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Axle Swap

Project "Urban Assault Vehicle" Receives a Dana 44 and Corporate 14 bolt full float axle swap

One of the nice things about building a full size 69-91 Blazer/Jimmy is the interchangeability of the front and rear axles.  The plan was to upgrade the axles at some point in the future when time and funds would be more appropriate, but that plan backfired after a 4 wheeling trip left the ColoradoK5.com project vehicle with grenaded spider gears in the rear 10 bolt axle.  Decision time, replace the corporate 10-bolt with another 10-bolt (I think we all know the answer to that), or go with one of the other options - Corporate 12-bolt, 14-bolt Semi-Float, 14-bolt Full-Float or have Dynatrac build a very expensive custom Dana 60.  After weighing the pros and cons of the various axles, the decision was made to swap in a Corporate 14-bolt (FF).

 

Pros and Cons of common rear GM axles

Axle

Pro Con
10-bolt High ground clearance/very easy to find/Warn full float kit available C-clip design/smallest ring & pinion of the bunch/considered weak
12-bolt High ground clearance/Larger ring & pinion/carrier bearings than 10-bolt/Warn full float kit available C-clip design/not as strong as 14-bolt axles/getting harder to find
14-bolt (SF) Larger ring & pinion than 12-bolt/6-lug pattern available Less ground clearance than 10 and 12 bolt/C-clip design/heavy
14-bolt (FF) Strongest of the bunch and very affordable/very easy to find Low ground clearance due to massive ring & pinion/need 8-lug rims/very heavy

At the same time all this was happening a friend had a Dana 44 front axle with 4:10.1 gears for sale, the same gear ratio that was commonly offered in a 14-bolt rear axle (I provided the excuse he needed to upgrade to a Dana 60), thus saving the expense of re-gearing the front 10-bolt axle and adding a little more strength up front.

 

Pros and Cons of common Front GM axles

Axle Pro Con
10-bolt Stronger axle shafts available/easy to find 0.313" wall axle tubes/most were 28 spline axle shafts
Dana 44 30 spline axle shafts/0.5" wall axle tubes Necked-down axle shaft section
Dana 60 Large 9.75" ring gear/very strong/35 spline inner axles 1.375", 30 spline stub axles/Expensive/very heavy

 

Rear axle swap steps:

1. Decide and locate what axle you want according to your needs and then arrange for transpiration (bring a friend, these are heavy). If the axle is used this is a good time to go through it and replace the gaskets, brakes, inside and outside bearings and all seals.

2. Securely raise the rear of the vehicle on a level surface (place jack stands under frame or sturdy bumper) making sure to block the front wheels and remove rear wheels. (picture A)

3. Start by removing the rear driveshaft (a plastic cup can be placed over t-case output if it is a slip yoke to catch fluid, see picture D), shocks, emergency brake cables, brake lines and differential vent tube.

4. Place a bottle jack under each side of axle tube (picture E) and scrap wood under pinion (weight of pinion will force axle to tip pinion down, see picture C) and begin loosening u-bolts one side at a time, you can now lower each side a little at a time until the axle is on the ground.

5.  Installation is in reverse order.

Rear axle swap Notes, 14-Bolt (FF):  Things to look for when shopping for a rear axle - Open the differential cover and inspect ring and pinion for burn marks and chipped teeth, pinion seal for leaks, also inspect brake lines and bearings for wear.  I pulled the drums and the axle shafts and inspected for wear (the drums were to far gone and could not be turned), luckily the salvage yard exchanged them.  It is generally a good idea to replace the brakes, seals and bearings when swapping in a used axle, so keep that in mind when you are inspecting an axle for wear.  The 14-bolt (FF) uses a 1350 series u-joint and will not match up to the 1310 series u-joint that the 10-bolt driveshaft uses, so a trick u-joint (1310 on one side with 1350 on the other) will have to be used to accommodate the two different sizes which can be purchased from a parts store or driveshaft shop.  On newer Chevy's, the brake backing plate (picture H) will have to be changed to a press in style backing plate from a 14-bolt (SF) with 13" brakes.  You will also need the spring plates and u-bolts from a 14-bolt (FF) because the diameter of the axle tube is larger.  If you plan on installing A Detroit locker, be sure to purchase an axle with an open carrier, the 14-bolts that have a factory Limited Slip Differential came with a completely different carrier that will not accept the Detroit.

 

Front axle swap steps:

1. Decide and locate what axle you want according to your needs and then arrange for transpiration (bring a friend, these are heavy). If the axle is used this is a good time to go through it and replace the gaskets, brakes, inside and outside wheel bearings and all seals.

2. Securely raise the front of the vehicle on a level surface (place jack stands under frame or sturdy bumper) making sure to set parking brake and remove front wheels. (picture K)

3. Start by removing the brake lines, shocks and differential vent tube. Here's where it gets fun, remove steering arm (3 cone washers) from knuckle with large sledge hammer or impact fork.

4. Place a bottle jack under each side of axle tube (picture K) and scrap wood under pinion (weight of pinion will force axle to tip pinion down, see picture C) and begin loosening u-bolts one side at a time, you can now lower each side a little at a time until the axle is on the ground.

5.  Installation is in reverse order.

Front axle swap Notes, Dana 44:  Things to look for when shopping for a front axle - Open the differential cover and inspect ring and pinion for burn marks and chipped teeth, also inspect ball joints, tie rods, pinion seal for leaks, brakes and rotors, locking hubs etc., for extensive ware.  The Dana 44 utilized a slightly different brake-line connection bolt (caliper end) which necessitated the need to change the brake lines to match the Dana 44 axle.  If you remove or do not have front degree shims between the axle and the leaf springs, the centering pin on the spring may have to be filed down so it doesn't bottom out in the spring perch. - Steve Fox CK5

 
A B C
Rear 10-bolt removed 14-bolt painted and ready to be installed Scrap wood used to hold pinion up
D E F
Bottle jack used to lift 14-bolt into place 14-bolt on bottle jacks 14-bolt installed
G H I
Side view of massive 8-lug drums Backing plate from Suburban 14-bolt before the spacers were installed
J K L
Side view after rear axle install Removal of front 10-bolt axle Front 10-bolt removed with Dana 44 ready for install
M N O
Dana 44 installed Side view of Dana 44 8 lug rotor Axle swap finished with "Ghetto Wheels"

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