Help with rear end gearing please.

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72Scamp_Swinger

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Hello, I am still learning so forgive me, but I have been reading almost every book ever made for Mopar vehicles, decided on every part for my car from brakes, suspension, rear end, trans and motor.

But now it is time to get into depth with somethings like my rear end gearing. Can't truthfuly get my head around gearing, which one is best for what? etc etc. I was told 4.10s would be great for my car, but it was from my brother who runs high horsepower import cars, so not sure if that is good for my mopar.

Anybody able to PM or just plain post on here a quick learning guide of what I need to know to figure out best gearing would be of great help to me, thank you so much. Also, if you need info about my car and whatnot I will post that too, just not sure what is needed.
 
'72 Scamp? What engine? Drag racing or street use? Fuel economy or acceleration? 4 speed or automatic? We'll get you the right gear!!!
 
"Scamp? What engine? Drag racing or street use? Fuel economy or acceleration? 4 speed or automatic? We'll get you the right gear!!!"

Correct it is a 1972 Plymouth scamp, engine is a 318 built by BJR 430hp/430tq, I plan to do car shows, drag runs, and cruises on the weekend with the wife. Acceleration basically, won't be driven alot, and it is a 727 auto. Tires will be 325/60R15 drag radials..
 
72Scamp_Swinger said:
"Scamp? What engine? Drag racing or street use? Fuel economy or acceleration? 4 speed or automatic? We'll get you the right gear!!!"

Correct it is a 1972 Plymouth scamp, engine is a 318 built by BJR 430hp/430tq, I plan to do car shows, drag runs, and cruises on the weekend with the wife. Acceleration basically, won't be driven alot, and it is a 727 auto. Tires will be 325/60R15 drag radials..
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I'm guessing you're running "a more than stock cam":toothy10: so I'd go 3.91. Great for cruising around town and short jaunts on the Interstate but still go like hell on the strip.

Terry
 
demon seed said:
I'm guessing you're running "a more than stock cam":toothy10: so I'd go 3.91. Great for cruising around town and short jaunts on the Interstate but still go like hell on the strip.

Terry
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Ya, I was told a 3.91 also, that is basically in my top 3. My 3 are a 4.10, 3.91, and a few people told me something in the 5s, but never heard of anybody running that.
 
Go with the 3:91s. You won't be sorry. Good at the strip and good for street use. Sounds like a stout package.:cheers:
 
72Scamp_Swinger said:
"Scamp? What engine? Drag racing or street use? Fuel economy or acceleration? 4 speed or automatic? We'll get you the right gear!!!"

Correct it is a 1972 Plymouth scamp, engine is a 318 built by BJR 430hp/430tq, I plan to do car shows, drag runs, and cruises on the weekend with the wife. Acceleration basically, won't be driven alot, and it is a 727 auto. Tires will be 325/60R15 drag radials..
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Is that to the rear tires or dynoed crank HP numbers?

With 410 your going to need a good working suspension and tires.
 
72Scamp_Swinger said:
I agree, I am hoping for it be very stout, I want 10s personally.
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IMO, that'll never happen....not tryin' to rain on your parade, but there's 528 Hemis that are scratchin' just to get into the 10's. I would say that if massive acceleration is what you're after, you'd better go with something in the 4's.....4.10's, 4.30's, 4.56's.....and forget about driving it on the freeway. Everything's a trade-off.
 
megajoltman said:
Is that to the rear tires or dynoed crank HP numbers?

That is motor power on a engine dyno.


With 410 your going to need a good working suspension and tires.
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I plan to use a full suspension rebuild kit, already mostly rebuilt the whole front end with new parts, rear end will take a bit longer til after christmas, wife wasn't happy with the $6,500 bill, she checked mail before me lol.

dano said:
Do you have a higher stall speed converter?
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Planning on a 9 1/2" 4200 I beleive, still checking around on that, taking a trip to some friends in Austin next week, they are transmission specialists. Hopefully have that under wraps before I get back.

cudavert said:
IMO, that'll never happen....not tryin' to rain on your parade, but there's 528 Hemis that are scratchin' just to get into the 10's. I would say that if massive acceleration is what you're after, you'd better go with something in the 4's.....4.10's, 4.30's, 4.56's.....and forget about driving it on the freeway. Everything's a trade-off.
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Sadly, I know, but 11s will be pretty simple if I do everything I want, and I always shoot for what I cannot reach. Allows me to always be in reach of my goals and never have to set others. High 10s on all motor with backseat and all steel parts with my small motor isn't possible, maybe if I add a couple hundred shot of nitrous, but I am not sure if I want to do that, always a fan of NA runs, more respect from myself that way. My brothers car has more power and less weight, barely makes low 10s, but anyhoot. Thanks for the suggestion on the rear end gearing, will take into consideration.
 
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