no rr roll/ no drive off

[bottomfeeder]

brand new chassis, but dont want to step on any toes, so i cant throw the name out there. 4bar/ 4bar over slung car with 600lf,550rf,200lr,150rr. bar angles are 30 deg. tl,10 deg. bl,16 deg. tr,0 deg. br. 700/2000 shaw pull spring(3/8 preload, purple bisquit). not exact on j-bar drop, but it looks like more than 7 inches, mounted below centerline of driveshaft. car wont roll on rr, it will hike up in rear, but rolls to rf and not rr. wont lift lf off ground. also no drive off, have to run 110 lbs of bite with driver and still doesnt work well. car works good on heavy track, but if track slicks off at all, we have nothing. any help appreciated guys, were fairly new at this and all these bars to change arnt seeming to help.

[johnny v]

LS % ?
Rear % ?
Shocks?
What's the basic handling like? Tight entry? Tight Middle? Are those spring #'s what the setup sheet calls for?

[Kojak_9x]

More then 7 in of rake in your J-bar is why you have no rr roll. It is acting like a kickstand on a bicycle... Im guessing that you are having problems in the middle also then... I would def lower the J-bar... I would drop it down to 5'' and go from there. I run mine between 3ish-5ish". (even with pinion on 9" or 1 hole below with Q/C) Just look at it from the rear of the car at ride hight and i just keep it slightly above level and adjust as I need to. Keep in mind I run 200lb RR. If this helps then you can lower your LBL bar as needed. May even go down on the J-Bar on pinion side also... Make sure your Rear % and Cross is right also (57ish rear and 52ish cross) The above worked for us, hopefully it will get you going in the right direction... Good Luck..

[bottomfeeder]

left side %=52
cross=50.5
rear=56.5
im not sure on all the shock #'s, i know its a 6 shock package were we change lr and rf for feature. car was originaly tight on entry, but now its better. ive just noticed when we get in the corner and burp car and back on gas car stands straight up both lr an rr with a little roll to rf. weve changed rr from 175 to 150, and have swapped front springs to no avail. we'll measure the j-bar drop and go from there. weve also been told were to heavy on front springs, to go to 500lf and 450 rf and 1450 pull spring. wouldnt the front springs softer hurt what we want to do?

[washeduptoo]

How much lr drop do you have at full lift? Does this car have a brake floater and how much angle in it? Jbar angle is something you have to find what fits your chassis/driver/track but I do think you've got too much rake, that is where I would start. Best of luck.

[bottomfeeder]

i guess im not sure what you mean by lr drop at hike. yes car does have brake floater, but not sure how to check angle. its were it came when we got the car. we were also told to put more pinion in car. we are at 8.5 deg., and told to go to 10 deg. we will raise the j-bar on rear end and put 5 inches of drop and try from there. thanks guys.

[washeduptoo]

By left rear drop I mean, at the bc at ride ht, take a measurement from axle tube to decking or something straight above it and then put a jack in front of lr and jack it up until lr tire is about to clear and take a measurement again at the same place. Then substract between the 2 measurements that will give you the drop. In my experience too much drop will cause the chassis to roll on rf hard, but usually causes lf to lift,not always thou. Put an angle finder on the lr brake floater forward bar. Did you have a brake floater on previous chassis, the reason I ask is we've had a driver that had problems with using a brake floater and had to run it level, made a big difference in car handling with that driver. Best of luck.

Be sure to reset the rear end side to side to chassis specs after moving the jbar.

[28m]

Kojak is right on. Too much angle in your j-bar. You said you were going to lower the pinion...I wouldnt. I would lower on the frame instead. This assuming your on dry. Your front springs seem OK where they are. Too soft on the RF and you will start to losse drive off.

7 inchs of j-bar split is a bunch. It will make the car stand up on the gas and very erratic.

[bottomfeeder]

thanks guys. i think we are going to raise j-bar on rearend plate one hole and then measure up 4-5 inches. try to get it closer to level. also going to try and take a link out of chain on rr to tie car down. going to leave pinion angle at 9 degrees and go back to a 175 rr shock. will let you know. thanks again

[bottomfeeder]

well guys we set the j-bar level and still had over 6 inches of drop. car still didnt work so well. we changed the pinion to 10 degrees and added weight and full tank of gas for feature, and car seemed to be better, but still needs more. my question now is can we still lower j-bar on frame to get to 5 inches of drop even though it will be going down hill towards frame? also does anyone have to start rear % at 58-59% for slick,sandy track?

[anissa5]

You must be measureing you j-bar wrong at ride height measure from the ground to the chassis mount then measure from the ground to the pinion mount .

[racin6mod]

well guys we set the j-bar level and still had over 6 inches of drop. car still didnt work so well. we changed the pinion to 10 degrees and added weight and full tank of gas for feature, and car seemed to be better, but still needs more. my question now is can we still lower j-bar on frame to get to 5 inches of drop even though it will be going down hill towards frame? also does anyone have to start rear % at 58-59% for slick,sandy track?

depending on how the j-bar is bent(some have a bigger bend than others)you can have a angle that looks lower at the frame but that bar only knows the heim locations.

you need to keep the chassis balanced to much rear will over power the front tires and the thing will only go straight.balance in the chassis is key on a dry sandy track

[not clamped up]

On the several cars I have tried to help the last couple of years 61/2 up from the bottom of the frame to the center of the J-bar bolt and above the pinion (would be the top hole on most plates) if its a quickchange is a good place to start,i've read this topic a few times but I still don't think I know what your after,there is some good answers posted,one thing I would do is measure between the back tires and make sure the pullbar is at least in the center if its to the right then thats probably alot of your issues,and I don't know who is telling you to put a 450 in the RF but thats a great way to take more drive out of the car unless your running a 5th arm with a 5th coil.

[bottomfeeder]

we run a 9 inch. we are going to move j-bar down on frame some more to get closer to 5 inches of drop. i just dont get it its a 5 inch rake j-bar and level should be 5inches of drop, but its not, no matter were we measure from. so were going down hill towards frame mount. also going to try to mess with pullbar preload, to keep drive shaft from going over center. we also found out guys using 450 and 400 lb. rf spring are running on bump stops.
not clamped up - we are trying to get car to have more drive off the corners, car wants to be completely side ways when on the gas. if we feather car off corner everyone drives by us.

[powerslide]

we run a 9 inch. we are going to move j-bar down on frame some more to get closer to 5 inches of drop. i just dont get it its a 5 inch rake j-bar and level should be 5inches of drop, but its not, no matter were we measure from. so were going down hill towards frame mount. also going to try to mess with pullbar preload, to keep drive shaft from going over center. we also found out guys using 450 and 400 lb. rf spring are running on bump stops.
not clamped up - we are trying to get car to have more drive off the corners, car wants to be completely side ways when on the gas. if we feather car off corner everyone drives by us.

I think you are worried about some wrong things. dont worry about what the j-bar looks like in the car only two mounting points.
When measuring jbar people use the difference in the measurements between the pinion side and frame side. This is the "split" You take a measurement from floor to center of bolt on pinion then a measurment from center of frame bolt to floor. the difference is the split. on a 9in most people start around even w/ the pinion or just below.

Washed up was asking about the "drop" in the LR. Meaning take measurement at R/H from top of birdcage to somewhere above. Jack LR up infront of LR tire until chain or shock or underslung stops the rearend. Measure in same spot again. the difference is the drop in the LR.

As you adjust pinion angle it messes with the angle in the j-bar as well because it is moving it up and down.

I'm not trying to be mean just want to make sure we are looking at the correct things and seeing eye to eye.

I'm with everyone else it sounds like the j-bar is too high on the frame. measure like i mentioned above on the pinion then place the j-bar about 5in higher on the frame(dont worry about how it looks in car). you are also running alot of LR bar angle might try backing it down a hole on each bar.

Also we still havent heard how much LR drop you are running.

Also if those %'s are w/ driver doesnt look like you have enough Ls%

[not clamped up]

I agree with powerslide dropping both L.S. bars will help and I would put the 600 in the RF and the 550 in the LF,I just had a guy do these same things including what they are telling you with the J-bar and it fixed the sideways down the straights problem he was having.There are still plenty of cars winning races with a heavier RF spring than the left.

[powerslide]

also interested to know how much trail you have. If its over 1/4in try shortening it up.

[bottomfeeder]

ok guys, heres what weve done. we have lowered our top left bar 2 holes, we are lowering our j-bar to 5 inches drop from center of bolt on frame side to center of bolt on rear end side. these %'s are without driver, we dont scale with driver in car. weve been told not to. i will check on lr drop tonight, weve been getting so much info lately that it just seems to get overwelming sometimes. we try to do things that we get common input on. big step from stock car to these mods.

[not clamped up]

The Left Bottom Bar needs to go down also,it is the bar that allows the LR to move forward,the more angle in the bar the further foward it can move,making the left side of the car shorter on wheelbase than the right,just a thought.

[bottomfeeder]

worked on car last night. car has 3 inches of lr drop. car has 1/4 inch of lead. also lowered left bottom bar one hole. will let you know after this weekend. thanks