63 Tach Drive Distributor - Part 2

[Stuart F.]

I asked a question in the previous thread on this subject w/o response, so I'll try again.

I too have my distributor out of the engine now, and I can take care of everything pretty well myself, but I am not too familiar with one aspect;

When and how do you go about changing to a bronze or nylon button on the end of the tach drive gear. I believe my gears are ok, but I do see what may be a shaft end wear pattern in the distributor housing. I don't want to try and put one in if it's not needed. Why mess with a good thing, right?

Stu Fox

[Joe L.]

Re: 63 Tach Drive Distributor - Part 2

I asked a question in the previous thread on this subject w/o response, so I'll try again.

I too have my distributor out of the engine now, and I can take care of everything pretty well myself, but I am not too familiar with one aspect;

When and how do you go about changing to a bronze or nylon button on the end of the tach drive gear. I believe my gears are ok, but I do see what may be a shaft end wear pattern in the distributor housing. I don't want to try and put one in if it's not needed. Why mess with a good thing, right?

Stu Fox

Stu------

I HIGHLY recommend a brass or nylon button for the tach cross gear. Either requires that a hole be drilled at the end of the tach gear cavity in the housing. However, the external hole can be filled with epoxy, dressed and painted so as to be "invisible". You can use the center of the wear mark on your housing as the point to center the drill. As I recall, the hole size is 11/64" (but double check before you drill).

Addendum: I just recalled that some of the vendors sell a tool to allow you to drill a perfect hole. I think it's, basically, a brass fitting with the proper size hole. You either screw it or insert it into the fitting orifice, then drill through the hole. This ensures a perpendicular hole of the correct size. I think the tool is of modest cost or you might be able to get it on loan.

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Thanks for your help on this.

How accurate must the hole be, I.e. Are we talking drill press and a jig by a professional machine shop, or just a good careful use of a hand drill?

Thanks again.

Stu Fox

[Joe L.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Thanks for your help on this.

How accurate must the hole be, I.e. Are we talking drill press and a jig by a professional machine shop, or just a good careful use of a hand drill?

Thanks again.

Stu Fox

Stu------


Well, the hole needs to be perfectly perpendicular to the surface into which it's drilled. If you can do that with a hand drill, it'll be OK. However, remember you only get one shot to get it right.

Addendum: I just recalled that some of the vendors sell a tool to allow you to drill a perfect hole. I think it's, basically, a brass fitting with the proper size hole. You either screw it or insert it into the fitting orifice, then drill through the hole. This ensures a perpendicular hole of the correct size. I think the tool is of modest cost or you might be able to get it on loan.

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Understand. Thanks.

Stu

[Joe L.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Understand. Thanks.

Stu

Stu-----


See my addendum, above

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Wow! That would be the way to go. I hate to job out work on my original 63 accessories. I've lost some including my original master cylinder and AFB carb. Took me many years to replace.

I will investigate sources for such a device.

Thanks again.

Stu

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Ecklers has what they call a "Drill and Tap" kit. The description for use seems to drill a hole alright, but then they follow by saying the hole would be tapped for a socket head set screw. Am I looking at the right tool(s) for what I want to do with a bronze button?

Stu Fox

[Steve G.]

Re: 63 Tach Drive Distributor - Part 2

Yes, that is the tool. It is not just about the button, it is about end play. The set screw allows you to set the end play of the drive pinion.

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Thanks Steve. I'm sure I can use it. Can you tell me how you measure or evaluate a proper end play adjustment?

Mine didn't seem to have much movement (play) in and out, but upon inspection it was obvious there was a wear pattern in the housing from the end of the cross gear.

Stu Fox

[Joe L.]

Re: 63 Tach Drive Distributor - Part 2

Joe;

Ecklers has what they call a "Drill and Tap" kit. The description for use seems to drill a hole alright, but then they follow by saying the hole would be tapped for a socket head set screw. Am I looking at the right tool(s) for what I want to do with a bronze button?

Stu Fox

Stu------

Yes, that's one version of the cross shaft end-play control set-up. It's very difficult to measure the end play, although you can just run the set screw in until there's no end play, then back it off a bit. I don't like the set screw adjustment, though. For one thing, I think it's over-kill. For another, you really can't "disguise" the external hole/set screw. However, some folks use it with success. For me, the special alloy brass button is the simplest and easiest solution. You could probably use the same tool as the one supplied with the kit you referenced.

By the way, the brass button is, basically, a modification of the end play control adopted by GM in about 1971. That system used a nylon button and it worked PERFECTLY. The nylon button, GM #1957329, is discontinued and I don't know if a good reproduction is available. However, the brass button works as well or better.

[Steve G.]

Re: 63 Tach Drive Distributor - Part 2

The kits come with instructions for setting end play,essentially tighten the set screw so that it's tight to turn then back it out a predetermined amount.

The end play adjustment is crucial. GM brought out the wear button to prevent the gear from wearing into the housing, which is what was happening. I distinctly recall years ago buying a new GM pinion and having it fail again before long. Failure was attributed to excessive endplay in the cross gear.

The new button will reduce the further amount of wear, but it may or may not take up the excessive endplay from wear in the housing that has occurred.

I locktited the screw in and cut it off flush. Then you can dress it up to make the invisible repair.

Forgot to mention, pack the gears and housing fully with a quality grease.

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Thanks Joe and Steve. Not sure which way I will go yet, but Eckler's on-line notes that the kit is now in limited supply. So, guess I will drive out there today and pick one up. They have a number of other cross shaft parts of different quality that I may be interested in, but they tend to be a bit pricey compared to other vendors. Still, I may want to make the drive worth while, as opposed to shipping costs.

Picked up a can of NGLI #2 grease yesterday (Valvoline Synthetic). This the nice "gooie" black stuff.

Thanks again.

Stu Fox

[Timothy B.]

Re: 63 Tach Drive Distributor - Part 2

Stu,

Be aware that some have reported wear in the bronze repair buttons, I have not seen this on my distributors but I just want to pass along FWIW.

You can use the factory screw in bushing with a correct (large) size drill bit to start the hole as the bit will knock off the indentation that the gear made in the housing. Then, get the correct size drill bit for the button, I can't remember the size and drill through the housing. Some report not drilling all the way through the housing but for me it's easier to drill through, install the button then butter the hole with some J&B weld and paint. If you don't want to use the bronze bushing, you can make one from mild steel, you get the idea.

As far as end play, install the bushing so it sits flat with the surrounding surface of the inside of the distributor housing and all is fine. There will be some movement noticeable when you spin the distributor gear by hand and that's OK so long as the button sits flush inside. Remember the thrust is inward when the engine is running that's why the cast surface wears inside.

Lube her up and she's good to go. :-)

[Stuart F.]

Re: 63 Tach Drive Distributor - Part 2

Tim;

Thanks for your valued advice. Just one question; late in your second paragraph i believe you changed your description from "Bronze Button" to a "Bronze Bushing"? I'm a little new on this distributor tach drive fix so I want to be sure I understand completely (sorry).

Last time I had this distributor apart (tach drive part) was probably in the early 70's when I installed my Dyna-Flyte ball bearing plate. I believe everything looked ok then.

Thanks again;

Stu Fox