Factory ride height?

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PA Dodger

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I'm in the process of a disc brake swap along with a suspension rebuild/upgrade. I like the way my car sits now. I think it's a little lower than stock. I took ride height measurements before I started the project. I measured from the floor to the top center of the wheel openings front and rear. Can anyone tell me what the factory ride height is supposed to be for a '69 Dart GT with a 340? I think maybe the leaf springs were HD for a 340 so the rear may be a little higher? I don't want to order springs that put the back end up in the air and also, the PST 1.03 torsion bars that lower the car might put my car where it is now.
 

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I
think it's a little lower than stock. I took ride height measurements before I started the project. I measured from the floor to the top center of the wheel openings front and rear

Measuring from body parts is of no use, as suspension has to be set relative to its components, in relation to floor. Body parts are not consistently mounted, and are aligned to mate with their neighbor, not suspension parts. These cars don’t have close build tolerances.

Per Factory Service manual:

Front suspension heights must be held to specification for a satisfactory ride, correct appearance (this subjective to today’s eye), proper front wheel alignment and reduced tire wear,

First vehicle has to have full tank of fuel, no passengers, no luggage in trunk excepting spare tire & jack, properly inflated tires, and on sitting on level floor.

Clean all crud from lowest portion of steering knuckle arm, and height adjustment blades directly below lower control arm inner pivots.

Jounce front of vehicle several times releasing it on a downward motion.

Measure from lowest point of adjusting blade to floor (measurement A), and from lowest point of steering knuckle arm to floor (measurement B); measure only one side at a time.

Subtract distance A from B and adjust height by big bolt in center of LCA adjusting as necessary until A-B= 2 ½” +/- 1/8th inch. Per 1967 A Body height spec for both standard & HD suspension; I suspect it is the same for a 1968 & 69 A bodies.

After every adjustment jounce front end before remeasuring. Both sides should be measured even though one side was adjusted. Adjust other side.

Ping pong left to right making adjustments until each side is within 1/8th inch of the other.

I think maybe the leaf springs were HD for a 340 so the rear may be a little higher

I’m not fluent in ’69 340 rear suspension, but suspect it is identical to S Cuda set-up which I believe used a six lief factory ride height rear spring. Even though a six lief spring was used, it was not significantly stiffer than stock springs, but provided better axel control under hard acceleration.

Your choice of one inch torsion bars is a good one; these cars left the factory with mushy low spring rates on the front end compared to today’s cars. GM and Ford’s suspensions were even sloppier than Mopar’s in the day providing almost no suspension control, they were simply dreadful wallowing hogs.

I have fitted six lief stock ride height rear springs to My Dart rag top with an 8 3/4th inch rear, with 0.940” torsion bars all at factory ride height, and car handles neutrally with a well behaved rear axle.

Rear spring ride height changes in one inch increments are available if one desires a slight lift of rear end. As rear of an A body over stock ride height increases, the more tail happy (tendency to over steer) it will become.

Call Spring N Things… ESPO for the details, A body rear springs are not listed on their site: http://www.springsnthings.com/
 
Mopar defined front "ride height" by measuring two points on the lower control arm compared to the ground -- essentially, this was the angle of the lower control arm, which is controlled by the torsion bar adjuster bolt.

Measuring any part of the body or frame to the ground is dependent on your wheel and tire combination, and even the tire pressure and temperature, so it wouldn't be a consistent measurement.

I don't quite understand the bit about the 1.03 torsion bars "lowering" your car. Since they have a stiffer rate, I would assume they would raise the front of the car -- then you would have to use the adjuster bolt to lower the front to where you wanted it. This would be a different number of turns than the original t-bars required.


I

Measuring from body parts is of no use, as suspension has to be set relative to its components, in relation to floor. Body parts are not consistently mounted, and are aligned to mate with their neighbor, not suspension parts. These cars don’t have close build tolerances.

Per Factory Service manual:

Front suspension heights must be held to specification for a satisfactory ride, correct appearance (this subjective to today’s eye), proper front wheel alignment and reduced tire wear,

First vehicle has to have full tank of fuel, no passengers, no luggage in trunk excepting spare tire & jack, properly inflated tires, and on sitting on level floor.

Clean all crud from lowest portion of steering knuckle arm, and height adjustment blades directly below lower control arm inner pivots.

Jounce front of vehicle several times releasing it on a downward motion.

Measure from lowest point of adjusting blade to floor (measurement A), and from lowest point of steering knuckle arm to floor (measurement B); measure only one side at a time.

Subtract distance A from B and adjust height by big bolt in center of LCA adjusting as necessary until A-B= 2 ½” +/- 1/8th inch. Per 1967 A Body height spec for both standard & HD suspension; I suspect it is the same for a 1968 & 69 A bodies.

After every adjustment jounce front end before remeasuring. Both sides should be measured even though one side was adjusted. Adjust other side.

Ping pong left to right making adjustments until each side is within 1/8th inch of the other.



I’m not fluent in ’69 340 rear suspension, but suspect it is identical to S Cuda set-up which I believe used a six lief factory ride height rear spring. Even though a six lief spring was used, it was not significantly stiffer than stock springs, but provided better axel control under hard acceleration.

Your choice of one inch torsion bars is a good one; these cars left the factory with mushy low spring rates on the front end compared to today’s cars. GM and Ford’s suspensions were even sloppier than Mopar’s in the day providing almost no suspension control, they were simply dreadful wallowing hogs.

I have fitted six lief stock ride height rear springs to My Dart rag top with an 8 3/4th inch rear, with 0.940” torsion bars all at factory ride height, and car handles neutrally with a well behaved rear axle.

Rear spring ride height changes in one inch increments are available if one desires a slight lift of rear end. As rear of an A body over stock ride height increases, the more tail happy (tendency to over steer) it will become.

Call Spring N Things… ESPO for the details, A body rear springs are not listed on their site: http://www.springsnthings.com/
 
I also like the car to sit a little lower than the factory height, plus that method is a PITA. I set about an inch between the LCA bumper and frame. Then I make sure both sides are equal by measuring from the frame to a common place on each LCA. The car should be moved or bounced to settle the height, plus incorrect toe CAN cause the car to pull down on forward movement.
 
Thanks for the advice. I want to baseline the car now and try to get the same height when I'm done.
I don't quite understand the bit about the 1.03 torsion bars "lowering" your car.

The PST have the torsion bar hexes clocked differently thus lowering the car when installed correctly.

My concern is the back end being jacked up from stiffer HD springs or the front being too low from using the wrong torsion bars. Supposedly PST is working on 1.03" bars with factory style hex orientation.
 
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