Identification, Data, and Specs

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 (not all, varies by year and application).
• Comes in two widths - 63" and 67" wms-wms, easily converted from one to the other (that axle shafts are common to both, it is the different hubs that account for the different widths, and these are easily interchanged).
• Removable pinion support, unbolts from the rest of housing, makes for easier gear setup.
• Diff housing has built-in threaded carrier preload 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 and 1410 series U-joints.
• Fairly commonly came stock with 4.10 and 4.56 gears and sometimes factory Detroit Lockers.
• Cheap and easy to find, buy, and build.
• Easy to convert to disc brakes.
• Easy to "shave" for 2" inch gain in ground clearance.
• Pinion length shorter than other 1 ton full-float rear axles (like the Dana 60 & Dana 70), for improved driveshaft length and angles.
• Large ID spindles.
• Shares common spindle-nut threads with Dana 60 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.
• 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.
• Uses a crush sleeve to set pinion preload.
• Relatively low ground clearance in stock form.
• Heavy in stock trim.

Overall, I think they are a superb choice for a heavy duty off-road machine. The following quote from " H8Monday" (a rock crawling competitor and devout throttle-crazy maniac who runs a 14b behind a very healthy 5.0.) sums things up nicely:

"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 [when installing] a Detroit [locker],(its basically a massive lunch box locker). So a Detroit only costs 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.

These pics are of the carrier removed. Mine is fully welded up making it a huge spool. I have read about some folks just welding the spider / side gears by filing in the valley's between the teeth and then reinstalling them. I personally have never understood this. It's not as if you need to save the carrier, since they are cheap and extremely plentiful. Also, I would think that in this manner, those welds would see quite a bit of shock loading. It's also a real bugger to reassemble the carrier and gears after you have just welded up the teeth and are trying to save the carrier.

Dana Catalogue Page on GM 14-Bolt (10.5")

West Coast Differentials Catalogue Page on the GM 14bolt (10.5")

GM 14-Bolt Specs

(all data for single-rear-wheel (SRW) truck 14-Bolt axle - others may vary).

The Different Types of 14-Bolt

Before we get into the different types of 14-Bolt axle, a quick review of some truck terminology that will keep popping up is in order.

Truck Lingo

When talking about truck, especially with respect t rear axles, we often use the terms SRW, DRW, C&C, and WMS. Here's what they mean:

Back to the 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.

*CAUTION* - With this axle, as indeed with all things "axle" - there are no hard and fast laws - for every "fact" I shall present, I know there's at least one person out there, possibly many, who claim they own or know of exceptions. This is very likely true, and is due to the way in which OEM vehicle construction occurs. This variability and ambiguity is just a fact of life and unfortunately cannot 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 mileage may vary" as they saying goes.

14-Bolts can be broken down into 4 broad groups. There is also at least one year break that brings minor changes, but this is in fact far less significant than the "type" of 14-Bolt axle in question.

Once again - this article is concerned only with GM 14-Bolt full-float rear drive axles. With that said, the following table attempts to capture the data.

* Note that these names (or designations) are of my own invention. They are not the official designations used by the manufacturer. Unfortunately, I do not know what the official designations are, or I wold have used them. So, don't call up your local junkyard and ask if they have a 14-Bolt with "Type B" hubs and "Type 1" shafts - they will look at you funny (yes, even over the phone!) I have simply invented and used these terms to help illustrate the differences and similarities between the different axle types that are out there.

Notes:

• The width of the housings and the length of the shafts used in the SRW and C&C axles are the same. The reason they are different widths WMS-WMS is because of the difference in the hubs used (see below for different hub types). The housings are actually identical except for the location of the backing plate flange (except axle tube OD and thickness may vary slightly with year and application). The brake drums & hubs are different, but the backing plates, brake 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 Type A (SRW/Van) hubs and the Type B (C&C/DRW) hubs can be interchanged. Doing so will result in a change to the axle's WMS-WMS as follows:
  • Swapping Type A hubs onto where Type B hubs used to be will cause an increase in axle width WMS-WMS.
  • Swapping Type B hubs onto where Type A hubs used to be will cause a reduction in axle width WMS-WMS.
  • See section below for pics of the different types of hubs to see why this is so.
• 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"
• If it helps, you can think of the C&C axle as a hybrid of the SRW and DRW axles. It uses the housing and shafts of the SRW axle fitted with the hubs of the DRW axle. This accounts for why it is the narrowest axle measured WMS-WMS (which in turn is why it is often highly sought-after for swapping into smaller 4x4s like Jeeps and buggies.
• C&C and DRW brakes are the same.
• In all cases one side axle-shaft is shorter than the other and pinions are centered.
• 1350 appears to be the only available stock pinion yoke, but aftermarket 1410 yokes are available (see the XXX article for details).
• 1-ton pickup trucks feature 40.5" leaf spring perch spacing - whether SRW or DRW.
• C&C axles feature 36" leaf spring perch spacing.
• 3/4-ton leaf spring perch spacing is 42.5" spacing. \
• 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. The seal journal diameter is different

Type A and Type B Hubs

The following pics, courtesy of Brawler, illustrate the differences between the Type A and Type B hubs.

Different Years

The year split is '72-88 (so-called "first design") and 89+ (so-called "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.

• Second design axles have more fins on the center section.
• First 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.

When working on a 14-Bolt axle, the biggest difference between the first and second design to be aware of is the different bearings used in the diff.

The wheel bearings, pinion seal, and front pinion bearing are common to both first- and second-design axles.

The first-design axle uses a different rear pinion bearing than the second-design axle.

And the really confusing part is that the first-design and second-design axles use the same pinion straddle bearing EXCEPT for the 1984-1985 first-design axles which use a different straddle bearing from all the rest.

Perhaps the best way to explain this is to simply list the part numbers.

The seal & bearing numbers are*:

• Pinion Seal (1973-1999): 21955
• Front Pinion Bearing, Cone, (1973-1999): M802048
• Front Pinion Bearing, Cup, (1973-1999): M802011
• Rear Pinion Bearing, Cone, (1973-1988): HM803149, (1988-1999): HM903249
• Rear Pinion Bearing, Cup, (1973-1988): HM803110, (1988-1999): HM903210
• Pinion Straddle Bearing, (1973-1984 & 1986-1999): R1581-TV
• Pinion Straddle Bearing, (1984-1985): DC57524

* Cone = the roller or bearing, Cup = the race.

14-Bolt Wheel Studs

One of the most popular modifications to any 14-Bolt axle used in an offroad truck is to remove the huge, heavy drum brakes and swap to disc brakes. I wrote a compete article on this process which you can read for detailed info.

One thing though, is that when you swap from drums to discs, the wheel studs are usually no longer long enough because they have to pass through the disc and the hub (that's how the disc is held to the hub).

Over the years there has been much discussion and experimentation with using different wheel studs, with different folks reporting different levels of satisfaction with different options. As far as I know there has never been a universally accepted one perfect solution, but the following data I consider quite reliable and should at least allow you to narrow down some choices with which to experiment to achieve a level of satisfaction you are comfortable with.

How to Cure the 14-Bolt of it's Achilles Heel weak link!

The mighty 14-Bolt does have 1 terrible weak link - an Achilles Heel.  It's the crappy, lousy design, weak, expensive and hard to find straps for holding the U-joint in the pinion yoke.

Fortunately - there is a solution - and a very cool one at that - read all about it  - the High Angle Driveline 1410 Pinion Yoke kit

Shaving the 14-Bolt

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.

The following pics illustrate the nicest case of the later, more extreme, shaving job that I have come across. It is the work of Phil Jensen, from Ottawa, Canada.

Originally, Phil made a quick cover by altering a stock cover. It didn't last well enough for his liking, so in the end he constructed a complete custom cover from 3/8" plate steel, which has reportedly held up very well. Unfortunately, I have no pictures of the later cover, but here are some of the original.

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 grinder
• Diamond-tip on lathe
• Ceramic inserts on lathe
• Wire EDM

I believe the preferred method is the wire EDM. Here's what engineersedge.com has to say about EDM.

More Great 14-Bolt Articles The Following are additional BillaVista technical articles related to the 14-Bolt axle:
	14-Bolt Disc Brakes V2. A new and more complete look at converting a 14-Bolt to disc brakes, including weld-on and bolt-on brackets, a larger calliper option, and a detailed look at wheel stud and wheel nut options.
	14-Bolt Gear Setup. Detailed, step-by-step instruction for setting up gears in a GM 10.5" Full-Float 14-Bolt rear axle. Contains theory and tech of interest and use in setting up gears in other axles too.
	ARB RD114 14-Bolt Air Locker Install. A mini-bible on ARB air lockers, including installation tips and techniques and a large FAQ section.
	Yukon 14-Bolt Gears and Install Kit Review.
	Jethro-Bilt 14-Bolt HD Diff Cover Review.
	14-Bolt Disc Brake Conversion. Detailed look at how I added disc brakes to the GM Corp. 14-Bolt rear axle in the Wolf. Procedure can be used for other rear axles too (D60, D70, etc). Contains hints and tips on other axles. Includes detailed part numbers. Also contains excerpts from Military 14-Bolt maintenance manual on axle shaft R&R and wheel bearing R&R and adjustment.
	14-Bolt 1410 Yoke Install. How to cure the 14-Bolt of it's Achilles Heel weak link!

14-Bolt Part Numbers from the On-line Listing at DTS

14-Bolt Wheel bearings and Seals