Rear jumps to the right while power shifting
01-22-2015, 07:03 PM
#12
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
I suggest you measure the heights of the chassis-side and axle-side pivot bolt centers. Pictures can be deceiving; it looks like the passenger side LCA is inclined upward going toward the axle, as does the driver side LCA. But the front of the driver side LCA is too obscured to tell with any certainty where its chassis-side bolt is.
You really want to measure these heights with somebody sitting in the driver seat or with a bunch of barbell weights standing in for your weight. It makes a difference, and you might as well measure the car up the way it would be when you drive it.
Norm
You really want to measure these heights with somebody sitting in the driver seat or with a bunch of barbell weights standing in for your weight. It makes a difference, and you might as well measure the car up the way it would be when you drive it.
Norm
Last edited by Norm Peterson; 01-22-2015 at 07:05 PM.
01-24-2015, 03:11 PM
#14
2nd Gear Member
Thread Starter
Join Date: Sep 2010
Location: TX
Posts: 220
I have a suspicion that axle roll steer may be involved. Lowering without relo brackets and LCA inclination adjustment results in significantly more axle steer than OE, and when the car briefly "un-squats" during the upshift it will "un-steer" slightly as well. You'd have been compensating for this steer in 1st gear, but the sudden loss of some axle steer will catch you with too much steering wheel input to the left with an axle that suddenly wants to run less to the left (which will then feel like it steered a little to the right).
Norm
Norm
01-24-2015, 06:55 PM
#15
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
For LCAs I have some made by Currie (I think they called them something like 'Currectrac'). Pretty beefy units with Johnny-joints on the axle ends and poly bushings at the other. I tweaked the poly ends a little to permit freer rotation and reduced "bind". What's kind of funny is that the only place that listed them specifically was the same small GM intermediate-oriented business that I'd had some dealings with earlier, when I was modifying a '79 Malibu.
My car is still on its OE springs and not using relo brackets of any sort. Some measurements I made quite a long time ago put the axle pivot centers 3/8" higher than the chassis-side pivot centers.
If I try hard enough, it'll wheel-hop on a soaking-wet road from a roll in 1st gear, but I've only done that a couple of times when trying to determine how effective my car's TC was (it was absolutely worthless in that situation). I have no comparable dry weather data, sorry.
Norm
My car is still on its OE springs and not using relo brackets of any sort. Some measurements I made quite a long time ago put the axle pivot centers 3/8" higher than the chassis-side pivot centers.
If I try hard enough, it'll wheel-hop on a soaking-wet road from a roll in 1st gear, but I've only done that a couple of times when trying to determine how effective my car's TC was (it was absolutely worthless in that situation). I have no comparable dry weather data, sorry.
Norm
Last edited by Norm Peterson; 01-24-2015 at 06:56 PM. Reason: editd out the blank lines that forum software insists on inserting - can't anybody fix this?
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