Need gearing help for my charger

[Darryl]

Hey everyone, I’m coming too a close on my engine build and now I’m to the point of picking a rear gear for the car. It’s a ‘73 charger with a 340 (now 373) with magnum heads, I’m primarily driving the car on the street with very little highway driving. I’m looking for a good gear to hook well on the street to terrorize some hellkittys my thought is 373s or 355s. I’ve got 295/60/15s powered by a 8 1/4 (has a 3:23) soon to be Dana 60

 

[Cranky]

I'm one that likes a lot of rear gear so I'd pick 4.10's....especially if it's not on the highway. Once ran 4.56's in a mild 71 340 Cuda with 275-60's and well, just left it in 2nd and if floored, they would spin, shift to 2nd right away and grab. It was fun

 

[Don Frelier]

Even with 4.10's you won't be terrorizing any hellcats.

 

[#41]

The challenge with a Dana of course is that it is much harder to change gears compared to an 8-3/4... so it is important to choose right the first time. I would lean toward keeping it streetable and able to drive on the highway should you choose to do more of that in the future. The perf difference between 3.55 and 3.73 in a heavy small block car is not going to be substantial. Your tire is not terribly tall, so I'd go with 3.55 between the two. In the future if you do more highway driving you could put 28-29" tall tire on the rear and make it a little more highway friendly.

I've had several cars with 3.55s and one with 3.73, however that the 3.73 car had an OD unit. I was glad that OD was there.

PS - Dig your ride! I had a 74 Rallye exact same color combo as yours for 20+ years.

 

[joe smith]

With a NON overdrive transmission I would not go over 3.55... Even those will be too low if you happen to get on the freeway...
Had a 4.10 4 speed car when I was young... I still twitch when I hear " 4.10's... Hated those gears

 

[68Moparmaniac]

I agree with most above, 3:55's. I feel it's kind of a sweet spot ratio.

 

[Kern Dog]

A Dana in a LA block car ?
Did you know that the 8 3/4” axle was standard in HEMI cars that had automatics? The Dana is overkill.
Find a truck 8 3/4 axle and modify it to fit.

 

[400sforever]

I’m running an 8 3/4 in my 74 charger with 3.91 gears. .but I have a 512 ci motor. Excellent tire roasting ratio up to about 55 mph. Then it hooks and pulls like a rocket. Those are nice street gears in my opinion. At 60 mph with 275/60 r15 tires I’m turning about 3000 rpm

 

[Darryl]

Even with 4.10's you won't be terrorizing any hellcats.

I think I forgot to mention I have 640hp and 545tq and a built 727 to match, Im going with a Dana because I’m eventually gonna go for over 1000 with a Ritter block so I don’t wanna buy another rear

 

[Darryl]

The challenge with a Dana of course is that it is much harder to change gears compared to an 8-3/4... so it is important to choose right the first time. I would lean toward keeping it streetable and able to drive on the highway should you choose to do more of that in the future. The perf difference between 3.55 and 3.73 in a heavy small block car is not going to be substantial. Your tire is not terribly tall, so I'd go with 3.55 between the two. In the future if you do more highway driving you could put 28-29" tall tire on the rear and make it a little more highway friendly.

I've had several cars with 3.55s and one with 3.73, however that the 3.73 car had an OD unit. I was glad that OD was there.

PS - Dig your ride! I had a 74 Rallye exact same color combo as yours for 20+ years.

Thanks man, I’ve had mine since I was 13 and I don’t plan on getting rid of it, I do want to go on a road trip of Route 66 with it a few years from now so 355s might be a better option

 

[72sunroof]

It is a 340, 3.73 with your tire is 2700 rpm at 65 mph. That is perfect that engine could run there all day.