Distributor Cross Shaft Plastic Button
Thread Starter
Pro
Joined: Jan 2010
Posts: 518
Likes: 12
From: Panhandle
Distributor Cross Shaft Plastic Button
My distributor doesn't have a hole drilled in the back of the cross shaft. Hence there is no place to install the plastic button. May be an early version?
The QUESTION is, do I need to drill a hole and tap the hole for the plastic button and a set screw?
Who sells the "square" felt piece to lube the points cam?
Many thanks.
The QUESTION is, do I need to drill a hole and tap the hole for the plastic button and a set screw?
Who sells the "square" felt piece to lube the points cam?
Many thanks.
Last edited by TeaEye; Dec 26, 2017 at 04:50 PM.
Team Owner
Joined: Sep 2006
Posts: 31,198
Likes: 4,287
From: Westminster Maryland
Hi T,
I believe the little hole appeared during 1970 production so there are many tach drive distributors around without the hole.
I guess that's why the 'kits' to drill the holes so the button can be used are available and popular.
Regards,
Alan
I believe the little hole appeared during 1970 production so there are many tach drive distributors around without the hole.
I guess that's why the 'kits' to drill the holes so the button can be used are available and popular.
Regards,
Alan
Last edited by Alan 71; May 21, 2016 at 10:36 AM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Your distributor is a older one from a midyear 70 or older. I think the hole started showing up in mid 1970 production. I can't remember what the break off was, I'd have to go check my notes. But... Originally the Teflon bushing just snapped in the hole.
The wear in your distributor wall is very minimal to be honest, did it eat up the cross gear? Typically the wear is much more sever and worth drilling and inserting a bushing. If it's a factory style Teflon bushing you are using you can simply drill the hole and snap it in place. There should be enough clearance in the gear run out.
Willcox
The wear in your distributor wall is very minimal to be honest, did it eat up the cross gear? Typically the wear is much more sever and worth drilling and inserting a bushing. If it's a factory style Teflon bushing you are using you can simply drill the hole and snap it in place. There should be enough clearance in the gear run out.
Willcox
Last edited by Willcox Corvette; May 25, 2016 at 05:16 PM.
Melting Slicks
Joined: Dec 2009
Posts: 3,226
Likes: 654
From: Thunder Bay
I wasn't aware that the factory ever put that hole in the distributor. I thought that was an aftermarket modification. Regardless, the early cars didn't have the hole, as my '66 did not have it. If originality is important to you, don't drill the hole. In fact, if the Teflon button is important to you, you might want to find a replacement distributor with the hole, as original distributors are getting rare. If you maintain your distributor properly ie. remove and lubricate it regularly, you don't need the button.
Melting Slicks
Joined: Oct 2001
Posts: 2,064
Likes: 1,382
From: Halifax, Nova Scotia, Canada
I wasn't aware that the factory ever put that hole in the distributor. I thought that was an aftermarket modification. Regardless, the early cars didn't have the hole, as my '66 did not have it. If originality is important to you, don't drill the hole. In fact, if the Teflon button is important to you, you might want to find a replacement distributor with the hole, as original distributors are getting rare. If you maintain your distributor properly ie. remove and lubricate it regularly, you don't need the button.
I did need to replace the gear and shaft a few years ago. (A failed TI ignition and several backfires killed the gears)
I didn't have a lot of wear in the housing, however I used the brass button and cross shaft.
To maintain originality I only drilled the housing about 2/3 through from the inside. (No hole visible on the outside)
I had to shorten the "peg" on the brass button a bit. I setup the end play on the cross shaft to spec and have not had any issues since.
Thread Starter
Pro
Joined: Jan 2010
Posts: 518
Likes: 12
From: Panhandle
Your distributor is a older one from a midyear 70 or older. I think the hole started showing up in mid 1969 or 1970 production. I can't remember what year it was, I'd have to go check my notes. But... Originally the Teflon bushing just snapped in the hole.
The wear in your distributor wall is very minimal to be honest, did it eat up the cross gear? Typically the wear is much more sever and worth drilling and inserting a bushing. If it's a factory style Teflon bushing you are using you can simply drill the hole and snap it in place. There should be enough clearance in the gear run out.
Willcox
The wear in your distributor wall is very minimal to be honest, did it eat up the cross gear? Typically the wear is much more sever and worth drilling and inserting a bushing. If it's a factory style Teflon bushing you are using you can simply drill the hole and snap it in place. There should be enough clearance in the gear run out.
Willcox
No it didn't damage the cross gear. Just decided to refresh the distributor and noticed there was no place to install a plastic/brass button.
So the question now is....is there anything I need to install at the end of the cross gear shaft or between the shaft and the distributor housing? The only place to insert anything seems to be at the end of the cross gear shaft? And the hole at the end of the cross gear shaft seems very tiny.
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Melting Slicks
Joined: Oct 2001
Posts: 2,064
Likes: 1,382
From: Halifax, Nova Scotia, Canada
No it didn't damage the cross gear. Just decided to refresh the distributor and noticed there was no place to install a plastic/brass button.
So the question now is....is there anything I need to install at the end of the cross gear shaft or between the shaft and the distributor housing? The only place to insert anything seems to be at the end of the cross gear shaft? And the hole at the end of the cross gear shaft seems very tiny.
So the question now is....is there anything I need to install at the end of the cross gear shaft or between the shaft and the distributor housing? The only place to insert anything seems to be at the end of the cross gear shaft? And the hole at the end of the cross gear shaft seems very tiny.
If it's near that spec, then you don't have room to put in a "button", nylon or brass.
If within spec (.010"), I would use a high quality synthetic grease on the cross gear and housing, and that should last for many years.
It's lasted this long with minimal wear and likely was with minimal grease.
To check the end play, I used a 1/8" wooden dowel about 2" long and pressed it into the end of the cross gear.
When you install the cross gear this gives you something to grab to check the end play. (Check the end play without any grease applied)
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
No it didn't damage the cross gear. Just decided to refresh the distributor and noticed there was no place to install a plastic/brass button.
So the question now is....is there anything I need to install at the end of the cross gear shaft or between the shaft and the distributor housing? The only place to insert anything seems to be at the end of the cross gear shaft? And the hole at the end of the cross gear shaft seems very tiny.
So the question now is....is there anything I need to install at the end of the cross gear shaft or between the shaft and the distributor housing? The only place to insert anything seems to be at the end of the cross gear shaft? And the hole at the end of the cross gear shaft seems very tiny.
Barry is correct about the run out and there is a real easy way to know if you are in the correct range. The distributor should turn smoothly forward and backwards if you have the correct run out. If you don't have the correct run out the teeth will bind up when you switch direction. If you go back with either the brass or the Teflon button and you are too tight, some of the new distributor cross gears have a brass end on them if you are too tight you can machine the (or sand) the end down slightly for clearance.
Willcox
Teflon button
Last edited by Willcox Corvette; May 25, 2016 at 05:28 PM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
I drilled and threaded the hole and used a set screw instead of the button. After the end play was set, I staked the screw. I thought that if GM used metal to metal contact and the distributor lasted many tens of thousands of miles, a set screw would be OK.
Thread Starter
Pro
Joined: Jan 2010
Posts: 518
Likes: 12
From: Panhandle
I would check the end play of the cross gear to see if it's excessive. .010" is the correct amount.
If it's near that spec, then you don't have room to put in a "button", nylon or brass.
If within spec (.010"), I would use a high quality synthetic grease on the cross gear and housing, and that should last for many years.
It's lasted this long with minimal wear and likely was with minimal grease.
To check the end play, I used a 1/8" wooden dowel about 2" long and pressed it into the end of the cross gear.
When you install the cross gear this gives you something to grab to check the end play. (Check the end play without any grease applied)
If it's near that spec, then you don't have room to put in a "button", nylon or brass.
If within spec (.010"), I would use a high quality synthetic grease on the cross gear and housing, and that should last for many years.
It's lasted this long with minimal wear and likely was with minimal grease.
To check the end play, I used a 1/8" wooden dowel about 2" long and pressed it into the end of the cross gear.
When you install the cross gear this gives you something to grab to check the end play. (Check the end play without any grease applied)
This is important, but I'm not seeing where and how to do this....need some visual aids. Help
Melting Slicks
Joined: Oct 2001
Posts: 2,064
Likes: 1,382
From: Halifax, Nova Scotia, Canada
I don't have any pictures when I did this.
Just jam a 1/8" wooden dowel into the cross shaft (Where the end of the tach cable goes).
Then assemble the cross shaft into the dist housing.
When assembled, you now have a wooden dowel sticking out where the cable attaches.
You can grab this "stick" with your fingers and move the cross shaft gear "in & out".
The amount of movement is the cross shaft end play. .010"
I used a dial gauge on the end of the wooden dowel.
Hope this helps.
Thread Starter
Pro
Joined: Jan 2010
Posts: 518
Likes: 12
From: Panhandle
I assume you mean setting up the end play.
I don't have any pictures when I did this.
Just jam a 1/8" wooden dowel into the cross shaft (Where the end of the tach cable goes).
Then assemble the cross shaft into the dist housing.
When assembled, you now have a wooden dowel sticking out where the cable attaches.
You can grab this "stick" with your fingers and move the cross shaft gear "in & out".
The amount of movement is the cross shaft end play. .010"
I used a dial gauge on the end of the wooden dowel.
Hope this helps.
I don't have any pictures when I did this.
Just jam a 1/8" wooden dowel into the cross shaft (Where the end of the tach cable goes).
Then assemble the cross shaft into the dist housing.
When assembled, you now have a wooden dowel sticking out where the cable attaches.
You can grab this "stick" with your fingers and move the cross shaft gear "in & out".
The amount of movement is the cross shaft end play. .010"
I used a dial gauge on the end of the wooden dowel.
Hope this helps.
I think I'm getting closer....
The distributor is assembled, after tightening the brass screw I still have a lot of end play. Is this where I add shims?
End play: is there a difference in pulling the dowel in/out versus allowing it to turn? Allowing it turn, it comes out a lot further, like 1/8 inch and can no longer turn the brass screw in any more.
Last edited by TeaEye; Dec 26, 2017 at 04:50 PM.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
The end play is the amount the driven cross shaft moves in and out when the main shaft is rotated in opposite directions. The brass, or plastic, should be surface milled to keep this measurement 010. I did it the easy way with the set screw.
Melting Slicks
Joined: Oct 2001
Posts: 2,064
Likes: 1,382
From: Halifax, Nova Scotia, Canada
I did my end play adjustments without the main shaft installed. With the main shaft installed, then the gear will turn due to it's engagement with the main shaft.
Quick answer, allow the cross shaft to turn, end play is full in then full out regardless of any turns.
If you have about 1/8" then you have a few options.
- Shim the cross shaft (Washers)
- Use brass or nylon button
- Set screw method.(Easy and adjustable)
I used the brass button as I didn't want to have a hole in my original distributor, just a personal preference.
As jnb5101 stated, if you use the button option, you need to adjust/mill the surface of the button to get the desired .010" end play.
Quick answer, allow the cross shaft to turn, end play is full in then full out regardless of any turns.
If you have about 1/8" then you have a few options.
- Shim the cross shaft (Washers)
- Use brass or nylon button
- Set screw method.(Easy and adjustable)
I used the brass button as I didn't want to have a hole in my original distributor, just a personal preference.
As jnb5101 stated, if you use the button option, you need to adjust/mill the surface of the button to get the desired .010" end play.
Thread Starter
Pro
Joined: Jan 2010
Posts: 518
Likes: 12
From: Panhandle
Many thanks....understand how to do it!
One last question? on the main shaft there is a rubber bushing and looks like it is suppose to have a retainer. I know what the purpose is, but Should I just install an e clip? Do the bushings come in various sizes? Thanks.
One last question? on the main shaft there is a rubber bushing and looks like it is suppose to have a retainer. I know what the purpose is, but Should I just install an e clip? Do the bushings come in various sizes? Thanks.
Last edited by TeaEye; Dec 26, 2017 at 04:50 PM.