Big Body Axle Shortening

“Shorten your axle so you can wear your skirts” Sometimes getting the right wheel and tire fitment to your dream ride is harder than it looks, and trying to tuck wire wheels into a classic is a prime example. In order to get the look you need, you usually have to shorten the rear end, especially if you are looking to use a 14×7 wire wheel. Those Impala owners out there looking to rock the skirts also need to take this modification into consideration as well. This month, we are going to show you how the axles and housing need to be shortened in order to achieve these looks. Of course, each vehicle has its own requirements, so there is no set standard on just how much modification you will need. You need to examine the specs of the vehicle you own and figure out the look you are trying to achieve in order to dictate the amount that will need to be trimmed off of the housing. For example, if you want to run skirts on a ‘70-72 Monte Carlo, you will need to knock two inches off of each side. Most of the Impalas need one inch trims off of each side to be able to run skirts, and in this month’s tech, we shortened a big body rear end by trimming it down 1-1/4-inch on each side as we wanted to make sure that our 14×7 reverse wire wheels didn’t get caught up in the skirts. Many technicians who practice this trade on the west coast have left the area to take their talents overseas, making it harder and harder to find someone reliable and knowledgeable to trust with the task of shortening the rear end on a vehicle. In this month’s tech, we visited Cooks Machine Works, a So Cal company who specializes in differentials and also performs its fair share of drive shaft servicing. Cooks Machine Works has been in the same location for decades, as their business was started in the city of Los Angeles back in 1946. The famous green colored building can be seen off the service road that runs parallel to the 5 freeway, and it has become a haven for many Lowrider builders. In fact, the family-run business has been shortening axles and housing for over 30 years in the Lowrider community, as a Cooks rear end treatment is crucial to tucking in a set of 5.20’s and laying properly on the pavement. We had the pleasure of receiving a demonstration from Jim McCaslin and Paul Thompson of Cooks Machine Works, so follow along as they show us how to shorten the axle and housing on this big body Cadillac.

1. The setup.


2. This big body axle was set up for hydraulics which had a set of CCE hydraulics cups to hold the coils in place.


3. The axle was examined to see how straight the housing was before any work was started on it.


4. The white on the housing shows where the axle was bent from the miles of service on the car.


5. The housing’s tubes were welded in the center, using a traditional stick welding method which is a stronger weld then the now common wire-feed weld.


6. These welds were done continuously and are actually just as clean as a wire-feed welder.


7. The factory spot welds that hold the axle tubes together were also re-welded.


8. Once the axle was straightened out and reinforced, the ends were measured to figure out how much was going to be removed.


9. Using a lathe helped to allow the first cut, which will determine the amount of material that is needed to be removed.


10. A 1-1/4-inch cut was marked on the housing as the starting point of the material that was going to be removed.


11. With the housing still on the lathe, Paul removed the ends by using a hacksaw.


12. Since the majority of the cut was done on the lathe, the only thing that needed to be done was to clean off any metal burrs left on the axle from the hacksaw cut.


13. The prepared end of the axle was ready to be placed back onto the axle.


14. Jim started welding the ends back onto the original housing.


15. The housing end was reassembled and from these type of welds, you know that it will not come loose. The housing was allowed to cool off while the next step was done.


16. Jim made sure that the axles were straight before attempting to do any work on them.


17. Since the axle needed the spline to be bigger, additional material was welded onto the original axle.


18. The hardened axle was treated so it could be reworked; with that said, the welded materials will allow new splines to be cut onto the axle.


19. The axle was cut down.


20. With the welds machined down, the axle was given a face cut to assure that the axle was straight when all the precision cuts were added to it.


21. With the axle all squared up, Jim moved onto the crucial cuts.


22. Since this axle was set up as a c-clip axle, the c-clip needed to be checked for fitment.


23. The final cuts for the c-clip were added to the axle before moving on to the next step.


24. Cooks’ spline cutting machine was used to create the new splines on the axle.


25. This axle was cut to stock specs, as it was also hardened to ensure that the axle wouldn’t fall apart from the torque of the drivetrain.


26. The ABS gears for the axle were heated up to allow them to reattach themselves onto the axle as the heat makes them expand.


27. The ABS gear went on smoothly.


28. Using the stock axles will save you money when shortening the rear end.


29. This Big Body rear end was ready for some skirts.

Date: 30th, 2014


  • 1937 Slant Back Ford. Cooks narrowed and built the rear end for my Hot Rod! Thanks for the fast work.


  • Thanks for the quick turnaround. You guys are great.

  • One of our many satisfied customers: Larry shows off his 1959 Austin Healey (its narrowed rear end was built by Cooks). Another happy customer!