One of the first changes most of us plan to make to our trucks is the installation of custom wheels. After all, stock wheels are no way to roll, but for Chevys with one too many lug nuts, the options are limited. Despite the huge assortment of wheel designs, diameters, widths, and offsets to choose from, many of the most popular are only available for five-lug applications.
Changing the lug bolt pattern on the front of Chevy pickups often comes along with a disc brake swap. In many cases, later model GM pickup rotors are used, which results in a 5 on 5-inch bolt pattern (other options are Chevy passenger car 5 on 4 3/4 and the Ford/Mopar pattern of 5 on 4 1/2).
For those who have upgraded the front, the next chore is to make the rearend match. Unfortunately the six-lug axle flanges can't be re-drilled, as there isn't enough space for the five-lug pattern to fit between the existing holes. However, there is an easy and affordable way to lose one lug—replacement axles from Speedway Motors. Speedway's new axles with the 5 on 5-inch bolt pattern are available for '63-70 Chevy trucks ('63 and '64 require new side and spider gears). Complete kits come with axles, studs, and new '71-72-style finned drums that fit with the earlier brakes.
Swapping axles is quick and easy, the following photos show how to remove the old axles, and installation of the new components is simply the reverse procedure. For those working with a good rearend, since your hands will be dirty anyway, it's a great time to change wheel bearings and freshen up the brakes. In this case we discovered the ring and pinion will have to be replaced, which is a story for another time. We elected to go ahead with the axle swap so we could mount our new wheels and check clearances and ride height.
1. Speedway Motors' axle kit includes everything necessary to convert a Chevy pickup rearend from six lugs to five.
2. The five-lug axle kit provides a 5 on 5-inch stud pattern and includes later model finned brake drums.
3. Chevrolet's six-lug axles limit the number of custom wheels that can be used.
4. Axles in '63 and '64 1/2-ton trucks used 17-spline axles, the replacements have 30 splines.
5. Installing finely splined axles necessitates a change in differential side gears and spiders. They're included in the '63-64 kit.
6. The original six-lug axles had 7⁄16-inch studs, the replacement axles have 1/2-inch studs, also included.
7. To gain access to the clips that retain the axles the rear cover is removed.
8. This is the infamous C-clip that fits into a groove in the end of the axle and holds it in the housing.
9. The differential side gears fit on the ends of the axles; between them are the spider, or differential gears, mounted to a removable shaft.
10. This special cap screw holds the shaft in place.
11. With the retainer screw out, the shaft and spider gears can be removed.
12. After the shaft is out of the case, the axles are pushed into the housing and the C-clips can be removed. Notice the rust on the gears from years of sitting; fortunately these gears will be replaced.
13. With everything out of the differential case, it was time to give what's left a thorough cleaning and inspection. Unfortunately, in this case, the ring and pinion will have to be replaced.
14. One of the peculiarities of the GM rearend is the axles act as the inner wheel bearing race. Note the dark ring where the bearing has worn the shaft.
15. An obvious advantage to the new axles is a fresh bearing surface.
16. Here is a replacement wheel bearing; note the lack of an inner race. New bearings should be installed with the new axles.
17. If you have a cool set of wheels, but the bolt pattern doesn't match your truck, Rotten Leonard's Jalopy Shop offers this drill jig to cure the problem. This example changes the 5 on 5-inch to 5 on 4 3/4 or 5 on 4 1/2. Other combinations are available.
18. When re-studding axles, make sure the center register (the protruding center that locates the brake drum) will fit the wheels being used.
19. With the drill jig bolted in place, a pilot hole is drilled. Note the caps on two of the guides, they prevent drilling the wrong combinations of holes.
20. With the pilot hole drilled, the jig is rotated to locate the properly sized hole for the new stud.
21. Here's the finished axle and drum with a new 5 on 4 3/4 pattern.
Which five is the right five?
There are occasions when the five-lug pattern you have isn't what you need—like when you've got a rare set of wheels stashed with a bolt circle that's different from your truck. The standard cure is to re-drill the hubs/rotors/axle flanges, but the challenge is to do it accurately. Thanks to an assortment of drill jigs from Rotten Leonard's Jalopy Shop, that procedure is a simple DIY operation.