rich5962

I got my rebuild/reseal kit from Hydro-E-Lectric the other day but couldn't play with it.
After spending a 400 mile day around Florida inspecting and doing a short-trip transport of a really nice Rally Red/Blk '66 L79, PW, PS, 4Spd, Air Conditioned Convertible for a Michangan gentleman, I'm back at the '56 PT work.

I've played around with pumps in the past, but my ?'s are specific to the original GM pumps used on the Corvettes and Passenger cars. Corvette motors run the pump only one direction, as the solenoid valves direct flow in 2 directions based on limit switch configuration. Pass car pumps have bi-directional electric motors to drive the pump, so reversing polarity does the up or down motions.

So, the 1961 Pass Car Shop manual has a nice diagram of the pump internals. But I'm stumped on something and want to figure it out before I reassemble it hopefully for the last time.

There are 2 machined holes in both the endplate and the coverplate. Each is 0.250" diameter and 0.250" deep.

I'm wondering if these are for alignment dowel pins, that were missing when I took it apart. The diagram doesn't show the inside of the coverplate, so I can't tell from the pic. however, they call it a "assembly" so I'm thinking it's got dowel pins there.

Or maybe they're just machining tool locating holes when the parts were machined.

Thoughts? ....... Dowels or Machine tool holes?

Rich

rich5962

I figured it out so I'll continue for future reference.....

All my info pointed to dowels. I found the part listed in the parts books and it also calls it a assembly.

Alignment dowels makes sense because just the 5 bolts are not good at keeping alignment as the openings are enlarged. I made a pair of dowels on my lathe this morning from a 5/16 shank bolt. Assembly is done and retested on the bench. Tested fine. No motor leaks or problems.

back to the original thread.

3310vette

Rich, I went back and looked at the photos of my pump and there were no dowel pins in those holes. I would be careful placing anything in those holes as they may play a part in fluid flow. I can't say for sure whether my pump had ever been taken apart, but it did not appear as though it had. I was careful to document every part as I removed them and no dowels.
Joe

rich5962

Joe,

Thanks for checking, but I already installed them. Hmmm, it really aligns the 2 pump plates better. Maybe they left them off yours at some time if your pump was apart before or it's a rebuilt unit.

It made more sense also because when I was making the dowels and test fitting, the diameter of 2 holes in the coverplate was just slightly smaller than the endplate(motor end) where the dowels go into when the cover goes on. So... they were a slight press fit in the endplate, and went into the endplate with a slip fit. I made the dowels 0.265" diam, 0.460" long. My earlier reference in post#1 was wrong and I'll fix it.

The other clue, is in the coverplate, there is a hole behind each dowel, which I believe is to remove the dowel. I had to remove one which was going in a bit angled so I drifted it out and restarted.

The cavities in the endplate are just that, cavities with no access to anything. If they were drilled out at center, they'd go into the pressure port and return ports where the lines attach, which go to to the cylinders which would make the unit inoperable due to bleed through.

I ran the bench test again and the system ran flawlessly, better than ever. BTW, the '59 owners manual I have says the top should operate in 20 seconds or less.

I'm putting it in the car for the next phase......wiring in the relays and connecting to the top frame for a real test. Job for tomorrow-man.

Rich