Help me with low rear end gearing....

[bo duke]

Hello,



I am looking at putting a cummins 5. 9l into a 1971 Dodge W500 truck.



This is a big 2 ton truck,and is 4wd. It has a gvwr of 20,000. The front and rear ratio is 6. 80 to 1, geared verry low.



I will put a cummins in it but I am unsure of how to overcome the low gear ratio.



I can not change the ring,pinion gears as I won't find any thing to fit it.



By my calculations with a nv4500 I will be going 48 mph at 2000 rpm.



I need a overdrive ratio of . 58 for optimum cruse rpm.



There is about 3 1/2 feet between the transmission and transfer case.



I have thought about a gearvendors overdrive behind the nv4500, but it is expensive and am unsure how well it will hold up in the long run.



Does anyone have any suggestions on how to overcome the low gear ratio?

 

[GOT-Torque]

Very big tires



I saw a 2nd gen dodge riding on 46" tires of some sort last week. Looked pretty sweet :-laf



Getting into the truck looked impossible though#@$%!

 

[JFlagg]

I don't have any experience with the GearVendors, other than once looking at putting one in my CTD, but I would think that strength shouldn't be a problem. If you look at some of the vehicles they advertise them in, a stock, or even a built 5. 9 shouldn't make more HP/TQ than it can handle. Though, thats just based on their advertisments, so who knows? I really don't see any other options, if you can't regear it, go with bigger tires. Not a transmission guy by any means either, but can you build a transmission with new gear ratios? Cost might be the only drawback there too. Another thought, what about different axles? If they have to be big ones, what about Rockwells, Almost every Ring and pinion shop that caters to off-roaders will have gear sets and parts for them, I know for a fact that you can regear them up to 5. 56(I think thats right) Thats still better than 6. 80s. Good Luck!

 

[HRDROKN]

If my memory is correct... I had looked into GearVendors OD unit and I believe that it was rated at 2000 lb. ft. of torque.....

 

[RDupree]

you can get an stand alone transmission with 3-4 speeds to put in there,they have underdrive,direct and overdrive. none of them have that big a ratio jump though,i've seen a . 60 overdrive (i have one)

i am putting one in my crewcab conversion today,i've had them in my last 4 trucks. i think aldermans truck parts in ohio has some of them,and i have the one for sale. most have the . 74 overdrive ratio. these trannys are know as brownies.

 

[LeeJ]

Do you have any info or a web site where I could look into what they have? I have an 83 conversion and Im looking for something to tighten my ratios. Thanks if you can

 

[Bob4x4]

I don't have any experience with the GearVendors, other than once looking at putting one in my CTD, but I would think that strength shouldn't be a problem. If you look at some of the vehicles they advertise them in, a stock, or even a built 5. 9 shouldn't make more HP/TQ than it can handle. Though, thats just based on their advertisments, so who knows? I really don't see any other options, if you can't regear it, go with bigger tires. Not a transmission guy by any means either, but can you build a transmission with new gear ratios? Cost might be the only drawback there too. Another thought, what about different axles? If they have to be big ones, what about Rockwells, Almost every Ring and pinion shop that caters to off-roaders will have gear sets and parts for them, I know for a fact that you can regear them up to 5. 56(I think thats right) Thats still better than 6. 80s. Good Luck!

I have seen gear vendors fail with that kind of weight and way under 2k torque.



Bob