Is this wear typical and can be returned to service, or too far gone?



Thanks.
Steve

 

too far gone

 

Yep. Time for a new one.

 

Okey dokey guys.

Thanks.
Steve

 

Lars recommends the shafts made by Paragon.

 

Steve

 

The mainshaft gear will "applecore," and destroy the shaft, as a result of excessive wear on the housing crossgear thrust surface - you cannot simply replace the mainshaft and crossgear to repair your problem - it will destroy itself again almost immediately. You have to machine your damaged housing thrust surface, and then machine a custom thrust surface insert to repair it. Only then can you install new mainshaft and crossgear with any chance of success.

Lars

 

I believe you Lars.
Can you do the machining of the distributor/insert?

Steve

 

We use the oylite inserts in the housings after we machine them. I've never had the first issue with this process, but I've read where Lars posted the other day he did. I'm not sure why, but we may switch over to steel inserts vs. the oylite, either is just as easy to make as the other for us.

You can see from this picture how the inner housing is machined out to allow for the wall to be repaired below. ..

PR makes the best upper and lower bushings and they are the only bushing will purchase. But know that in most cases you have to re-size them after installation. Pr doesn't make their own distributor shaft though.

 

Best kind of grease to use there?

 

Normally, I would prefer Oilite in this type of application-
Is there really that much thrust against that side gear that it would wear out an Oilite surface?
I'm in the process of rebuilding a distributor core and it's an older unit (no thrust bushing of any kind) and I can barely see any wear on the nose of the old side gear or the housing.
It seems that if everything is set-up properly with correct tolerances and lubrication, this shouldn't be an issue?

Willcox, are you saying you mainshaft bushings are Oilite as well?
I'm getting an order ready for some distributor bits.

 

Here is what I posted on the subject over on C1/C2 based on the following post:
I build one to two distributors per week, and I get, on average, one per month that has the brass button installed with severe damage: The brass button is too soft to provide durable service, and I see them fail in as little as 500 miles. Commonly, I see total failure of the buttons, where the crossgear has worn completely through the brass, leaving only the "stem" in the housing pin hole. In every case, the metal shards from the shredded brass end up in the lower bushing, and this destroys the bushing and scores the mainshaft severely.

Here is one that I received just this week: This is from a Forum Member who rebuilt this distributor just a few hundred miles ago, but he was not happy with the advance curve, so he sent it to me for checkout and curve. The crossgear and the thrust surface had plenty of lube. The crossgear end surface was not scored up, yet the brass button is clearly headed for early failure. It's hard to get a 3-dimensional view from this 2-dimensional photo, but the thrust surface is worn almost halfway through. This is one of the better brass buttons I have seen after use:



The brass shavings had scored up the lower bushing pretty bad, but the mainshaft was still in serviceable condition. I replaced the lower bushing, polished up the shaft, fabricated a good, mild steel insert, and got this one set up and tested at a nominal cost.

When I first started rebuilding tach drive distributors about 10 years ago, I thought the brass buttons would be great: I used them in several of my early builds. I received every single one of those distributors back in less than a year with complete thrust button surface failure, and I lost my butt on the work. Needless to say, I don't use them any longer, and I haven't had a failure since.

Lars

 

Thank you for the info Lars!
So the next question is who sells buttons out of something harder than brass?
What would be the preferred material?
Would bronze be better suited than steel?
Thanks!
Elm

 

I can relate to what Lars has said. About four years ago I was on my way to a car show for charity when a knock developed in the engine. By ear I traced it to the distributor. OK, I was near home and made it back. Pulled the distrib and here is what I found. I had a rebuilt spare in the basement from my 1967 days and popped that in to get through the summer. In fact it is still in the car to this day.

What failed I do not know? But the bushings and just about everything else were toast. Brass filings everywhere!







So I had the great idea that I would rebuild it at home using the "typical" kits. That did not work out very well in that the bushings did not fit. Machining had to be done. So I contacted the parts supplier and they agreed to do the job for a modest cost and it was done.

This winter has been terribly cold and I don't have much to do in the basement so I thought I would finish off the job with new NAPA points and condensor, now installed. But for some reason a B21 vacuum canister was put on. I asked Lars about that and he recommended a B20/B26, Eichlin VC1765. I will have that tomorrow.

But this thread worried me about the button: teflon, brass, nylon, steel, bronze, or nothing. No consensus yet here. So I pulled the darn thing apart today and the company (a supporting vendor) that did the work ~four years ago machined that area and used a steel button. So based on Lars' comments I am relieved!

You learn something new here each day. Ready to go for 2015 if I need it.

 

Most interesting Paul.
And that thing really looks great now. Ready for the real test.

Steve

 

Perhaps. The car ran well last summer. I have a bad habit of fixing things until they are broken. But it is nice to have a good distrib in reserve if need be.

 

Just poking around it appears Paragon has bronze thrust buttons and they also sell a kit to tap a hole for a 1/4"-28 set screw to keep the side gear end play in check-
Seems to be the most elegant solution yet?

 

Searched & found a plastic button for sale somewhere yesterday, before all the comments today about buttons. But can't remember where it was.


Steve

 

Willcox calls it teflon (that is normally just a coating). It is probably nylon.

http://willcoxcorvette.com/product_i...ducts_id=27705

 

THAT'S IT!



Steve