Plymouth Duster Suspension/Tubbing Question - Drag Racing

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Wilson340

Wilson340

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I'm currently working on my 1973 Plymouth Duster 340 and need some advice. To be upfront I am very new to car building and I'm learning as I go. My goal is to build a 10+ second car for the quarter while keeping it a 340.

1) I'm in the process of getting an 8 point roll cage professionally installed and my rear suspension redone. I need to know whether to switch over to a coil over suspension (QA1 drag stage 2 coil over suspension kit is the one I'm considering) or if after market (Mopar Performance Leaf Springs paired with QA1 shocks) will suffice to reach my goal?

2) Does anyone know the max wheel width size a 73' Plymouth Duster can have with a leaf spring relocation done, no mini tub and not have the tire sticking outside the fender?

I'd appreciate any advice. Thank you!
 
Wilson340 said:
I'm currently working on my 1973 Plymouth Duster 340 and need some advice. To be upfront I am very new to car building and I'm learning as I go. My goal is to build a 10+ second car for the quarter while keeping it a 340.

1) I'm in the process of getting an 8 point roll cage professionally installed and my rear suspension redone. I need to know whether to switch over to a coil over suspension (QA1 drag stage 2 coil over suspension kit is the one I'm considering) or if after market (Mopar Performance Leaf Springs paired with QA1 shocks) will suffice to reach my goal?

2) Does anyone know the max wheel width size a 73' Plymouth Duster can have with a leaf spring relocation done, no mini tub and not have the tire sticking outside the fender?

I'd appreciate any advice. Thank you!
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Sounds like a fun build and not too different from mine. A 10 second 340 car is entirely possible with or without NOS or other boosters. I doubt that it would be streetable without boosters, though. But if you're only drag racing then no worries.

A leaf spring suspension is quite usable. No need to go to coil over/4 link suspension unless you want to. What I WOULD recommend is a set of fully adjustable shocks front and rear.

Don't have an answer for your second question but I am in the same boat as you and am interested in an answer..
:thumbsup:
 
If you are not doing a mini tub then moving the springs is a waste of money since the tubs will restrict the size of the tire.....If you want to keep it simple use a set of Cal Trac rear suspension...

You are going to limited to about a 9 inch tire..

CalTracs
 
70aarcuda said:
If you are not doing a mini tub then moving the springs is a waste of money since the tubs will restrict the size of the tire.....If you want to keep it simple use a set of Cal Trac rear suspension...

You are going to limited to about a 9 inch tire..

CalTracs
Click to expand...
There are a couple of people around here that have 68 barracudas w/ 10' slicks, stock wheel wells, that run mid 10`s, and one usually makes the power tour ! One has caltracs and I think the other might be s/s springs, not for sure .
An offset spring hangar kit put my spring right in line w/ the inner tub/frame .
 
dart_68 said:
Sounds like a fun build and not too different from mine. A 10 second 340 car is entirely possible with or without NOS or other boosters. I doubt that it would be streetable without boosters, though. But if you're only drag racing then no worries.

A leaf spring suspension is quite usable. No need to go to coil over/4 link suspension unless you want to. What I WOULD recommend is a set of fully adjustable shocks front and rear.

Don't have an answer for your second question but I am in the same boat as you and am interested in an answer..
:thumbsup:
Click to expand...

Thanks for the information! I was definitely planning on getting adjustable shocks for both front and rear. Just based off pictures of other 340 Dusters drag racing (some with the front end off the ground) I see they kept the leaf spring set up. I just wanted to get some advice from you all on here before spending the money and realizing coil over suspension was the way to go. But if I can get in the 10 second range with the leafs then I'll probably just stick with that.
 
70aarcuda said:
If you are not doing a mini tub then moving the springs is a waste of money since the tubs will restrict the size of the tire.....If you want to keep it simple use a set of Cal Trac rear suspension...

You are going to limited to about a 9 inch tire..

CalTracs
Click to expand...

Thanks for the link to the CalTracs. I'll definitely check them out. I am curious though, how would tubs restrict the size of the tire?
 
SS springs, 29x10.50's stock location and wheel wells trimmed, Yukon axles with 4:56 ratio and spool.15x10 centerlines, 4in. Offset. Adjustible pinion snubber.

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You will see stock eliminator cars running Caltracs with stock spring location. These cars run deep into the 10s.
 
Wilson340 said:
Thanks for the link to the CalTracs. I'll definitely check them out. I am curious though, how would tubs restrict the size of the tire?
Click to expand...

The mini tubs move the inside of the wheel tub to the frame rail, this typically adds about 3” to the depth of the wheel well tub from the outer fender. By moving the leaf springs in to the frame rail and not mini tubbing you really don’t utilize all the available room created by moving the springs as the wheel tub becomes the limiting factor on the tire width. The other limiting factor is the front lower wheel opening, this is where the tire height becomes limited as an interference point. My Demon is mini tubbed and springs moved and I am running a 28x12x15 tire without rolling wheel lips etc. there is plenty of clearance in there with no rubbing.

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Wilson340 said:
I'm currently working on my 1973 Plymouth Duster 340 and need some advice. To be upfront I am very new to car building and I'm learning as I go. My goal is to build a 10+ second car for the quarter while keeping it a 340.

1) I'm in the process of getting an 8 point roll cage professionally installed and my rear suspension redone. I need to know whether to switch over to a coil over suspension (QA1 drag stage 2 coil over suspension kit is the one I'm considering) or if after market (Mopar Performance Leaf Springs paired with QA1 shocks) will suffice to reach my goal?

2) Does anyone know the max wheel width size a 73' Plymouth Duster can have with a leaf spring relocation done, no mini tub and not have the tire sticking outside the fender?

I'd appreciate any advice. Thank you!
Click to expand...


Save yourself time and money. Don't relocate the springs, don't mini-tub it, just get Caltracs with their shocks with a 275/60 radial drag tire and that setup will be more than capable of enough traction to run into the 9s or faster. I'm sure half the members on this forum will tell you to use super stock springs because Caltracs are for Chevy's. That's pretty much the dumbest thing I've ever heard. SS spring will raise the *** end of your car 3' in the air. Caltracs has the option of stock ride height or 1" lower. I'd go with the lower. I used both on my car when I was drag racing. I though the Caltracs were much easier to make work.
 
racerjoe said:
Save yourself time and money. Don't relocate the springs, don't mini-tub it, just get Caltracs with their shocks with a 275/60 radial drag tire and that setup will be more than capable of enough traction to run into the 9s or faster. I'm sure half the members on this forum will tell you to use super stock springs because Caltracs are for Chevy's. That's pretty much the dumbest thing I've ever heard. SS spring will raise the *** end of your car 3' in the air. Caltracs has the option of stock ride height or 1" lower. I'd go with the lower. I used both on my car when I was drag racing. I though the Caltracs were much easier to make work.
Click to expand...

I appreciate the input. So you would recommend these CalTracs 4200 Drag Profile 2 Hole [4200 Drag Profile 2 Hole] - $369.00 : The Leader In Leaf Spring Innovation, - Calvert Racing with their Split Mono Leaf 2000s (Split Mono Leaf 2000 [2000] - $429.00 : The Leader In Leaf Spring Innovation, - Calvert Racing) and their adjustable rear shocks?

Aside from lifting the rear up are you would still recommend Caltracs Mono Leafs over Mopar Performance SS Leafs (Mopar Competition Leaf Spring - Left)

Lastly, another member said I'd be able to fit up to a 9" wide tire without tubbing or moving the suspension inboard all while not having it stick out the side of the fender. With our experience do you think a 9" rear tire is enough to get me into the 10s given all else set up properly? Basically I want the biggest tire possible without having it stick outside the fender.

Thank you
 
Wilson340 said:
I appreciate the input. So you would recommend these CalTracs 4200 Drag Profile 2 Hole [4200 Drag Profile 2 Hole] - $369.00 : The Leader In Leaf Spring Innovation, - Calvert Racing with their Split Mono Leaf 2000s (Split Mono Leaf 2000 [2000] - $429.00 : The Leader In Leaf Spring Innovation, - Calvert Racing) and their adjustable rear shocks?

Aside from lifting the rear up are you would still recommend Caltracs Mono Leafs over Mopar Performance SS Leafs (Mopar Competition Leaf Spring - Left)

Lastly, another member said I'd be able to fit up to a 9" wide tire without tubbing or moving the suspension inboard all while not having it stick out the side of the fender. With our experience do you think a 9" rear tire is enough to get me into the 10s given all else set up properly? Basically I want the biggest tire possible without having it stick outside the fender.

Thank you
Click to expand...

That's the correct Caltrac setup. I failed to mention I do have the 3/4" offset spring hangers, but those don't require nearly as much fab work as mini-tubs or the 3" spring relocation kit. The only fab required is moving the spring perch on the axle housing. This is not required, but it helps getting a little bit more tire under the car instead of closer to the wheel opening.
The mopar SS springs do work, and they are affordable. I don't like buying things if I just plan to upgrade later, that's why I recommend the Caltracs.

See pic below. This is a 8" wheel with a 28x10.5 ET Street, IIRC. It didn't measure those exact measurements. Full steel car, bench seat, through mufflers, 10:50s all day all motor. As mentioned above, a full weight car capable of 10s N/A isn't going to be very mild mannered on the street. You will need a relatively loose converter and 4.56-4.88 gears and a pretty large camshaft and perhaps high compression. Ask me how I know....
Also, if you plan to run 10s, you will need the safety equipment to do so, unless you just want to make one pass.
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I had the most fun when my car ran 11:50-11:75. It was super streetable, it had a solid flat tappet cam instead of a big nasty solid roller, and pump gas. Not to mention, it's pretty easy to put a 450HP engine together these days with all the aluminum head options out there.
 
I'm pretty sure you do not need the 3" relocation kit or the mini tubs with the Qa1 rear suspension.....and for what it is worth.....before you consider ANY 4-link / 4-bar for drag racing you should understand the why and how to properly tune it. Read a lot about fast Mopars with Cal-tracs .....but never once with the Qa1 set up. JMHO.

I think you started out asking the right questions.
 
I appreciate that insight and I honestly agree. Since I've posted this I have learned a lot and have done a good deal of research on what you all have suggested and mentioned. I've decided against the QA1 track and I'm going with the Cal-Tracs with a 3/4" offset. No mini tub or 3" relocation. I can get to my goal and not spend near the amount of money I otherwise would have. So thank you to all those in this thread.
 
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