My stomach dropped - The 1947 - Present Chevrolet & GMC Truck Message Board Network

paaw · 04-23-2007, 06:55 PM

I pulled my rear cover off today know that I had a non posi 373 and the numbers read 14:43 stamped could gm had made a mistake cause I know I was runnin over 3000 at 65 have 275/60/15 tires

when I divide 43/ 14 I GET 307

paaw · 04-23-2007, 07:04 PM

pic not turning out good but numbers are

3817779 14:43 gm 12-71 2

arkracing · 04-23-2007, 07:07 PM

What are your trying to ask exactly? -

if you want to know the gear ratio - you have to count the teeth on the "ring" and then on the "pinion" - divide the numbers to get the ratio.

over 3k @ 65 would probably be a 3.73 or lower (numerically higher) gear ratio.

jsbgump · 04-23-2007, 07:08 PM

I run 3200rpm at 70 in my 68 swb 350/350 3.73 posi

paaw · 04-23-2007, 07:15 PM

am I adding wrong or something I keep getting 3.07

1969k10stepside · 04-23-2007, 07:22 PM

14:43 means 3:07,thats the gears you have....Still dont believe?Count the teeth on the ring and pinion.If there is 43 and 14,which there should be,then its 3:07 gears.Period

powell72 · 04-23-2007, 07:39 PM

Your speedo must be off.

sodak69c10 · 04-23-2007, 07:45 PM

not to butt in but how can you adjust speedo mine is off by 20mph at 65it only reads 45, i know for sure because i used gps on a clear day to check it

**LockDoc** · 04-23-2007, 07:59 PM

-
Might find some info here for the speedo.....

http://www.transmissioncenter.net/sp...n_______va.htm

Here are the ratio numbers:

Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9

LockDoc

Longhorn Man · 04-23-2007, 08:00 PM

are you goin by the POS 35 year old tach?

724x4a/cchevy · 04-23-2007, 08:17 PM

Quote:

Originally Posted by Longhorn Man

are you goin by the POS 35 year old tach?

Funny you should mention that. Dad's original read 3k at idle the other day lol

paaw · 04-23-2007, 10:18 PM

going by after market tach, I would have know this I would have saved the money on the 700r and bought tires for my 20's, goint to have to count the teeth, cause it used to whine on the highway once I got over 70 with the factory trans in there

paaw · 04-23-2007, 10:19 PM

did 307 come factory 72

krue · 04-23-2007, 10:24 PM

Yeah

LUV2XCLR8 · 04-23-2007, 10:26 PM

Quote:

Originally Posted by LockDoc

-
Might find some info here for the speedo.....

http://www.transmissioncenter.net/sp...n_______va.htm

Here are the ratio numbers:

Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9

LockDoc

Good info

lukecp · 04-23-2007, 10:43 PM

My truck with the same rear gears and tire size pulled right at 75 mph at 3,000 rpm. 65 was around 2,600 rpm, IIRC.

bedsled71 · 04-23-2007, 11:05 PM

ive tryed to find my numbers on my axle, cant find.. can someone tell me where they are found and if the numbers are raised or not

1969k10stepside · 04-23-2007, 11:07 PM

The 14:43,ect numbers are located on the ring gear....inside the differential

paaw · 04-23-2007, 11:19 PM

how fast should i be running in 3rd gear at 2000 rpms with these gears

lukecp · 04-24-2007, 12:10 AM

Around 50 mph.

LonghornJeff · 04-24-2007, 12:28 AM

look on the back of your tach it might be set on the 6 cylinder setting.

eedgell · 04-24-2007, 12:39 AM

speedo gear in transmision? gear change in transmission?

ckhd · 04-24-2007, 12:40 AM

Doing the basic math with the numbers you gave gives the following:

27" tire.

IF you have 3.07 gears, and no overdrive, you should be running approx 2400 rpm* at 65. With 700r4 overdrive, about 1700 rpm*
IF you have 3.73 gears, and no overdrive, you should be running approx 2900 rpm* at 65. With 700r4 overdrive, about 2000 rpm*
IF you have 4.10 gears, and no overdrive, you should be running approx 3200 rpm* at 65. With 700r4 overdrive, about 2250 rpm*
* All rpms are rounded

Given the information you gave, it would appear someone has swapped your gears for something in the 4.10 range. If you have something other than that, you should check your speedometer against mile posts and a stopwatch, and check your tach against a different tach.

mnunn454 · 04-24-2007, 07:09 PM

Quote:

Originally Posted by arkracing

over 3k @ 65 would probably be a 3.73 or lower (numerically higher) gear ratio.

Or that the tach has been lying to you..........

stllookn · 04-24-2007, 08:20 PM

HTML Code:

Or that the tach has been lying to you..........

I hate it when they do that...then they just stop talking to you altogether like mine did...LOL!

04-23-2007, 06:55 PM	#1
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	My stomach dropped I pulled my rear cover off today know that I had a non posi 373 and the numbers read 14:43 stamped could gm had made a mistake cause I know I was runnin over 3000 at 65 have 275/60/15 tires when I divide 43/ 14 I GET 307 __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold Last edited by paaw; 04-23-2007 at 07:08 PM. Reason: add info

04-23-2007, 07:04 PM	#2
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	Re: My stomach dropped pic not turning out good but numbers are 3817779 14:43 gm 12-71 2 __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold

04-23-2007, 07:07 PM	#3
arkracing Weekend Warrior Join Date: Oct 2004 Location: CT Posts: 1,787	Re: My stomach dropped What are your trying to ask exactly? - if you want to know the gear ratio - you have to count the teeth on the "ring" and then on the "pinion" - divide the numbers to get the ratio. over 3k @ 65 would probably be a 3.73 or lower (numerically higher) gear ratio. __________________ -'07 GMC Sierra K2500HD -'66 C10 Suburban -'68/'71 K20 Service Bed Project -'69 Chevy C30 Mason Dump -'33Ford P/U 396ChevyPowered

04-23-2007, 07:08 PM	#4
jsbgump Gone Fishing Join Date: Aug 2005 Location: Fort Worth, Texas 76135 Posts: 12,361	Re: My stomach dropped I run 3200rpm at 70 in my 68 swb 350/350 3.73 posi __________________ 68 Chevy Short Fleetside LSX Swap Under Way 3.73 posi 2.5/4 drop Frame of resto has been started 2022 Hyundai Tucson Limited 2019 Chevy Traverse Redline Edition Wifes Ride Build Thread http://67-72chevytrucks.com/vboard/s...=1#post3483616

04-23-2007, 07:15 PM	#5
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	Re: My stomach dropped am I adding wrong or something I keep getting 3.07 __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold

04-23-2007, 07:22 PM	#6
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,020	Re: My stomach dropped 14:43 means 3:07,thats the gears you have....Still dont believe?Count the teeth on the ring and pinion.If there is 43 and 14,which there should be,then its 3:07 gears.Period

04-23-2007, 07:39 PM	#7
powell72 Senior Member Join Date: Jan 2005 Location: Loveland Co. Posts: 3,098	Re: My stomach dropped Your speedo must be off. __________________ Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html

04-23-2007, 07:45 PM	#8
sodak69c10 Registered User Join Date: Mar 2007 Location: Rapid City, South Dakota Posts: 285	Re: My stomach dropped not to butt in but how can you adjust speedo mine is off by 20mph at 65it only reads 45, i know for sure because i used gps on a clear day to check it __________________ ,Clint LOUD PIPES SAVE LIVES 69 C-10 short stepside 406 sbc, 02 YAMAHA WR250F, 07 SUZUKI SV650S, 81 Grand Prix 355 sbc, 81 XT 500 YAMAHA

04-23-2007, 07:59 PM	#9
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,419	Re: My stomach dropped - Might find some info here for the speedo..... http://www.transmissioncenter.net/sp...n_______va.htm Here are the ratio numbers: Ratio 2.56:1 - Tooth Combination 41,16 Ratio 2.73:1 - Tooth Combination 41,15 Ratio 3.07:1 - Tooth Combination 43,14 Ratio 3.08:1 - Tooth Combination 40,13 Ratio 3.08:1 - Tooth Combination 37,12 Ratio 3.31:1 - Tooth Combination 43,13 Ratio 3.36:1 - Tooth Combination 37,11 Ratio 3.42:1 - Tooth Combination 41,12 Ratio 3.55:1 - Tooth Combination 39,11 Ratio 3.73:1 - Tooth Combination 41,11 Ratio 4.10:1 - Tooth Combination 41,10 Ratio 4.11:1 - Tooth Combination 37,9 LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - Last edited by LockDoc; 04-23-2007 at 08:01 PM.

04-23-2007, 08:00 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: My stomach dropped are you goin by the POS 35 year old tach?

04-23-2007, 10:18 PM	#12
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	Re: My stomach dropped going by after market tach, I would have know this I would have saved the money on the 700r and bought tires for my 20's, goint to have to count the teeth, cause it used to whine on the highway once I got over 70 with the factory trans in there __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold

04-23-2007, 10:19 PM	#13
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	Re: My stomach dropped did 307 come factory 72 __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold

04-23-2007, 10:24 PM	#14
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Re: My stomach dropped Yeah __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

04-23-2007, 10:43 PM	#16
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Re: My stomach dropped My truck with the same rear gears and tire size pulled right at 75 mph at 3,000 rpm. 65 was around 2,600 rpm, IIRC. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

04-23-2007, 11:05 PM	#17
bedsled71 Registered User Join Date: Feb 2007 Location: yuma arizona Posts: 448	Re: My stomach dropped ive tryed to find my numbers on my axle, cant find.. can someone tell me where they are found and if the numbers are raised or not



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04-23-2007, 11:07 PM	#18
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,020	Re: My stomach dropped The 14:43,ect numbers are located on the ring gear....inside the differential Last edited by 1969k10stepside; 04-23-2007 at 11:08 PM.

04-23-2007, 11:19 PM	#19
paaw Registered User Join Date: Feb 2006 Location: nashville Posts: 217	Re: My stomach dropped how fast should i be running in 3rd gear at 2000 rpms with these gears __________________ 1997 pontiac grand prix gt (daily driver) for now; 2004 dodge ram quad cab (wife's truck) 4.7; 2000 pontiac booneville (wife daily driver) 1972 chevy cheyenne 350 bored 40 over 700r trans 373 gears ( posi) soon to be daily driver; 2002 gsxr750 sold

04-24-2007, 12:10 AM	#20
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Re: My stomach dropped Around 50 mph. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

04-24-2007, 12:28 AM	#21
LonghornJeff EZEKIEL 25:17 Join Date: Oct 2001 Location: Springfield IL USA Posts: 984	Re: My stomach dropped look on the back of your tach it might be set on the 6 cylinder setting. __________________ 68 CHEVELLE(HORSESHOE) 69 LONGHORN 396 70 NOVA 454(FOR SALE) 71 SWB 307 71 EL CAMINO 383 72 GMC JIMMY 350 87 BLAZER 350 WIW? http://blog.360.yahoo.com/blog-r5CJt...9_6Orzim4L5uWM Gun control, the theory that 110lb. women have the "right" to fistfight with 210lb. rapists. The reason animal rights activists are more passionate about fur than leather is because it's safer to harrass rich women than bikers...

04-24-2007, 12:39 AM	#22
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: My stomach dropped speedo gear in transmision? gear change in transmission?

04-24-2007, 12:40 AM	#23
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	Re: My stomach dropped Doing the basic math with the numbers you gave gives the following: 27" tire. IF you have 3.07 gears, and no overdrive, you should be running approx 2400 rpm* at 65. With 700r4 overdrive, about 1700 rpm* IF you have 3.73 gears, and no overdrive, you should be running approx 2900 rpm* at 65. With 700r4 overdrive, about 2000 rpm* IF you have 4.10 gears, and no overdrive, you should be running approx 3200 rpm* at 65. With 700r4 overdrive, about 2250 rpm* * All rpms are rounded Given the information you gave, it would appear someone has swapped your gears for something in the 4.10 range. If you have something other than that, you should check your speedometer against mile posts and a stopwatch, and check your tach against a different tach. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans? Last edited by ckhd; 04-24-2007 at 12:46 AM.

04-24-2007, 08:20 PM	#25
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	Re: My stomach dropped HTML Code: Or that the tach has been lying to you.......... I hate it when they do that...then they just stop talking to you altogether like mine did...LOL! __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)

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