Corporate 14 Bolt

The GM 14Bolt rear axle assembly is favored as one of the sturdiest axles available readily in salvage yards across the US.

The following comments and information are courtesy of Pirate4x4


The 14bolt is found in a huge number of GM 4x4 pickup trucks and vans, 3/4 and 1 ton, from the 70's right through until at least 2000. You can find it in:

* 73-96 C20, C25
* 73-00 C30, C35
* 73-00 G30, G35
* 73-00 K20, K25
* 73-00 K30, K35
* 84-88 CUCV
* 88-91.5 V30

Being a full float (FF) axle, it of course has full floating wheel hubs and axle shafts. I simply love full-float axles, and would never go back to running anything but a FF axle, for some very good reasons:

* The axle shaft does not support the weight of the vehicle, but merely transmits torque
* Because of the above - FF axle shafts are not subject to bending loads like semi float (SF) axles are and can therefore be made of harder materials making them capable of carrying greater torque loads
* If you should ever break a rear FF axle shaft, you will not loose the wheel too.
* If you need to change a FF rear axle, it is extremely easy and simple to do.
* The hubs run big, strong, common, reasonably cheap wheel bearings, races, and seals (14b Dana 60 and 70 bearings, front and rear, are all the same)
* The wheel bearings are not pressed onto anything, if need be they can be removed and replaced with nothing more than a screwdriver and big hammer.


Before we delve deeper into the 14bolt, let's just talk about why this is such an awesome axle. It has a number of distinct features / advantages:

* Gear strength - 10.5" ring gear, 1.750" 30 spline pinion, huge 2 piece carrier made of 8620 Heat treated alloy steel, extra pinion bearing support
* Shaft strength - 1.5' 30 spline full floating shafts
* Housing strength - massive cast iron center section, 3.25: x 0.5" tubes
* Comes in two widths - 63" and 67" wms-wms, easily converted from one to the other (shafts are common)
* Removable pinion support, unbolts from the rest of housing, makes for easier gear setup
* Diff housing has built-in threaded carrier pre-load adjusters, makes for easier gear setup
* Because the carrier is so large and strong, a "full" detroit locker fits in the stock housing, and is therefore easy to install without gear setup changes, and is much cheaper than other 1 ton FF lockers
* Pinion yokes commonly available for 1350 series u-joints
* Fairly commonly came stock with 4.10 and 4.56 gears and Detroit Lockers
* Cheap and easy to find, buy, and build
* Easy to convert to disc brakes
* Easy to "shave" for 2" inch gain in clearance
* Pinion length shorter than other 1 ton ff rear axles (D60, D70), for improved driveshaft length and angles
* Large ID spindles
* Common spindle nut threads with Dana60 front axle, meaning only one style of spindle nut and socket need be used / carried

Of course, there are drawbacks too:

* Lack of traction aiding differentials - especially spools and selectable lockers
* Lack of available gearing - only down to 5.13
* Lack of aftermarket alloy axle shafts
* Carrier break. Most 1 ton ff also have a carrier break though, so it's relative essays
* Uses a crush sleeve to set pinion preload heavy
* Low clearance in stock form
* Heavy in stock trim

Overall, I think they are a superb choice for a heavy duty off-road machine. I'll let H8Monday?, from the PBB, sum it up, as he does so well. H8 is a rock crawling competitor, devout throttle crazy maniac, who runs a 14b behind a very healthy 5.0. He says:

"One of the best things about the 14 bolt, other than they are dirt cheap and nearly indestructible, is the cost of building them. It is very common to find them with 4.56 gears, and often axle shops and junk yards will have used factory sets. They are very easy to set up, because they have an adjustable backlash. Spare axle shafts are nearly free, and the shafts are the same for the C&C or standard version. Not that spares are usually necessary with a 1.69" axle shaft diameter, (splines are 30). But, the best thing is, because the stock carrier is a monstrous hunk of an assembly, you do not change the carrier with a Detroit,(its basically a massive lunch box locker). So detroit only cost about $325(and that's if you don't shop around). My disk brake conversion didn't cost over $150 ($40 each for rotors, $40 for loaded calipers, plus about $20 for brake lines. I had about $1000 into my entire 14 build up, including cost of the axle, gears, locker, disc brakes, and new lug nuts. Not bad for a full floater, rear axle with discs, 4.56 gears and a detroit."

GM 14 Bolt Service Manual

Pinion Bearing Preload
(Inch lbs)

25 - 35 (new bearings)

5-15 (reused bearings)
Preferred Backlash
(.001 inch) 5 - 8
Ring Gear Bolt Torque
(Foot lbs) 120
Bearing Cap Torque
(Foot lbs) 135
Pinion Nut Torque Tighten as necessary to obtain correct preload
Pinion Bearing Retainer Torque
(Foot lbs) :65
Diff Cover Bolt Torque
(Foot lbs) 35
Axle shaft flange Bolt Torque
(Foot lbs) 115
Spindle Nut Torque
(Foot lbs) 50
Carrier Adjuster Ring Lock Bolt Torque
(Foot lbs) 20
Pinion Assembly Bolt Torque
(Foot lbs) 65
Axle Shaft Spline Length
(inches) 2.165" total
Axle Shaft Engaged Spline Length
(inches) short side 1.418"
Axle Shaft Engaged Spline Length
(inches) long side 1.569"
Axle Tube Dimensions
(inches) 3-3/8" x 0.5" thick
Spring Perch Span and Width
(inches) (1980 1 Ton 4x4, SRW, non Cab and Chasis) 42.5" x 2.5"
Axle Shaft Length
(inches) Right 37-5/8"
Left 31-5/8"
Axle Shaft Diameter
(inches)

@ splines 1.54", @ neckdown 1.367", operating diameter 1.351"
@ flange 1.458"

30 splines
Axle Flange Bolt Pattern
8 on 3.523", 1/2" holes, bolts are 1/2-NC13x1.5"
Pinion Yoke U-joint Strap Bolts
7/16 " head, 1.296" x 5/16-NF24
Diff Cover Bolts
Fourteen (14) 5/16-NC16 x 3/4"
Ring Gear Bolts
Twelve (12) 9/16-NF18
Pinion Nut Size 1.5"
Axle shaft to Hub bolts 3/4" head, 1/2-NC13, approx. 1.5" long

Ring Gear Diameter
10.5"
Pinion diameter
1.750" x 30 splines
Carrier Break
4.10 / 4.56
Approximate Weight
(lbs) 550 with brake drums
450 without brake drums
Width - WMS-WMS
(inches) SRW/DRW 67"
C&C DRW 63"


Axle Tech