ton of ride height up front to turn. If I remember right, they called for like 6 inch RF and 5.75 LF. When I had it close to that it pushed like a freight train on the brakes getting in. I raised it up from reason only God knows, and it was incredible. Up to like 7" plus. I know it sounds crazy but it worked.

[dirttrackrocker]

I'm talking about going back to what I had. I had a 275 on the swing arm, and went to a 250. I'm thinking that might be too soft. Thanks for all the help, I know some things to try now..

[cullen17racing]

i would add timing into both birdcages. i would start with 2 turn out of the upper bars and 2 into the bottom. this should free your entry considerably and will tighten your exit. also as others said move the j-bar up on the pinion and have a maximum of 3 inch split from where it mounts on the frame and pinion. i promise you will enjoy the results!

[tumbleweed]

I was having a push problem and was told I didn't know how to drive the car yet. Never been in a 4-bar car and was getting off gas completely going into corner, which dropped car off bars and created all kinds of reactions. Just this last weekend of racing tried to ease off throttle but not enough to drop car off bars, and, car handle much better. Still can't seem to do this every corner of every lap, but, was told it will take laps and laps to get where it seems second nature. Oh, by the way, I came out of a leaf mod and there is no comparision to the way the two cars drive. Just a thought.

[28m]

I was having a push problem and was told I didn't know how to drive the car yet. Never been in a 4-bar car and was getting off gas completely going into corner, which dropped car off bars and created all kinds of reactions. Just this last weekend of racing tried to ease off throttle but not enough to drop car off bars, and, car handle much better. Still can't seem to do this every corner of every lap, but, was told it will take laps and laps to get where it seems second nature. Oh, by the way, I came out of a leaf mod and there is no comparision to the way the two cars drive. Just a thought.

I had a 4 bar-4 bar DW back in 01. I hated it and stopped winning. I went to a mono leaf for the next 10 years and won my share including 4 championships. I bought a 4 bar 4 bar towards the end of last season and after flipping it on my 2nd lap of a test and tune, I came out the next weekend and lead 24 of 25 laps, won the 2nd night out and finished 3rd in a 7 k to win open race from 24th place the 3rd night out. Sooooooo, what I am saying is, if you set the 4 bar up right, you don’t have to trail brake it. You don’t have to re-learn to drive. It is WAY tougher to change your driving style (assuming you’re not new at racing) than it is to tune your car to you. With the shocks of today...which I didn’t have in 2001, you can put an 8-2 on the LR and the car won’t slam down. Trail braking is hard for me to do and it feels slower to me. JUST MY OPINION... With my 4 bar, I can back it in, throw it, or drive it in on the slick and it pretty much drive it like a mono car. LOVE IT.

Not arguing with you at all Tumbleweed...just offering another opinion from a fellow mono guy! :)

[dirttrackrocker]

UPDATE... Took the car out last night with the few changes I made and it was GREAT. Track wasn't the best as we were fighting rain, so it was slick and greasy, but, the car took a natural set and turned in real well. Thanks for all the help guys..

[hugoistanz]

very successful. Waiting for new jobs. See you soon

[washeduptoo]

Glad it worked better for you.

[padondeno]

Thank you for sharing. success in the new studies. Waiting. :)

[ask0329]

I was having a push problem and was told I didn't know how to drive the car yet. Never been in a 4-bar car and was getting off gas completely going into corner, which dropped car off bars and created all kinds of reactions. Just this last weekend of racing tried to ease off throttle but not enough to drop car off bars, and, car handle much better. Still can't seem to do this every corner of every lap, but, was told it will take laps and laps to get where it seems second nature. Oh, by the way, I came out of a leaf mod and there is no comparision to the way the two cars drive. Just a thought.

I think this is the problem I'm having as well. But my track is a D-shape and most my problem is in turn one which is a hard left. Back stretch is rounded off into 3 and 4 and front stretch is a straight shot. Had my first real race and it pushed like a dump truck in 1 and 2. Coming from a RWD ministock and a year off this was sure a change. By the end of the night I could get through 3 and 4 fairly well but 1 and 2 was hit or miss. Running a 3-link. Really dont have "setting" the car down just yet and are driving through the corners. Plenty of pull down the straights. Do 3 links get "up on the bars" like the 4 links do?

[dualdj1]

Glad to hear you made some progress!

ask0329 I'd suggest starting a fresh topic, and including a few more details about your car.

[ask0329]

sorry about that. I had no intention of hijacking the thread. Just thought it was an interesting reply about not having the expierence to turn the car just yet and thats how I'm feeling to an extent.

I havent met dirtrackrocker personaly, just on racing forums and facebook. Hes one smart dude and I try to read all his posts. He races at a track or two in my general area. I'm lookin forward to racing against him at a series race or two.

[dualdj1]

No prob, just thought you might get some better answers on a new thread :cool: