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Engine Restoration - Part 2

Updated: Jul 19, 2022

In part 2 we will show the restoration work of the timing and accessory drive sprockets, chains, and bearings. Every ball and roller bearing on the engine, transmission, clutch, drive line, front axle, differential, rear axle, steering box, fan, water pump, generator, magneto, and starter

were replaced with quality NOS.


Front of engine with timing cover in place. The fan pulley and generator/air compressor drive gear are visible. In the lower right corner the timing case pressurized oil line can be seen.

Front of engine with timing cover removed, the chains are very loose


The Simplex, Crane model 5 engine and chassis was designed by Henry Middleton Crane, a brilliant MIT engineering graduate. Simplex Crane model 5's were made to last and they did! However, after many years of use, the timing chains and sprockets were subject to eventual wear. Two of the three timing chains on this car were warn out. By some miracle, we were able to obtain a timing chain and an accessory drive chain, both original NOS and in the box!


The camshaft sprocket and crankshaft timing and accessory drive sprockets were in good usable condition. The three remaining accessory drive sprockets were all worn-out.

Upper accessory drive shaft with sprocket and generator/air compressor gear

The outer gear drives the four cylinder air compressor, the inner fiber gear drives the generator

Upper accessory drive sprocket after removal with chain guards attached

Since the chain guards were heavily gouged from the worn loose chain, all the low areas were filled in with brass and then resurfaced in one of our lathes.

Upper accessory drive shaft after restoration with newly fabricated sprocket and NOS roller bearings

Upper accessory drive shaft after restoration with fan belt pulley


The lower assembly drive shaft runs the water pump and magneto. The square end couples to the water pump. The sprocket seen below drives the upper accessory shaft that runs the generator and air compressor. This sprocket was one of the three which were worn-out and a new one was fabricated.

The sprocket after removal


The front sprocket on the lower accessory drive shaft was also warn-out. We were challenged to replace this sprocket. It was hardened and an integral part of the lower drive shaft assembly.

Front of the lower accessory drive shaft with chain guard removed


We decided to anneal the lower drive shaft assembly. We turned the old sprocket off on the 16" South Bend lathe and then bored the lower drive shaft assembly to accept a new smaller diameter shaft which was keyed to accept the new sprocket. Then the new shaft was pressed in and pinned to the old assembly.

The lower accessory drive shaft after restoration with new sprockets and bearings

The bottom portion of this picture shows the lower accessory drive shaft in place with restored chain guards. The top portion shows the drive sprocket for the upper drive shaft. The installation of this chain was very difficult. As you can see, the upper sprocket needed to be held in place to allow the installation of the upper drive shaft.

Installing the new accessory drive chain

Front of engine after restoration and installation of timing cover

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