Hi Guys-
It occurred to me that since the Slant 6 Forum has several "knowledge areas" for postings, and because all of you are so knowledgeable, I can ask you even more questions!

You may have noticed from my postings that I have several A body cars, so there is usually something that one of them needs.

So my question for the day is about the rear suspension on a 75 Dart 4 door sedan with a slant 6. It is as it was equipped from the factory with the exception of now having a Super 6 intake and carburetor on it.

I have owned this car for many years, and it has a lot of miles on it (about 140,000). OK that's not a lot for a slant 6 of course...

A few years back I bought new rear springs for it from Performance Suspension Technology, a place in New Jersey that makes/supplies all kinds of suspension components for many different car brands. (Has anyone else out there used these guys?)

The old springs were sagged in the rear, worse on one side than the other, and the handling had become horrible as a result.

When I ordered the springs, they asked lots of detailed questions on what equipment the car came with so that they could provide me with springs that are as close to factory specs as possible. i.e. they wanted to know engine, transmission, carburetor, rear axle, etc.

The problem is that I prefer a car with a relatively soft ride, and the new springs seem to be much stiffer to me, even though they are supposed to be exactly according to factory spec. They did appear to be exactly the same as the old ones, with the same number of leaves in them (i.e. 4), etc.

I had thought initially that I needed to be patient, and that it would just take some time for the springs to "settle in" and for the ride to soften up a bit.

Unfortunately this has not happened even over the course of about 3 years, and the ride is still a bit "choppy", or firm, for my taste- though the handling is a lot better. I have probably driven 8000 or 10,000 miles in that time.

It's very noticeable to me when I drive my other A body cars, and I see how much better the other cars ride- i.e. softly, with longer ride motions.

i.e. I'm comparing the 75 Dart sedan with a slant 6 to a 73 Scamp with a slant 6 and to a 74 Dart sedan with a 318, and I'm also comparing it to the way the 75 Dart sedan used to ride before the spring replacement.

I am wondering if there is anything I can do about this, or if you have any thoughts. Hopefully I've been specific enough here.

What have other people done when they needed to replace their rear springs?

I didn't have them re-arched because I heard this never lasts more than a year or two.

What I really would like is for the car to ride the way it would have- i.e. the way the factory intended it to, and I just don't think it does.

Thanks a lot for your thoughts.

This is just an opinion and a thought..... Beings the three aforementioned cars are virtually the same age, my thought would be the new sprung car is 'springing' like it SHOULD/DID from the factory, and the other 2 although not as bad as the one that got replacement springs are 'tired' as well.

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MRO....

Cheap, Fast, Reliable.... Pick 2...

You may well be right on that.
The only thing I can say is that the other two cars aren't sagged in the rear. But obviously you're right, the other cars have their original springs on them, so there is an age & time of use difference there.

I just thought these cars came as "soft riders" from the factory, and I had that expectation after I put in the new springs on the one car.

I like that American-style, boulevard cruiser, "cloud 9" type ride. Ha ha!

From experiencing driving these 40 year old cars when they were new, Chrysler products were almost always sprung a bit stiffer than Ford & GM. I suspect that the other examples you have are riding on are sporting weak springs.


What type and age of shock absorbers do you have on your car, they can dictate ride feel as well.

Another point to consider is replacing your torsion bars. They can become fatigued as well over time and miles driven. Up-grading front spring rates to stock or higher may give a more balanced ride at the seat of the pants.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

>>From experiencing driving these 40 year old cars when they were new, Chrysler products were almost always sprung a bit stiffer than Ford & GM. I suspect that the other examples you have are riding on are sporting weak springs.


What type and age of shock absorbers do you have on your car, they can dictate ride feel as well.

Another point to consider is replacing your torsion bars. They can become fatigued as well over time and miles driven. Up-grading front spring rates to stock or higher may give a more balanced ride at the seat of the pants.<<


Maybe you are right, I'm not used to the new feel, even after 3 years.
The ride motions are now shorter and firmer than I am used to/prefer.

The shocks are Gabriels. I'm pretty sure they are "Red Rider" or something like that. Nothing fancy. I did replace them, but it was a while ago. My guess would be 8 years ago. However, over the course of 8 years, I have put about 30,000 miles on the car. I doubt the shocks are worn out, but I guess it's possible.

I can tell you I've never done anything with the torsion bars, other than adjusting the ride height to be more in line with factory spec after I replaced the springs.

PST also sell a lot of high-performance, very firm polyurthane bushings.

Is there a possibility, that you got springs from PST with the much harder/firmer polyurthane bushings fitted, rather than the softer, original type rubber bushings?

If so, replaceing the poly's with rubber, may get the softer feeling back again.

Olaf.

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Aspenized

That's an interesting thought.
Yes, I do believe PST uses urethane bushings in the springs they sell, which is not factory. I never thought it would make a difference.

Yup, urethane stiffens up things under the car a lot when compared to 40 year old rubber bushings suspending worn out springs, and things.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC