1964 C30 HO72 Axle Swap to 14 Bolt - The 1947 - Present Chevrolet & GMC Truck Message Board Network

01-13-2021, 10:36 AM

Hi,

Background: I am working on a 1964 C30 complete restoration and want to swap out the HO72 5.13 133 inch wheelbase DRW axle assembly to a 14 bolt DRW. I have an upgraded custom-built SM420 which addressed the front leaky seal problem and added Syncro for 1st to 2nd gear. Replacing the 230 I6 and old SM420(Original Mileage 65K) with a custom-built Gen 1 SBC. I want the option of doing light to medium towing in the 5-8k lb range with good highway speed. Online speed calculator with 3.73 gears results at 2500 rpm, 30.5 in tires and 1:0 final gear ratio on the SM420 looks reasonable for highway cruising/towing.

Question: What year and options should I look for in a 14 bolt chevy w/10.5" ring gear? Also, I am adding power brakes and discs upfront but keeping the rear on drums. I'm ok with a junkyard find, but will still have it cleaned and gone through (rebuilt), or buy a remanufactured complete assembly. In addition to that, what's your thoughts on optionally moving to 3.55 or 3.4X since I've upgraded the powerplant. Any details and advice on this conversion would be much appreciated. Thanks

**cwcarpenter98** · 01-13-2021, 10:19 PM

Welcome!

That rpm range will probably be good for that sbc. On the rear axle, I think the squarebody axles (73-87 (but also to 91 for the bigger trucks)) are almost a bolt in deal.

I'm sure someone that's actually done the swap will chime in soon.

Post up a pic of your truck!

**Captainfab** · 01-13-2021, 10:47 PM

I would not go any higher than 3.73 gears in a 1 ton. Personally I would go with 4.10's in a 1 ton. The 10.5" 14 bolt was introduced in 1973 and used well into the 2000's. There are at least 3 different widths. There is the C/K 20/30 single wheel, the C/K 30 dually and the C/K 30 cab and chassis with duals. The Dana 70 is also an option that was used under GM 1 ton's.

62c30 · 01-13-2021, 11:53 PM

I have a 62 c30 that I swapped in a 1981 c30 14 bolt. It literally bolted in place. I replaced my u bolts but other than that I was driving the truck in a few hours.

01-14-2021, 08:19 AM

Quote:

Originally Posted by cwcarpenter98

Welcome!

That rpm range will probably be good for that sbc. On the rear axle, I think the squarebody axles (73-87 (but also to 91 for the bigger trucks)) are almost a bolt in deal.

I'm sure someone that's actually done the swap will chime in soon.

Post up a pic of your truck!

Will do. Thanks

01-13-2021, 10:36 AM	#1
LenDill Guest Posts: n/a	1964 C30 HO72 Axle Swap to 14 Bolt Hi, Background: I am working on a 1964 C30 complete restoration and want to swap out the HO72 5.13 133 inch wheelbase DRW axle assembly to a 14 bolt DRW. I have an upgraded custom-built SM420 which addressed the front leaky seal problem and added Syncro for 1st to 2nd gear. Replacing the 230 I6 and old SM420(Original Mileage 65K) with a custom-built Gen 1 SBC. I want the option of doing light to medium towing in the 5-8k lb range with good highway speed. Online speed calculator with 3.73 gears results at 2500 rpm, 30.5 in tires and 1:0 final gear ratio on the SM420 looks reasonable for highway cruising/towing. Question: What year and options should I look for in a 14 bolt chevy w/10.5" ring gear? Also, I am adding power brakes and discs upfront but keeping the rear on drums. I'm ok with a junkyard find, but will still have it cleaned and gone through (rebuilt), or buy a remanufactured complete assembly. In addition to that, what's your thoughts on optionally moving to 3.55 or 3.4X since I've upgraded the powerplant. Any details and advice on this conversion would be much appreciated. Thanks Last edited by LenDill; 01-13-2021 at 10:45 AM.

01-13-2021, 10:19 PM	#2
cwcarpenter98 Senior Member Join Date: Jan 2018 Location: Hickory Flat, GA Posts: 4,421	Re: 1964 C30 HO72 Axle Swap to 14 Bolt Welcome! That rpm range will probably be good for that sbc. On the rear axle, I think the squarebody axles (73-87 (but also to 91 for the bigger trucks)) are almost a bolt in deal. I'm sure someone that's actually done the swap will chime in soon. Post up a pic of your truck! __________________ Christian Carpenter 1963 C10 - Frankentruck 283, 3 speed with overdrive Overdrive wiring here 1963-ish truck bed trailer - Half-Wit 1981 C10 - Penny 305, th350 1995 Dodge Dakota Sport "I'll put it simple: if you're going hard enough left, you'll find yourself turning right." - Doc Hudson

01-13-2021, 10:47 PM	#3
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: 1964 C30 HO72 Axle Swap to 14 Bolt I would not go any higher than 3.73 gears in a 1 ton. Personally I would go with 4.10's in a 1 ton. The 10.5" 14 bolt was introduced in 1973 and used well into the 2000's. There are at least 3 different widths. There is the C/K 20/30 single wheel, the C/K 30 dually and the C/K 30 cab and chassis with duals. The Dana 70 is also an option that was used under GM 1 ton'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

01-13-2021, 11:53 PM	#4
62c30 Registered User Join Date: Jan 2017 Location: Derby Kansas Posts: 357	Re: 1964 C30 HO72 Axle Swap to 14 Bolt I have a 62 c30 that I swapped in a 1981 c30 14 bolt. It literally bolted in place. I replaced my u bolts but other than that I was driving the truck in a few hours.

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