I just finished installing a NOS shift quadrant, but am having some shifting issues. Basically when I move the lever in either direction, it stays there. I have to force it back to "center."
I do not believe it to be the return spring. I believe the problem is something to do with the little spring loaded tabs in the quadrant mechanism that rest/slide on the open slots in the plate. Part numbers #1 and #39 in the image:
I think I found the issue. The plungers in the NOS quadrant stick out about .5mm further than the used piece. Shown here by the red arrow in the picture:
If I understand the mechanism correctly, the slotted sides allow the lever to return to the center position. Since they have that little extra flat area, they are sticking in the cam plate and thus requiring force to return to center.
I am going to disassemble each quadrant and try to insert the old plungers into the new quadrant.
This job turned into way more than I was expecting...
The centering spring in the outside of the timing case has to overcome the force it takes to push the pawls back into the quadrant. If the pawls stick out too far the sides of the camplate windows will hit the cylinder and not the angled portion of the pins. The arms of the centering spring (17) cross each other to contact the pin (19) on the quadrant, yes? That provides the preload for centering. Someone might have put the plate (42) that retains the pawls in the wrong way around.
I had a "new" shift quadrant for a unit single once that wouldn't shift the cam plate correctly. Turns out the POS was machined wrong and the plungers were at a different angle than the original quadrant.
I used the stub shat repair on the original, the "new" quadrant got trashed.....BTW, the stub shaft came from the "new" part before I tossed it.
That's interesting, Rich. I (perhaps naively) hadn't even considered that the NOS units could be machined incorrectly as you and Gavin have pointed out. I was excited that I found some and it wasn't going to be a tedious job. Boy, was I wrong!
I think I have made a working solution, however. It took a fair bit of grinding with a Dremel and fitting over and over again. I ended up flipping the retaining plate (#42) upside down, even though I'm still not sure that's correct. It didn't fit immediately as when the raised sections were placed into the bore, they didn't quite fit. I took a bit of metal off the corners and sides so that the plate could sit flush and not interfere with the bore or the pawls. The working one is on the LEFT:
Take a lot at how the shifting pawls are machined. In this picture the one on the right is aftermarket and the one on the left is an original part. Notice how the stop on aftermarket is cut on an angle. This causes the pawl to stick out further. It also doesn't snap back as easily. I have another set of oem's and they also have the 90 degree step. The gearbox on my 70 Thunderbolt is now apart because I couldn't get 3rd and 4th gear. Just noticed this. Also, I replaced a really worn camplate and plunger. Hosted on Fotki