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#1 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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What gear ratio ?
Just wondering if someone knows what gear ratio would be in my truck? Or what was the most common for that year. It's a 1970 chevy cst. It came with the 350/350 turbo. Any info would be appreciated as I'm thinking of putting a 700r4 into it. It seems like it needs another gear on the highway. No clue what rpm it's running at, as I have no tach. Thanks hoping for the experts to chime in.
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#2 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
By the way it seems to be a posi judging by the two black strips it leaves in front of the house.
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#3 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What gear ratio ?
you left out the most important part... what size is your truck?
C/10 would be a 3.07 C/20 would be a 4.10 This is assuming there is no optional gear ratio or modifications done. |
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#4 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: What gear ratio ?
2quarts of rearend lube and a cover gasket will solve any doubt about it
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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 |
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#5 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What gear ratio ?
agreed one million percent!
Nothing like trusting 20 to 40 year old oil to keep your bearings rolling smooth huh? |
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#6 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
Its a C10. I was just thinking the must be a common ratio they ran in these.
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#7 |
Registered User
Join Date: Dec 2009
Location: N/A
Posts: 29
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Re: What gear ratio ?
Fry, are you the original owner? Also what I think cdowns is saying is the crack open your pumpkin and take a look for yourself. You really cant trust nothing has ever been done to you truck. Here's an example.... friend of mine bought what he thought was a California special fastback 68 mustang from a real estate sale. Turned out he actually got a 67 gt500. The paint was striped as was some of the body work due to a little driver door damage and it being prepped for a new paint job. He almost sold it until he ran the numbers...
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#8 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
I will have to pop the pumpkin cover, but just wanted to know what it came with. Also was wondering if there was any way to tell what it is without tearing it apart only because as of right now I'm just contimplating doing the swap but don't want to lose my lower end. Or buy a transmission that I can't use. Just basically collecting info. Thanks though guys.
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#9 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,217
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Re: What gear ratio ?
Ive been running a 3:08 rear gear with a 700R4 in my 70 for several years. It has a stock 350 engine. It works great You can cruise the high. & hardly hear the engine & you can drop it down a notch if you are pulling hard.
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#10 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What gear ratio ?
a 3.07 gear and a 700R4 is generally a bad combo in these rigs with old school engines. There's always the exception, but generally the MPG drops when you drop the RPMs that far.
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#11 |
Registered User
![]() Join Date: Oct 2009
Location: Panama City Beach, FL
Posts: 228
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Re: What gear ratio ?
Without having to open the diff, you could jack up the rear and put a mark on the driveshaft and one on the tire. Rotate the tire one revolution and count the number of turns the driveshaft turns will give you the ratio. Just over three turns of the shaft will be a 3.07, three and three quarters will be 3.73, etc...Of course the trans will need to be in neutral so be sure to properly support/secure truck.
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Justin 71' C10 SWB 00' Dakota R/T 05' Z-71 Silverado 16' Z-71 Silverado Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=376904 |
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#12 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What gear ratio ?
and that way you don't have to replace the 20 to 40 year old oil that isn't doing a whole lot to keep things cool and lubed
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#13 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
I was under the impression there is a tab on the cover that had info on the rear. Yes... you guys are right I'll just pop the damn cover off. Might as well replace it with a chrome one while I'm at it. I was under there welding my 4" exhaust cut outs in recently and it looks like its in need of some preventive maintenance. So thanks for the help. By the way should I run synthetic gear oil or is it just not worth the money?
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#14 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What gear ratio ?
regular oil will do, but synthetic is a lot better though. If the funds are there I'd say go for the better oils.
I've heard they had tags, but I have yet to see one in person. |
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#15 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: What gear ratio ?
from the factory posi rears had a plastic tag on the fill hole bolt
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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 |
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#16 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
I'll check the fill hole for the plastic (you guys have the strangest knowledge) I just went down my "mom and pops" local auto parts store and they will have a chrome cover and gasket kit in the morning for me. It was nice getting compliments on the truck too.
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#17 | ||
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: What gear ratio ?
Quote:
he now has a 99 burb c10 w/ 3.42 rear and better aerodynamics. the 3.42 is a good compromise and works good with the newer generation engine that has more power. mileage is around 22mpg. remember that trucks weigh a lot more than cars and the tall tires lower the rpm. my 72 burb c20 (307/3OT) turns 2900rpm at 60 w/ a 4.10 rear whereas my sister's old merc topaz (2.3/3 auto) would turn 3k w/ 3.22 gears. a stout rear with a good overdrive ratio is like having your cake and eating it too! straight 3.07 = 3.07 3.07 x .7 = 2.149 3.42 x .7 = 2.39 3.73 x .7 = 2.61 4.10 x .7 = 2.87 Quote:
Last edited by capev86; 05-24-2011 at 07:19 PM. |
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#18 | |
Big Red - Now its a SWB!
Join Date: Jun 2009
Location: Oroville, Ca
Posts: 1,624
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Re: What gear ratio ?
Quote:
Edit: here is the pic of the ratio tag, not the greatest pic but you can read 41-9 4.56 which denotes 4.56 rear gears ![]()
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68 3/4 ton ![]() ![]() 41 3/4 ton ![]() 01 Tahoe LT 4WD (my daily driver)-Magnaflow Muffler, Rollin on 22's 02 Ford Mustang Convertable (Wife's Car)-Flowmaster 50, Clear corners, Intake, sittin on 18's Last edited by Jacfourteen; 05-23-2011 at 09:19 PM. |
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#19 | |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: What gear ratio ?
Quote:
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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