Ride Height and Ground Clearance.
- Thread starter Kent mosby
- Start date
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I found an old *** smudge pot in our cistern from the apple orchards the other day, been here a year & still finding stuff
Which torsion bars do you have ?
I have PST 1.03 inch
Wow, that should be pretty good at keeping her off the ground.
There's nothing wrong with your current stance. Your ground clearance is on the low side, but even for a street car it's not terrible at all. I would be more inclined to change the oil pan and skid plate than raise the car.
As for some of the things that have been said regarding the ride height and alignment-
The factory ride height and alignment are strongly related to the soft original torsion bars and the bias ply tires these cars were originally equipped with. Running radial tires means you want to toss the factory alignment specs out the window and use the SKOSH chart as a base. But that's not the only thing to consider, because the original ride height was based on suspension geometry that was better for the factory alignment and bias ply tires.
What does that mean? It means the camber gain, toe change etc were based on the factory tires and alignment. It means, very simply, that the stock ride height does not provide the best suspension geometry for radial tires. Lowering the car improves the negative camber gain, which is better for radials. It also tends to increase your static negative camber, which is something else that you want for radials. The best suspension geometry for these cars with modern radial tires occurs when the control arms are roughly parallel to the ground. Which puts the A-B for the factory ride height pretty close to zero, or 1 7/8" lower than stock. A 1" drop is still an improvement over stock geometry. You can see that in the caster camber charts posted in this article by Bill Reilly. The article was centered around the FSM spindle geometry change, but the charts are for a car lowered 1" from factory. Basically the same as your car now.
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
You can also use the charts to see that a 1" change in ride height does in fact change the alignment enough to warrant a new alignment. No, it won't rip the tread off your tires if you don't but it can be enough to cause premature wear depending on what your original specs were. Raising the car also changes the alignment for the worse, so it's less forgiving than lowering the car and not adjusting the alignment.
The biggest things with running lowered is just making sure that you have enough travel between the bump stops so you're not constantly bottoming things out. With your aftermarket components you shouldn't have any trouble getting the proper alignment at your current height. You will want about 1" of travel between the top of the lower bump stop and the frame, so, if you don't have that you may need to shorten your lower bump stop accordingly. Or raise the car slightly. But a 1" raise will dramatically change the appearance of the car.
I run my Duster at basically a 0 A-B, it's lowered almost a full 2" from stock. The lowest point is my header flange on the drivers side, it's just a bit under 4" of clearance. Under normal conditions that's fine, it does require some caution on large speed bumps or highly angled driveway transitions. But I've been running that car as my daily on regular old lousy streets without issue at that height. But yeah, my first choice would be to use a more road race oriented oil pan, rather than something with a deep sump at that height.
As for some of the things that have been said regarding the ride height and alignment-
The factory ride height and alignment are strongly related to the soft original torsion bars and the bias ply tires these cars were originally equipped with. Running radial tires means you want to toss the factory alignment specs out the window and use the SKOSH chart as a base. But that's not the only thing to consider, because the original ride height was based on suspension geometry that was better for the factory alignment and bias ply tires.
What does that mean? It means the camber gain, toe change etc were based on the factory tires and alignment. It means, very simply, that the stock ride height does not provide the best suspension geometry for radial tires. Lowering the car improves the negative camber gain, which is better for radials. It also tends to increase your static negative camber, which is something else that you want for radials. The best suspension geometry for these cars with modern radial tires occurs when the control arms are roughly parallel to the ground. Which puts the A-B for the factory ride height pretty close to zero, or 1 7/8" lower than stock. A 1" drop is still an improvement over stock geometry. You can see that in the caster camber charts posted in this article by Bill Reilly. The article was centered around the FSM spindle geometry change, but the charts are for a car lowered 1" from factory. Basically the same as your car now.
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
You can also use the charts to see that a 1" change in ride height does in fact change the alignment enough to warrant a new alignment. No, it won't rip the tread off your tires if you don't but it can be enough to cause premature wear depending on what your original specs were. Raising the car also changes the alignment for the worse, so it's less forgiving than lowering the car and not adjusting the alignment.
The biggest things with running lowered is just making sure that you have enough travel between the bump stops so you're not constantly bottoming things out. With your aftermarket components you shouldn't have any trouble getting the proper alignment at your current height. You will want about 1" of travel between the top of the lower bump stop and the frame, so, if you don't have that you may need to shorten your lower bump stop accordingly. Or raise the car slightly. But a 1" raise will dramatically change the appearance of the car.
I run my Duster at basically a 0 A-B, it's lowered almost a full 2" from stock. The lowest point is my header flange on the drivers side, it's just a bit under 4" of clearance. Under normal conditions that's fine, it does require some caution on large speed bumps or highly angled driveway transitions. But I've been running that car as my daily on regular old lousy streets without issue at that height. But yeah, my first choice would be to use a more road race oriented oil pan, rather than something with a deep sump at that height.
Rat Bastid
Dunamis Metron
I’d leave it exactly where it is. Just don’t drive it like a Dukes Of Hazzard episode and it will be fine
Thanks for the thorough assessment. I will read the article tomorrow. As of yet, the car has never had an alignment at a shop since I got it. I bought an alignment kit from Summit and have used that to get what I have. So many options, thanks again for the knowledge based opinion.
mygasser
Well-Known Member
me too, i'd have the front a couple inches higher (at least) lol.
i'd keep the skid plate too, better to have less ground clearance and save the oil pan in the event of going over a rock in the road or suchlike.
neil.
Great article. It took a couple times reading it through to get all of it. I think I will leave it as it is for now.
72Duster440
Well-Known Member
I think it looks good as is. If it's at 4" of ground clearance to your skid plate, that's a little more than I have to my oil pan. Originally I was nervous with the clearance, but after 6 or 7 years of driving it and never hitting the oil pan, I don't even think about it now. It would have to be one heck of a deep pot hole to hit it at speed and be able to drop the entire side of the car fast enough to bottom it out. Speed bumps are a non concern, since the whole front goes up and down over them, I drag my exhaust collectors a good amount in those situations.
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