Gears

[Wizard62]

I have a 1971 C30 Cheyenne CST Longhorne Camper Special with a 402 and Turbo 400. It has 4:10 gears in the rear with a limited slip diff. I want to change the ratio to a more highway friendly setup since it will not be used for towing in the future. As long as I'm alive. LOL. Where would I look for a suitable new set of gears and what would be a good ratio to look at? I'm open to all advise. Thanks. Glen.

[Already Gone]

Originally Posted by Wizard62

I have a 1971 C30 Cheyenne CST Longhorne Camper Special with a 402 and Turbo 400. It has 4:10 gears in the rear with a limited slip diff. I want to change the ratio to a more highway friendly setup since it will not be used for towing in the future. As long as I'm alive. LOL. Where would I look for a suitable new set of gears and what would be a good ratio to look at? I'm open to all advise. Thanks. Glen.

Hi Glen and welcome to the greatest site on the net. We love pictures here and would like to see some of your C30 Longhorn. I cant help you with your gear question but I'm sure in short order you will get an answer.

[chevytruckluver]

Originally Posted by Wizard62

I have a 1971 C30 Cheyenne CST Longhorne Camper Special with a 402 and Turbo 400. It has 4:10 gears in the rear with a limited slip diff. I want to change the ratio to a more highway friendly setup since it will not be used for towing in the future. As long as I'm alive. LOL. Where would I look for a suitable new set of gears and what would be a good ratio to look at? I'm open to all advise. Thanks. Glen.

Welcome to the board!
The C30 has full floating rear axles and I don't know the available gear ratios for those, but if it helps, A more friendly gear ration would be 3.73 then 3.40 then even more friendly 3.08. There should be options close to those for your HD rear axle.
Most of the C10's you see on the street have a 3.08
Good luck

[Stocker]

Welcome to the board! Do you know what type of diff the truck has? Just asking because it's a C30, so it might be an Eaton. If so, 4.10 is the best you'll find, unfortunately.

[wbc409]

You could upgrade to a rear axle out of a newer truck or install a gear vendors overdrive unit. The add on overdrive is a bit expensive b UT virtually bullet proof.

[SS Tim]

With the factory Chevy/Eaton H072 rear axle, 4.10s were the highest ratio offered. Running a tall tire helps but the fact is it is a 5000lb truck designed to move a load. 33-31" tires are going to give you 2700-2900rpm at 65.

As pointed out above an axle change to a later 14 bolt will give you some higher choices thus cutting engine speed in all gears with about the same axle rating.

If you won't be carrying much in back you could downgrade (with stock parts) to the 3.54 Dana 60 axle used in some C20s. 33-31" tires are going to give you 2350-2500rpm at 65.

The O/D option is probably the best choice giving you and extra top gear and being able to plit the lowers, at a cost.

http://www.summitracing.com/expertad...tio-calculator

[hugger6933]

My one ton has 6:17 gears???!!! No wonder it is a low mile truck with the 400 small block someone put in it probably gets the best of about 4 mpg. No a cruiser for sure. Jim

[SS Tim]

Originally Posted by hugger6933

My one ton has 6:17 gears???!!! No wonder it is a low mile truck with the 400 small block someone put in it probably gets the best of about 4 mpg. No a cruiser for sure. Jim

Is it a ten lug wheel pattern?
If so it has the H0110 11K axle.

[Wizard62]

Originally Posted by Stocker

Welcome to the board! Do you know what type of diff the truck has? Just asking because it's a C30, so it might be an Eaton. If so, 4.10 is the best you'll find, unfortunately.

Posted via Mobile Device

[Wizard62]

Originally Posted by Stocker

Welcome to the board! Do you know what type of diff the truck has? Just asking because it's a C30, so it might be an Eaton. If so, 4.10 is the best you'll find, unfortunately.

How do I find out what type it is? I have the original build sheet. Thank you.
Posted via Mobile Device

[Stocker]

Pic of an Eaton. Notice the pinion preload (deflection) bolt on the left side of the case. There are basically two types, HO52 on 3/4 tons and HO72 on one-tons. The center sections are virtually identical and the primary differences are brakes. Also, some HO52s have the load bolt and some do not -- all HO72s have it.

[SS Tim]

Here is a 71 C30 Longhorn H072 rear as installed from the factory.

[GASoline71]

A lot of people mistake the Eaton for a "10 bolt" since there are only 10 bolts holding the diff cover on.

Gary

[davepl]

If it were me, and it recently was, I actually went to deeper gears (4.56) and an overdrive (0.67) 200-4R trans. That gives me an effective final drive of 3.05. With out tall truck tires that's probably like 2.73s in a car.

It may well be cheaper to swap the trans than to change the gears. I have $3K into my rear axle (Dana 60) to rebuild it, change the gears, and add posi.

[Wizard62]

Originally Posted by Already Gone

Hi Glen and welcome to the greatest site on the net. We love pictures here and would like to see some of your C30 Longhorn. I cant help you with your gear question but I'm sure in short order you will get an answer.

I would love to post more pictures but I can't find out how to do it. Thanks

[kwmech]

My Longhorn had a dana 60 in it with 3.54s and a 396.

[hugger6933]

The way I read my GVW tag I thought it said 11000 pounds. But it does have the 8 lug pattern am I missing something? Would a vin number do better in helping me figure out what is in the rear of my truck? Don't mean to thread jack but that rear gear chart has me thinking about a truck I haven't driven more than a couple hundred yards. Probably won't drive it much more than that if it is that low geared. jim

[Stocker]

^^ Best way to know for sure, open it up and count the teeth. Next best method, jack it up and count the driveshaft revolutions to rotate the tire one time.

[special-K]

If your truck is original there is absolutely no doubt it has an HO72. No Dana 60 available in a 1t. I have that ratio in my '72 and I'm just fine with it. How fast do you need to go?
Your only choice to go taller gears is a later axle swap. Most modify the 14-bolt

[67 chevelle]

Originally Posted by special-K

If your truck is original there is absolutely no doubt it has an HO72. No Dana 60 available in a 1t. I have that ratio in my '72 and I'm just fine with it. How fast do you need to go?
Your only choice to go taller gears is a later axle swap. Most modify the 14-bolt

Great advise , they are plentiful and bulletproof , Id look for 342 gears as long as you are not running tall tires

[57taskforce]

I'll further tims advice on the 14 bolt by saying if you can find one that has stamped steel spring perches, they are easier to get off than the cast steel perches. Modifying it s easy if you can weld.