68 c10 factory 4.11 ratio? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70ssclone · 01-15-2017, 08:59 PM

My 68 i aquired was an unmolested survivor , besides a motor replacement it was an original v8 3 speed truck . I just put a tach in it and according to gps mph at 55mph it's turning around 2600ish rpm with a 31in tire out back . Does that sound right ? I didn't think 1/2 ton trucks got that steep of a ratio . One thing is for sure, I can't go with any smaller tire .

**68bowtie** · 01-15-2017, 10:16 PM

it should be against forum rules to say the phrase "unmolested survivor" without posting pictures.

i would jack it up and check the gear ratio, i believe they did come with high gears in 68. do you have the spid sticker in the glove box?

Alex V. · 01-15-2017, 11:26 PM

That sounds about right for 4.10's and yes, anything over 55 on anything smaller than those 31's is gonna have it wound pretty tight. Bringing your tires down a size with an OD transmission should make it pretty nice, or bumping down to a 3.73/3.55 unless you want an especially long-legged cruiser.

68panelman · 01-16-2017, 09:03 AM

My 67 has the factory 4:10 rear. With a six and 225/75/15, she's happy at 55-60.

Mike C · 01-16-2017, 09:11 AM

What does the SPID say? I would assume the standard gear for that was 3.73 so the next gear option would most likely be 4.10. Towing package?

01-15-2017, 08:59 PM	#1
70ssclone Registered User Join Date: Dec 2016 Location: Havre de grace ,MD Posts: 14	68 c10 factory 4.11 ratio? My 68 i aquired was an unmolested survivor , besides a motor replacement it was an original v8 3 speed truck . I just put a tach in it and according to gps mph at 55mph it's turning around 2600ish rpm with a 31in tire out back . Does that sound right ? I didn't think 1/2 ton trucks got that steep of a ratio . One thing is for sure, I can't go with any smaller tire .

01-15-2017, 10:16 PM	#2
68bowtie Senior Member Join Date: Jan 2007 Location: Turlock, CA Posts: 8,738	Re: 68 c10 factory 4.11 ratio? it should be against forum rules to say the phrase "unmolested survivor" without posting pictures. i would jack it up and check the gear ratio, i believe they did come with high gears in 68. do you have the spid sticker in the glove box? __________________ Please help my sister in law with her battle with cancer https://gofund.me/902f6fce Project "C10 Fever" (68 factory black 396 swb) Project "Little Sister" (70 c10 blue original paint refresh) Project "Blue Bomb" (70 c30 blue original paint refresh) SOLD Project "Vitamin C" (71 c10 orange original paint refresh) SOLD

01-15-2017, 11:26 PM	#3
Alex V. Registered User Join Date: Mar 2013 Location: Campbellsville, KY Posts: 888	Re: 68 c10 factory 4.11 ratio? That sounds about right for 4.10's and yes, anything over 55 on anything smaller than those 31's is gonna have it wound pretty tight. Bringing your tires down a size with an OD transmission should make it pretty nice, or bumping down to a 3.73/3.55 unless you want an especially long-legged cruiser. __________________ Alex V. ------ 1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs. 1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue.

01-16-2017, 09:03 AM	#4
68panelman Registered User Join Date: Jan 2011 Location: Delaware and Long Island, New York Posts: 3,455	Re: 68 c10 factory 4.11 ratio? My 67 has the factory 4:10 rear. With a six and 225/75/15, she's happy at 55-60.

01-16-2017, 09:11 AM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,723	Re: 68 c10 factory 4.11 ratio? What does the SPID say? I would assume the standard gear for that was 3.73 so the next gear option would most likely be 4.10. Towing package? __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax



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