The top picture is a standard four speed housing. The one below it is a Telaio Rosso housing. I can only assume that when Guzzi decided to rush out 150 V7 Sports from the Race Department, the new ribbed five speed housing was not ready. As I mentioned earlier, the first batch of V7 850s in 1971(Loop frame Variants) came with four speed gearboxes. Since they were done with the four speed casting mold they altered the mold to produce a batch of special smooth case housings that could be used with some of their new five speed internals. Note the differences, especially, in the upper left hand quadrant where the preselector would be. The housing cavity is roughly the same shape, but the outer shape or perimeter in this area is entirely different. The new five speed cover was apparently ready, but this too is modified for the TR and would not work on a five speed housing. Interestingly, it carries the same part number on the inside as the standard five speed cover used on Eldorados.
		This TR gearbox did not have it's original gearbox internals, but instead, had a poorly modified set of standard five speed internals. I had to redesign a new set of five speed gears to work safely in this TR housing. A five speed layshaft is too long for this housing and many parts had to be altered. The locating pins for the cover are in the same location as on the four speed. Consequently, the special five speed cover for the TR has matching bosses and holes for these locating pins. On the five speed housing, the position of the locating pins was changed(shown in the next picture below) and new bosses were added to the cover to accomodate this change. The old boss location was retained and they are present on all five speed covers. A hangover from this very small, very special run of parts. Note that the gasket area was never finished off with a mill and still has it's rough cast surface.
		A typical five speed housing. This is a late Eldo or newer since it accomodates the three bolt retainer for the clutch shaft. The inner cavity is still the same shape and size as the four speed, but the outside of the housing has grown to deal with the increased torque of the new five speed and 850cc motor. Vestiges of the four speed casting mold remain as evidenced by the oil tray drilling and on the clutch side, bosses and raised passages for oil way drillings to feed oil to the bushings under the layshaft gears. Five speeds use needle roller bearings for the gears which are effectively oiled by splash. Even the five speed is cast from a modified four speed mold. Evolution at it's finest. See a clear illustration on the next page  why five speed internals would be very difficult indeed to put in a standard four speed housing.                  Next Page

Powered by CityMax.com