4x4 Gear ratio ideas? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Landon · 10-01-2009, 09:35 PM

I am in the process of building a 1970ish (lots of years) short bed 4x4. The axles I have appear to be 3.08s (by turning the pinion and counting). The question is.... will these gears spin 33" tires with a standard trans.? It's not going to be a rock crawler...just a driver. I'd like to be able to just drive it to work like a human. Any one have any experience with gears this high on the street with big rubber? I see no need for 4.10s and listening to the engine screaming down the highway.
Thanks

*2tons of fun* · 10-01-2009, 11:19 PM

yes they will. but you could also do it with a 5hp briggs.

it realy depends on your motor.

K2Orion · 10-03-2009, 09:19 PM

Which trans?
With a 465 you will proably get to use 1st. But you'll see better mileage as well.
I had a 700r4 and 3.08s with 33"s. That didn't work out so well.

vectorit · 10-03-2009, 10:07 PM

IMO 4.56 is a minimum for the 33" and up rubber you are runnin.

My 4 speed 68 K20 burb is runnin 4.57's with 33" tall BFG's, and it drives very nice to me.

My 02 yota 4x4 with 31" tall tires with 4.56 gears, runs a bit high rev but it is a 5 speed so it's all good to me.

4.11 may squeek by as a DD that never see's the dirt or serious work, and is just a run around rig meant to just look like a 4x4.

Anything taller than 3.70's and you will be driving a dog of truck and get terribly MPG on top of that.

GMCMAX · 10-03-2009, 11:48 PM

Mine is 3.08 with 33's, it's not bad running around, but wind up in 3rd on the steeper grades around here.
Max

*2tons of fun* · 10-04-2009, 02:47 PM

4.56 and 33 with a v8 is stupid. i have 4.56 with 38" and its to slow for the rpm.

with a 33 you will be just fine with a 3.73.

BIGBLU 72 · 10-04-2009, 08:52 PM

i run a 4.10 with 33's and love it! drives great on the highway, drove it 800 miles one way last summer. got 12 mpg tho....not great but not awful either

sierra4x4 · 10-04-2009, 09:21 PM

I have to agree with 2tons of fun on this one. I started out with 3.08's and 33's with a 465 and a 350 and it worked ok(thanks to the granny low). Then went to a 427bb wich worked really well with the extra torque. And later I switched to 3.73's and I was almost just as happy with the 3.08's as i was with the 3.73's the only real benifit was it didn't labour so hard going up hills on the hiway. I think if you have a small block 4 speed then 3.73 is the better choice. But with a big block then 3.08's will work. What are you running for an engine?

loretta · 10-04-2009, 09:25 PM

I have 33's on my truck with 3.07's and a th350 with a mild 350 and it is OK, I beat my buddies brand new F-150 in a drag. I am going to switch to at least 3.73's though it will be way more fun!

vectorit · 10-04-2009, 09:40 PM

All the guys runnin 3 what evers with tall tires, and especially automatics... I'll make all kinds o' cash pullin you're stuck butts out of the sand/mud/hole

But if you just want to get down the road then that is different story, I just wouldn't want to be behind you when you are goin up a hill or pulling a trailer.

If you run that combo in a 4x4 with tall tires, and actually want to put true effecient HP/Torque then low gear is the best.

4.56 and a 33" tall tire stupid? Then I guess I am, but I am still driving and pullin you.

72chevyk10 · 10-04-2009, 10:26 PM

im runin 4.10s with 35's and have no problem off road...

69GMCLonghorn · 10-05-2009, 03:09 AM

This is a battle that could go on forever. The option that a lot of guys are not looking at is the addition of MORE gears, not just higher or lower. If you take the good ideas above and melt them all together, you need low end for some good off roading, and overdrive for cruising, yet you still need a 1:1 on the highway for the bigger hills. So look into adding more gears via a 4 speed auto or 5 speed manual with O/D and you'll have the most drivable truck around.

Batman · 10-05-2009, 01:08 PM

My truck never sees off-road action. 250HP 350 th350 with 33s and 3.07 gears. It works great as a driver, doesn't have much on the low-end though, it feels like if I'd get a cam and such in the engine to get 350HP or so out of it it'd probbably be better. But, once you get it rolling on top of those gears and the tires it pulls up to 70mph without blinking. Heck at 60 I'm barely turning over 2k RPM.

shilo · 10-05-2009, 07:28 PM

Quote:

Originally Posted by vectorit

All the guys runnin 3 what evers with tall tires, and especially automatics... I'll make all kinds o' cash pullin you're stuck butts out of the sand/mud/hole

But if you just want to get down the road then that is different story, I just wouldn't want to be behind you when you are goin up a hill or pulling a trailer.

If you run that combo in a 4x4 with tall tires, and actually want to put true effecient HP/Torque then low gear is the best.

4.56 and a 33" tall tire stupid? Then I guess I am, but I am still driving and pullin you.

In my old k30 i had 4.56 and 44" tsl's. No way were you pullin me around. 33's and 3.08 are pretty close to 4.56 and 44's. My 71 now has 37's and 4.10s. the old 396 hauled arse and the new 496 will be just insane. Alot depends on your motor

LONGHAIR · 10-05-2009, 08:12 PM

First of all, calling people "stupid" is not acceptable. Opinions are fine but negitivity like that is considered trolling...and against the rules.

(Fair warning given)

As for my opinion, gearing is very important to performance. It is part of a correctly assembled "package". It matters as much as the proper cam and torque converter combination.
Sure the truck will move with nearly any mess of parts....but is that what you really want?

As the tires get taller the gear ratio has to get lower compensate....and that is just to maintain status quo, assuming that it was somewhat right in the first place. Of course this is limited to available gear ratios, so the is some "play".

Just because "the factory did it" or it was an "available option" doesn't make it right. Heck the factory put 2.73s in a lot of trucks w/overdrive no less?....and 2.56 was available, just to make it worse, if you think you need to?

I have replaced a lot of gears for people over the years and every one of them was amazed at the difference it made. Most of them said that it was "not the same truck" or something to that effect. It's all about the right combination.

Quote:

Originally Posted by Landon

Any one have any experience with gears this high on the street with big rubber? I see no need for 4.10s and listening to the engine screaming down the highway.
Thanks

Yes, plenty....and the whole point is that it won't be "screaming" with a tall tire.

onlyifihadachevy · 10-05-2009, 11:26 PM

It maybe be a little slow off the line but it will work for good gas mileage compared to some.

*2tons of fun* · 10-06-2009, 12:25 AM

Quote:

Originally Posted by vectorit

but I am still driving and pullin you.

if its a slow race or a pull off you want then lets rock. cause scooter, you got nothin on me.

vectorit · 10-06-2009, 10:16 AM

Quote:

Originally Posted by 2tons of fun

if its a slow race or a pull off you want then lets rock. cause scooter, you got nothin on me.

Cool your jets turbo...

I wasn't callin anyone out to a "race", and your call out to me is laughable.

I simply pointed out the obvious, when buidling an effecient and capable 4x4 with tall tires.

Being called "stupid" and challenged to a "race" in this thread of oppinion.. Wow, ok - whatever.

LONGHAIR · 10-06-2009, 06:27 PM

Quote:

Originally Posted by onlyifihadachevy

It maybe be a little slow off the line but it will work for good gas mileage compared to some.

That is not necsesarily so, I you are cruising too low in the RPM range of your engine, it is not helping fuel mileage. General city driving with a gear ratio that is too high will cause you to drive deeper into the throttle just to get going, which hurts fuel mileage too. Optimum RPM range is best, even if it is a bit higher than most think.

K2Orion · 10-08-2009, 09:38 PM

http://www.currieenterprises.com/ces...Calculator.htm

Try these calculators to figure it out.

onlyifihadachevy · 10-08-2009, 10:02 PM

I firgured I would have to rev to 6000 for a long time to get to 150mpg, i found what i want to do.

willett · 10-09-2009, 02:19 AM

i'm running 3.73's on 35's with a 454

no problems, but i spin around 3500 at 115 kph. (70 mph)

oh yeah... th 400

blazinzuk · 10-09-2009, 02:27 AM

I think 3.73s will be your best bet. I really liked them with my 35s. I had a stock motor and the rpms worked out really well for me. I cruised at 75. I put 3/4 tons in they had 4.10s I loved that gear ratio with 38s. Once again allowed me to cruise at 75 all the time. I got 10 mpg with the 38s.

10-01-2009, 09:35 PM	#1
Landon Registered User Join Date: Feb 2009 Location: Higganum CT Posts: 10	4x4 Gear ratio ideas? I am in the process of building a 1970ish (lots of years) short bed 4x4. The axles I have appear to be 3.08s (by turning the pinion and counting). The question is.... will these gears spin 33" tires with a standard trans.? It's not going to be a rock crawler...just a driver. I'd like to be able to just drive it to work like a human. Any one have any experience with gears this high on the street with big rubber? I see no need for 4.10s and listening to the engine screaming down the highway. Thanks

10-01-2009, 11:19 PM	#2
2tons of fun Account Suspended Join Date: Jan 2009 Location: galt ca, Posts: 749	Re: 4x4 Gear ratio ideas? yes they will. but you could also do it with a 5hp briggs. it realy depends on your motor.

10-03-2009, 09:19 PM	#3
K2Orion Registered User Join Date: Jan 2009 Location: St. Louis, MO Posts: 75	Re: 4x4 Gear ratio ideas? Which trans? With a 465 you will proably get to use 1st. But you'll see better mileage as well. I had a 700r4 and 3.08s with 33"s. That didn't work out so well.

10-03-2009, 10:07 PM	#4
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: 4x4 Gear ratio ideas? IMO 4.56 is a minimum for the 33" and up rubber you are runnin. My 4 speed 68 K20 burb is runnin 4.57's with 33" tall BFG's, and it drives very nice to me. My 02 yota 4x4 with 31" tall tires with 4.56 gears, runs a bit high rev but it is a 5 speed so it's all good to me. 4.11 may squeek by as a DD that never see's the dirt or serious work, and is just a run around rig meant to just look like a 4x4. Anything taller than 3.70's and you will be driving a dog of truck and get terribly MPG on top of that. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

10-03-2009, 11:48 PM	#5
GMCMAX Active Member Join Date: Jan 2006 Location: Lower Mid-East Ca. Posts: 326	Re: 4x4 Gear ratio ideas? Mine is 3.08 with 33's, it's not bad running around, but wind up in 3rd on the steeper grades around here. Max __________________ Never try to teach a pig to sing; it wastes your time and annoys the pig! Gets More Chicks My lugnuts require more torque than your honda makes! 68 GMC, 4X4 conversion w/73 k20 running gear and springs, 350 4spd, 4.10's, D44 powerlok front, 14BFF govlock rear, 33" tires, lifted 4".

10-04-2009, 02:47 PM	#6
2tons of fun Account Suspended Join Date: Jan 2009 Location: galt ca, Posts: 749	Re: 4x4 Gear ratio ideas? 4.56 and 33 with a v8 is stupid. i have 4.56 with 38" and its to slow for the rpm. with a 33 you will be just fine with a 3.73.

10-04-2009, 08:52 PM	#7
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	Re: 4x4 Gear ratio ideas? i run a 4.10 with 33's and love it! drives great on the highway, drove it 800 miles one way last summer. got 12 mpg tho....not great but not awful either __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-04-2009, 09:21 PM	#8
sierra4x4 Registered User Join Date: Jan 2009 Location: Canada Posts: 308	Re: 4x4 Gear ratio ideas? I have to agree with 2tons of fun on this one. I started out with 3.08's and 33's with a 465 and a 350 and it worked ok(thanks to the granny low). Then went to a 427bb wich worked really well with the extra torque. And later I switched to 3.73's and I was almost just as happy with the 3.08's as i was with the 3.73's the only real benifit was it didn't labour so hard going up hills on the hiway. I think if you have a small block 4 speed then 3.73 is the better choice. But with a big block then 3.08's will work. What are you running for an engine?

10-04-2009, 09:25 PM	#9
loretta Registered User Join Date: Jan 2009 Location: British Columbia, Canada Posts: 9	Re: 4x4 Gear ratio ideas? I have 33's on my truck with 3.07's and a th350 with a mild 350 and it is OK, I beat my buddies brand new F-150 in a drag. I am going to switch to at least 3.73's though it will be way more fun!

10-04-2009, 09:40 PM	#10
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: 4x4 Gear ratio ideas? All the guys runnin 3 what evers with tall tires, and especially automatics... I'll make all kinds o' cash pullin you're stuck butts out of the sand/mud/hole But if you just want to get down the road then that is different story, I just wouldn't want to be behind you when you are goin up a hill or pulling a trailer. If you run that combo in a 4x4 with tall tires, and actually want to put true effecient HP/Torque then low gear is the best. 4.56 and a 33" tall tire stupid? Then I guess I am, but I am still driving and pullin you. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU Last edited by vectorit; 10-04-2009 at 10:02 PM.

10-05-2009, 03:09 AM	#12
69GMCLonghorn Registered User Join Date: Dec 2006 Location: Porter Ranch, CA Posts: 978	Re: 4x4 Gear ratio ideas? This is a battle that could go on forever. The option that a lot of guys are not looking at is the addition of MORE gears, not just higher or lower. If you take the good ideas above and melt them all together, you need low end for some good off roading, and overdrive for cruising, yet you still need a 1:1 on the highway for the bigger hills. So look into adding more gears via a 4 speed auto or 5 speed manual with O/D and you'll have the most drivable truck around.

10-05-2009, 01:08 PM	#13
Batman Registered User Join Date: May 2007 Location: Central IL, USA Posts: 51	Re: 4x4 Gear ratio ideas? My truck never sees off-road action. 250HP 350 th350 with 33s and 3.07 gears. It works great as a driver, doesn't have much on the low-end though, it feels like if I'd get a cam and such in the engine to get 350HP or so out of it it'd probbably be better. But, once you get it rolling on top of those gears and the tires it pulls up to 70mph without blinking. Heck at 60 I'm barely turning over 2k RPM. __________________ 1972 GMC K1500 350 V-eight TH350 4x4. Last edited by Batman; 10-05-2009 at 01:08 PM.

10-05-2009, 11:26 PM	#16
onlyifihadachevy Registered User Join Date: Mar 2009 Location: seaside,ca Posts: 778	Re: 4x4 Gear ratio ideas? It maybe be a little slow off the line but it will work for good gas mileage compared to some. __________________ 72 gmc 2500 2wd drive convert My 72 thread http://67-72chevytrucks.com/vboard/s...d.php?t=346712 THe other truck, wheeler 69 1/2 4x4, yellow and rusty. http://67-72chevytrucks.com/vboard/s...d.php?t=350300

10-08-2009, 09:38 PM	#20
K2Orion Registered User Join Date: Jan 2009 Location: St. Louis, MO Posts: 75	Re: 4x4 Gear ratio ideas? http://www.currieenterprises.com/ces...Calculator.htm Try these calculators to figure it out.

10-08-2009, 10:02 PM	#21
onlyifihadachevy Registered User Join Date: Mar 2009 Location: seaside,ca Posts: 778	Re: 4x4 Gear ratio ideas? I firgured I would have to rev to 6000 for a long time to get to 150mpg, i found what i want to do. __________________ 72 gmc 2500 2wd drive convert My 72 thread http://67-72chevytrucks.com/vboard/s...d.php?t=346712 THe other truck, wheeler 69 1/2 4x4, yellow and rusty. http://67-72chevytrucks.com/vboard/s...d.php?t=350300



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10-09-2009, 02:19 AM	#22
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	Re: 4x4 Gear ratio ideas? i'm running 3.73's on 35's with a 454 no problems, but i spin around 3500 at 115 kph. (70 mph) oh yeah... th 400 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

10-09-2009, 02:27 AM	#23
blazinzuk Registered User Join Date: Oct 2009 Location: Afton Wy Posts: 77	Re: 4x4 Gear ratio ideas? I think 3.73s will be your best bet. I really liked them with my 35s. I had a stock motor and the rpms worked out really well for me. I cruised at 75. I put 3/4 tons in they had 4.10s I loved that gear ratio with 38s. Once again allowed me to cruise at 75 all the time. I got 10 mpg with the 38s.

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