Hi Folks,

My 68 Dart 270 has a very hard ride to it... It needs rear springs and rear shocks (the air shocks the last owner put on it have recently died). But the front end has been rebuilt with a (rubber) front end kit and KYB gas shocks. I'm running Goodyear TA radials all the way around.

When I go over bumps it feels like my tires are made of cement.
This happens with both the front and rear tires. I understand the back, but not the front.

Torsion bars were set to spec (height), then I tried raising them, just to make sure I wasn't hitting the rebound bumpers.

Tire pressure is 30 PSI.

Although it's been 25 years or so since I owned my last A-Bodied Mopar, I just don't remember them riding so hard.

Suggestions appreciated as always.

-Mac

That last one may be the issue. A-bodies weren't terribly harsh for their time, but compared to a modern car, they transmit more vibration to the driver than a car that softly sprung would. I had an engineer who worked on NVH issues for one of the Big Three wincing when I described some of the details of the suspension setup. I believe one of the keys is the way they anchor the torsion bars so far back - it transmits vibrations from bumps directly to the floor pan under the seat.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

I think my 64 rides rather well.................



(off course my other vehicle is a 4x4 toyota pickup that's sagged down to the overload springs...........)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

If you are looking for a more comfy ride:

(1) get your springs re-arch, not replaced. if you do replace them go for a four leaf set, non-heavy duty

(2) NEVER EVER EVER RUN AIR SHOCKS IN AN A-BODY. The upper shock mount is not designed to take the extra stress of supporting the weight of the body and WILL rip out. Replace the blown shocks with a set of Monroe sensa-tracs or Napa premium gas shocks

(3) dump the KYBs up front and run a matching pair (with the back) of Monroe sensa-tracks or Napa premiums

(4) get a taller tire. Alot of little bumps are absorbed by flex in the idewall of the tire. A short tire transfers more "road feel" to the chassis of the vehicle.

(5) reset the front suspension back to stock height, especially after you get the rear springs fixed.

An a-body will never ride like a Cadillac, unles syou spend alot of oney on custom springs and bars. These little cars just don't weigh enough or have the wheelbase for a truly "luxury" ride.

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Casually looking for a Clifford hyperpak intake for cheap.

How fresh is the rebuild? It can take a while for the moving parts to settle in and work smoothly.

What size are the torsion bars?

What size tires? Low aspect ratio tires will often ride a bit harsher as well. I went plus-two (13" rims to 15") and from an 80-series tire to 60-series. That's a big difference right there.

All the suspension/rolling stock changes make the car ride and drive differently, and it may take awhile for you and it to get reacquainted.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I think it's the KYB's. I've got a set on the front as well, and although I appreciate the handling benefits, they do tend to "crash" a bit on some road irregularities from time to time.

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vm

I've never noticed that..............

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I noticed a huge change in how my car rides and handles, but I had made a lot of changes all at once - brake swap, 340 bars, plus-2 tires/rims, HD bushings. All the breaks in the pavement made themselves known. Now, it feels a lot better than either the baseline (firmer, less mush and roll) or the first test after the work (less harsh, maybe quieter).

Either it smoothed out a lot, or I got used to it, or a combination of the two.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

These older cars did not come with steel radials from the factory. They are usually a fair amount noisier and harsher than they were with bias plys. TA radials are not the smoothest radial out there either. A good touring tire would be smoother, but there go's the whole sporty ride. Some vibration damping insulation like dynamat on the floor will not really smooth the ride will should help quiet things and lesson the overall perception of harshness.

I left this out. Try increasing the tire pressures. Sounds wrong, but it may make it better. With stiff suspension (shocks) I have had cars that ride better around 35 psi. It makes the suspension work better and the tires roll up and over the bumps without slapping them so much. No amount of debate will make this work or not work, it will depend on your setup. It's free and very easy so worth a try. Trying to get a smooth ride with stiff suspension and mushy tires is kind of like having frame mounted axles.

Thanks everyone.

To respond to some of your comments-
I'm pretty sure that mine is still way too hard. Bangs on even small pavement irregularities.
I agree. The car came with them when I bought it a year or so ago, and I have been busy with other repairs first. But will go with regular shocks when I replace the springs.
Stock 6 cylinder torsion bars.
About a year old, with better than 10k miles on it.
14" 70 Series, if I remember correctly.
"Crash" is an excellent descriptor. That's exactly what it feels/sounds like. I would swear I was impacting the rebound bumpers...
I will give it a try!

The more I think about it, the more I think the KYB's may be the issue. Are Monro Sensa-Tracks a popular choice & good shock for combination of handling and ride? (I know that asking opinions on balancing handling and ride is opening a big can of worms here!)

Thanks!

-Mac

Now that I think about it, the ride did get stiffer when I installed KYB's. I have no idea what the shocks were in there before - may have been the originals for all I know!

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Don't be so sure it's the KYBs. When I install KYBs in place of parts-store shocks (good ones or worn ones), my experience is that the ride gets smoother, not harder and "crashy".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Do you hear or feel the crash?

I had installed new rear shocks in my parents car (focus wagon), and didn't sufficiently torque the shock mounts (real pain in the ass to do) the first try.

Retightened them and everything was fixed............. (I was hearing the crash....)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I swear that I both feel it and hear it. The problem is most pronounced on sharp bumps...

Here in Boston we get lots of potholes that consist of only the top layer of asphalt coming up, so this leaves a hole that is maybe 1 inch deep, 6" across, with a smooth asphalt "floor" to it. On these holes the car "bangs" loudly.

Turning up the torsion bars helped, it now takes a more pronounced irregularity in the road to make it bang, but it really didn't help much.

-Mac