Looking for some insight on a swing arm modified

I just bought an old swing arm modified to get me through the rest of this season. I don't know a whole lot about swing arm cars, I was wondering if I can get some pointers. The springs in the car are currently a 600 rf, 650 lf, 375 lr and a 350 rr. Shocks are 6 lf, 3/5 rf, 9/2 lr and 4 rr. Rear end is square in the car, no lead. Both of The top bars are on a slider, all the way down. the bottom bar brackets have 2 sets of 3 holes. Both arms are in the furthest back, middle hole now. Its got a biscuit style pull bar on it, no lift arm. It came with a J bar and a short panhard bar(12" center to center on heims). Running Hoosier e mod tires. Its got a metric clip with nova lowers. Its supposed to be an old lightning, but I have no idea for sure what it is. I'm curious on scale numbers too. Use to be on my buddies old swing arm car he'd run 280lbs of bite on dry slick, and 190 on a tacky track. I'm a 4 bar guy so that sounds crazy to me. Is that worth trying? He was always real low on cross too, 45-46%. Seems like you'd want somewhere around 49-52%? I'd appreciate any opinions.

Big lr bite numbers were very common on swing arm cars. I would consider taking your friends advice to start swing arm cars are a different animal.

Swingarms are great on a rough track and have good forward bite ... if you keep the car on the LR spring. My experience with them is they don't have the side bite of a 4-bar, but a driving adjustment will help you. My first impressions with your set up is that you are a little too soft on the RR and RF (springs)...close, but a little soft. I personally would square or flip the front springs, soften or square the front shocks (40s or 50s...and start without the split-valves) and take half the angle out of the top bars (even less on the RR, assuming the bottom links are 15". Try 50s on the back shocks to start. Try a little more angle on the LR link than the RR bottom (start at 0 degrees on the RR bottom bar).

Good luck

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Originally Posted by langdonracing48

I just bought an old swing arm modified to get me through the rest of this season. I don't know a whole lot about swing arm cars, I was wondering if I can get some pointers. The springs in the car are currently a 600 rf, 650 lf, 375 lr and a 350 rr. Shocks are 6 lf, 3/5 rf, 9/2 lr and 4 rr. Rear end is square in the car, no lead. Both of The top bars are on a slider, all the way down. the bottom bar brackets have 2 sets of 3 holes. Both arms are in the furthest back, middle hole now. Its got a biscuit style pull bar on it, no lift arm. It came with a J bar and a short panhard bar(12" center to center on heims). Running Hoosier e mod tires. Its got a metric clip with nova lowers. Its supposed to be an old lightning, but I have no idea for sure what it is. I'm curious on scale numbers too. Use to be on my buddies old swing arm car he'd run 280lbs of bite on dry slick, and 190 on a tacky track. I'm a 4 bar guy so that sounds crazy to me. Is that worth trying? He was always real low on cross too, 45-46%. Seems like you'd want somewhere around 49-52%? I'd appreciate any opinions.

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It doesn't sound like one of our old cars, but I would run the J bar, because the straight bar sounds too short. Run stiffer front springs and run 100 lbs RF heavy, like 850 and 750. Bite numbers from 150 to 200 are common. If your buddies car was that low on cross with that much bite it must have had a bunch of left side weight %. Try it at 54% left with driver and make the front wheels even in weight. That should get you in the ballpark.

Thank you everyone. Sounds like i will probably like this a lot. i like a free car, as long as its going forward. i appreciate the help. ill get some heavier springs and some shocks and hopefully will get to try it out next friday.

LR rear top bar down in the rear adds lift and traction to that corner.
RR rear top bar down early in night to add steer (if needed) slicker track gets raise to level
200-240 lbs lr bite
I had great success with a 700lf 900fr
what length are your rear swing arms?
are the shocks through spring, or on rear of birdcage?

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Originally Posted by HEAVY DUTY

It doesn't sound like one of our old cars, but I would run the J bar, because the straight bar sounds too short. Run stiffer front springs and run 100 lbs RF heavy, like 850 and 750. Bite numbers from 150 to 200 are common. If your buddies car was that low on cross with that much bite it must have had a bunch of left side weight %. Try it at 54% left with driver and make the front wheels even in weight. That should get you in the ballpark.

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Agree with HD as usual. Shorty works the LR which you got a Sh!t ton of. That much bite low cross you"d have to strap an elephant to the LR 1/4 panel to get those numbers. Post results as I would love to here Swing can run out front ! Its my Fav

Justadddirt, both top and bottom arms are 19" center to center on the heims. Spring is on a weight jack with shock behind axle on birdcage.

1blacksheep, I had the opportunity to run a loose gruff swing arm mod Saturday night. The front end geometry was way off so it was pretty tight, but holy forward bite! That thing had a ton of it! They are.gonna get the front end taken care of and I'm going to drive it again this weekend. I think the.thing can win a bunch of races. And it looks pretty similar to my car so everything I learn from this I can hopefully apply to my car

i have said numerous times, that my swing arm car from 05-07 had more traction than any 4 link car I have ever driven. just a bit harder to get side bite in the swinger.

What rear springs should you run on the swing arms and shocks on the rear of the birdcages or should you run the shocks and spring together thanks

ill still rip that ulgy door bar off mike. hang on buddy!!!

anissa

If you run the shock and spring together, you will have to have a set of shocks built.
If you run shock on back of birdcage it should be an off the shock.
Spring rates depend on lengths of arm, and were the pivot point is (motion ratio)
My old lightnings were a 17" bar, and about a 50% motion ratio, which meant a 400 lb spring was a 200.

Please do Jason! Lol!