Rebuilt the distributor on my '78SC.
 

Well I pulled the distributor and rebuilt it this past weekend and I have some questions (at the bottom of this thread) that I'd love some folks to answer for me. The original thread (http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=54115) details questions on removal and timing. However, an older thread wherein I asked If I could just "throw some WD40 down the distributor to free up the mechanism" was the spark for this project. Warren scolded my laziness and questioned why I didn't take the extra 10 minutes and just pull the dizzy.

Boy was he right.

On disassembly and inspection I found that the grease had turned to wax/gum, and both weights were sluggish on their posts, moving with some effort. There were bits and pieces of very small metal on the CDI magnet, and the whole unit, though solid, was very much in need of a cleaning. I would say that anyone spending any money on performance parts needs to ensure that their dizzy is clean and working right to realize the full potential of their investment.

I will post a complete procedure for performing the cleaning operation for a '78SC with Wayne's edit and OK, but for now would like to make these points. First off, this job is reasonably easy, but does require patience, a scribble pad to note the relation of pieces to one another, and the ability to use a punch and hammer very close to an expensive part.

The rough overview is this:
= Remove cap/vaccum hose(s), electrical connection AT JUNCTION (not at the distributor body; that one is screwed in)
= Z1 w/rotor to dist mark: mark dist. base to engine and pull unit.
= Remove screw holding support for electric plug; remove.
= Mark relation of pinion to dist. shaft (at bottom: mine had a green blob on one side of pinion) and drill out malleable pin at shaft/pinion. Remove with liberal amounts of WD40 to wash all particulates away: this is an interference fit that does not tolerate any metal shavings.
= Unscrew 3x hex screws at top (look down into dist.: they are revealed through three "cutouts" at the edges)
= Unscrew vacuum unit screws and gently coax distributor shaft up while "breaking" vacuum unit arm from pin inside dist. Do this by tilting vaccum unit up and away from dist body.
= Continue pushing shaft up to remove from body of distributor to separate internals from body.

At this point, one could remove the upper circlip and take the reluctor, etc. apart (I think?) but I had complete access to everything I needed to clean and so went ahead cleaning things and re-oiling the essential bits. Weights come off posts easily with a small screwdriver at the circlips, etc.

What I wish I had done is purchased the rebuild kit prior to this. I ended up making my own pin (size for pin is >5/32; <11/64) out of a malleable material and crushed each side of the pin into a mushroom head once I had the pin through the pinion/shaft hole.

The distributor now turns very freely in the bearings and the weights swing out and in smoothly. Very satisfying fix!

Now, a question for those who have done this before: Does the pin that hold the pinion to the shaft at the bottom of the dist ever get an extreme shear load under normal conditions? I ask this since the pin was quite malleable and thus meant either to shear first under binding OR be easy to drill out OR both? In all events, I found a perfect fit in a roll pin, but that is hardened, so did not use it.

Next question: there are two bushings in the distributor body at the bottom that hold the shaft. I thought that there might be a felt piece between these to hold oil in, but found instead that was not the case. Should I have seen a bit of felt there, or do the spiral windings in the shaft encourage oil into the cavity between the bushings?

Last question: does anyone have a schematic of the SC distributor with CDI brains? Warren's pic is good for the early distributors but I need the correct schematic/exploded view to write up a proper how to with the correct terminology.

Thanks very much for your help guys! I will try to get a full procedure on this operation ASAP.

John

John,

I'm looking forward to reading your full procedure. I've been putting off doing this to my dizzy (also a '79), but with your procedure (and your help), I'll do it very soon. Can I see a rough draft of your procedure?

Where can I get a rebuild kit for my dizzy?

If you have a source for the rebuild kit please post, I was able to obtain the pin from Pelican but could not find any other components. Also important to note that this should be done in a clean workspace, there are many little parts to be lost.

Good post Jdub, look forward to reading the full procedure!

Bill:

(With thanks to KenH): "Rebuild kit is Bosch P/N 123-7010-00. It contains a new pin and a variety of washers and spacers. There is also -- PORSCHE P/N 930 602 922 00 -- I am told this P/N for the crush pins that hold the gear in place, but I have not tried to use buy one." (from http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=6907&highlight=distribu tor+AND+rebuild+AND+kit)

If you will be performing this fix over Christmas get in touch with me offline as I am three days away from vacation. I don't figure to have this procedure written up this week anyways.

John

BUMP.

Could *really* use answers to my questions above; to wit:

=SHEAR ON PINION?
Does the pin that holds the pinion to the shaft at the bottom of the dist ever get an extreme shear load under normal conditions? I ask this since the pin was quite malleable and thus meant either to shear first under binding OR be easy to drill out OR both? In all events, I found a perfect fit in a roll pin, but that is hardened, so did not use it.

= MISSING FELT OR NOT?
There are two bushings in the distributor body at the bottom that hold the shaft. I thought that there might be a felt piece between these to hold oil in, but found instead that was not the case. Should I have seen a bit of felt there, or do the spiral windings in the shaft encourage oil into the cavity between the bushings?

DO YOU HAVE AN SC DIST. EXPLODED DIAGRAM?
Does anyone have a schematic of the SC distributor with CDI brains? Warren's pic is good for the early distributors but I need the correct schematic/exploded view to write up a proper how to with the correct terminology.

SHIMMING DIST. FOR VERTICAL PLAY: WHERE?
To shim the vertical play of the distributor do I place washers between the pinion and dist. body, on the dist. shaft or do I place washers internally, between weight "plate" and dist. body?

Thanks VERY much in advance folks. This information will help me write up a how-to for this.

John

First, it is best to replace the bushings while you have it apart, if you have not already done so. I would not expect to see felt between the bushings. If you don't have a press (and perhaps even if you do), the best way to install the bushings is to put the bushings in the freezer and put the dist housing in the oven. Not too hot if it's aluminum, but 250 degrees isn't going to hurt anything. When you install the bushings, do it quickly and they will slide in easily. You can get bushings at your local industrial supply place.

I wouldn't worry about the strength of the pin. No, that shaft and gear are not subject to any strong forces. The shaft turns, that's all. It turns against a magnetic force, but the pin and shaft and gear are not under any real stress.

I don't know where to shim it and I have no exploded diagram. Sounds like your distributor is in good hands, though.

Thanks Super!

The bushing-to-shaft play was nonexistant, so didn't think I needed to fool with those. Frankly, I think I would spring for the rebuilt/NOS Bosch dist. should I need to go that far. I do know that the '78, other than turning counterclockwise, also featured a pinion gear that had a different pitch or somesuch from later SC models; you want to be careful on that score.

I am guessing that the shims must go between pinion and body, on the dist. shaft as shims placed internally will shift the relation between the star-shaped reluctor and the "dead" towers that force the spark and create the overall waveform. I'd like to be accurate about this though...

John

John-
Thanks for the timely post-my 78's vacumn advance is completely seized. I disconnected the vacumn unit from the outside of the distributer and tried pushing on the arm manually when I made the discovery. I'm eagerly awaiting your tech article to give me the courage/know-how to go in there and fix it myself.

I would like to buy the Bosch rebuild kit before 'going in', but my local Bosch certified shop was of no help when I first inquired about this problem. Then again Cheyenne isn't exactly a hotbed of European cars-does anyone know of a rebuild kit supplier?

Thanks Again!!

Tony:

If you could remove the advance mechanism from the side of the distibutor without fuss then there is a slight possibility that the arm of the dist (specifically the hole in it) was not attached to the pin on the advance plate proper. Just a thought. To get it back in you have to angle the little bugger up and then catch the pin internally before mating the two to one another in their proper relation.

I am unsure of where we might find rebuild parts, and I think that the idea is that, nowadays, the distributor for our SCs is just meant to be replaced, thus no rebuild kits *readily* available.

I am off to vacation tomorrow, so will have time at home to write this up. What I really need is a digital camera and another SC distributor! I may head out to a junkyard with a box of donuts and see if I can get them to "lend" me a distributor for pics.

John

Tony,

I concure that a rebuild kit will be hard to find. I spent considerable time looking for the above part numbers, several months ago, with no luck. As Superman stated the bushings can be obtained at a local bearing supplier but as for washers and pins?????

That stuff can all be found. If someone did locate and purchase a rebuild kit, the price would likely be in the $200 range. Cost from your local industrial supply house would be closer to $20, total. Maybe closer to $10, even.

Fellas,
Old post, but worth reviewing. After diagnosing an ignition related problem, I decided that I'd have a look at my distributor just to elimniate that as a source. Upon inspection I found the shaft was binding and I could make it "chirp" by spinning it by hand. I then realized that what I had thought was my belt squealing at startup since I owned my SC was probably my distributor shaft! Even with readjusting my belt, putting belt dressing and eventually replacing it, I'd still get the occassional squeal. This all came to me as I was spinning the thing in my hand in the garage, thinking...hmmm, that sounds awfully like the 20-30 seconds of squealing I sometimes get on startup (however, it did not happen every time....maybe 4 out of 10 starts). Anyway, diassembled and it was a mess...and dry. Cleaned, lubed and reassembled and all is well. Thing spins like a top, and I feel confident that once it's back in the car the squealing will stop. I think I probably saved myself from a eventual dist shaft failure...

R/
Dustin

Well what do you know - I've been amiss dropping oil into the felt under the dist. cap. Just a reminder to anyone who has neglected this small task.

Age - it captures us all!

Rebuilding a '81 Dizzy this weekend. It's ready for assembly after replacing the bushings (the top one was trashed) and using a rebuild kit.
And there are questions!
1) what lube should I use on the shaft when assembling it. I don't want to clog the oil ingress threads - should I just use motor oil?
2) does the bottom of the pinion bottom out once installed? I see lots of wear on the underside of the weight plate on the shaft - I suspect that happened due to the top bushing getting torn up and actually pressed below the distributor housing. I only see axial play info for a 930. Does anyone have the specs for axial play for a SC distributor?

1) I'm not sure where you want to place lube on the shaft. There is the felt pad that needs motor oil or 3 in 1 oil. I also use Bosch distributor grease on the shaft O-ring and for lubrication of the plates and weights.

distributor lube...

2) The axial play should be:

I posted this information in 83 sc distributor and other threads.

Thank you HaroldMHedge for reposting the axial play info. I had misread that as for a Turbo only.

I was looking to lube the seal that is just below the top bushing in the housing. I guess the oil will do its job there as well. Thanks again.