1971 Duster Handeling

[snowcrane2005]

Looking for some help. I have a 1971 duster and I can't get it to handle when speed gets around 120. It is all over the road. Would like car to handle up to speed of 150. Already put qa 1 suspension on it with front sway bar still did not cure problem. Is there any way to accomplish this without severely modifying the car.
Thanks

 

[Ironracer]

How is all your front end components? Tires? Alignment settings? What about steering box/ linkage play?

 

[72bluNblu]

Yup, gonna need to know a lot more about your set up. And what you’re doing with the car at 120 mph…

 

[72bluNblu]

Although, I will add that if this only happens at 120 mph it's possibly this might have a lot more to do with the aerodynamics of your car than it does your suspension.

 

[RustyRatRod]

Just send the car to me. Them Dusters caint handle worth a snot.

 

[George Jets]

Check your front end Toe In with a tape measure. Want about 1/8th" toe in at the front of the front tires.

If it is Toed Out it will definatly be all over the road.

 

[diymirage]

Although, I will add that if this only happens at 120 mph it's possibly this might have a lot more to do with the aerodynamics of your car than it does your suspension.

yup, he needs one of these

 

[72bluNblu]

Check your front end Toe In with a tape measure. Want about 1/8th" toe in at the front of the front tires.

If it is Toed Out it will definatly be all over the road.

That's true, but that would be a problem all the time, not just at 120 mph.

yup, he needs one of these

View attachment 1715909831

Actually he probably needs the Daytona style nose cone more than the wing. The wings added downforce on the rear, but the car being squirrely is more than likely being caused by the front end lifting. The wing without anything up front would make that worse.

If 120-150 mph stability is the goal, blocking off the grille so the front of the car is flat (vs the inset grille) and adding some kind of chin spoiler to limit the amount of air going under the nose would probably help the most. The DC "ducktail" spoiler was also allegedly created and tested for this. Supposedly the DC spoiler was good for about another 10 mph of top speed when it was tested, but I've never seen any empirical results from that testing to have any idea how they actually figured that out.

 

[snowcrane2005]

That's true, but that would be a problem all the time, not just at 120 mph.



Actually he probably needs the Daytona style nose cone more than the wing. The wings added downforce on the rear, but the car being squirrely is more than likely being caused by the front end lifting. The wing without anything up front would make that worse.

If 120-150 mph stability is the goal, blocking off the grille so the front of the car is flat (vs the inset grille) and adding some kind of chin spoiler to limit the amount of air going under the nose would probably help the most. The DC "ducktail" spoiler was also allegedly created and tested for this. Supposedly the DC spoiler was good for about another 10 mph of top speed when it was tested, but I've never seen any empirical results from that testing to have any idea how they actually figured that out.

That's true, but that would be a problem all the time, not just at 120 mph.



Actually he probably needs the Daytona style nose cone more than the wing. The wings added downforce on the rear, but the car being squirrely is more than likely being caused by the front end lifting. The wing without anything up front would make that worse.

If 120-150 mph stability is the goal, blocking off the grille so the front of the car is flat (vs the inset grille) and adding some kind of chin spoiler to limit the amount of air going under the nose would probably help the most. The DC "ducktail" spoiler was also allegedly created and tested for this. Supposedly the DC spoiler was good for about another 10 mph of top speed when it was tested, but I've never seen any empirical results from that testing to have any idea how they actually figured that out.

Can anyone tell me what they can get for top speed out of there duster and actually handle it in the road?

 

[dukeboy440]

Yup, gonna need to know a lot more about your set up. And what you’re doing with the car at 120 mph…

And where are you doing it at?

 

[dukeboy440]

Can anyone tell me what they can get for top speed out of there duster and actually handle it in the road?

Doing 120 mph on the road is quite dangerous in a car that wasn’t really designed for it.

once you get over 100 mph, aero becomes a HUGE factor. Drag under the car can create life, which will cause the car to feel skate-ish and loose. You need to smooth out the underside, add an air dam up front, a rear diffuser out the back and probably side skirts. Maybe even fender chimneys

 

[snowcrane2005]

Doing 120 mph on the road is quite dangerous in a car that wasn’t really designed for it.

once you get over 100 mph, aero becomes a HUGE factor. Drag under the car can create life, which will cause the car to feel skate-ish and loose. You need to smooth out the underside, add an air dam up front, a rear diffuser out the back and probably side skirts. Maybe even fender chimneys

Is there anything I can do and not add aftermarket exterior pieces?

 

[dukeboy440]

Is there anything I can do and not add aftermarket exterior pieces?

Honestly, no. Not really. I mean maybe a chin spoiler, but even that would be aftermarket. These cars weren’t ever designed for that speed even if their speedometers claimed it. They were designed for a few quarter mile passes, sure. But not sustained on road speeds of that nature.

why the need for that speed on the road? Heck, the roads here can’t even support that kind of speed, too many pot holes

 

[snowcrane2005]

Honestly, no. Not really. I mean maybe a chin spoiler, but even that would be aftermarket. These cars weren’t ever designed for that speed even if their speedometers claimed it. They were designed for a few quarter mile passes, sure. But not sustained on road speeds of that nature.

why the need for that speed on the road? Heck, the roads here can’t even support that kind of speed, too many pot holes

Can an e body or b body even handle that kind of top speed?

 

[dukeboy440]

Can an e body or b body even handle that kind of top speed?

Factory, probably just the AARs and TAs as they had the factory chin spoilers. Really the cars from the factory that could handle that would be the B bodies mostly. Besides the obvious Daytona/SuperBird/Charger 500, but the 3rd Gen B bodies were some of the most aero dynamic Bodies Ma Mopar produced in mass quantities back then.

 

[72bluNblu]

Can anyone tell me what they can get for top speed out of there duster and actually handle it in the road?

Tim Werner has done 160mph in his Valiant at Willow Springs and Portland, but that car runs a chin spoiler and has lots of other modifications...

This Duster runs the Australian Trans Am series (chin spoiler, wing)

Is there anything I can do and not add aftermarket exterior pieces?

Not really. These cars were not designed for sustained speeds over 100 mph. Their inset grilles, relatively large frontal areas and bodywork that sits well above the ground all mean that at higher speeds the front end tends to lift, which makes the front end light and squirrely.

If you want to keep the nose down you have to reduce the amount of air going under the front of the car.

Can an e body or b body even handle that kind of top speed?

Yes, there are lots of E-bodies built for that kind of speed!

T/A cars...

Jess Neal's Pike's peak car...

Australian Trans AM 'Cuda competitor

And look, more T/A cars. Notice something the ALL have in common, even across different makes and models?

That's right, they're all sporting large chin spoilers and rear wings of some kind. It's almost like '70's musclecars weren't designed to do 150 mph without modifications...

Speaking of which, other than some QA1 parts and a sway bar, what does the rest of your suspension set up look like? Because again, you're not going to do 150 mph in a '71 Duster safely and reliably without a lot of modifications to the suspension and bodywork.

 

[snowcrane2005]

Factory, probably just the AARs and TAs as they had the factory chin spoilers. Really the cars from the factory that could handle that would be the B bodies mostly. Besides the obvious Daytona/SuperBird/Charger 500, but the 3rd Gen B bodies were some of the most aero dynamic Bodies Ma Mopar produced in mass quantities back then.

Tim Werner has done 160mph in his Valiant at Willow Springs and Portland, but that car runs a chin spoiler and has lots of other modifications...
View attachment 1715910242

View attachment 1715910243

This Duster runs the Australian Trans Am series (chin spoiler, wing)
View attachment 1715910249





Not really. These cars were not designed for sustained speeds over 100 mph. Their inset grilles, relatively large frontal areas and bodywork that sits well above the ground all mean that at higher speeds the front end tends to lift, which makes the front end light and squirrely.

If you want to keep the nose down you have to reduce the amount of air going under the front of the car.



Yes, there are lots of E-bodies built for that kind of speed!

T/A cars...

View attachment 1715910240

View attachment 1715910244

Jess Neal's Pike's peak car...
View attachment 1715910241

Australian Trans AM 'Cuda competitor
View attachment 1715910246

And look, more T/A cars. Notice something the ALL have in common, even across different makes and models?
View attachment 1715910248

That's right, they're all sporting large chin spoilers and rear wings of some kind. It's almost like '70's musclecars weren't designed to do 150 mph without modifications...

Speaking of which, other than some QA1 parts and a sway bar, what does the rest of your suspension set up look like? Because again, you're not going to do 150 mph in a '71 Duster safely and reliably without a lot of modifications to the suspension and bodywork.

View attachment 1715910247

I have the stage 2 qa 1 suspension and a Hotchkiss front sway bar, and a new borgenson steering box. Would be interested to know besides the chin spoiler whats done to the valiant? That spoiler dosent look that bad actually. So basically no bone stock mopar besides a gen 3 b body can do140 to 150?

 

[dukeboy440]

So basically no bone stock mopar besides a gen 3 b body can do140 to 150?

Not really. The aero cars, aka The Daytona’s, Superbirds, Charger 500s could easily. The 3rd Gen B Bodies, The 1st Gen chargers could probably do it, maybe. The TAs, AARs probably as well. Course that’s gonna all be on a track of some sort.

that said, no way am I doing that on a street or even a highway. Too many variables that could go wrong.

You still haven’t answered the question, why do you need to do 120-150 mph sustained on the STREET?

 

[K.O. SWINGER]

Is Someone wanting to chase modern muscle ?

 

[dukeboy440]

Is Someone is wanting to chase modern muscle ?

Sounds that way.

 

[Rat Bastid]

As nublu has pointed out, the body is generating lift. You have to get the air from under the car.

One example was the junky Daytona Pro Stock cars. Over about 150 MPH they generate a big amount of lift. You could help it, but it couldn’t be cured and pass NHRA bodywork rules.

They were a handful to drive and more than one guy told me they put mud in their shorts more than once with those cars.

 

[66fs]

My 64 Barracuda would do 140 mph and be quite stable. No bodywork or gimmicks. Basically stock Formula S suspension with the best HD front end parts and bushings. Get your front end down, I adjusted the front end so my closed fist, about 4 inches, would just clear the lowest point of the K frame. Shorter high speed tires all around. Wheel bearings adjusted to spec on all 4 wheels. Spring clamps on the front of the rear leaf springs.

Have to agree with safety, at 140 mph you need to be able to see waaaaaay far ahead and to the sides. When I would run that fast, it was in South Dakota on a flat stretch with wide clear shoulders and no sight obstructions. I also knew If something bad happened, I probably would not survive. I would not drive that fast where I live now.

 

[DC Dart]

That 150 MPH mark in an a body is huge. 120 is not so bad. As you start going over 120 everything starts getting amplified in small increments.
The 160 mph valiant is awesome. Would be interesting to see what all was done on that car.
I think the width of the E and B bodies helps the stability of the cars at speed. Even though they are a bigger inefficient brick going through the air. On B body's any way.

 

[Rat Bastid]

My 64 Barracuda would do 140 mph and be quite stable. No bodywork or gimmicks. Basically stock Formula S suspension with the best HD front end parts and bushings. Get your front end down, I adjusted the front end so my closed fist, about 4 inches, would just clear the lowest point of the K frame. Shorter high speed tires all around. Wheel bearings adjusted to spec on all 4 wheels. Spring clamps on the front of the rear leaf springs.

Have to agree with safety, at 140 mph you need to be able to see waaaaaay far ahead and to the sides. When I would run that fast, it was in South Dakota on a flat stretch with wide clear shoulders and no sight obstructions. I also knew If something bad happened, I probably would not survive. I would not drive that fast where I live now.

Those Gen 1 Barracuda’s were pretty slick for their day. I’ve always loved those cars.

 

[snowcrane2005]

Those Gen 1 Barracuda’s were pretty slick for their day. I’ve always loved those cars.

Does anyone think this will help much?


https://www.spoilersbyrandy.com/70-73-duster