View Full Version : Swing Arm sidebite
07-27-2010, 01:43 PM
I am burning half the tread width off of rr, car has great forward bite but no sidebite. I have not been spinning off corner. My straight bar is attached to rr axle tube and is hooked to lr 4 inches up off under rail...springs ar lr 325, rr 300, rf 900, lf 800.. 50lbs wedge, 48.8% cross weight, 57% rear, 55% left.. any and all help would be great..
07-27-2010, 03:19 PM
One intial questions is the J-bar placement. You stated 4" off the rail. The measurement needed is the hdight difference between the axle mount and frame mount. A good starting point is 5"-6" difference. Also, where is this bar mounted in relationship to the pinion? In-line is a good spot, if not just below. Measure to that point to the ground and set the frame mount 5"-6" above that measurement. It will raise the roll center.
I'm sure there are other thoughts out here.
07-27-2010, 04:57 PM
the bar is mounted 2 inches below pinion on the right side and frame mount is 4 inches up from underslung rail on the left rear.
07-27-2010, 06:39 PM
I have never seen a swingarm car work with less than 180 lbs of wedge. Most use around 225 lbs of LR bite. Im talking about true swingarm where the spring is on the arm on both sides. Since the swingarm uses weight instead of the upper bar for drive. Also, swingarms tend to use much softer pullbars as compared to 4 bars.
Plus from the groun d what is the difference to each of you straight bar mounting hieghts like LFMotorsports said.
07-27-2010, 08:33 PM
I'm guessing that this car has a long panhard bar running behind the rear end to the axle tube? Have you tried to lower the rr bar? Have you tried a softer spring on rr or different off set on rr, like going from a 3 to a 4? Good luck.
07-27-2010, 08:53 PM
What is your RR tire pressure.
07-27-2010, 10:05 PM
We run one of the RC Rayburn Modifieds, your numbers are way off if you're running a true swingarm car.
Springs; LF 750, RF 700 or 800 depending on track size etc..., RR 500 or 400 again depending on track size and slickness, LR 350
We run our pan hard bar on the right side also, couldn't tell you the measurements because we NEVER move it, chassis builder and Rayburn said leave it alone!
Weights w/driver LF 520ish, RF 470 ish, LR 830ish, RR 650ish, we try and start with 180lbs of bite, feature or dryslick we take two out of left and put two in right. We also hang 25lbs lead RR
Percentages; Cross 52.5 to 53, Left 54, Rear 59 to 60%.
Bar angles, RR 5 degrees up, RF don't know never moved chassis builder set and said leave it alone. LR we start out 1 hole down from level, usually move the bar down one more hole for feature. If the track is real slick we'll move the RR bar two holes up from level. This will let the car sit on the RR a little longer before transfer.
Total car weight with driver and ready for heat is 2450.
As far as pressure's we run UMP Hoosier's LF 11, RF 15, RR 10, LR 10 (heat) 8 (feature). Goodluck!
07-28-2010, 07:03 AM
Yes this car is a true swing arm.. I have tried 200lbs of left rear and 100lbs of lr and the car was horrible both nights. with this much left rear the car feels the best. where i run we have an open tire rule and i run american racer mediums so air is left side 12 right side 15.. i race on a high banked shale race track.. my straight bar is mounted behind the rear end going to left rear. bar angles start at 7 degrees down hill. lr bar is in middle and rr bar is 1 hole above middle. car is nuetral i can take off straight bar and car doesnt roll over to right or left at ride height..i have a set of 400 lb springs for the rear that i can put on.
07-28-2010, 07:12 AM
I would lower the rr bar down and be sure to reset everything to your specs. Good luck.
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