14 Bolt Axles: The Differences Between SRW, DRW, and C&C

The GM 14 bolt is found in 3/4 and 1 ton Chevy and GM vehicles. There are many different types, but we'll do a quick pass over the most common ones here. We aren't going to talk about semi-floaters.
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14 Bolt Axles: What makes them so good?

14 bolts have been produced from the 1970s to the present.  They are used in all kind of vehicles and are a heavy duty, cheap axle.  

  • They're extremely common. A normal junkyard will have several 14 bolts and they're easy to find on Craigslist.
  • They're cheap due to being so common.
  • They're one of the cheapest light truck axles you can buy before you go to an aftermarket axle, Mogs, or deuce and a half axles.
  • Many of their hubs, retainers, carriers, axleshafts, and other parts are either shared or interchangeable. 
  • Full floating 14 bolt axles are extremely strong and will stand up to almost any abuse you put them through. They are suitable for relatively high horsepower (such as in a V8 swap), big tires with low gearing, and full size trucks.

14 Bolt Axles: The bad and the ugly

A 14 bolt's great features come at a cost - they're strong, but also heavy.

  • They are very heavy. 14 bolts Typically have a 1/2" thick axle tube and the typical 14 bolt is probably about twice the weight of a Dana 35. Most wheelers in lighter vehicles  don't need the strength (and resulting weight penalty) of a 1/2" axle tube.
  • They are large. 14 bolts are usually found on full size trucks and similarly large vehicles so a full size 14 bolt won't fit under a Jeep or small Toyota without some mods. The centersection is huge and will drag on rocks unless you  shave it. The massiveness of even a shaved 14 bolt may be too much for vehicles with smaller than 37" tires.
  • They came in a wide variety of configurations in many different vehicle types. While there is probably a little more apparent consistency among full size Chey's and GMSs trucks, don't count on measurements you find online for box vans, C&Cs, and panel vans. When buying a 14 bolt, always measure spring pad, and WMS to WMS in person.

What Do SRW, DRW, and C&C Mean?

SRW (Single Rear Wheel)

SRW stands for single rear wheel and simply means that the axle in the stock configuration came with a single rear wheel.  SRW is the same configuration that's in a typical full size pickup.

DRW (Dual Rear Wheel)

Again, this is pretty simple.  A DRW axle has dual rear wheels, two wheels on each side.  It has dual rear wheels so that it can carry more weight in the rear.  DRW trucks are extremely wide in the rear and often have fenders that stick out far from the bed to cover the extra tire.

C&C (Cab and Chassis)

Cab and Chassis trucks come from the factory with a cab and bare frame.  If you picture a pickup truck without the bed, that is essentially a C&C truck.  These are often delivered by the manufacturer to another vendor that modifies the truck for some purpose.  These often get turned into 1st responder vehicles, tow trucks, delivery, and other purpose-built vehicles.  C&C axles can come in SRW and DRW configurations but usually have different axle characteristics than those for 3/4 and 1 ton pickup trucks.

14 Bolt Axle Housings and Hubs

There are two basic 14 bolt axle housing types:

  • SRW/C&C
  • DRW/Van

And there are two different 14 bolt hub types:

  • Outboard
  • Inboard

If you compare an inboard hub to an outboard hub, you would notice that the WMS (wheel mounting surface) differs by approximately 2". This difference changes how much your tires and hubs stick out (or tuck in) and you can use this to fit a 14 bolt axle in a narrower 4x4.

Outboard Hubs

Outboard hubs are stock on SRW axles and van axles. They have these characteristics:

  • WMS surface is further from the centerline of the axle - wheels are mounted outward
  • Wider WMS to WMS measurement
  • Hub center "innie" (hub tucks in)

Inboard Hubs

Inboard hubs are stock on DRW axles and C&C axles. They have these characteristics.

  • WMS surface is nearer to the centerline of the axle - wheels are mounted inward
  • Narrower WMS to WMS measurement
  • Hub center "outie" (hub sticks out)

Making a Narrow 14 Bolt Axle with C&C Hubs

Need to make your 14 bolt axle narrower? Since the WMS differs by 2" between inboard and outboard hubs, and an axle needs two hubs, an axle with inboard hubs will be 4" narrower than an axle with outboard hubs (2 hubs x 2" each = 4"). This means that you can change your WMS to WMS measurement by about 4" total just by swapping your existing hubs.  This is a pretty common swap to make wide axles 4" narrower at the wheel mounting surface. 

Typically, this is done by taking a very common SRW 14 bolt axle and swapping on C&C hubs.  We single out the SRW/C&C combo because:

  • SRW 14 bolts are extremely common since they came in so many 3/4 and 1 ton trucks
  • C&C axles are extremely common in most junkyards.  We've seen prices as low as $10/pair for hubs in Pick 'N Pull type junkyards 

If you have an SRW axle this a simple, cheap swap that will net you a 4" narrower track width.

C & C Hub Swap Extra Details

One issue with the SRW/C&C swap is that the inboard hubs will result in an "outie", a hub center that sticks out.  The hub center will stick out 2" further relative to your tire and wheel.  If you run a narrow wheel with a lot of backspacing, your hub center could stick out uncomfortably far. 

For instance, with a Hummer H1 wheel that is 9" wide and has 7" of backspacing, the wheel mounting surface is 2" from the face/front of the wheel.  Since the hub center isn't safely nestled inside the wheel, it's much more susceptible to rock damage.  Plus, it looks a little funny.  If you're currently running a stock SRW with stock H1s, you should imagine your hub center sticking out another 2" before doing this swap and figure out if this works for you.

Most wheelers also swap out the stock 14 bolt drum brakes for some discs. This gives you better brakes, but it also eliminates a ton of weight - the stock drums are huge and heavy. If you swap on some discs, make sure you get the correct caliper brackets. The type and axle and hubs you have will change the offset of the brackets that you'll need.

14 Bolt Disc Brake Brackets

Putting rear discs on your 14 bolt is a big upgrade. You get easier maintenance and you lose a ton of weight from the axle. Because the different axle combos, there are 4 different disc brake brackets available. These suit the SRW, DRW, and SRW with DRW hubs axles. However, one more wrench in the works is that 1999+ 14 bolts had varying mounting hole arrangements. Therefore, if you have a post '99 14 bolt, you need a weld-on bracket. Here are the options for putting discs on your 14 bolt:

Single rear wheel (SRW) 14 bolt disc brake brackets

Cab and Chassis (C&C) 14 bolt disc brake brackets

Single rear wheel 14 bolt with C&C hubs disc brake brackets

1999+ Weld-on 14 bolt disc brake brackets

14 Bolt Axle Dimensions

14 Bolt Axle Dimensions
WMS to WMS width '73-'91 Axle tube diameter Axle tube thickness Hub type Driver axle shaft length Pass. axle shaft length Wheel stud threads Brake type Pinion centered
SRW 67.5" '89-'00 3.375" 0.5" Outboard 37.625" 31.625" 9/16"-18 Drum Yes
SRW 65" '00-07 3.375" 0.5" Outboard 37.625" 31.625" M14-1.5 Drum Yes
SRW 68" 3.375" 0.5" Outboard 37.625" 31.625" M14-1.5 Disc Yes
DRW 72" 3.5" 0.5" Inboard 9/16"-18 Drum Yes
C&C DRW 63.5" 3.5" 0.5" Inboard 37.625" 31.625" 9/16"-18 Drum Yes
SRW Van 70" 3.5" 0.5" Outboard 39.375" 33.375" 9/16"-18 Drum Yes
14 Bolt Axle Spring Perch Width
Axle Spring perch spacing
3/4 ton 14 bolt 42.5"
1 ton 14 bolt 40.5"


Mike Johnson

Mike came out of the womb with a Birfield in one hand and a stick of 6010 in the other, ready to weld any piece of trail-busted steel back together. He has wheeled, broken, and modified a variety of rigs, from Toyotas to Jeeps to Fords to Chevies. He likes doing long distance overland travel and would happily spend every night in the bed of a pickup under the stars.

Last updated: June 3, 2019