Tach Drive Distributor Bushings

[Joe C.]

Are these still available from GM?

If so, then are they "better" than those available elsewhere?

Any other recommendations for a high quality bushing? The bushings were replaced using parts purchased through one of the larger Corvette parts houses. The lower bushing has already worn badly, resulting in about 1/16" lateral slop after only 6,000 miles.

Thanks in advance.

[Gary R.]

Re: Tach Drive Distributor Bushings

Joe
Don't know if you have any access to a lathe or not? When I did a couple of my distributors 7-8 years ago I think I used either 660 bronze or oilite and machined them to size. If I recall correctly the bushings sold were just oilite bronze as well.

[Joe L.]

Re: Tach Drive Distributor Bushings

Are these still available from GM?

If so, then are they "better" than those available elsewhere?

Any other recommendations for a high quality bushing? The bushings were replaced using parts purchased through one of the larger Corvette parts houses. The lower bushing has already worn badly, resulting in about 1/16" lateral slop after only 6,000 miles.

Thanks in advance.

Joe-----


The bushings for the 1962-74 distributors were NEVER available from GM, although the bushings for the 1955-61 distributors which were once available from GM might work. No matter, even those have been discontinued for more than 30 years.

[Clem Z.]

Re: Tach Drive Distributor Bushings

Are these still available from GM?

If so, then are they "better" than those available elsewhere?

Any other recommendations for a high quality bushing? The bushings were replaced using parts purchased through one of the larger Corvette parts houses. The lower bushing has already worn badly, resulting in about 1/16" lateral slop after only 6,000 miles.

Thanks in advance.

in the area between the 2 machined surfaces that fits into the lifter oil gallery drill a .032 hole so you have pressurized oil to the bottom bushing

[Joe L.]

Re: Tach Drive Distributor Bushings

in the area between the 2 machined surfaces that fits into the lifter oil gallery drill a .032 hole so you have pressurized oil to the bottom bushing

clem-----


Do you mean drill the hole through both the housing and the bushing?

[Clem Z.]

Re: Tach Drive Distributor Bushings

clem-----


Do you mean drill the hole through both the housing and the bushing?

yes. also if you replace the bushing and the shaft is scored it will wear out the bushing quickly.

[Joe C.]

Re: Tach Drive Distributor Bushings

in the area between the 2 machined surfaces that fits into the lifter oil gallery drill a .032 hole so you have pressurized oil to the bottom bushing

I'm not sure if I like that idea. If the upper bushing is not a close fit, some of that oil might find it's way into the housing's grease recess and beyond, as well as out the tach drive. I'll have to look for the old, original bushings and try to modify the new replacements to match them. The main concern is their iron content.

When I built the distributor years ago, I used a new shaft as well as new bushings. I believe I bought all of it from CC, although I bought a lot of parts from CC, Zip, Paragon, LICS, and Doc Rebuild at the time. The bulk of the parts came from Zip, CC and Paragon, so could have been from any of those three.

I remember that there was something different about the originals.................they were perforated and/or rifled, like a barrel of a gun, to draw oil along its surface. The replacement bearings are flat.

As far as getting a REAL, high quality oilite bearing, it's mostly hit-and-miss. I have been through this with crank pilot bushings and many of them are junk, containing enough sintered iron to attract a magnet. A real, high quality oilite bushing should be made of nearly 100% bronze, and should not attract a magnet.

[Clem Z.]

Re: Tach Drive Distributor Bushings

I'm not sure if I like that idea. If the upper bushing is not a close fit, some of that oil might find it's way into the housing's grease recess and beyond, as well as out the tach drive. I'll have to look for the old, original bushings and try to modify the new replacements to match them. The main concern is their iron content.

When I built the distributor years ago, I used a new shaft as well as new bushings. I believe I bought all of it from CC, although I bought a lot of parts from CC, Zip, Paragon, LICS, and Doc Rebuild at the time. The bulk of the parts came from Zip, CC and Paragon, so could have been from any of those three.

I remember that there was something different about the originals.................they were perforated and/or rifled, like a barrel of a gun, to draw oil along its surface. The replacement bearings are flat.

As far as getting a REAL, high quality oilite bearing, it's mostly hit-and-miss. I have been through this with crank pilot bushings and many of them are junk, containing enough sintered iron to attract a magnet. A real, high quality oilite bushing should be made of nearly 100% bronze, and should not attract a magnet.

there is a large hole in the housing right above the bushing that oil in the lifter area is to go into to oil the bushing so the pressurized oil will come out this hole before getting up to the top of the dist.

[Joe C.]

Re: Tach Drive Distributor Bushings

there is a large hole in the housing right above the bushing that oil is to go into to oil the bushing so the pressurized oil will come out this oil before getting up to the top of the dist.

That's better.

[Clem Z.]

Re: Tach Drive Distributor Bushings

if drilling the hole for pressurized oiling worries you you can spiral groove the shaft in the bushing area to allow more oil to flow in that area

[Joe C.]

Re: Tach Drive Distributor Bushings

if drilling the hole for pressurized oiling worries you you can spiral groove the shaft in the bushing area to allow more oil to flow in that area

I'm not convinced that insufficient oiling caused that bushing to wear so quickly. I would think that the shaft and bushings should normally have very little lateral loading on them. I have to try to figure what else may have caused the accelerated wear.

[Clem Z.]

Re: Tach Drive Distributor Bushings

I'm not convinced that insufficient oiling caused that bushing to wear so quickly. I would think that the shaft and bushings should normally have very little lateral loading on them. I have to try to figure what else may have caused the accelerated wear.

just about every dist i took apart showed signs of wear on the lower shaft and it never happened after using full pressure oil to the lower bushing. since the cam drives the dist and the dist drive the oil pump and pressure needed to do this would want to force the dist gear away from the cam gear causing side pressure on the bushing. this would be more true with hi pressure hi volume oil pumps. JMHO

[Joe R.]

Re: Tach Drive Distributor Bushings

OK, here's the problem with the bushings that are currently available from ANY Corvette Warehouse! When the bushing is driven into the distributor housing the ID of the bushing is decreased and makes the bushing either tight or too tight.
The perfect bushing is a bronze-silicone-aluminum bushing or oilite with teflon. Either can be obtained from ANY distributor that specializes in bearings. Specify the correct OD and make sure the inside (ID) is either the same or smaller than the stock bushing.
NOW the problem is making the ID correct and this cannot be done with a DRILL BIT! You will have to borrow or obtain a set of reemers with the correct ID size.
OR you can have a lathe like Gary R. suggests and turn (reem) the ID to the correct size.
What I am really saying is that this is not a job that the shade tree mechanic can accomplish without the correct equipment.
Bite the bullet boys and PAY someone to do a professional job.

JR

[Robert K.]

Re: Tach Drive Distributor Bushings

All,

You may already know this, but there are a couple of good articles on the website shown below related to distributors and the replacement of bushings, shafts, etc.

http://www.tispecialty.com/

Take care,

[Clem Z.]

Re: Tach Drive Distributor Bushings

the chevy dist shaft is a odd size .490 i believe and to ream it you need what is called a adjustable reamer that you can set to the proper size. http://www.youtube.com/watch?v=qxxU0I_gvPE