Best rear gears for 700r4 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*Jdbfish* · 09-11-2013, 04:14 PM

What is the best rear end to run behind a stock 350 with a 700r4 auto? Most of my driving will be at hwy speeds. Will a 3.08 be ok?
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**steelhorse** · 09-11-2013, 04:26 PM

Should be fine. The 700r4 has a real low first gear so take off shouldn't be too bad. Depending upon your tire size you may actually end up with a lower rpm at highway speeds than you would like. I say try it then adjust if you aren't happy.

cdowns · 09-11-2013, 04:30 PM

most guys over the years have had very bad results and an actual decrease in fuel milage when useing a 700r4 and 308 rear gears// where the guys with the 700r4 and the 373 get best results and fuel milage increases

MARKDTN · 09-11-2013, 04:43 PM

3.42 is the best ratio with tall tires for a mixed use. If you are pulling more, then maybe 3.73.

slow-1 · 09-11-2013, 05:14 PM

I have 3.08 gears, 700r4 trans, 255/70/15 tires, perfect from 60 mph up.

Around 55mph it feels like it is lugging a bit but my "RV" cam doesn't care.

I like it, I can't say they are the "best" gears as I haven't run it with any others to compare.

My mileage went from 11 mpg with the saginaw 3 speed to around 18 mpg overall (that was with 235/70/15 tires, haven't checked it since I upgraded).

Can't speak for others though.

buddylj1990 · 09-13-2013, 12:37 AM

saginaw i now thats for 3 on tree what is saginaw mean

**Already Gone** · 09-11-2013, 05:30 PM

Quote:

Originally Posted by MARKDTN

3.42 is the best ratio with tall tires for a mixed use. If you are pulling more, then maybe 3.73.

X 2 especially with a 28/29 inch tire.

Dova · 09-11-2013, 04:28 PM

From what i've seen people on the site using, a lot of them do not like the 3.08 because of to sluggish on the highway. Most seem to use 3.73's

**WIDESIDE72** · 09-11-2013, 06:03 PM

3.73
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Andy4639 · 09-11-2013, 06:41 PM

I run the 700 r4 with 4:10's and get 16-18 MPG depending on how fast I'm running. At Highway speed (70MPH) I'm turning around 2300RPM's.
I like the way it runs and it performs well for a 305!

Tx Firefighter · 09-11-2013, 07:11 PM

Literally over 75 percent of the 2wd 88-98 trucks that were V8 and 700r4/4L60/e overdrive equipped came stock with 3.42 gears. Perfect ratio. GM got it right on that one.
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1968ratrod · 09-11-2013, 07:44 PM

I am currently running 3.08's and my truck don't like it at anything below 60 mph, I am in the process of switching to 3.73 .

**special-K** · 09-12-2013, 07:00 AM

Quote:

Originally Posted by Tx Firefighter

Literally over 75 percent of the 2wd 88-98 trucks that were V8 and 700r4/4L60/e overdrive equipped came stock with 3.42 gears. Perfect ratio. GM got it right on that one.
Posted via Mobile Device

That's it ^

That's the sweet spot. 3.42s weren't offered in these trucks back when needs (for the most part) were different from now. 3.08-3.73 leaves a wide gap and 3.42s fill it perfectly. It's a great ratio for hiway with or without O/D,yet spill has grunt. I'm building my '67 with an M22 and 3.42s and it's a hiway machine who's bed will get used. When I can afford it,a Gear Vendors will go in. This ratio will work either way.
I know this is manual/no overdrive talk,but this give perspective on the the range of ratios we're talking. The truck I helped my neighbor with ('68 SWB) has a 4spd and he didn't want it to suck the gas too hard. He went with 3.08s...hated it. Changed to 3.42s and it's good. Now he's got a ZZ3 in there and realizes he just wants a hot rod and,no matter what,it's going to like gas and he's not going to commute or travel in it. So,he's wanting 3.73s now for bit more grunt. If it was me,now,I'd be swappin' 4.11s!!

**LockDoc** · 09-12-2013, 10:31 AM

-
So basically the only way to get 3.42's is to use the later, wider rear end and weld on new mounting pads?

LockDoc

Keith Seymore · 09-12-2013, 10:36 AM

3.73's are perfect.

The overdrive in the trans brings it back as though they are 3.42's.

K

Tx Firefighter · 09-12-2013, 10:40 AM

Quote:

Originally Posted by LockDoc

-
So basically the only way to get 3.42's is to use the later, wider rear end and weld on new mounting pads?

LockDoc

New gear sets are a couple of hundred dollars. Summit carries a ton of options.
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**LockDoc** · 09-12-2013, 11:36 PM

Quote:

Originally Posted by Tx Firefighter

New gear sets are a couple of hundred dollars. Summit carries a ton of options.
Posted via Mobile Device

Thanks Kevin.... I checked with my local independent mechanic and he said it would run around $100 to install the gears. I'm not sure I want to invest $300 to put 3.42's in the Burb... I'm just a tight a$$ I guess...

LockDoc

71meangreenc10 · 09-13-2013, 03:45 AM

Quote:

Originally Posted by LockDoc

-
So basically the only way to get 3.42's is to use the later, wider rear end and weld on new mounting pads?

LockDoc

I use the 3.08 carrier and put in new gears. I have used Motive gears from Jegs and havent had any issues at all. I replace everything and set the backlash to Motives specs. Dont need a whole new axle.

Smitty

*Jdbfish* · 09-11-2013, 07:53 PM

Is there a stock 3:42 6 lug rearend option for a 70 model? Thought only 3.08, 3.73 or 4.10 were available
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tlcrz1972 · 09-11-2013, 08:21 PM

350 FI / 4L60E / 3.08's / 30x9.5 tires great setup; take off is not a problem and at speed it works perfectly even with 6000 to 7000 lbs in tow in OD in the hills.

cruising speed of 70 MPH, rpm's are only 1650-1700 and fuel mileage is well above 17 MPG (unloaded)

*Fitz* · 09-11-2013, 08:27 PM

Quote:

Originally Posted by Jdbfish

What is the best rear end to run behind a stock 350 with a 700r4 auto? Most of my driving will be at hwy speeds. Will a 3.08 be ok?
Posted via Mobile Device

A 3.08 will lug around town with that trans. TX had it right when he said 3.48 is optimal but failing that try a 3.73. Below are the RPM vs MPH for a 700 R4 for the 3.08, 3.48 and 3.73 in that order

Eddie H. · 09-11-2013, 10:08 PM

My son's 71 GMC with a 350, 700R4, and 3.08 gears is a bit sluggish for my liking. We will probably change to 3.73 sometime in the future.

**LockDoc** · 09-11-2013, 10:30 PM

-
I changed the 3.08 to a 3.73 in the '69 Suburban. Made all the difference in the world.... it has a 2004r OD trans in it. Averaged 16 mpg on a 550 mi round trip to Kansas City, MO last weekend. I'm lovin' it...

LockDoc

lha1992 · 09-11-2013, 10:34 PM

My '89 C1500 has a 350 FI, 700R4 and 3.08s in the rear with 31in tires on it.

Thinking of going to a 3.73 since its got a bigger tire on it.

**LockDoc** · 09-11-2013, 11:55 PM

Quote:

Originally Posted by lha1992

My '89 C1500 has a 350 FI, 700R4 and 3.08s in the rear with 31in tires on it.

Thinking of going to a 3.73 since its got a bigger tire on it.

My Burb has 31's on it too.

LockDoc

09-11-2013, 04:14 PM	#1
Jdbfish Account Suspended Join Date: Apr 2013 Location: Belton, tx Posts: 51	Best rear gears for 700r4 What is the best rear end to run behind a stock 350 with a 700r4 auto? Most of my driving will be at hwy speeds. Will a 3.08 be ok? Posted via Mobile Device

09-11-2013, 04:26 PM	#2
steelhorse Senior Member Join Date: Apr 2008 Location: Franklinton NC Posts: 1,309	Re: Best rear gears for 700r4 Should be fine. The 700r4 has a real low first gear so take off shouldn't be too bad. Depending upon your tire size you may actually end up with a lower rpm at highway speeds than you would like. I say try it then adjust if you aren't happy.

09-11-2013, 04:30 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Best rear gears for 700r4 most guys over the years have had very bad results and an actual decrease in fuel milage when useing a 700r4 and 308 rear gears// where the guys with the 700r4 and the 373 get best results and fuel milage increases __________________ 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

09-11-2013, 04:43 PM	#4
MARKDTN Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 2,159	Re: Best rear gears for 700r4 3.42 is the best ratio with tall tires for a mixed use. If you are pulling more, then maybe 3.73. __________________ '83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project

09-11-2013, 05:14 PM	#5
slow-1 Registered User Join Date: May 2013 Location: Central NC Posts: 830	Re: Best rear gears for 700r4 I have 3.08 gears, 700r4 trans, 255/70/15 tires, perfect from 60 mph up. Around 55mph it feels like it is lugging a bit but my "RV" cam doesn't care. I like it, I can't say they are the "best" gears as I haven't run it with any others to compare. My mileage went from 11 mpg with the saginaw 3 speed to around 18 mpg overall (that was with 235/70/15 tires, haven't checked it since I upgraded). Can't speak for others though. __________________ 1972 Cheyene C-10 "Ole Green" My Grandfathers truck (early 70's to 1983) My first vehicle (1983) Original 350 (3 rebuilds) 700R4 from Bowtie Overdrives

09-13-2013, 12:37 AM	#6
buddylj1990 Registered User Join Date: Aug 2013 Location: waynesville georgia Posts: 164	Re: Best rear gears for 700r4 saginaw i now thats for 3 on tree what is saginaw mean

09-11-2013, 04:28 PM	#8
Dova Registered User Join Date: Jul 2007 Location: Silverdale, WA Posts: 263	Re: Best rear gears for 700r4 From what i've seen people on the site using, a lot of them do not like the 3.08 because of to sluggish on the highway. Most seem to use 3.73's

09-11-2013, 06:03 PM	#9
WIDESIDE72 Senior Member Join Date: Aug 2008 Location: Cedar Park, Texas Posts: 7,500	Re: Best rear gears for 700r4 3.73 Posted via Mobile Device

09-11-2013, 06:41 PM	#10
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Best rear gears for 700r4 I run the 700 r4 with 4:10's and get 16-18 MPG depending on how fast I'm running. At Highway speed (70MPH) I'm turning around 2300RPM's. I like the way it runs and it performs well for a 305! __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-11-2013, 07:11 PM	#11
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: Best rear gears for 700r4 Literally over 75 percent of the 2wd 88-98 trucks that were V8 and 700r4/4L60/e overdrive equipped came stock with 3.42 gears. Perfect ratio. GM got it right on that one. Posted via Mobile Device

09-11-2013, 07:44 PM	#12
1968ratrod Registered User Join Date: Oct 2009 Location: Lufkin Texas Posts: 171	Re: Best rear gears for 700r4 I am currently running 3.08's and my truck don't like it at anything below 60 mph, I am in the process of switching to 3.73 . __________________ 1965 Chevy Suburban 2003 Chevrolet S10 2011 Harley Streetglide

09-12-2013, 10:31 AM	#14
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,649	Re: Best rear gears for 700r4 - So basically the only way to get 3.42's is to use the later, wider rear end and weld on new mounting pads? LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

09-12-2013, 10:36 AM	#15
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,213	Re: Best rear gears for 700r4 3.73's are perfect. The overdrive in the trans brings it back as though they are 3.42's. K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

09-11-2013, 07:53 PM	#19
Jdbfish Account Suspended Join Date: Apr 2013 Location: Belton, tx Posts: 51	Re: Best rear gears for 700r4 Is there a stock 3:42 6 lug rearend option for a 70 model? Thought only 3.08, 3.73 or 4.10 were available Posted via Mobile Device

09-11-2013, 08:21 PM	#20
tlcrz1972 Registered User Join Date: Apr 2013 Location: Gainesville, TEXAS Posts: 658	Re: Best rear gears for 700r4 350 FI / 4L60E / 3.08's / 30x9.5 tires great setup; take off is not a problem and at speed it works perfectly even with 6000 to 7000 lbs in tow in OD in the hills. cruising speed of 70 MPH, rpm's are only 1650-1700 and fuel mileage is well above 17 MPG (unloaded) __________________ 1972 Chevrolet Cheyenne LB 1/2 ton finished restoration/rebuild 1995 350 throttle body FI, 4L6E (running on modified GM wiring harness) 3.08 posi rearend, factory A/C on 134A, p/s, p/b, late 70's power windows and locks and cruise, speakers in the dash + 6x9's behind the seat, factory tilt, 40 gallon fuel tank in the bed with integrated tool box, air assist bags on the rearend, sway bar up front and much more. 1972 chevrolet SNB finished 2002, 350 TB FI, TH400, factory A/C, p/b, p/s, (FOR SALE) 1969 Chevrolet 1 ton in work, home made PTO dump bed extended frame, 350 CI , 1972 Chevrolet 3/4 ton suburban future project 1972 Chevrolet 3/4 ton p/u maybe a project one day 1966 Toyota Landcruiser my playtoy



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09-11-2013, 10:08 PM	#22
Eddie H. Registered User Join Date: Mar 2001 Location: Paradise TX USA Posts: 1,200	Re: Best rear gears for 700r4 My son's 71 GMC with a 350, 700R4, and 3.08 gears is a bit sluggish for my liking. We will probably change to 3.73 sometime in the future. __________________ "Negative people always seem to have a problem for every solution"

09-11-2013, 10:30 PM	#23
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,649	Re: Best rear gears for 700r4 - I changed the 3.08 to a 3.73 in the '69 Suburban. Made all the difference in the world.... it has a 2004r OD trans in it. Averaged 16 mpg on a 550 mi round trip to Kansas City, MO last weekend. I'm lovin' it... LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

09-11-2013, 10:34 PM	#24
lha1992 Registered User Join Date: Apr 2010 Location: Everett, WA Posts: 504	Re: Best rear gears for 700r4 My '89 C1500 has a 350 FI, 700R4 and 3.08s in the rear with 31in tires on it. Thinking of going to a 3.73 since its got a bigger tire on it.

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