race front & rear suspension related info

grumpyvette

Administrator
Staff member
Tubing the rear, setting up a 4 link etc.


Tubing the rear & suspension changes

links are well worth reading thru

http://phors.locost7.info/contents.htm

http://dazed.home.bresnan.net/narrowinga9.html

http://kevinstang.com/Ninecase.htm

http://www.therangerstation.com/tech_li ... xles.shtml

http://www.mustangsandmore.com/ubb/Ford ... sions.html

viewtopic.php?f=46&t=373&p=455#p455

http://www.crankshaftcoalition.com/wiki ... _a_rearend

http://www.bhjproducts.com/bhj_content/ ... ng/dnk.php

http://www.maxchevy.com/tech/2008/iii_9 ... ion-1.html

http://www.sears.com/shc/s/p_10153_1260 ... rigin=prod

viewtopic.php?f=33&t=667

http://www.carcraft.com/techarticles/cc ... to_01.html

http://www.hotchkis.net/technical_articles.html

http://www.carcraft.com/techarticles/cc ... ndex1.html

http://www.chevyhiperformance.com/techa ... rings.html

http://www.hardcore50.com/technical_art ... gPart2.htm

http://cgi.ebay.com/ebaymotors/%22How-T ... 116003r479

http://www.baselinesuspensions.com/info ... ag_Car.htm

http://home.earthlink.net/~whshope/

http://www.suicidedoors.com/catalog/4-link-parts

http://www.ridetech.com/forum/

http://www.maxchevy.com/tech/2008/iii_9 ... ion-1.html

http://www.buickperformance.com/Pinion.htm

http://picasaweb.google.com/fritz199090/WheelTubs#

http://www.popularhotrodding.com/tech/0 ... index.html

http://www.carcraft.com/howto/ccrp_0512 ... nsion.html

http://www.wolferacecraft.com/detail.aspx?ID=184

http://oldsjunction.classicoldsmobile.c ... /ofsus.htm

http://www.jbrcaustralia.com/rearsuspension.htm

http://autofabcart.net/rearsuspension.aspx

http://www.streetrodderweb.com/tech/090 ... index.html

http://www.lescanfield.info/rear_suspension.htm

http://www.jegs.com/webapp/wcs/stores/s ... 2621006780

http://www.jegs.com/i/Competition+Engin ... 7/10002/-1

http://www.globalwest.net/TLC_Drag_Raci ... nsion..htm

http://www.jegs.com/i/Jegster/550/40011/10002/-1

http://www.jegs.com/i/Jegster/550/40020/10002/-1

http://www.jegs.com/i/Jegster/550/40019/10002/-1

ccrp_0806_14_z+chevy_chevelle_rear_axle_swap+compare_ford_9_inch_to_dana_s60.jpg

dana 60 vs 12 bolt chevy
 
Tracy /AKA IROCKZ4me posted this

Both, pinion angle and instant center are effected by the torque arm. Lowering the car will effect both
Negative pinion angle is when the nose of the carrier housing (the pinion area) is pointing down towards the ground instead of parallel with the tailshaft of the transmission. Positive pinion angle is when the carrier housing & pinion are pointing up from the parallel line.
Pinion angle is measured at the pinion when the vehicle is sitting at rest and is the angle of the pinion, it is not necissarily the angle of the torque arm.

If you do not change the outside diameter of the rear tires, and you lower the vehicle with springs then the rear axle is still at the same height from the ground, but the front torque arm mount is lower in relation to both the ground and the rear axle. Since the rear of the torque arm is solidly attached to the rear axle, If you lower the front of the torque arm that will twist the front of the axle down. This would cause negative pinion angle. To return the pinon angle to 0° or to just make the pinion angle adjustable you can use a torque arm with a turnbuckle or threaded rod-end at the rear axle end of the torque arm. This will allow for adjustment of the pinion angle in relation to the trannies tailshaft. You can also change pinion angle by moving the front mount of the torque arm up or down but that also changes the point known as the instant center.
Ideally you want 0° pinion angle at all times.
When using constant velocity U-joint driveshafts, both ends must be at the same angle (0° difference) to maintain constant velocity. Any angle difference, positive or negative will cause driveshaft U-joint binding with pulsing and surging. This will eat U-joints over time and the vibration, pulsing and surging will cause traction loss and the binding wll slow the car.
Drag cars are set up with negative pinion angle when at rest (usually around -4° or so) so that when the axle twists under extreme force from acceleration and the pinion moves up towards the floor board the pinion angle will be 0°. The idea is to have 0° pinion angle while accelerating so there is no surging, pulsing or binding in the driveline. If the pinion has positive angle (angled up) when at rest and then when under acceleration it moves up more, that would throw the driveshaft and U-joints way out of line and cause a very large amount of bind and surge.

Now for the fun stuff:

Where the instant center is effects traction much more than pinion angle. When the rear axle twists under acceleration it applies a rotating force on the control arms and the torque arm. This force pushes up and back on the body of car. The point at which this force is concentrated is called the instant center Moving the instant center back will push up on the car body over the rear tires, forcing the tires down into the pavement. Think about doing pushups. Your arms lift your shoulders away from the ground while pushing your hands into the ground. Moving the instant center up in relation to the cars center of gravity will help transfer more of the front weight of the car onto the back tires.

Finding the instant center is easy on a car with a four-link rear suspension. Draw a straight line through the center of the front and rear bushings of the upper rear control arms to the front of the car. Do the same thing for the lower rear control arm. The point where the lines cross is the instant center.
Move the mounting location of either the front or rear mounting location of either the upper or lower control arms and you will move the instant center. The front and rear mounting points of both the upper and lower rear control arms of a four link are static. Their bushings pivot around bolts and have no forward or backward movement.
The front and rear mounting location of the rear control arms on an F-body is also static. The rear mount of the torque arm is also static but the torque arms front mount is not. The front of the torque arm not only rotates in the bushing but it also slides forward and backward in the mount. This makes it a little more difficult to find the instant center in an F-body, but it is still the same basic relationship between the torque arm and the control arms. In simplest terms the torque arm more or less replaces the upper control arms of a four-link.

On an F body, instant center is affected by the angle of the torque arm (front mount height in relation to the axle), the length of its front mounting location from the rear axle, and the angle (front and rear mounting locations) of the rear control arms.

When Tory moved his front torque arm mount up he moved his instant center upwards, in relation to the center of gravity, helping to transfer more of the weight of the car onto the rear tires. Moving the front of the torque arm up twists the axle and would cause positive pinion angle. When you add the natural twist of the axle when under acceleration it would go even more positive causing bind and pulsing in the U-joints. The pinion angle would then need to be adjusted to compensate unless the car had too much negative pinion angle before moving the front torque arm mount up.

If you lower an F-body you lower the front mount of the torque arm in relation to the rear mount of the torque arm, moving the instant center down. You also move the front mounting location of the rear control arm down in relation to its rear mount. Due to the short length of the rear control arms their angle changes drasticly. This moves the instant center way further forward and way, way down. This will seriously hurt traction. A lowered car needs to have the mount of the axle end of the rear control arm lowered also to correct the instant center geometry.

------------------

Tracy /AKA IROCKZ4me
 
Holy.... I am searching for hours and the gold mine is right here!!!!

Thanks all!
 
stick to the site for a few minutes, and use the search feature and you might be surprised at what you find.
keep in mind, when narrowing a rear differential, the non-equal length tubes that house the axles on most rear differentials are the result of the pinion gear being located to one side of the ring gear, thus making the drive shaft center line location slightly offset, if the person doing the narrowing had experience, and assuming the rear differentials are getting re-installed in the same car after being narrowed, he measures the flange to flange distance of the rear provided and subtracts the same amount from each side,to get the desired width, necessary, then cuts the tubes , re-welds fresh flanges, measures carefully and orders matching shorter axles, on a RACE CAR, you usually tell the guy the exact lengths you want on each tube to get the ideal drive shaft location for your application.
you may be able to cut and relocate your spring perches to compensate and get the tires centered in the wheel wells if its only an inch or so, difference, but ideally you get the tubes and axles cut the first time to center the tires correctly, and that your certainly not restricted to a common brand of brakes and axles etc, if you want a Dana 60 center with ford brakes on the tube ends you can certainly have the correct bastard axles and flanges welded or machined to fit your particular application with mopar splines and ford bearing and brake flanges, possibly even a Chevy bolt pattern if you want too re-use that wheel. just be VERY carefully measuring and explaining to the guy fabricating the components exactly what your doing and ASK for advice because some components are far more common and stronger and less expensive than others
 
Back
Top