My TPS has some bad spots and so I opened it up and adjusted the contacts to a new sweep. That lasted a while, but it started hesitating on takeoff, idling odd. Sure enough it had dropouts again.

I ordered a new, red TPS. Really nice construction and smooth output. But I couldn’t bring myself to buy that $97 USD adapter.

If you remove the screw head filler on the bottom of the TPS you car remove the three screws, separate the cap from the body and see the mechanism.

Remove the steel tension band from the plastic d-shaft receiver.
Remove the hub.
Remove the plastic holding the contact strips and remove the strips.
Saw the pointed hub top off flush With the hub top.
Mark the new TPS’ flat shaft on the center of the hub, and carefully cut out this slot with a fine, sharp knife. Be careful!
Wipe the TPS shaft lightly with paraffin.
Press the TPS shaft into the hub slot.
Turn the hub over and fill the bottom of the hub with JB Weld. Only the very bottom! Just cover the end of the shaft. And don’t get any on the sides. This step isn’t necessary as the hub material is very strong, but makes this connection absolutely solid.
Remove the new TPS from the hardened JB’d hub. You did put paraffin on it, right?
Reinstall the hub in the old TPS housing.
Reinstall the steel tension band.
Remove the connecting cable and copper contact pad from the cap.
Bore a hole in the center of the cap matching the diameter of the new TPS neck.
Insert the new TPS into the cap and drill mounting holes in the cap. These will fall in the channel of the cap. Filling all the channels with JB weld first would have provided me better purchase with the screws, but even without and while going into this thin area they hold very well.
Reinstall the cap on the TPS.
Mount the new TPS on your new Bourns TPS adapter.

The depth of the cap is not quite sufficient for the Length of the shaft, so two Stacked washers on each side sit between the old and new TPS’.

Positioning notes: The new TPS needs a lot of adjustment from it’s sprung closed state to reach .32vdc. Note the Adjustment positions in the final pic. This is with the red TPS under no tension. Full adjustment available on the red TPS, a little available on the black.
This is not a good default position. Give yourself full adjustment on both. With this default position I was able to reach .33vdc at full adjustment. I’d have like a bit more headroom.









“Bourns TPS adapter”

 

EXCELLENT fix JJJ. The red TPS is a more robust item I believe. When I did mine, for the same reason of the silly adaptor price, I cut down the spindle on the capstan and made a blade shape on it to fit the TPS. Same idea, just a slightly different method.
For the info of others, new Bournes TPSs are now available from David Manners.

 

LUV IT.

I told you years ago, we would have you thinking like an Aussie eventually.

WELL DONE.

Looks better than my Brass Welch Plug arrangement.

 

pic of my TPS , $3.50 radio supply store! potentiometer! old Yankee inginuity.
ron