Place the rear end in the chassis and bolt up the torque tube. Set the axles on 6” set-up blocks if it’s a standard chassis. 5” on the left side and 6” on the right if it’s a 1" raised rail car. 5.5” on the left side and 6” on the right if it’s a 1/2" raised rail car. Level your chassis with a level or an angle finder. Secure the birdcages with spacers and the wheel nuts. Measure the distance from the rear round machined portion of the torque tube to the outer edge of the chassis by placing a straight edge vertically against the frame.
Center the rear end by equalizing this distance on both sides of the car. This distance should measure between 10 1/8” and 10 ¼”. Now with the rear centered side-to-side, start with the right side and measure from the leading edge of the rear axle to the front edge of the motor plate. On a 40” car this measurement is 38 5/8”. Roll the axle forward or back on the blocks to achieve the correct distance. Once you have secured that distance on the right side check the left side. Ensuring that the rear is still centered in the frame and the right side measures correct, the left side may vary by as much as 1/16”. This is generally left to lie as is.
With the radius rods connected, place a level or angle finder on the flat bottom portion of each bird cage and adjust the rods so that each cage is level with the bottom frame rail. Now bring your rear arms up to each bird cage flag and adjust each rod end so that the lower bird cage bolts slide freely through the cage and the rod end. Having completed this, recheck all of your measurements to ensure that nothing was moved during the previous processes. If all measures correct bring your jacobs ladder to the rod end or clevis and adjust the rod end or clevis in or out so that the bolt also slides freely. With these operations complete check your work by ensuring the torque ball is free and the jacobs ladder is not bound. Now you are ready for race height setup blocks and stops.
Set the front axle on 4” set-up blocks if a standard chassis. A 3” and 4” if it is a 1" raised rail car. A 3.5” and 4” if it is a 1/2" raised rail car.
Offset the axle 1” to the left side by adjusting the sway bar. This gives clearance to the left front torsion arm and combo steering arm.
Measure 13 5/8” from the center of the right front torsion tube to the center of the axle on the right side.fter roughing in the radius rods to this measurement, measure from the leading edge of the rear axle (still on 6” blocks) to the rear edge of the front axle on the right side.
After having gained this measurement we will set the lead.
Check the left side the same way and adjust the rod length so that the left measurement is equal to or up to ¼” set back depending upon driver preference and size of track. With the axle now square we can adjust the caster. Place an angle finder on the right front steering arm . Adjust the top right front radius rod so that the angle reads anywhere from 6 to 10 degrees. Again this is driver preference, some drivers like more positive feel in the front end than others. With this complete you can drop the axle down to race height set-up blocks and adjust the stops. Don’t forget to set the tow. An 1/8” - 3/16" of tow out is generally the norm.
Torsion bars must always twist in the direction it originally twist. When twisted in opposite direction car will begin to sag and loose ride height. Torsion bar will also loose ability to crisply rebound.
RF & LR Bars can be exchanged.
RR & LF Bars can be exchanged.
Leave a gap of 1/16” of free play between stop and torsion tube bushing. To allow for torsion bar to wind up without causing a bind. Torque pinch bolt to 20 ft/lbs on all aluminum arms and stops. Over torquing will distort splined hole making installation and removal difficult. Torque pinch bolt to 30 ft/lbs on all steel stops. Leave ¼” maximum of free bolt under stop to allow for adjustment. Anymore than this could cause failure to adjuster bolt drastically changing setup. Use thread lube on all pinch and adjuster bolts. A dry fastener cannot be Properly torqued. Grease entire length of torsion bar. Leaving center of bar dry can cause excessive friction as bar winds up and bows and rubs against inside of torsion tube. Replace torsion bars every 20 nights to retain a crisp feel. Torsion bars don’t last forever and eventually become slow in response, causing your car to be lazy and non responsive to adjustments.
Replace torsion bars after a hard crash. Hard crashes can wind your torsion bars past there yield point causing a permanent twist in your torsion bar.
When cleaning torsion bars inspect for nicks and cracks and shiny spots. Shiny spots can indicate a bent torsion tube which can cause binding and friction. Nicks and scratches will lead to permanent bar failure, replace torsion bar immediately. When installing torsion bars it’s very important to make sure they spin inside the bushings with ease. A torsion bar that is hard to turn could be a bent torsion tube or bent torsion bar. A bent torsion tube will not let the bar wind up correctly as it will first bow the bar then start to wind up. Discard bent torsion bar Always when cleaning torsion bars, inspect torsion stop pad to make sure it has not dimpled the torsion tube. If you can feel a dimple inside the torsion tube, the stop pad has failed and will cause the torsion tube to bind up on the torsion bar.