MGB Tubed Type Rear Axle Tech Session
Many of our MGs have a ‘clunk’ in the tubed type rear axle (as used from 1968 onwards). Specially when reversing direction, it sounds like a little free play before the gears engage and propel the car in the opposite direction from where it was going. And that’s usually exactly what it is. A little bit too much free play in the little gears inside the differential because of wear of four washers that cost no more than about $5 a piece from the major national vendors such as Moss and Victoria British, to name a few.
Inside the differential are four small gears which allow the rear wheels to spin at different speeds. They are commonly known as the 'spider gears' but the factory parts manual calls two of them just ‘wheel differential' and the other two are ‘pinion differential'. Consequently, the washers behind these gears are called 'thrust washer wheel’ (made of some fiber-like material) and 'thrust washer pinion’ (made of bronze). The 'spider gears' are held in place by a ‘pinion pin, which in-turn is held in place just by a thin roll pin. That’s right the entire differential part of the rear axle is held together by about a 1/8 inch roll pin. Therefore it is always a good idea to use a new one and maybe add some additional security if you like. You can see the parts in the factory parts list or the catalogs of said major vendors.
Replacing just the washers can be done with the rear axle under the car, but for most other work inside the differential it is necessary to take the whole thing of the car. And it just so happened that the rear axle of Abe Cheij’s MGBGT had a few problems, not limited to just the ‘clunk’. Abe took it to Barry Rosenberg’s British Car Services new location in Jasper. And on Saturday, February 15, Barry will demonstrate how to set up the gears and how to replace these washers in Abe’s differential while it is on the work bench.
Most British Cars used the same differential concept; all have ’spider gears’ and work similarly. So, even if your MG or OM (Other Make) does not have the exact same 1968-1980 tubed type rear axle, this Tech Session will of interest as the technique to service them is generally applicable.
We’ll start at 9:30 am and the work will probably take a few hours. Afterwards we can go for lunch to Rocco’s, close to Barry’s shop.
The club will offer coffee, soda, and donuts, so it is advisable to let us know that you’re planning on coming.