Suspension and Alignment: A Saga

HazN

HazN

True Classic
Welcome intrepid reader. I have a tale that in which mystery abounds. Many years ago, I installed Vick’s performance springs with KYB gas struts in my ’86 X1/9. After a while, I noticed that the rear was lower than the front. Measuring the pinch welds behind the front wheels and in front of the rear wheels, the difference was 1¼”. I then fabricated spacers that fit at the top of the struts in the rear. The car was now level. I drove it this way for more years. Noticing some tire wear in the front, I decided to have a four wheel alignment. The alignment was done to the specifications in the manual. Afterwards, a very strange thing happened to the steering. If the steering wheel was straight, when I went around a right intersection turn, the steering wheel was cocked to the right about 20° when driving straight. After a left intersection, the steering wheel returned to straight. Thinking the steering rack was shifting in its mounts, I replaced the bushings. No change. I talked to someone at Vick’s and was informed that the rear was not sitting low, but the front was sitting high due, I think, to the gas struts lifting it. I the decided to remove the spacers in the rear and lower the front by cutting off ½ coil from the front. I also installed camber bolts but they are at the null setting for future alignment. Now, I know that this redo affected the alignment front and rear. The car is now ½” high in the front and I can live with that. Upon driving the car in this new attitude, the steering wheel no longer did the funky thing and remained on center regardless of the turns. So it seems that the stock specs for the alignment may have been the culprit. I trust the shop that did the alignment. So my question is this: What does the collective mind of the Forum recommend for the alignment specs? Also, as a side issue, I’m going to replace the 185-60H15 tires. I seems the most available are the Achilles and Federal brands. Recommendations? I drive the local rural twisties with occasional enthusiasm.

Thanks in advance for any input.
 
My recommendations.

Ok, here is my recommendations on this.

Ride height. Make sure the inner mounting point for the lower a-arm (rear) or lower control arm (front) are level with the center of the lower ball joint. This should give you the height you are looking for and keep the car with as much suspension travel as you can get without having to do tricks, such as flipping the tie rods over to accommodate the height change.

For the front, on my daily driver I prefer to drive it with about 1/8" toe out at the front and 1/8" toe in at the rear. However, while this means you will have a car which will dive into corners, it also means it will want to wander around a bit on long straights.

if you are doing more highway the twisties, then I would suggest 1/16" toe in on the front to keep things straight.

I would also stick to stock caster settings as well.

Hope this helps.
 
The tires are 185/60/15? This would make the overall wheel/tire diameter about 23.7" which is over an inch larger than it should be.

Wheel/tire rubbing anywhere? This problem is aggravated when he exxe is lowered.

Ideally the wheel/tire combo should be about 22.5" overall.


Toe affects tire wear more than camber. It is possible the ball joints on the ends of the steering rack, rear toe adjusters or other ball joints are knackared. Based in the description, the toe is front or rear or both is changing after the suspension has been loaded from cornering.


***Check all the ball joints, bushings and all suspension related components, ascertain they are in absolute good working order before proceeding.***

As for toe, my preference is 0 toe in the front, about 2-3mm toe in for the rear. Make absolute sure the toe front -vs- rear is relative to each other. This means no setting up the rear toe using toe plates. Ideally, the front & rear toe should be adjusted with a precision string rectangle on the chassis relative to the wheels. What I have learned after designing and building and using precision hub stands for chassis alignment, the wheels can add a significant amount of error to the overall precision of chassis alignment.

It is normal for the exxe to be sightly nose up. This has proven to be the case after the LeMons racer has been corner weighted to 50% cross weights with 45% weight front / 55% weight rear. Stock is closer to 60% rear, 40% front.

IMG_0899.JPG


As for camber, about on degree negative in the front, about one to two degrees negative in the rear for a street or road car. Road race cars on radials are going to need much more negative camber than this to achieve good stick. When all is properly set up the tire temperatures all around, inside, middle outside of the tire should have no more than a 10 degree F spread. When this has been achieved, tire wear is good with good stick and uniform tire wear with no scrubbing.


Bernice
 
Bernice,

Love those hub stands. Can you share the design?
I think I'd like to make up a set like that.
 
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