best rearend gears? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

useRc10 · 03-18-2003, 06:53 PM

what would be the best gear ratio for meto put on my truck for mileage/performance? its a 350 witha 3spd/column...i'm not sure what else you'd need to know...i have a posi on a parts truck but not sure of gear ratio right now...
thanks, -Nick

Wabash · 03-18-2003, 07:27 PM

myself i like the 3:73's

tom hand · 03-18-2003, 07:37 PM

mileage/performance? You get to pick one. Actually your not going to get much mileage regardless unless you go to an overdrive trans so you might as well go with a 3.73

jku72 · 03-18-2003, 08:08 PM

Yes, if its just rear-end you are talking about, you have to decide, because while a 2.76 rear gear is available, and gives decent fuel mileage, you get crap performance.
On the other hand, 3.73 gives good performance, but count on miserable fuel mileage.
Of course, there are part-way compromises, like 3.23, 3.55, etc, but the the only way to get the best of both worlds is to swap the trans to a newer 4 speed overdrive, or, in the case of manual, a 5 speed overdrive, or, add an aftermarket overdrive. RBasing it on rear gears is compromising your desired result in some way.

cdowns · 03-18-2003, 08:31 PM

it also depends what the ratio is for your posi,there's one posi for 373 and higher gears another for lower gears , i personellay plan on changing from the 411 im using now to a 323 to get a bit more milage out of the old girl because i'm only gettin about 15mpg

mikep · 03-18-2003, 10:50 PM

Why compromise? Get a daily driver and play with the toy. I just rebuilt a 5.14 geared locker eaton pumpkin and its going in this weekend.

bigjimzlll · 03-18-2003, 10:55 PM

going in what Mike? if its the truck, I hope your only running an 1/8 mile...

mikep · 03-18-2003, 11:38 PM

Ive got 32 inch tires on it now and will probably go to 33's in the near future. 5.14's will put me at about 6000 rpm at 110 mph or even a bit faster. Since theres no way that that pig is going to run over 110 mph while I own it I can live with that. Peak power is 5500-6000 anyway. It'll work. I dont consider 6000 rpm excessive and since most of my driving is in town at speeds lower than 50 mph I dont see a problem. If I do I have 2 other pumpkins set up for 4.11 and 4.56 gears.

gmc67swb · 03-18-2003, 11:43 PM

3.55 TO MAYBE 3.73 WOULD BE SWEET WITH AN O/D. BEST OF BOTH WORLDS. OR YOU COULD GET SOME 4.10'S WITH A 6 SPEED. THE MORE GEARS THE BETTER

crazy longhorn · 03-18-2003, 11:56 PM

3.73 is a good all around gear for a 1/2 ton truck. If you do a lot of highway, 3.42- 3.55 may be a better choice. The 3 spd stick trans leaves a lot to be desired as far as gear spacing tho. A combo that i ran for a while had 3.40 gears, & a saginaw 4 spd with a 3.50 1st gear(Monza trans). it worked pretty good as far as power , & ran resonable rpms on the on the highway. Good luck,crazyL

**kwmech** · 03-19-2003, 01:06 AM

Most of what you want is to keep the bottom end of the power band at cruising speed that is where the engine is going to be most efficient considering the type of carburation/injection. My crewcab which has a 6.5 diesel runs 3.73 with a gear vendor o.d. with 33s. My suburban runs a 4.56 with a 700r4 and 32s with a tbi 350. My tow truck-- 454 -- 4.56 with 33s and a 5 speed. Another tow truck I' starting to build will have 5.13s and 37s with a long rod 400 sb and a 5 speed. I install gears and lockers and build custom axles all day long everyday, it just depends on quite a few variables and what you want the vehicle to do at a certain speed.

bigjimzlll · 03-19-2003, 01:14 AM

the 32" tires will help a ton

1969 GMC · 03-19-2003, 03:52 AM

The p/o of my truck swapped out the original 4.11 gears for 3.73 so he could travel on the highway a little more efficiently, I think it was a good choice. They give me decent fuel mileage and when I want to, they will make the truck get up'n go. Well, at least to me...this is my first truck.

03-18-2003, 06:53 PM	#1
useRc10 Registered User Join Date: Feb 2001 Location: Mechanicsville, VA, 23111 Posts: 1,138	best rearend gears? what would be the best gear ratio for meto put on my truck for mileage/performance? its a 350 witha 3spd/column...i'm not sure what else you'd need to know...i have a posi on a parts truck but not sure of gear ratio right now... thanks, -Nick __________________ -'02 Chevy Avalanche, 5.3L, 4x4... needing a small lift and bigger tires -'72 Chevy C-10(350, bored 60 over)dual flowmasters, 3 on the tree -'85 K5 Blazer,305 NO MORE...350 is in,2" lift,33" Mickey Thompson Baja Claw Radials -dads '70 burb (red, 5-7 drop, 350...) www.geocities.com/userc10/truckhome.html AIM: Auntjoedadda

03-18-2003, 07:27 PM	#2
Wabash Registered User Join Date: Apr 2001 Location: Alberta, Canada Posts: 534	myself i like the 3:73's __________________ 1972 C/10 LWB 1972 K/5 Blazer

03-18-2003, 07:37 PM	#3
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	mileage/performance? You get to pick one. Actually your not going to get much mileage regardless unless you go to an overdrive trans so you might as well go with a 3.73 __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

03-18-2003, 08:08 PM	#4
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	Yes, if its just rear-end you are talking about, you have to decide, because while a 2.76 rear gear is available, and gives decent fuel mileage, you get crap performance. On the other hand, 3.73 gives good performance, but count on miserable fuel mileage. Of course, there are part-way compromises, like 3.23, 3.55, etc, but the the only way to get the best of both worlds is to swap the trans to a newer 4 speed overdrive, or, in the case of manual, a 5 speed overdrive, or, add an aftermarket overdrive. RBasing it on rear gears is compromising your desired result in some way. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

03-18-2003, 08:31 PM	#5
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	it also depends what the ratio is for your posi,there's one posi for 373 and higher gears another for lower gears , i personellay plan on changing from the 411 im using now to a 323 to get a bit more milage out of the old girl because i'm only gettin about 15mpg __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-18-2003, 10:50 PM	#6
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Why compromise? Get a daily driver and play with the toy. I just rebuilt a 5.14 geared locker eaton pumpkin and its going in this weekend. __________________ No truck :-(

03-18-2003, 10:55 PM	#7
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	going in what Mike? if its the truck, I hope your only running an 1/8 mile... __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

03-18-2003, 11:38 PM	#8
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Ive got 32 inch tires on it now and will probably go to 33's in the near future. 5.14's will put me at about 6000 rpm at 110 mph or even a bit faster. Since theres no way that that pig is going to run over 110 mph while I own it I can live with that. Peak power is 5500-6000 anyway. It'll work. I dont consider 6000 rpm excessive and since most of my driving is in town at speeds lower than 50 mph I dont see a problem. If I do I have 2 other pumpkins set up for 4.11 and 4.56 gears. __________________ No truck :-(

03-18-2003, 11:43 PM	#9
gmc67swb Registered User Join Date: Feb 2003 Location: Mesquite, Tx Posts: 396	3.55 TO MAYBE 3.73 WOULD BE SWEET WITH AN O/D. BEST OF BOTH WORLDS. OR YOU COULD GET SOME 4.10'S WITH A 6 SPEED. THE MORE GEARS THE BETTER __________________ GM 330HP/350, Magnuson 122HH, Tremec TKO 5spd

03-18-2003, 11:56 PM	#10
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	3.73 is a good all around gear for a 1/2 ton truck. If you do a lot of highway, 3.42- 3.55 may be a better choice. The 3 spd stick trans leaves a lot to be desired as far as gear spacing tho. A combo that i ran for a while had 3.40 gears, & a saginaw 4 spd with a 3.50 1st gear(Monza trans). it worked pretty good as far as power , & ran resonable rpms on the on the highway. Good luck,crazyL

03-19-2003, 01:06 AM	#11
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,408	Most of what you want is to keep the bottom end of the power band at cruising speed that is where the engine is going to be most efficient considering the type of carburation/injection. My crewcab which has a 6.5 diesel runs 3.73 with a gear vendor o.d. with 33s. My suburban runs a 4.56 with a 700r4 and 32s with a tbi 350. My tow truck-- 454 -- 4.56 with 33s and a 5 speed. Another tow truck I' starting to build will have 5.13s and 37s with a long rod 400 sb and a 5 speed. I install gears and lockers and build custom axles all day long everyday, it just depends on quite a few variables and what you want the vehicle to do at a certain speed.

03-19-2003, 01:14 AM	#12
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	the 32" tires will help a ton __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

03-19-2003, 03:52 AM	#13
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	The p/o of my truck swapped out the original 4.11 gears for 3.73 so he could travel on the highway a little more efficiently, I think it was a good choice. They give me decent fuel mileage and when I want to, they will make the truck get up'n go. Well, at least to me...this is my first truck. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650



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