I Intend to use this article to gather all the info and pics I can find on the venerable GM "corporate" 14 Bolt (14b) full-floating rear axle, also referred to as the 10.5" (after the size of the ring gear in inches.) There are "other" 14b axles out there - a 9.5" ring gear semi-float for one, and even a 11.5" ring gear full-float version. This article is NOT about them.
It is almost certainly destined to be a perpetual "work in progress" as I gather more and more info.
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, C2573-00 C30, C3573-00 G30, G3573-00 K20, K2573-00 K30, K3584-88 CUCV
88-91.5 V30
As well as a whole lot more cab and chasis trucks, delivery vans, etc.
It is most easily distinguished by its huge, uniquely shaped diff cover that is, of course, held on with 14 bolts.
It is also fairly easily distinguished from other 1 ton full-float rear axles by the removable pinion support, that can be clearly seen just behind the pinion yoke in this picture.
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 loadsIf 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 shaftsHousing strength - massive cast iron center section, 3.25: x 0.5" tubesComes 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 setupDiff housing has built-in threaded carrier pre-load adjusters, makes for easier gear setupBecause 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 lockersPinion yokes commonly available for 1350 series u-jointsFairly commonly came stock with 4.10 and 4.56 gears and Detroit LockersCheap and easy to find, buy, and buildEasy to convert to disc brakesEasy to "shave" for 2" inch gain in clearancePinion length shorter than other 1 ton ff rear axles (D60, D70), for improved driveshaft length and anglesLarge 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 spoolsLack of available gearing - only down to 5.13Lack of aftermarket alloy axle shaftsCarrier break. Most 1 ton ff also have a carrier break though, so it's relative Uses a crush sleeve to set pinion preload heavyLow 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."
Let's have a closer look at the beast
Closer look at the hub (brake disc or drum removed, looking at it from the back [inside]) and wheel bearing / spindle hardware.Note that the spindle threads are the same as for Dana 60 front and rear axles and Dana 70 rear axles. This means all the different styles of spindle nuts (4 slot, 6 slot, hex, rounded hex) and lock washers can all be interchanged.Part numbers for the spindle hardware, courtesy of KWTMECH, from left to right are:
Spindle flat washer: Dorman 618-048, spindle nut: Dorman 615-130, spindle lock washer: Dorman 618-049, spindle nut: Dorman 615-130
Watch out for this when you go to remove the wheel hub outer bearing and race. The bearing does not simply fall out of the end of the hub on most FF axles - its OD keeps it captive. Instead, a snap ring in the hub, accessible from the back of the hub (yellow arrows) needs to be removed so the wheel bearing can come out the back.
Blue arrows show corrosion, indicating requirement for replacement bearings and races.
The snap ring
Spindle OD is approximately 1.985"
Spindle ID is approximately 1.540"
Take the cover off, and you discover the massive 2 piece carrier and 10.5" ring gear
The bearing caps have small integrated locking devices that serve to lock the carrier preload adjusters into place
With the carrier removed, here's a look inside the diff:
(The pic failed to upload)
Threaded carrier preload adjusters
3/8-NC16 diff cover bolt hole (14 in total)Extra (third) pinion support bearingMagnet for attracting and holding metal particles / debris in the gear oilAre where my 14b has been ground down for clearance
3.25" x 1/2" thick axle tubes
Close up of pinion support bearing
Threaded carrier preload adjuster and 1/2" thick axle tube
The shafts are different length L and R. The Left is the short side at 31-5/8". The Right is the long side at 37-5/8"
They are a large 30 spline axle. However, the pressure angle on the splines is not the same as other manufacturers (Dana, for example)
Dimensions on the shafts are:Spline Diameter (yellow arrow) 1.59""Neckdown" (green arrow) 1.367"Operating diameter (purple arrow) 1.351"Spline length (blue arrow) 2.165"Spline engagement (red arrow) short side 1.418"Spline engagement (red arrow) long side 1.569"
Axle diameter by the flange - 1.458"
The following pics, courtesy of Benny Langford (Bigger Valves) and Clay Moulton (yotacowboy) illustrate an alternate method of retaining the wheel bearings in the 14 bolt. For the record, the truck is an '87 1 ton Chevy V30 (crewcab 4x4 350 tbi).
It's very simple setup that consists of one hub nut, one key, and one clip ring. The nut accepts the regular 6 prong 14 bolt socket and has 6 square grooves around its inner diameter. These grooves are what you line up with the spindle groove to make the key way.
I just tighten down to the correct preload and then tighten until the next groove in the nut lines up with the spindle groove.
Then you simply slide the key in the key way and put on the clip ring. The clip ring has a curved end that fits in the spindle groove to securely block the key from backing out. The clip is very thin and flimsy which makes it easy to remove with just a screwdriver and allows it to fit snugly around the spindle in the threads.Part numbers for this style spindle hardware, courtesy of KWTMECH, are:
Hub nut: Dorman 615-132, Key: Dorman 615-140, Clip Ring: Dorman 615-141
The different types of 14 bolt.
There are many different 14 bolt axles available, with an almost dizzying array of possible widths, tube OD's, hub types, brakes etc. Fortunately, all are pretty similar, a huge number of parts interchange, and through the power of the internet and Pirate4x4.com we are beginning to catalogue all the available data here.*CAUTION* - With this axle, as indeed with all things "axle" like - there are no hard and fast laws - for every "fact" I shall present, I know there's at least one person out there, maybe many more, who claim they own or know of exceptions. This is very likely true and due to the way in which oem vehicle construction occurs, can not be avoided or completely resolved.What follows is what i believe to be true, or the most correct, information based on the research I have done and the letters I have received from what I judge to be the most reputable sources. Use the data with caution - "your mielage may vary" as they say.14 Bolts can be broken down into 4 broad groups. There is also at least one year break that bring minor changes, but this is in fact far less significant than the "type" of 14 bolt axle in question.
Notes:
The SRW and C&C axles use the same housings and shafts, with the difference in width being in the hubs. The housings are actuallly identical except for the location of the backing plate flange. Drums & hubs are different, but backing plates, shoes, and wheel cylinders are the same) * The SRW and Van axles use the same hubs, the C&C and DRW axles use the same hubs; Though different, the SRW/Van hubs and the C&C/DRW hubs can be interchanged causing a change to the axles WMS (see pics below) SRW and C&C axle shafts are the same ** Van, DRW, and SRW/C&C axle shafts are all different lengths as follows (long/right side / short/left side):
Type 1 - SRW/C&C - 37-5/8" / 31-5/8 "Type 2 - DRW - ??
Type 3 - Van - 39-3/8" / 33-3/8"
C&C and dually brakes are the same.In all cases one side axleshaft is shorter than the other; pinions are centered. 1350 appears to be the only available stock pinion yoke.1-tons feature 40.5" perch spacing - whether C&C or pickup, whether SRW or DRW. 3/4-ton is 42.5" spacing. (COUNTER) - The perchs on my C&C measure 36"Wheel studs went metric for the 88-up C/K trucks, and 96-up vans
Front 60 and rear 14b spindles have the same bearing spacing and same bearing journal sizes. Seal journal is different
Different years
The year split is '72-88 and 89+. I shall refer to these as "first design" and "second design". Of course, there may be variations. Differences between these years are noted below. Where the difference is known only to apply to certain "types", I shall indicate this. Otherwsie, it is not known whether the differences noted between the years apply to all types or not.
Second design axles have more fins on the center sectionFirst design axles 1984 and earlier use a different pinion straddle bearing than 1985 and later
Second design SRW axles in 1-ton pickup trucks and 3/4 ton Suburbans changed to allow for a slide-off drum (drum can be removed without pressing out the wheel studs). The backside of these hubs is not machined flat to accept a rotor, for example. The hub flange is also further inboard to allow for the thickness of the drum.
The only real disadvantage to the 14b is the huge size of the differential, and subsequent scarcity of ground clearance. I must admit, in stock form, they do tend to hang a little low and get hung up on stuff. Most users will "shave" them. This can range from simply smoothing out the bottom with a hand grinder, to cutting a big chunk out of the bottom of the diff housing and machining down the diameter of the ring gear.
From the research I have done (I have no personal practical experience) the methods that have been used successfully for trimming the OD of a ring gear for a radical shave job are:
Abrasive grinderDiamond-tip on lathe Ceramic inserts on lathe
Wire EDM
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