Rear end gearing recommendations

[68Superbee68]

I am currently running a 383 with aluminum heads an intake, 3" long tube hooker headers, solid lift cam and a demon carb. The car has a727 3 speed and 4:10 gears in the rear. My question is what should I change the rear gears to so that I can cruise the highway and still have a decent low end pull.

As a side note I am considering putting a supercharger on the engine if I do this would I need to change the gear again?

 

[Sweet5ltr]

If you plan on a centrifugal supercharger and you're looking for performance, 3.55 is about the highest gear I would run; as centrifugal's build boost with RPM. If you just want to enjoy the car (meaning you actually drive it to shows and events), 3.23's are the way to go. A few tenths in the quarter isn't worth dealing with low gears on the street without an overdrive transmission.

 

[Mike67]

Don't know about superchargerss and gearing I would look at the spec on your cam, is it good for low rpm you also need to take into consideration your tire size... I agree with Sweet5 that a 3.55 is a great all around gear, I will be running 3.73 w/ 28" tall tire which will give me some low end grunt, cruise the streets...the highway I should be @ 3000 rpm @65....if you know what speed and gear combo will look like use Richmond's calculator and mess with it....
http://www.richmondgear.com

 

[69 GTX]

I would say 3.55 naturally aspirated & 3.23 supercharged. The more power you have the less gear you need. You may need to change your cam/pistons for the supercharger depending on compression ratio.

 

[747mopar]

3:55s are the cutoff point for me on the highway, they'll put your around 3,100 rpm @70 mph with 27" tall tires. 3:23s are a better pick for cruising so it's a toss up on what's more important plus the rpm range of the motor needs to be considered.

 

[HT413]

What size tires are you running? My 30" tires and 4.10's put me at 3000 rpm at like 65mph.

 

[68Superbee68]

Thanks for all the input guys. Currently I have 29'' tires on my car. I am planning on swapping the rims and tires out, but I'll probably maintain my 29'' tire or maybe go to a 30''. Right now when I'm going about 65 or so my Rpms are around 3000. I was leaning towards a 3:73 gear w.o the supercharger and probably a 3:23 with it

 

[MOPOWER871]

3.23 great gear, 8-3/4.?

 

[SublimeSixpack]

I think you'd be pretty happy with 3.55's. If mostly highway cruising I'd go with 3.23's.

 

[HT413]

Thanks for all the input guys. Currently I have 29'' tires on my car. I am planning on swapping the rims and tires out, but I'll probably maintain my 29'' tire or maybe go to a 30''. Right now when I'm going about 65 or so my Rpms are around 3000. I was leaning towards a 3:73 gear w.o the supercharger and probably a 3:23 with it

Gotcha, so we have the same setup. Coming down roughly 10% in gear to a 3.73 will bring your rpms down 10% or to about 2700 rpm.

 

[68Superbee68]

Yep MoPower I have a 8 3/4 in the car.

I think you are right sublime. Although I think the 3:55 might be the best compromise for me if I keep it NA. With the supercharger it will definitely be a 3:23.

That makes sense HT. like I said up top here it might actually make a bit more sense to drop to the 3:55 instead then if I stay with 29'' tires.

 

[mlktst]

Mike67 this is off subject but, I have a 67 Charger it looks to be the same color and we are neighbors. And I must say thats a good looking car, Trying to get son to get my car pics up i am computer dummy

 

[MOPOWER871]

What is in your 383 that your thinking of supercharging? I'll tell you first hand make shure your motor is up to snuff. before spend the money on a supercharger i would call BDS and ģet there catalog, its full of info on what you need to know about supercharging a engine. if your just want to add a few pony ok,you might get away with running minimum boost, but there's a reason blown motor requires a double keywayed crank snouts, pistons designed for blower aplications , light weight valve train, .... don't want to preach, just don't want to see you hert your motor

 

[petieg383]

What's the rest of your combo like? Compression ratio? Cam specs and intended rpm power range? What converter are you running, what's the stall speed on it?

You can't (actually shouldn't) just drop a bunch of gear out of the car and expect it to be happy unless you can answer these questions and know what to expect.

 

[Lionized]

This should be a poll!
3:55 is my vote.