Two Speed Parts, LLC

Specializing in Columbia Overdrive
Two Speed Axle Parts and Control Systems

Rebuilding the A-32 Synchro Clutch Assembly

A word of CAUTION

This is information you NEED to know: We highly suggest you consider Rebuilding your Synchro Clutch when rebuilding your Columbia unit. It is well worth the effort


When the Columbia Two-Speed Rear Axle is operated in standard drive, the sun gear is locked to the housing of the planetary gear set and rotates at the same speed as the rear axle. When the unit is shifted to overdrive, the sun gear is brought to a stop by engaging it with the stationary clutch on the carrier housing. (Part A-34.) The reverse happens when shifting from overdrive to standard drive.

To absorb the impact of these sudden shocks to the gears, bearings, and housings, Columbia installed a brake-clutch mechanism which they called a "synchro clutch." This clutch is designed to slip and dissipate the shock of shifting through friction and heat. Inside the drum are 10 each: springs; shoes; and linings. Originally the clutch had linings made of sheet cork which were glued to the shoes from the Columbia factory. [A shoe is a steel pad sandwiched between the spring and the lining.] CAUTION: The original sheet cork, over time, can adhere to the hub inside the drum because the glue eventually migrates through the cork to the drum wall. When this happens, the synchro clutch can "freeze." This is not good.

Regular use of the Columbia unit will greatly help in keeping the cork lining functional. However, if a Columbia has been sitting for a period of time it is STRONGLY recommended you make the effort to dissassemble, clean and replace the ruined cork with a new spaceage lining (in our kit). It may save a catastrophic failure in the long run for you.


We sell a REBUILD KIT. It is the A-32-K Synchro Clutch Rebuilding Kit. We provide rebuilding instructions and photos of the parts to assist you. Our kit includes everything you need. You must keep the "shoes."

If you do not feel comfortable, we can assist by doing this task for you. Just call to find out more information about the costs involved with the labor and parts.

Photo of Synchro Clutch unit on top of the A-6 unit
Cork adhered to inside of drum. Not good. Can cause catastrophic failure.
Cork stuck to Shoe (keep your shoes) we do not reproduce the shoes. These are special formed pieces which are not available. SAVE THEM!!
Cleaning the old Cork off of the "Shoe." You need to do this!
Exploded View of Columbia Unit, highlighting A-32 Synchro Clutch Assembly
A-32 assembly internal PARTS
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