Thread: Another 700R4 Question

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To answer my own question and maybe shed some light on one aspect of the 700R4 I include a picture of the problem I have had with the "Speedometer Gear Cover". The problem started when I tried to install the pulse generator for my digital speedometer. Sadly, the width of the transmission mount that came from Brookville for my frame is just not quite wide enough to attach the cable plug on the pulse generator. This was solved by the purchase of a right angle adapter. However the combined weight of the pulse generator and the right angle adaptor caused it to flop backward where it came in contact with the H-pipe of my exhaust system where the wire would eventually short out after the insulation burned off, sooooo I tried to tighten the coupling of the right angle adapter so as to keep the pulse generator away from the H-pipe BUT (!) I used a 12" adjustable wrench and I snapped off the snout of the fitting. After searching the Internet I learned several facts. First there are TWO types of covers. One type is for a larger speedometer gear which is off-center (40-45 teeth) and the other is for smaller gears (34-39 teeth). The smaller gear allows the gear shaft to be centered so when you spin the cover on the gear shaft (in your hand) it does not wobble. However the gear cover for the larger speedo gear has an off-center hole to allow space for a larger gear. Although the gear covers have writing cast into them the easiest way to tell the difference is to spin the cover on the gear shaft when it is held in your hand and the cover will wobble due to the off-set hole. In the picture shown you can see the broken plastic cover with a 44 tooth gear. In the middle you can see the better auminum cover with the cumbersom pulse generator and the adapter with a 42 tooth gear. On the right you can see the cover for the (34-39 tooth gears. Since I do not plan to change the nylon gear on the transmission output shaft I will swap the matching 44 tooth gear from the broken cover and use the middle aluminum cover. I have to chalk up the slight cost of the smaller gear cover ($25) to education. The lesson for others here is twofold. First, avoid the plastic cover and use the aluminum cover whenever possible. Second, if you have to use the plastic cover note that it is fragile and a 12" wrench handle is too much torque for that brittle plastic!

Don Shillady
Retired Scientist/teen rodder