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Choosing the right Gears

Suave25

Suave25

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Guys I need some serious help.

I am in the process of building my engine. Its 440BB with 600hp. I would think that i would be also aiming for 650 -700 ftlb of torque. We are aiming 10.5.1 - 10.8.1 compression.

I want to stay with a 727 TF Tranny and will have to get it rebuilt and also changing out the drum and some components.

I want to drive it in the city but also sometimes on highway (literally sometimes). Tires will probably be around 28"

I am having an issue with choosing the gear ratio. Originally its an 8 3/4 with I believe 27x gears.

Some folks are telling me to go with 373 and others 355.

I am wondering with that much power what should I go with and if any of you have any suggestions for the transmission kit. I also need to make sure that I get accurate readings on my OD. I read in a forum that I might have to chage the part with the teeth.

Car is a 1968 Dodge Charger. I am going with a Stroker build with Aluminum heads and forged Pistons, Crank and Hydraulic Roler CAM. Will be going with a TCS Torque Converter and need to aslo figure out my Stall. Not trying to build a race car but want to find the best of both worlds. I like to cruise and also need the power when I want it.

Please help as I need to make a decision soon.

Thanks Mopar friends
 
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I have 3.73’s in mine with a 27.5” tire.

I’m glad I went that way.
I’m at around 3500 on the highway at 70MPH.

The taller tire makes the 3.73 feel like a 3.55 with a 26” tire.
 
What about your Power. I am excessive on power and don't want to loose out on that.

What you running under the hood and do you have a 3 speed transmission?
 
Suave25 said:
What about your Power. I am excessive on power and don't want to loose out on that.

What you running under the hood and do you have a 3 speed transmission?
Click to expand...
I’ve got a warmed up 446.
Probably around 425HP.

I’m sure you would have the torque to pull the shorter gear.

I like the tall gears off a dead stop and I don’t mind spinning at 3500 for the highway. I run my boat engine at 4000 under load for miles on end. 3500, lightly loaded, doesn’t bother me in the least.
 
The gears should probably match the camshaft's power rpm range along with the TQ stall rating and tire size. I spend more time on the highway than in the city and I find the 3.55s push the rpms over 3200 at 60mph. Rpms are higher than I like for hwy use in my setup, though this is what is recommended to match my cam spec. I'm going to try 3.23s in the spring to see the effects on low rpm driving and highway use.
 
Have you given an OD trans or even using a GV unit any thought? Are you planning on making any passes down the 1/4 mile? With 600 hp, gear ratio isn't a problem but traction will be....
 
Glenwood said:
The gears should probably match the camshaft's power rpm range along with the TQ stall rating and tire size. I spend more time on the highway than in the city and I find the 3.55s push the rpms over 3200 at 60mph. Rpms are higher than I like for hwy use in my setup, though this is what is recommended to match my cam spec. I'm going to try 3.23s in the spring to see the effects on low rpm driving and highway use.
Click to expand...
Thanks for your input
 
Cranky said:
Have you given an OD trans or even using a GV unit? Are you planning on making any passes down the 1/4 mile? With 600 hp, gear ratio isn't a problem but traction will be....
Click to expand...
Will probably put Gear Vendors down the road.

My concern is that I don't want to regret having done the wrong choice down the road.
 
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So basically you're ok with 600+hp for a street car but are worried about not being able to use it due to poor gear choice ? I guess it comes down to what do you want out of that car ? What are you willing to sacrifice ? If it were me I would be in the 4. Something for gears. Especially if you're only planning on mostly city driving.
 
This is just a very old school way. Ask yourself, Where am I driving ? Meaning your area. For me when I was living in rural Pa,it was twisty turny roads that hardly has a straight-away for maybe 100 yards.So a deeper gear was chosen.We did many cars with 3.73 or 4.10. As a kid in high school my 340 4 speed Duster had 5.13's.Fun when your a kid !
Now living in the Nevada desert,any direction 3 miles from home base,speed limits are 65-75 mph and miles and miles of straight open roads.The 3.23 gear in the car now is just about right with a 28'' tire.I have no plans on track duty for the car.
So I guess what I'm saying is maybe look at your environment around you and the driving conditions.
We built a 'Cuda in Pa for a friends son and did a Passion 4 speed OD with 3.73 gears.For 2 reasons. The boy was taking it on the Hot Rod Power Tour #1. and #2 is where he lives it's 1st gear,2nd gear,3rd back off cause you ran out of road !
My 2 cents .
 
To work properly your setup has to work together. Compression, cam, rear gear, tire size, and vehicle weight. From the information provided, I'd recommend at least 3k stall converter and 3:73 gears. 440'
 
As Glenwood said, camshaft has allot to do with it too.The first car we built with a Tremic 5 speed,I didn't factor that in. With 3.55 gears and a .68 OD the RPM range the car hated 5th gear and would lug at speeds under 65-70.
Now using a Torqueflight and converter your results will vary.
 
Darter6 said:
This is just a very old school way. Ask yourself, Where am I driving ? Meaning your area. For me when I was living in rural Pa,it was twisty turny roads that hardly has a straight-away for maybe 100 yards.So a deeper gear was chosen.We did many cars with 3.73 or 4.10. As a kid in high school my 340 4 speed Duster had 5.13's.Fun when your a kid !
Now living in the Nevada desert,any direction 3 miles from home base,speed limits are 65-75 mph and miles and miles of straight open roads.The 3.23 gear in the car now is just about right with a 28'' tire.I have no plans on track duty for the car.
So I guess what I'm saying is maybe look at your environment around you and the driving conditions.
We built a 'Cuda in Pa for a friends son and did a Passion 4 speed OD with 3.73 gears.For 2 reasons. The boy was taking it on the Hot Rod Power Tour #1. and #2 is where he lives it's 1st gear,2nd gear,3rd back off cause you ran out of road !
My 2 cents .
Click to expand...

Agree, I could not image a 4.10 gear like I had in my Satellite in central NY in the SW deserts! There are times the 2.93 seems to low after driving hours at 75-80! Especially when I have to fill the gas tank!
 
Darter6 said:
This is just a very old school way. Ask yourself, Where am I driving ? Meaning your area. For me when I was living in rural Pa,it was twisty turny roads that hardly has a straight-away for maybe 100 yards.So a deeper gear was chosen.We did many cars with 3.73 or 4.10. As a kid in high school my 340 4 speed Duster had 5.13's.Fun when your a kid !
Now living in the Nevada desert,any direction 3 miles from home base,speed limits are 65-75 mph and miles and miles of straight open roads.The 3.23 gear in the car now is just about right with a 28'' tire.I have no plans on track duty for the car.
So I guess what I'm saying is maybe look at your environment around you and the driving conditions.
We built a 'Cuda in Pa for a friends son and did a Passion 4 speed OD with 3.73 gears.For 2 reasons. The boy was taking it on the Hot Rod Power Tour #1. and #2 is where he lives it's 1st gear,2nd gear,3rd back off cause you ran out of road !
My 2 cents .
Click to expand...
Hey thanks man.

I do intend to drive it more in the city thannon the highway. So I think 373 will do just fine.
 
Suave25 said:
Will probably put Gear Vendors down the road.

My concern is that I don't want to regret having done the wrong choice down the road.
Click to expand...

We don't know the cam, don't know the converter, don't know if there will be an OD, and don't really know what your goal is. This renders picking the "right" gear impossible.
 
Nothing is stopping you from having 2 or more pigs set up ready to swap. Going to Florida-put in the 2.73s, etc.
Mike
 
Don't forget to beef up your rear yoke while its apart. Also u-joints! 1350 everything IMO. Driveshaft loop too.
Suave25 said:
My concern is that I don't want to regret having done the wrong choice down the road.
Click to expand...

Where have I heard that before, over and over again.
 
I'm with you 493Mike. I was traveling during school semester breaks between Denver and Pittsburgh Pa. Installed 2.94 for the cross country trip and then put in the 3.91's when I got to the destination. Oh to be young again....:steering:
 
after all he did say "literally sometimes"
mostly city driving

3.73:1 is a great compromise, especially with a 28" tire
if it works properly with the cam & converter it "should have"
the 3.73:1 works great with a venders OD too
if you want to do better off the line/bottom end grunt
(yes even with a stroker combo, it does help, especially heavy cars)

& if you really don't drive on the open road/freeway much
3.91:1 will give it a bit more early movement, if it can even hook

not a huge difference between 3.73:1 & 3.91:1, with a 28"+ tall tire

it's like the difference between 3.23:1 & 3.55:1 in shorter 25"-26" tires

especially if the hwy, open hwy driving is rare

yes it will suffer more on open roads but, constant RPM's freeways
but;
still have the stoplight to stop-sign bottom end grunt/city gran-prix

I have 3.23:1 in my current car, right now
I live in the sticks, never drive on a freeway, they're 100 miles away
& I will be going back to the trusty 3.73:1 gears
sometime in the future again

as said before we don't know the actual combo
so it's all speculations as of now, best wild as guess

you could have 2 or more sets of gears too

good luck
 
slepr1 said:
Don't forget to beef up your rear yoke while its apart. Also u-joints! 1350 everything IMO. Driveshaft loop too.


Where have I heard that before, over and over again.
Click to expand...
Rear Yoke is going 2 5/8 at the ears. Also gonna put forged UJoints
 
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