What gear ratio works best for 33's? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gregbr · 04-15-2005, 08:53 PM

I was womdering what is the best gear ratio to use with 33x10.50's on a 67 4wd 350/T350/np203....if the xfer model matters.

uncle_handsome · 04-15-2005, 09:33 PM

I'm guessing any gear not under 3.73's.

*1FaastC10* · 04-15-2005, 09:47 PM

actually, a 3.08 would be pretty managable with a non-overdrive truck as a daily driver. 4.10s on an OD daily driver. for an offroad toy that wont ever see highway milage, the sky is the limit.

OhioChevy · 04-15-2005, 10:41 PM

3.73.....will do fine with this gear.

Don

**kwmech** · 04-15-2005, 11:34 PM

I would go with the 3.73 also. I had a 71 years ago with 4.10s and 33s--seemed like it always needed another gear on the freeway.

Hoods69BadBowTie · 04-16-2005, 12:06 AM

I would say about 3.73 or a little bit lower should be good.
-Later

gregbr · 04-16-2005, 12:26 AM

Thanks, the truck currently has 33's, but I'm not sure what ratio it has. The 350 seems to be running fast at 55, and it doesn't seem to have alot of power. Just need time to smoke it over....I've only had it a week or so.

1969K10 · 04-18-2005, 11:48 AM

With my 33's & 3.73's, i've not yet had a problem with a lack of torque on the low end... been thru some interesting old abandoned logging trails...
Anyway, at 75MPH, i'm spinning right at 3K RPM, and still don't have a use for 1st gear when taking off unloaded on pavement (except for traffic jams!!!) I can get you more MPH vs. RPM's if you need.

**JIMs70GMC** · 04-18-2005, 11:55 AM

Just to echo what others have said 3.73-4.10 would be best all around. I have 4.10s w/35s(GMC) and 4.56s w/35s(Chevy). I'd have to lean towards the 4.10s, because I'll probably go w/38s w/ the 4.56s.

Jason915 · 04-18-2005, 12:14 PM

depends on what your doing, if its a daily driver that you have on the interstate going 75mph then go with a 3.73 or higher. If its a truck that don't see 75mph very often and you want to tow with it and go fourwheeling/mudding then go with 4.10's. For me I tow up mountain passes that the speed limmit is only 50-55 MPH so 4.10's work perfect for me.

fasteddie · 04-20-2005, 06:46 AM

i have had 2 3/4 ton chevy's with 33's and both had 3:73 gears and they worked well for all around
i did alot of high driving back and forth to college
and alot of play in the woods as well as plowing

fasteddie · 04-20-2005, 06:48 AM

also it makes a difference if you have over drive
with over drive you can go lower gears
neither of mine had over drive
but if i did, i would have went with 4;10's

ryanroo · 04-20-2005, 11:34 AM

my SWB has 33s and 3.73 and i am happy with it. ive towed with it and it did well, but if you plan on just driving it, a 3.08 would be ok, but i think it would be a dog.
Ryan

Mudder · 04-20-2005, 12:15 PM

3.08's and 33's are dogs. I ran that combo for several years. 33's and 3.73's are pretty good.

poff · 04-21-2005, 01:12 PM

I run 4.10s with 33's and have no problem crusing 75mph with a 4 spd. I use my truck offroad a lot and actually wish I had 4.56s. If I go to 35s I will definitly go to 4.56. If you only drive on the street 3.73 should be fine. If you offroad a lot 3.73 may be to high, especially without a granny gear.

GMC71k20 · 04-21-2005, 01:24 PM

jim- how are 4.10s and 35s. thats what my daily driver tires are going to be this summer.

k5keith · 04-24-2005, 03:34 PM

i have 411/410 combo on my 70 3/4 ton 4x4 with 33 12.50's and a t350 and my truck just starts to breath at 70 mph. hmmmm must have something to do with the cam

stan79chevy · 04-24-2005, 04:38 PM

its great in the mud..but on the highway im maxed out at about 60is.. but i can pull anything

Russell · 04-24-2005, 07:38 PM

I was looking at calculators online, and if I ran with 4.10s, 35" tires, and an overdrive tranny, I'd be at like 1900 rpm at 65 mph, not calculating slippage in. Is that too low of an RPM for a 355 TPI with a mild cam, and dual exhaust / headers?

*1FaastC10* · 04-24-2005, 08:16 PM

depends on your cam, and compression ratio should be adjusted accordinly.

Russell · 04-24-2005, 08:36 PM

It has an XE262 comp cam in it, and should be sitting at about 9.5:1 once I install the 64 cc TPI Camaro heads I want to go with.

Hawged-67 · 04-25-2005, 11:52 AM

i'm runnin 35 with 3.08 gears, 355 low rpm torque cam, 4 speed and 205 transfer. Nice going on flat ground but long hills sucks, bogs down. But gearing was great when my T-221 Rockwell took a **** on me drove in 4 low about 50 miles to get home.
My dad had a 76 k10 he bought new with 4speed, 205, 3.08 gears, 35 in hawgs, said he could go down the highway at 90mph downshift to 3rd and never tell the differnce. Once got a speedin ticket in 3rd going 60mph

*1FaastC10* · 04-25-2005, 05:57 PM

Quote:

Originally Posted by Russell

It has an XE262 comp cam in it, and should be sitting at about 9.5:1 once I install the 64 cc TPI Camaro heads I want to go with.

personally, i'd back it down the 9:1. that would give you about a 7.75:1 dynamic compression ratio, and you could run it on the cheap stuff. 9.5:1 would require premium. other than that, it sounds good. a factory 86 Trans Am or Z-28 runs from 1600-2000 rpms @ 65, so your 1900 sounds pretty good. make sure you run a BIG trans cooler if your OD is an auto.

Apache · 04-26-2005, 04:13 PM

Id go with 3.73's. 3.55's maybe better if alot more road use....3.73's good all around, and if you want it offroad mostly, then its all up to you keep going high as you want.

Jason915 · 04-26-2005, 05:07 PM

4.10's don't fear the gear

04-15-2005, 08:53 PM	#1
gregbr Senoir Member Join Date: Mar 2002 Location: Rock Hill, SC USA Posts: 1,214	What gear ratio works best for 33's? I was womdering what is the best gear ratio to use with 33x10.50's on a 67 4wd 350/T350/np203....if the xfer model matters. __________________ 67 Chevy, Small back glass, Factory 4WD, Factory Shortbed, Factory V8, Lifted 4" 70 GMC Sierra Grande, Factory Shortbed, Factory 402/400 turbo, Super Custom Interior. Numbers matching with SPID & Build Sheet. 68K Original Miles. Restored 2010 70 GMC Restoration Pictures http://67-72chevytrucks.com/gallery/...00&ppuser=4424

04-16-2005, 12:06 AM	#6
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	I would say about 3.73 or a little bit lower should be good. -Later __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

04-16-2005, 12:26 AM	#7
gregbr Senoir Member Join Date: Mar 2002 Location: Rock Hill, SC USA Posts: 1,214	Thanks, the truck currently has 33's, but I'm not sure what ratio it has. The 350 seems to be running fast at 55, and it doesn't seem to have alot of power. Just need time to smoke it over....I've only had it a week or so. __________________ 67 Chevy, Small back glass, Factory 4WD, Factory Shortbed, Factory V8, Lifted 4" 70 GMC Sierra Grande, Factory Shortbed, Factory 402/400 turbo, Super Custom Interior. Numbers matching with SPID & Build Sheet. 68K Original Miles. Restored 2010 70 GMC Restoration Pictures http://67-72chevytrucks.com/gallery/...00&ppuser=4424

04-18-2005, 11:48 AM	#8
1969K10 Senior Member Join Date: Jul 2004 Location: Clarks Hill, Indiana Posts: 733	With my 33's & 3.73's, i've not yet had a problem with a lack of torque on the low end... been thru some interesting old abandoned logging trails... Anyway, at 75MPH, i'm spinning right at 3K RPM, and still don't have a use for 1st gear when taking off unloaded on pavement (except for traffic jams!!!) I can get you more MPH vs. RPM's if you need. __________________ 1969 K10 - V8, 465, 205, 12 bolt, D44 2002-current 1969 K20 - V8, 465, 221, Eaton, D44 2012-current Nothin' but drums on all 4 corners! past horses in the stable 72 C10-short step (97-02), 68 C10-long fleet (06-12)

04-18-2005, 11:55 AM	#9
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Just to echo what others have said 3.73-4.10 would be best all around. I have 4.10s w/35s(GMC) and 4.56s w/35s(Chevy). I'd have to lean towards the 4.10s, because I'll probably go w/38s w/ the 4.56s. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

04-15-2005, 09:33 PM	#2
uncle_handsome Uncle H. is this cartoon Join Date: Nov 2004 Location: Mississauga, SC (I wish! lol!) Ontario Posts: 797	I'm guessing any gear not under 3.73's.

04-15-2005, 09:47 PM	#3
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	actually, a 3.08 would be pretty managable with a non-overdrive truck as a daily driver. 4.10s on an OD daily driver. for an offroad toy that wont ever see highway milage, the sky is the limit.

04-15-2005, 10:41 PM	#4
OhioChevy Senior Member Join Date: Jun 2004 Location: Southern Ohio Posts: 489	3.73.....will do fine with this gear. Don

04-15-2005, 11:34 PM	#5
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	I would go with the 3.73 also. I had a 71 years ago with 4.10s and 33s--seemed like it always needed another gear on the freeway.

04-18-2005, 12:14 PM	#10
Jason915 Registered User Join Date: Jan 2005 Location: Colorado Springs Posts: 693	depends on what your doing, if its a daily driver that you have on the interstate going 75mph then go with a 3.73 or higher. If its a truck that don't see 75mph very often and you want to tow with it and go fourwheeling/mudding then go with 4.10's. For me I tow up mountain passes that the speed limmit is only 50-55 MPH so 4.10's work perfect for me. __________________ 1971 GMC K1500 SWB Fleetside, 4" skyjacker softride and, 14 Bolt FF, HD Dana 44 4.10's 1970 K5 TBI conversion lifted etc SOLD 1968 C20 camper truck SOLD “To ban guns because criminals use them is to tell the innocent and law-abiding that their rights and liberties depend not on their own conduct, but on the conduct of the guilty and the lawless.” Jeff Snyder

04-20-2005, 06:46 AM	#11
fasteddie Registered User Join Date: Nov 2004 Location: south bend in Posts: 7	i have had 2 3/4 ton chevy's with 33's and both had 3:73 gears and they worked well for all around i did alot of high driving back and forth to college and alot of play in the woods as well as plowing

04-20-2005, 06:48 AM	#12
fasteddie Registered User Join Date: Nov 2004 Location: south bend in Posts: 7	also it makes a difference if you have over drive with over drive you can go lower gears neither of mine had over drive but if i did, i would have went with 4;10's

04-20-2005, 11:34 AM	#13
ryanroo Senior Member Join Date: Apr 2004 Location: sw colorado Posts: 2,720	my SWB has 33s and 3.73 and i am happy with it. ive towed with it and it did well, but if you plan on just driving it, a 3.08 would be ok, but i think it would be a dog. Ryan __________________ 72 K20 12v build 72 K20 "parts truck" A place for your diesel swap questions

04-20-2005, 12:15 PM	#14
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	3.08's and 33's are dogs. I ran that combo for several years. 33's and 3.73's are pretty good. Last edited by Mudder; 04-20-2005 at 12:16 PM.

04-21-2005, 01:12 PM	#15
poff Registered User Join Date: Dec 1999 Location: san diego, ca Posts: 546	I run 4.10s with 33's and have no problem crusing 75mph with a 4 spd. I use my truck offroad a lot and actually wish I had 4.56s. If I go to 35s I will definitly go to 4.56. If you only drive on the street 3.73 should be fine. If you offroad a lot 3.73 may be to high, especially without a granny gear. __________________ '70 K-20 San Diego, CA



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04-21-2005, 01:24 PM	#16
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	jim- how are 4.10s and 35s. thats what my daily driver tires are going to be this summer.

04-24-2005, 03:34 PM	#17
k5keith Registered User Join Date: Apr 2005 Location: Portland Oregon Posts: 38	i have 411/410 combo on my 70 3/4 ton 4x4 with 33 12.50's and a t350 and my truck just starts to breath at 70 mph. hmmmm must have something to do with the cam

04-24-2005, 04:38 PM	#18
stan79chevy Registered User Join Date: Sep 2003 Location: COVINGTON GEORGIA Posts: 477	im running 4.56 with my 33's its great in the mud..but on the highway im maxed out at about 60is.. but i can pull anything __________________ 79 chevy k20 350/350/205/D44/14bFF 4.56 gears rock LWB pimer black 01 S-10 ZR2 extended cab 4.3/4L60E/233 3.73 gear 31" DICK CEPEK CRUSHERS

04-24-2005, 07:38 PM	#19
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I was looking at calculators online, and if I ran with 4.10s, 35" tires, and an overdrive tranny, I'd be at like 1900 rpm at 65 mph, not calculating slippage in. Is that too low of an RPM for a 355 TPI with a mild cam, and dual exhaust / headers? __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

04-24-2005, 08:16 PM	#20
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	depends on your cam, and compression ratio should be adjusted accordinly.

04-24-2005, 08:36 PM	#21
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	It has an XE262 comp cam in it, and should be sitting at about 9.5:1 once I install the 64 cc TPI Camaro heads I want to go with. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

04-25-2005, 11:52 AM	#22
Hawged-67 Registered User Join Date: Oct 2004 Location: Coshocton OH Posts: 27	i'm runnin 35 with 3.08 gears, 355 low rpm torque cam, 4 speed and 205 transfer. Nice going on flat ground but long hills sucks, bogs down. But gearing was great when my T-221 Rockwell took a **** on me drove in 4 low about 50 miles to get home. My dad had a 76 k10 he bought new with 4speed, 205, 3.08 gears, 35 in hawgs, said he could go down the highway at 90mph downshift to 3rd and never tell the differnce. Once got a speedin ticket in 3rd going 60mph __________________ '67 chevy on '79 K10 frame Metallic Grey-Fleet White top 35in Ground Hawgs 355 ci, SM 465, NP 205 "A Dying Breed...Classic Chevy"

04-26-2005, 04:13 PM	#24
Apache Registered User Join Date: Jun 2004 Location: South Carolina Posts: 419	Id go with 3.73's. 3.55's maybe better if alot more road use....3.73's good all around, and if you want it offroad mostly, then its all up to you keep going high as you want. __________________ 54 Chevy Bel Air 4dr powerglide 54 Chevy SWB 58 Chevy Big Window SWB Fleetside project 58 Chevy LWB 235/4spd 76 Chevy Nova 350/TH350 4.88's *10kmiles on "new" engine 79 Chevy 4x4 SWB 350/4spd 3/4 ton 81 Mazda RX7 84 F@!d Mustang 96 F@!d Ranger 2.3L/5spd

04-26-2005, 05:07 PM	#25
Jason915 Registered User Join Date: Jan 2005 Location: Colorado Springs Posts: 693	4.10's don't fear the gear __________________ 1971 GMC K1500 SWB Fleetside, 4" skyjacker softride and, 14 Bolt FF, HD Dana 44 4.10's 1970 K5 TBI conversion lifted etc SOLD 1968 C20 camper truck SOLD “To ban guns because criminals use them is to tell the innocent and law-abiding that their rights and liberties depend not on their own conduct, but on the conduct of the guilty and the lawless.” Jeff Snyder

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