top of page

Rear Axle Restoration

The rear axle assembly of the Simplex Crane model 5 is massive. All of its components were manufactured by the company exclusively for this model!

The first step in our restoration after the drive line was removed was to remove both axles. After the axles were removed we had to remove the locking nuts from deep within the hubs. We were then able to remove the hub / brake drum assemblies. The interior and exterior of the entire axle assembly were thoroughly cleaned. The backer plate and emergency brake components were removed for cleaning and restoration.



Next we removed the top cover from the carrier assembly and drained the lubricant. After the rear axle housing assembly was cleaned inside and out, we removed the rear drive line sliding roller assembly. The rear drive line assembly is threaded into the pinion gear bearing housing. These two assemblies are joined together. In order to remove both assemblies six cap screws needed to be removed from the split flange that holds these assemblies in place and locks the pinion gear lash adjustment. Before these assemblies can be unscrewed this flange needs to be spread. During reassembly the pinion gear lash is adjusted by rotation of the large brass spanner nut. When proper lash has been achieved the split mounting flange lock bolt can be tightened to positively secure the adjustment.

After these assemblies have been removed the pinion shaft nut can be removed. This allows the two assemblies to be separated. After the assemblies have been separated the pinion gear can be pressed out of its housing. At this point the pinion bearing can be removed. Fortunately for us, the pinion gear and bearing were in very fine condition and did not require repair or replacement. Simplex automobiles featured the highest quality parts. The axle, pinion and carrier bearings were no exception. The size and quality of the pinion bearing were unparalleled in the automotive industry!


Carrier assembly with top cover removed

Lash locking flange with assemblies attached

Preparing to separate the assemblies

Assemblies after separation

Pinion gear housing ready for bearing removal

Pinion gear bearing after thorough cleaning


After the removal of the pinion gear and axles there is a two bolt bearing retaining cap that holds the ring gear in place and secures the side to side position of the ring gear after gear lash adjustment. Once the retainer is removed the ring gear can be lifted out of the differential housing. The other side of the ring gear is supported by a smaller bearing that is pressed into that side of the differential housing. After cleaning and inspection we found the ring gear to be in excellent usable condition. Its contact wear pattern was very good. The manufacturer did offer several gear ratios. This vehicles differential ratio is 3 to 1. There are 48 teeth on the ring gear and 16 on the pinion.


Ring gear

Ring gear large bearing with support and lash adjustment features

Differential with restored ring gear and carrier assembly in place

Note the size of the two bolt bearing retaining cap

It is no wonder that the car is so heavy!


Crane model 5's feature a split hub assembly. After the outer axle nut is removed the hub and attached brake drum may be removed from the rear axle tube. After initial cleaning the brake drum and hub can be separated. They are joined by 12 bolts. The inner fiber bearing grease seal is held in place by a brass retainer that attached to the hub with two small set screws. After these small set screws are removed and the retainer and seal are removed, the huge inner axle bearing can be taken out of the hub. All of these parts were restored and all bearings replaced with NOS.


Backer plate and axle tube with nut after restoration

Rear axle assembly cleaned, painted, and partly restored

161 views0 comments

Recent Posts

See All
bottom of page