Distributor shaft and tach drive gear recommendation?

[tigernut]

My tach drive gear and shaft are stripped and it's time for a rebuild.

Noticed that Mid America has this combination (along with new bronze coupling) for $89.

http://www.madvet.com/shop?frame=1.1169

Seems like a reasonable price.

Anyone have good/bad experience with this particular part?

Thanks,
Doug

 

[61 Silver]

Hi! Doug

I believe that most supply houses get them from the same maker. I purchased a set on Ebay for my 65 and when I contacted the person listing the gears, he said that his machine shop supplied most of the part houses. I also purchased the shim washers from the same vendor.

Another point; you need to check the casting directly behind the small tach horizontal gear for wear. I rebuilt the distributor and it only lasted a few days and stripped the gears again. A vendor that repaired distributor at Carlisle suggested that I use JB Weld and filled in the small wear hole and it worked fine. You can also have the casting drilled out and a plastic insert installed like the later distributors.

Hope I have helped!

Ray

 

[tigernut]

Ray,

Thank you for the information on suppliers.

One of my big concerns was quick stripping of the new gear set.

I've read an article by Dave Fielder that discusses this problem:
http://www.tispecialty.com/

I hadn't heard of the jb weld fix.

I was debating whether or not to go with the "set screw" method. My car is for the most part totally unoriginal, but I'm still undecided on whether or not to modify the distributor housing permanently like that.

Doug

 

[67l36driver]

I used the set screw and jam nut method to repair the dist in mine. You can adjust the endplay on the cross gear down to only a few thousands of an inch.
I started with a hex socket 5/16"-24 cup point screw and ground and polished the point flat. Used the cable coupler as a drill guide in an end mill to spot the hole, removed the coupler and finished the hole with the correct tap drill.
The vendors sell a kit for this but it is mostly stuff you can get at any hardware store. :eyerole

 

[allcoupedup]

I used the bronze button to fix this issue. The set screw is a better solution but the bronze button tolerates some installtion error.... meaning it is better for those who can't seem to drill a hole in the center of a circle.

I didn have to shave the button down with some sandpaper until the end gear end play was correct.

http://65corvette.nonethewiser.net/monthly_journals/winter03-04/distributor_rebuild33.jpg
Brian

 

[tigernut]

Thanks for the pictures Brian.

How do you go about measuring correct end play for the tach drive gear?

Doug

 

[allcoupedup]

You can assemble the cross gear and coupler and move th mainshaft in different directions. Due to the way the gears mesh, the cross gear will move in and out. I used the opposite end of a digitial caliper to figure this out. Basically, I shaved down the bronze button by rubbing it on sandpaper until everything fit together without binding.

The set screw makes this easy but at the time I didn't know about it. Plus.... I would have screwed it up because of my poorly centered hole.

Brian

 

[GTR1999]

Nice job Brian.
One word on the replacement gears. If you're looking at the black ones with the brass plug on the face, be careful. These are common on the market and I've had several bad from the start,same with the main shafts. This was last year when I was rebuilding a few tach drive distributors. The new gears and shaft bound up by hand. I thought it was me at first, then I installed a good used GM gear and it fit perfect. When I aked the 2 vendors about this I couldn't get an good answer. I was told they had to be fit by filing the brass button. I set it up in a lathe and removed .001" at a time until there was no brass left, then made a new brass plug and it still didn't fit. If I used those in a car they would have failed in the first 30 sec's.
I went to HyTech in FL who make the bearing cross gear,they had one that fit better then all the others-except the GM ones.

Good luck maybe the QC is better then it was a year ago:eyerole

Gary

 

[JohnZ]

Hi-Tech Innovations in Hollywood, Florida (727) 942-4003, I believe makes most of the (good) replacement mainshafts and cross-gears for the vendors; I used to talk to Jim Dwyer, who was the owner, but he passed away a year or so ago and I think his son is running the business now.

 

[GTR1999]

John,
Jim's wife used to answer the phone, is she still there? I'm sorry to hear about that, it must have happened right after my last dealings with them?

Gary

 

[JohnZ]

Dunno - last time I called was about a year ago; Jim had passed away recently, and his son answered the phone. They "rescued" several very old C-1 bowl-type dual-point distributors for me that I couldn't get part for seven or eight years ago.