Back half regrets?

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Garry in AZ

Garry in AZ

Building a 9 second Valiant
Joined
Jul 13, 2017
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Location
Mesa, AZ
I'm interested in hearing from anyone who has back-halfed an A-Body and later regretted it, and why. I'm leaning strongly in that direction right now, (complete kit from S&W) but before I fire up the plasma cutter, I figured I'd ask those who have done it. Any regrets?

Thanks, Garry
 
I mini-tubbed my '68 Valiant and I regret not back halving after it was all said and done. I do like keeping the back seat in it though.
 
Okay here i go, big tire cars are cool. Small tire cars running #s at the track kicking @@@ on the street way more cool in my book. And with the technology today? Why big tires? I'm sure I'm going to get alot **** for saying my opinion!
 
IMO, small tire car with decent power, will take more suspension tuning time to get down track safely and consistently. A big tire car with 14 X 32's and a ladder bar setup will get down about any track, just unloading it off the trailer. Mine with a mini tub has 325-60 drag radials, so their not real small, but with the Calvert setup, I'll have to do a little work to get it all working.
 
Demon540 said:
Okay here i go, big tire cars are cool. Small tire cars running #s at the track kicking @@@ on the street way more cool in my book. And with the technology today? Why big tires? I'm sure I'm going to get alot **** for saying my opinion!
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I agree. I was a big tire back half guy but not anymore. Drag radials have come a LONG way and I can hook them just as well as a slick MOST of the time LOL. It is nice to have a full size trunk and a back seat too. I thought a long time about cutting up the Duster but decided I would rather have a 275 and keep the fold down rear seat. If you can't hook 10 inches with Caltracs, you need to find some help!
 
Mopar-Man said:
I agree. I was a big tire back half guy but not anymore. Drag radials have come a LONG way and I can hook them just as well as a slick MOST of the time LOL. It is nice to have a full size trunk and a back seat too. I thought a long time about cutting up the Duster but decided I would rather have a 275 and keep the fold down rear seat. If you can't hook 10 inches with Caltracs, you need to find some help!
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I have not been able to hook my 295 65 15 d.r. w/ caltracs yet , just turns sideways when I get in it . Which ever way the road slopes. No dragstrip as of yet tho. I regret not tubbing it when I built it! 68 fast bastback form S business coupe anyway .
 
10.50 tire is small tire. Over that is big tire.

My car is mini tubbed. In my opinion that is plenty of tire unless you are making obscene hp numbers. I actually had to buy 10.50's so I could run some of the small tire classes.
 
I have a 540 in my demon makes 852hp 742 tq. N.a. caltracs 29x10.5 tire afco double adjustment shocks front and rear. Best run to date 9.06 @149 mph. 575 1/8 1.29 60ft. It definitely takes suspension tuning and I still have alot to learn. I'm glad I didn't back half, as I almost did.
 
Wouldn't think you need to do a full b/half these days, I went big tire back in my day and ruined a good '69 Cuda but it was race only, tech wasn't as good back in the late 80's. My mate with his Dart mini tubbed and with a 1" move of the axle got 13x31's on there with dble adjustables and SS springs and that handled a 600hp 440 easy...can do it with less tyre as well, just got to know what your doing.
 
famous bob said:
I have not been able to hook my 295 65 15 d.r. w/ caltracs yet , just turns sideways when I get in it . Which ever way the road slopes. No dragstrip as of yet tho. I regret not tubbing it when I built it! 68 fast bastback form S business coupe anyway .
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I haven't found anything that will hook on the street. IMO on a poor surface a bias tire is better.

I mini tubbed my Dart several years ago when i installed the Dana, it has 325 M/T radials on it. It's been 1.38 60' on a good track but on a poorly prepped track it spins. I do however believe that now with affordable decent double adjustable shocks radials are easier to make work.
 
To answer some of the questions... the car will be used primarily for NHRA drag racing and have really limited street use. (No AC, heater, wipers, etc) Mostly bracket racing, with about 750 HP at the crank. The motor is a stroked (416) aluminum block LS3 with a Procharger. I'm already doing a full NHRA approved 12 point cage, frame connectors, torque boxes, etc. Probably will need a wheelie bar. The rear end will be a Moser built, narrowed Dana 60. I'm looking to run consistently in the 10's.
I don't need or want an 18-22 inch wide tire right now, I'm going to start with a 28 x 11 drag radial on a 10" rim with 3.5" backspacing. I know I don't need more than a 10.5" slick with 700HP, but I may want to step things up in a year or two, and then a small tire won't work. If I back half the car now, and later on need to go to a big tire, I can keep the rear end and increase the wheel backspacing... because I'll have room between the frame rails. Hence the back half solution...
My problem is that the cost of a RMS or Gerst 4 link is about the same as a complete back half from S&W. But with the back half, I get a much more adjustable rear suspension, a stiffer more consistent chassis, and if I ever decided to do a serious motor (1000+ HP) I'd have a car that I could put the big tire on, and still have a chassis that would handle it. I just don't want to have to do it twice... Hell I can barely afford to do it once!

Thanks to all who offered advice, opinions and experiences. Much appreciated!

Garry
 
Not sure of your skills/fab abilities but if a gray area call Comp Chassis and have a chat with Mike. He’ll make your car work! Second of all I’d keep the hood down if your running a power adder LS and hope to achieve “10’s”.

FWIW.... my car is mini tubbed and I run a 10.5 tire. 1.27 60 if all is perfect, but I’m only running a small block with a 4150 carb N/A.
 
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Thanks A body, I understand what you're saying. The LS3 won't have a ton of boost in the beginning, but the bottom end of the motor is built for 1500 HP. So maybe one day the boost will go up... but I need a bunch of passes and seat time before then. As far as the fab work goes, I can usually handle that pretty well, and if I need help with any tricky welding, I have a buddy who welds for the nuclear industry.
Aside from running my Corvette down the track a few times a year, it's been 15 years since I regularly drag raced, so the driver will need as much tuning as the car. I will have some learnin' to do when it comes to getting the car set up, but I've got some experienced friends, a degree in physics, and a well read copy of Doorslammers... so I'll just tweak on it a weekend at a time. I have no pressure to perform at the track, I can just go out and have fun and gradually get the car working.
That 1.27 60 ft is pretty damn impressive! I'm just hoping 1.27 isn't my RT. LOL
 
Is that a factory aluminum block? It's my understanding they aren't really strong. I know a few local guys that are running boosted LS engines and they all run iron blocks. There are several reasons you see a ton of mustang bodies in the fast small tire classes, but the biggest is that they come with what is essentially a factory four link rear suspension. Adjustable bars for them are just a phone call away.
If it were mine and I was planning on putting big power on it later I'd go straight to a four link and save my self some headache and money later. Also I'd go with a good 9" rear, used aluminum bolt through cases can be found for reasonable costs and as you step up the power you'll need less gear. My buddy built a single turbo 5.2 LS in a early 90's Mustang for his teenage son to drag race and it runs 5.60-.70"s (1/8) with a 3.50 gear on Pro 275's.
 
Yes, plus weight and more options for brakes. BTW I have a Strange S60 in my Dart. lol
 
justinp61 said:
Yes, plus weight and more options for brakes. BTW I have a Strange S60 in my Dart. lol
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I have an S60 as well. It's funny the guy at moser pushed me away from the Ford 9". YOu can't argue with parts availability though.

My S60 has Wilwood discs and allegedly weighs the same as a stock 8.75. It's also supposed to be good for "1,000hp all day". It will never see quite that much in my car so i'll never know for sure.

dana.jpg
 
QUOTE: I have not been able to hook my 295 65 15 d.r. w/ caltracs yet , just turns sideways when I get in it . Which ever way the road slopes. No dragstrip as of yet tho. I regret not tubbing it when I built it! 68 fast bastback form S business coupe anyway .

LOL...That's because they're not designed to hook on a sloping road. A back half ladder bar car would to the same thing...
 
roccodart440 said:
I have an S60 as well. It's funny the guy at moser pushed me away from the Ford 9". YOu can't argue with parts availability though.

My S60 has Wilwood discs and allegedly weighs the same as a stock 8.75. It's also supposed to be good for "1,000hp all day". It will never see quite that much in my car so i'll never know for sure.

View attachment 1715122769
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My buddy ran high 8's for years with the same Dana 60 on a blower car. Car weighs 3900lbs so it took a beating! Once he got to mid 8's it started eating ring gear teeth. So now it has a fabricated 9" under it and is doing well. Car makes 1350hp.
 
dusterdoug said:
QUOTE: I have not been able to hook my 295 65 15 d.r. w/ caltracs yet , just turns sideways when I get in it . Which ever way the road slopes. No dragstrip as of yet tho. I regret not tubbing it when I built it! 68 fast bastback form S business coupe anyway .

LOL...That's because they're not designed to hook on a sloping road. A back half ladder bar car would to the same thing...
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Didn`t say they were, just pointing out that I haven`t had it on the strip yet. Don`t get around to things as fast as I used to! My ex 600 horse vega , had 14x32`s on it w/ a ladder bar suspension, it would hook some and not turn sideways on the street, of course it only weighed 2440 pounds.
 
If you are planing on upping the power and getting the car faster at a later date, why do the rear end work twice? Since it is a race car and not a street car, why don't you go ahead and back half the car and be done with it? That way, the rear will be ready for whatever you throw at it later on... 0.02....
 
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