Mounting a throttle position sensor to the ZS CD-175 is done without altering the carburetor so it can still function as a carburetor or now as a throttle body.
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| NOTE: On later model TR6's with smog pumps an AIR tube passes down to the exhaust manifold close to the rear of the carbs. After all these years there are few TR6's still equipped with smog pumps and AIR tubes but if your car is still so equipped there may be clearance issues. One solution has been to gently bend the tube rearward. Be careful as those tubes are often very fragile and replacements are hard to find. |
Installation |
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The original nut holding throttle linkage onto the end end of the throttle shaft can be removed with a 7/16" or 12MM wrench. Turn counter clockwise to remove it. Remove the nut and the star washer behind it. Usually there are two thick slotted washers- remove one of them. |
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Shown here is the new TPS driver installed. DO NOT over tighten it as it will strip the threads on the throttle shaft and that can only be repaired by replacing the shaft! Place a wave washer from the kit onto the shaft and thread on the driver in place of the original nut. As a starting point, the driver should be positioned with the slot aligned in the 10 / 4 o'clock postion. Inside the driver is an Allen head set screw that is tightened to lock the driver in place and allow adjustment. You will need a 1/8" Allen wrench.
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This is what the stainless steel bracket will look like once installed. Notice the angle of the driver's slot at idle. The top bracket tab goes under the nut holding the carburator to the intake manifold.
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The bracket mounts to a carb mounting stud underneath the carb. Removing the nut will require a 1/2" open end wrench. With this nut and the top mounting bolt removed, the bracket can be installed. It is tricky but it can be done. Start with the driver thru the hole in the bracket then lay the bracket over the stud and finally working it in place at the top on the manifold. Put the nut and washer on finger tight.
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Position the bracket so that the driver is centered in the hole then tighten the mounting bolts. You can test the alignment by slipping the TPS sensor onto the shaft. If the sensor's locating ring slides into the bracket without binding, the alignment is correct. If the alignment is still off you may need to loosen the bracket mounting nuts and reposition or even slightly bend the bracket with a pair of pliers. The driver is locked in place by tightening the internal Allen screw.
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Install the sensor using the two screws supplied. You will likely need to wiggle the sensor or move the throttle shaft to engage the sensor's tabs. Be sure the tabs are engaged properly before tightening the mounting screws. Using your hand, be sure that the throttle moves freely over it's range without binding or sticking. That's it. |
