Tach Drive Gears gone.
Hi all..my tach gear drive stripped out last week..I thought it was just the driven gear but it also took out the drive gear on the shaft also..I bought the bronze gear set and some shims but I need the shaft now also..ok..so is there a way to set up the gears in this so it doesn't rip itself apart again..what type and how much lube should be in there..and do you have a recommendation on where to get a good gear drive shaft..I have a late 69 350..also there is what seems to be a tag around the neck of the upper housing ..looks like a bird tag..is this the only markings I should take pictures of..or are there other markings I should document as well..since I have it out now..thanks all.
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Re: Tach Drive Gears gone.
OK, you need to look into the hole the bushing screws into. Generally when your problem occurs the crossgear has eaten into the housing to a sufficient depth that the tach drive gear becomes misaligned with the gear on the mainshaft thus destroying the gears. There are bushings available to insert into the housing to repair the problem, but they take a little work to fit into place without being noticable from the outside. Lots in the archives on this, do a search on distributor gear and you should turn up a lot of info.Bill Clupper #618 -
Re: Tach Drive Gears gone.
Rich
From your description it appears that the distributer shaft gear is striped also? this is not good news if so. I could be wrong but I vaguely remember that there was an area in the distributer that was to hold lubricant. It was a light oil. I could not pin point were it should be. But what I had to do was buy a 90 degree adapter that helped with the all full angle that the cable attach's to the distributer. On the adapter is a grease fitting that I am able to inject grease in to the drive area.
JoeComment
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Re: Tach Drive Gears gone.
I figured I had some work to do with this..I can't do a search since I am mobile..will try in the morning when I get to work..
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Re: Tach Drive Gears gone.
Rich------
To preserve your original centrifugal advance configuration, you'll want to have the autocam from the top of the old shaft transferred to a new shaft. I don't know who does this anymore. However, Dave Fiedler at TI Specialties probably does it.In Appreciation of John HinckleyComment
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Re: Tach Drive Gears gone.
Joe,
If you need that 90 degree fitting your distributor is improperly installed, or the tachometer drive cable is improperly installed. NO Corvette left the factory with that fitting. It is an aftermarket part searching for a home. There are at least four previous threads on this subject. I believe the last one was within the last two or three months. There is even a picture from Chevrolet Service News of the proper orientation of small block distributors for C2s and C3s -- they are different.TerryComment
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Re: Tach Drive Gears gone.
Since you are replacing the distributor shaft/tach gears a NCRS member and owner of a distributor repair/rebuild facility has provided a excellent article on rebuilding/repairing a distributor like your 69's. The upper cavity in your 69 most likely has no lubrication left, only crud to clean out.
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Re: Tach Drive Gears gone.
Well that's a great post Jim..haven't read it all yet but I have nothing but time..new shaft and small parts kit on the way..I will see what the new cam looks like versus the old..if it needs changed I can tig it on no problem..one thing I do need is a vacuum advance..mine doesn't pull or hold a vacuum at all..the numbers on it are MS 360 12..is this something I can find somewhere..if somebody has one I can buy that would be great..or does a company make a correct one? Carlisle is coming up in a few weeks..so if there is a GM part number to look for does anyone know it? Thanks againComment
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Re: Tach Drive Gears gone.
Rich-----
The autocam is BRAZED to the top of the shaft. I would use the same process to attach the old cam to the new shaft.
It does not take much difference in the shape of the autocam to make a big difference in centrifugal advance curve.
The part number for the vacuum control is GM #1115360. This piece was discontinued more than 20 years ago, though. A Standard Motor Products vacuum control of stamped number "B10" is equivalent to the 1115360. You can obtain one of these under GM #19138049 or NAPA VC-1765SB.In Appreciation of John HinckleyComment
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Re: Tach Drive Gears gone.
Thanks Joe that hit the spot..I like to braze stuff its a fun old school deal..not real hard to do either..kinda looks like a plumbing braze..I guess I could brake out the torch..I just like the tig that I have ..also is the new number vacuum advance a correct part for replacement that would pass somewhat for judging? I guess the only thing you can see is the canister anyhow..so as long as it looks right I should be ok..thanks again.Comment
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Re: Tach Drive Gears gone.
Rich------
You probably will get docked a few points for the aftermarket vacuum control. There is a reproduction available for the '360' that costs about 50 bucks. However, while it might be a good match to the original in appearance, I've heard of performance problems with it.
One of the advantages of brazing the autocam is that if you need to transfer the piece again, it will be easier than if you TIG weld it.In Appreciation of John HinckleyComment
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Re: Tach Drive Gears gone.
Joe that does make sense to braze it..tig is pretty permanent ..I found the GM part number..I was told the new one was discontinued also..but there are still a few out there..I ordered 3!! Maybe it will be worth like the air filters one day!Comment
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Re: Tach Drive Gears gone.
Rich,
I just wanted to add for you to re read post #2 about repairing the hole that has wore into the back of the cast distributor. There is good information in the archives about this and you can do it yourself at home.
If the damage in the distributor is not repaired you will wipe the new gears out in a hurry.
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