14 bolt axle swap info - Fri Jan 05 2018 05:00 PM
Work in progress, what questions and ideas do you have, what is missing?
Purpose of this thread is to explain how to perform a 14 bolt rear axle swap, not skipping over the tricky parts, and including part numbers wherever possible.
Specifically a 14 bolt rear axle for use in 48-54 GM 3/4 and 1 tons. Also good for other years, but only discussing the AD trucks here and now.
There are already various scattered and watered down details and info in this forum and others about the 14 bolt swap.
Some other threads and resources:
https://www.stovebolt.com/ubbthread...nstorming-and-solutions.html#Post1145468
http://www.pirate4x4.com/tech/billavista/14b_bible/
14 bolt Wikipedia
Service manual:
http://www.pirate4x4.com/tech/billavista/14b_bible/14b.pdf
Gear swap/setup instructions:
http://www.pirate4x4.com/tech/billavista/PR-ARB/articles/14b_Gear_Setup/
New parts sources:
http://www.cmgearworks.com/
http://www.northerndrivetrain.com/
http://www.ruffstuffspecialties.com/catalog/
https://eastcoastgearsupply.com/
http://www.ratechmfg.com
Background:
The 14 bolt was introduced about 1973 and used through about 2000 in countless 3/4 and 1 tron GM products. It replaced the HO72 Eaton axles in these applications, and has some similarities. The AAM axles that followed the 14 bolt are also similar.
Available gear ratios are 3.21, 3.42, 3.73, 4.10, 4.56, 4.88, 5.13, and 5.38
14 bolts in trucks up through about 1987 used 9/16" wheel studs and thereafter used metric, vans switched to metric in 1996. The earlier axles are probably more desirable for our purposes. To identify the 1989 and newer axle housing look for lots of cast in fins on top, the older ones lack fins.
The Eaton axle used in 3/4 and 1 ton GM trucks 48-54 measures 62.625" from Wheel Mounting Surface to Wheel Mounting Surface. Same for single and dual wheel trucks.
The 3/4 and 1 ton AD truck rear springs are 41.5" center to center.
The 14 bolt comes in a few different housing widths, hub types, and brake sizes and type.
Primary concern for this swap is the 14 bolt axle installed in "Cab & Chassis" trucks, which could be a pickup cab with a service body, an RV, or a step van (and other similar applications). This axle would have come with "dual wheels" and large drum brakes.
The WMS to WMS measurement is 62.75", It's basically a very narrow dual wheel axle, narrower than any other version of 14 bolt therefore a good fit for our old narrow trucks. Remember AD 1 tons even with dual wheels use same axle width as the single wheel trucks. The C&C 14 bolt axle can be run with single wheels or dual wheels.
In other words the 14 bolt C&C axle is perfect for any AD 3/4 or 1 ton.
Spring centers are 40" + or - 1/8" on 14 bolt C&C axles I've measured.
Tangent discussion the 14 bolt axle under a single wheel pickup has same housing width and axle shaft lengths as the C&C axle, but has different hubs making for a wider and unsuitable WMS width. The "dual wheel type hubs" can be swapped to the single wheel pickup axle housing, making it again ~63" WMS to WMS measurement, but brake backing plates don't bolt on in the right place... The spring center measurements on the single wheel pickup axles are 40.5" for the 1 ton, and 42.5" for the 3/4 ton. Further tangent a dual wheel axle from under a pickup bed is just way too wide. Van axles are also different... or kind of the same... hard to find reliable info.
Difficulties:
--The C&C axle as it comes needs spring pads moved outward a little to match spring center measurement on your old truck.
--Clearance between springs and the brakes leaves little room for u-bolts, and nearly no room for bleeding brakes.
Following post will address these issues and solutions
Tangent/caution Many places (catering to the 4x4 truck crowd) sell "disc brake brackets" to convert a 14 bolt to disc brakes, either bolt or weld on, and if using the right (expensive) caliper you can even have parking brake too. The components used are usually from a 1/2 ton or 3/4 ton truck, they're not very robust in comparison to the later model 3/4 and 1 ton disc brakes. I have not used this type of disc conversion for the rear of a 14 bolt, but it is my opinion that it's a step backwards in safety and braking ability in comparison to the 13x3.5" drum brakes. I will not be covering this possible brake option but will cover a different disc brake swap.
Purpose of this thread is to explain how to perform a 14 bolt rear axle swap, not skipping over the tricky parts, and including part numbers wherever possible.
Specifically a 14 bolt rear axle for use in 48-54 GM 3/4 and 1 tons. Also good for other years, but only discussing the AD trucks here and now.
There are already various scattered and watered down details and info in this forum and others about the 14 bolt swap.
Some other threads and resources:
https://www.stovebolt.com/ubbthread...
http:/
14 bolt Wikipedia
Service manual:
http:/
Gear swap/setup instructions:
http:/
New parts sources:
http://www.cmgearworks.com/
http://www.northerndrivetrain.com/
http:/
https://eastcoastgearsupply.com/
http://www.ratechmfg.com
Background:
The 14 bolt was introduced about 1973 and used through about 2000 in countless 3/4 and 1 tron GM products. It replaced the HO72 Eaton axles in these applications, and has some similarities. The AAM axles that followed the 14 bolt are also similar.
Available gear ratios are 3.21, 3.42, 3.73, 4.10, 4.56, 4.88, 5.13, and 5.38
14 bolts in trucks up through about 1987 used 9/16" wheel studs and thereafter used metric, vans switched to metric in 1996. The earlier axles are probably more desirable for our purposes. To identify the 1989 and newer axle housing look for lots of cast in fins on top, the older ones lack fins.
The Eaton axle used in 3/4 and 1 ton GM trucks 48-54 measures 62.625" from Wheel Mounting Surface to Wheel Mounting Surface. Same for single and dual wheel trucks.
The 3/4 and 1 ton AD truck rear springs are 41.5" center to center.
The 14 bolt comes in a few different housing widths, hub types, and brake sizes and type.
Primary concern for this swap is the 14 bolt axle installed in "Cab & Chassis" trucks, which could be a pickup cab with a service body, an RV, or a step van (and other similar applications). This axle would have come with "dual wheels" and large drum brakes.
The WMS to WMS measurement is 62.75", It's basically a very narrow dual wheel axle, narrower than any other version of 14 bolt therefore a good fit for our old narrow trucks. Remember AD 1 tons even with dual wheels use same axle width as the single wheel trucks. The C&C 14 bolt axle can be run with single wheels or dual wheels.
In other words the 14 bolt C&C axle is perfect for any AD 3/4 or 1 ton.
Spring centers are 40" + or - 1/8" on 14 bolt C&C axles I've measured.
Tangent discussion the 14 bolt axle under a single wheel pickup has same housing width and axle shaft lengths as the C&C axle, but has different hubs making for a wider and unsuitable WMS width. The "dual wheel type hubs" can be swapped to the single wheel pickup axle housing, making it again ~63" WMS to WMS measurement, but brake backing plates don't bolt on in the right place... The spring center measurements on the single wheel pickup axles are 40.5" for the 1 ton, and 42.5" for the 3/4 ton. Further tangent a dual wheel axle from under a pickup bed is just way too wide. Van axles are also different... or kind of the same... hard to find reliable info.
Difficulties:
--The C&C axle as it comes needs spring pads moved outward a little to match spring center measurement on your old truck.
--Clearance between springs and the brakes leaves little room for u-bolts, and nearly no room for bleeding brakes.
Following post will address these issues and solutions
Tangent/caution Many places (catering to the 4x4 truck crowd) sell "disc brake brackets" to convert a 14 bolt to disc brakes, either bolt or weld on, and if using the right (expensive) caliper you can even have parking brake too. The components used are usually from a 1/2 ton or 3/4 ton truck, they're not very robust in comparison to the later model 3/4 and 1 ton disc brakes. I have not used this type of disc conversion for the rear of a 14 bolt, but it is my opinion that it's a step backwards in safety and braking ability in comparison to the 13x3.5" drum brakes. I will not be covering this possible brake option but will cover a different disc brake swap.