Gears - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tony S. · 10-03-2016, 03:24 PM

Have a 64 with a 454/400th and a stock rearend and I'm looking to upgrade for a tighter twist and better RPMs at 70. Any recommendations as to what a poor boy can do? Thanks all!
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vince1 · 10-03-2016, 03:40 PM

You probably have a 3.73 ratio. A 3.07 will work a lot better. I've got one from I believe an early 71 which is about 1 1/2 wider. After that they go to 5 stud. With 65 and up the panhard bar is shorter and mounts differently.

vince1 · 10-03-2016, 03:48 PM

Yours will probably have 17 spline axles and pressed on backing plates. In 65 I think they went to 30 spline, different drums and backing plates. Preferably get the 65 and up if you are getting a complete differential.

bpmcgee · 10-03-2016, 04:39 PM

Why not just put in a new ring and pinion? Seems a lot easier than changing an axle no?

B

dracko · 10-04-2016, 05:13 PM

3.42 is an option too. Like mentioned, you can just swap the ring and pinion.

**Captainfab** · 10-04-2016, 10:12 PM

I agree that the gears can be changed. But unless the OP has the skills himself to perform the gear change and setup, paying someone to do it will more than likely exceed his 'poor boy' budget.

A '65-'70 12 bolt from a C10, will be a direct bolt in except for the panhard bar.

Depending on tire size a 3.07 or 3.42 gear will work. Changing tire size can help as well to reduce rpm's.

ol_skool_chevy · 10-05-2016, 12:02 AM

I have a 496 big block my truck had 3.72 and i swapped in a set of 3.42...much better.

dracko · 10-05-2016, 12:15 AM

Ya that's true, I sold a complete 3.08 rear end for $100 last year so if you can find one that's prob cheaper. Not real easy to find though...and the 3.42 seem even more scarce around here.

LVPhotos · 10-05-2016, 10:38 AM

Need address your purpose of truck. If a daily driver over 55, then gear swap maybe. Is it lowered? Because a 1 to 2 inch of tire will do same as gears. A 3:73 to 3:42 sees little rpm benifit. My 308 gears and 27 in tire ran 3000rpm at 75. If a 29 in tire a 500 rpm drop. These trucks were not built for today's speed. So like me check brakes and steering for worn out parts. It's not all about speed but a 50 year old truck needs help to be safe. I would look for t700 or t200 od trans before gears and a good front end rebuild before hand.

vince1 · 10-05-2016, 11:20 AM

A 700R4 is on my wish list too. Unfortunately for me someone went through the junkyard and stripped all the transmissions of their kick down cable assemblies and speedo cable drives.

With a 700R4 I could go back to 3.73 gears by putting the parts from a good 64 diff into the original 66 housing with the trashed gears.

10-03-2016, 03:24 PM	#1
Tony S. Registered User Join Date: Oct 2015 Location: Clackamas, Oregon Posts: 57	Gears Have a 64 with a 454/400th and a stock rearend and I'm looking to upgrade for a tighter twist and better RPMs at 70. Any recommendations as to what a poor boy can do? Thanks all! Posted via Mobile Device

10-03-2016, 03:40 PM	#2
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,169	Re: Gears You probably have a 3.73 ratio. A 3.07 will work a lot better. I've got one from I believe an early 71 which is about 1 1/2 wider. After that they go to 5 stud. With 65 and up the panhard bar is shorter and mounts differently.

10-03-2016, 03:48 PM	#3
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,169	Re: Gears Yours will probably have 17 spline axles and pressed on backing plates. In 65 I think they went to 30 spline, different drums and backing plates. Preferably get the 65 and up if you are getting a complete differential.

10-03-2016, 04:39 PM	#4
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	Re: Gears Why not just put in a new ring and pinion? Seems a lot easier than changing an axle no? B

10-04-2016, 05:13 PM	#5
dracko Registered User Join Date: Jan 2010 Location: Regina, SK Posts: 804	Re: Gears 3.42 is an option too. Like mentioned, you can just swap the ring and pinion.

10-04-2016, 10:12 PM	#6
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,250	Re: Gears I agree that the gears can be changed. But unless the OP has the skills himself to perform the gear change and setup, paying someone to do it will more than likely exceed his 'poor boy' budget. A '65-'70 12 bolt from a C10, will be a direct bolt in except for the panhard bar. Depending on tire size a 3.07 or 3.42 gear will work. Changing tire size can help as well to reduce rpm's. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

10-05-2016, 12:02 AM	#7
ol_skool_chevy Registered User Join Date: May 2010 Location: Hillsboro, Oregon 97123 Posts: 1,300	Re: Gears I have a 496 big block my truck had 3.72 and i swapped in a set of 3.42...much better. __________________ Measure with a yard stick Mark with Chalk Cut with a torch Built it yourself, don't count on others to to do it for you or with you. It will never get done

10-05-2016, 12:15 AM	#8
dracko Registered User Join Date: Jan 2010 Location: Regina, SK Posts: 804	Re: Gears Ya that's true, I sold a complete 3.08 rear end for $100 last year so if you can find one that's prob cheaper. Not real easy to find though...and the 3.42 seem even more scarce around here.

10-05-2016, 10:38 AM	#9
LVPhotos Registered User Join Date: Jan 2013 Location: Las Vegas, NV Posts: 1,857	Re: Gears Need address your purpose of truck. If a daily driver over 55, then gear swap maybe. Is it lowered? Because a 1 to 2 inch of tire will do same as gears. A 3:73 to 3:42 sees little rpm benifit. My 308 gears and 27 in tire ran 3000rpm at 75. If a 29 in tire a 500 rpm drop. These trucks were not built for today's speed. So like me check brakes and steering for worn out parts. It's not all about speed but a 50 year old truck needs help to be safe. I would look for t700 or t200 od trans before gears and a good front end rebuild before hand. __________________ 1962 shortbed 408cui small block, TKO 600 5-speed, bagged Porterbuilt suspension. 18" Salt Flats http://www.cardomain.com/ride/332579...t-c-k-pick-up/ http://67-72chevytrucks.com/vboard/s...d.php?t=560081

10-05-2016, 11:20 AM	#10
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,169	Re: Gears A 700R4 is on my wish list too. Unfortunately for me someone went through the junkyard and stripped all the transmissions of their kick down cable assemblies and speedo cable drives. With a 700R4 I could go back to 3.73 gears by putting the parts from a good 64 diff into the original 66 housing with the trashed gears.



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