Rear gear ratios for the 47RE/Cummins combo

Bobcat698

Bobcat698

Pure Diesel Power
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Apr 24, 2006
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What are most of you guys running for axle gear ratios?

I currently run 3.54's and I know that 4.10s aren't kosher.

I plan on running 4.88 gears so I can get up to 3rd gear sled pulling, but am curious on how much advantage I'll have vs 2nd gear and 3.54 gears.

Technically since I am spinning the drive shafts faster they should live longer, correct?

Any input?
 
Less torque should help the everything but the axles live longer. Should be about a 5% higher ratio in drive than second with 3.54. Will also relieve some of the massive torque on the pinion also. Just make sure that 4.88 is the right gear. The DMAX guys are running 4.10 in the 2.8 class. I know I have even said 4.10 is a crap gear, but as the HP goes up a something higher than a 4.88 might be the ticket. I have an idea for an equalizer, but I need to make some phone calls to see how feasible it is. As the HP goes up they may start loading the sleds heavy enough to keep the wheel speeds from getting crazy.
 
4.10's and third gear just isn't feasible IMO.. Van said even the mod trucks can't run a gear that steep.

If its harder on the axles, thats fine, I'm stepping to 37 spline next year :)
 
Running a gear that size is depending on the RPM you need to keep the charger lit. I had read somewhere that the DMAX can still be on the A5K charger at 2600 rpm. If you can get a motor that breathes that well and a charger that is that efficient 4.10 is feasible. I just don't see it on a 3.0 charger on a 12V dodge though. 2.6 definately possible though.
Personally at this point 4.88 is gonna be the route I go, with a set of 33's and a set of 35's. Run the 33's at say a DHRA pull, run the 35's at the looser tracks/sleds.

Of course the mod trucks can't run it, they are turning 6000+ running down the track.
 
I ran 4:10 last year with my dodge and an RH third locked up uasally except at scheids then it was just 3rd. I started out this year with 4:88 and an RH and it was the best thing I did for that setup it would light my charger with RPM only by 15 the 20ft mark, but your trany needs to be set up for it ,mine would shift at 4800rpm.
Know the down side is it makes it alot harder for the brakes to hold it back and try to spool it up on the line.
any other ? on it feel free to call me Garrett
 
4.10s worked fine with my 66 charger, I'm talking a 3" or larger charger that need 3200RPM+ to keep lit down down track, so 4.10's would be pretty steep to run at 3500+ down the track in 3rd gear.
 
smokinrod said:
I ran 4:10 last year with my dodge and an RH third locked up uasally except at scheids then it was just 3rd. I started out this year with 4:88 and an RH and it was the best thing I did for that setup it would light my charger with RPM only by 15 the 20ft mark, but your trany needs to be set up for it ,mine would shift at 4800rpm.
Know the down side is it makes it alot harder for the brakes to hold it back and try to spool it up on the line.
any other ? on it feel free to call me Garrett
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Rod, you let your trans shift automatically? Why not manually shift?

Also, you had enough power to run 3rd with 4.10s? Nice!

I'll give you a buzz tomorrow.
 
I was tunnin a GT4202R that is a 3.0 charger, I would allways run at 3800-4200rpm with my 4:10's I went to 4:88's cause I wanted to run 4500-4800rpm's down track
 
yes it shifted automatically, HTS says you will break stuff if you shift manually from first to second with a RH, I'll talk at you tomarrow.
 
if I recall correctly

terry coppess runs 3.54's and pulls 2nd
scott amos runns 5.13's and pulls 3rd
both trucks are very competitive
george peterson runs 4.10's and hits 3rd but jumps back to second at the end of the track
 
gotta12v said:
if I recall correctly

terry coppess runs 3.54's and pulls 2nd
scott amos runns 5.13's and pulls 3rd
both trucks are very competitive
george peterson runs 4.10's and hits 3rd but jumps back to second at the end of the track
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COppes is having trouble with 2nd gear and RPM at RPM limited pulls.
Are you sure Peterson just wasn't unlocking the convertor down at the end?
Yes 2nd with 3.54's and 3rd with 5.13's are the same. I think Amos is running a 4.88 gear, won't swear on it. One thing to consider is wheel speed and 4500 rpm limit if it exists. With the DMAX being able to run at least 4000 rpm in 4th with with 4.10's you don't want to gear it too low so at 3rd gear 4500 rpm you can't cut the mustard. OD is just too big of jump to run. There is the 4.30 option, or if don't plan on drag racing the 4.63/4.56 combo.
 
zstroken said:
COppes is having trouble with 2nd gear and RPM at RPM limited pulls.
Are you sure Peterson just wasn't unlocking the convertor down at the end?
Yes 2nd with 3.54's and 3rd with 5.13's are the same. I think Amos is running a 4.88 gear, won't swear on it. One thing to consider is wheel speed and 4500 rpm limit if it exists. With the DMAX being able to run at least 4000 rpm in 4th with with 4.10's you don't want to gear it too low so at 3rd gear 4500 rpm you can't cut the mustard. OD is just too big of jump to run. There is the 4.30 option, or if don't plan on drag racing the 4.63/4.56 combo.
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I have also thought about that one like the mud racers it would be a positive thing I think to have the front pulling alittle more .
 
Not on dirt , I would put a taller tire in front mine are 1 in taller helps take the bounce out and the front pull a little harder . It would help if u had more gears in the auto . The dmax has an adavantage IMO with 4 gears versus 3 , just like the big rigs on the road the more gears u have the better it pulls , I would try a gearvendor u would have 5 gears to play with then
 
gear venders have been tried and they don't hold up. I have even heard off fords breakin them, I beleive bbunting used to have one but broke it acouple of times before he got reid of it.
 
smokinrod said:
gear venders have been tried and they don't hold up. I have even heard off fords breakin them, I beleive bbunting used to have one but broke it acouple of times before he got reid of it.
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I remember that day in IL
 
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