too much pinion angle?

Posted By: rebel

too much pinion angle? - 09/16/11 11:55 PM

how will too much pinion angle affect my car? with trying to get my car as low as possible we found the pinion angle was pointing upward. i had my chassis man extend the holes so i can relocate the front ladder bar down further. unfortunatley the hole i want to use snaggs the rose joint on part of the chassis. so being the lazy buggar i am, i used the next hole down but found my pinion angle is about 6*. how is my car likely to react at this angle? it was already lifting the front wheels in the original position but the car would run straight and handle well at speed 140mph.

Posted By: dOrk !

Re: too much pinion angle? - 09/17/11 12:17 AM

With a ladder-bar or 4-link ...you want as little angle as possible - since there is no angle movement(ORE should not be)

If there is too much angle ... U-joints can wear-out and or break ..

Posted By: gregsdart

Re: too much pinion angle? - 09/17/11 01:00 AM

You may be able to reduce the angle by raising the tail shaft of the engine/trans. See if you have room for shims. If you can get it below five I would think it should be OK. When you think about it, recommended for a leaf suspension is 5 to 7, and the rear axle is not angled from being under load on deceleration or real light loads. So it doesn't sound as critical at 5 degrees as we think.

Posted By: Cab_Burge

Re: too much pinion angle? - 09/17/11 05:25 AM

The lower the bars the less it will lift the chassis

Usually

Go try it, also try measuring(the pinion angle) the car at rest and at full front end extension hieght with the front wheels off the ground also, see how much it changes and go from there, watch the rear U joint angle and clearances

Posted By: rebel

Re: too much pinion angle? - 09/17/11 10:56 PM

i thought the pinion pointing downward would cause the front to lift? or have i got this a about face? at the present set up we lifted the front & pretty much dropped it straight back down. i was hoping to carry them a little further & was told lower the bars will do this. i cant test at present as the engine & trans are out while the car is getting a facelift but do adjustments at the rear whilst this is happening.

Posted By: MR_P_BODY

Re: too much pinion angle? - 09/17/11 11:40 PM

Quote:

i thought the pinion pointing downward would cause the front to lift? or have i got this a about face? at the present set up we lifted the front & pretty much dropped it straight back down. i was hoping to carry them a little further & was told lower the bars will do this. i cant test at present as the engine & trans are out while the car is getting a facelift but do adjustments at the rear whilst this is happening.

Actually the higher the front point the harder the
hit... lower is softer... if it was out farther it
would tend to lift the front more(closer to the CG
of the car)... from what your saying it pops it up
then drops, its hitting the tire too hard... also
the lower will tend to push more

Posted By: CMcAllister

Re: too much pinion angle? - 09/18/11 04:07 AM

Pinion angle is a setting, not an adjustment.

Posted By: gregsdart

Re: too much pinion angle? - 09/18/11 02:15 PM

Quote:

i thought the pinion pointing downward would cause the front to lift? or have i got this a about face? at the present set up we lifted the front & pretty much dropped it straight back down. i was hoping to carry them a little further & was told lower the bars will do this. i cant test at present as the engine & trans are out while the car is getting a facelift but do adjustments at the rear whilst this is happening.

Like Mr P said, a lower point will "push" . This means it will help it pitch rotate upward in front on the hit. You will see a less aggressive lift in the back, or it may drop slightly if you end up with the front ladder bar below the neutral line. The neutral line is a line from the rear tire at ground level to about the top of the front tire.
Basically the lower point will give the front end a little help ,but engine torque has to be very high to carry the fronts out further by any large amount.