By replacing an old worn straight-six motor with a 300-plus horsepower motor you will likely wear out the stock transmission and, more importantly, the stock rearend. We will save the transmission for another story and focus on the rear housing of '55-59 Chevy chassis. Rear axles and housings tend to confuse a lot of people when searching for what they think they need, but what you think you might need and what would work best for your application just may be two different things. Will a full locker work for a normal street truck or 28-spline axles for drag racing? Maybe they will, but in a practical application a locking rear differential will wear out your rear tires prematurely in a daily driver, and the strength of 31-splined axles are no match for the 28-splined nontapered stock axles.
So to take some confusion out of the equation I made a phone call to Currie Enterprises of Anaheim, California, and asked if they could share some of their years of experience and knowledge of rear axles. Brian at Currie Enterprises invited me to take a shop tour and show me the process of how a normal order would make it through the shop. Walking around their giant warehouse full of axles and housings I noticed one thing right away: This is all they do. Countless employees were working away and Brian pointed out that each employee has a very specific job to perform in order to complete a single housing. This means one employee will machine the tubes to length and another will set and tack-weld them on, while a qualified welder will finish welding the tubes in place. This assembly line style of housing production ensures each employee knows that part of the build very well.
I started my order with Currie knowing that my stock axle on my Chevy Fleetside was 63 inches wide from end to end. I also knew that I would be putting the much wider 8x16 rear wheels from Wheel Vintiques and 205/60R16 American Classic 11/2-inch whitewalls from Coker Tires. Measuring for a replacement Currie Enterprises rear axle is really straightforward if you know what to look for. The first thing I look at is the wheel placement in relation to the outer fenders and framerails. Also, look for the bedwood on the inside of the fenderwell. After you measure and are happy with the overall length of the housing you will need to figure out your pinion offset. The pinion offset is the rearend input yoke's side-to-side relation to the driveshaft and the transmission. If your transmission's rear yoke is offset then you will need to measure the pinion offset to match. Otherwise the rearend, driveshaft, U-joints, and transmission will suffer from the extreme angles and misalignment. In my case the pinion offset was zero and the overall housing length from end to end was measured at 621/4 inches.
After the parts and measurements...
After the parts and measurements were entered into the computer a work order of all the specifications and parts being used was printed. Here is a Currie Enterprises 9-Plus housing center before mock-up.
Here Alfonso drilled a hole...
Here Alfonso drilled a hole for a fill cap. This should make for easier service under harsh conditions.
Next, Alfonso drilled out...
Next, Alfonso drilled out the bottom for a drain plug and cleaned off the metal shavings.
The next step was off to Javier,...
The next step was off to Javier, where he installed a mock-up third member case and secured the housing to a fixture.
The axle tubes were placed...
The axle tubes were placed in the housing followed by a long metal rod that will assist in checking the axle tube straightness.
Ford Torino-style ends were...
Ford Torino-style ends were placed on the end of the tubes along with an alignment plate and secured with Vise-Grips.
The tubes are measured and...
The tubes are measured and cut to proper length as determined by Currie's computer when the overall length is put into the system during ordering.
Javier adjusts the axle tubes...
Javier adjusts the axle tubes with a soft hammer and rechecks the measurements.
By using two levels, one on...
By using two levels, one on top of the third member case and the other on the tube ends, Javier can check both of the tube ends for alignment.