83 SC Ignition Distributor Bushing Replacement

[Gordo2]

Background

The bushings in my distributor are shot. After researching and considering my options and priorities, I've decided to replace the bushings myself.

I realized the dizzy was worn out about 6 months ago when the car started running rough and finally died on me. I took the distributor cap off to find the rotor had broken and the contacts inside of the cap were excessively worn (very similar to the cap picture in NOLAsc's thread: SC distributor bushing replacement)

I put a new cap & rotor on while I contemplated my options (I'm rebuilding a 3.2 motor to drop in the car this fall). About 6 months & 3,000 miles later, my cap and rotor are looking pretty worn again .

While replacing the cap & rotor I noticed that the distributor shaft clearly had excessive play (both up and down and side to side). I also noted that I couldn't get consistent timing (intermittently drifted/jumped +/- ~5 degrees when I tried to time it - idle would intermittently jump or drift ~ 250 RPM).

I called a few reputable places that rebuild distributors ~ $600-$800 to refurbish ( a bit more than I want to put into a dizzy that I only plan to use until I swap in the 3.2 this fall). I considered buying a used distributor, but figured it was a crap shoot (how worn??? ... plus I didn't get many replies to my WTB thread). The reputable shops that rebuild distributors can repair & modify all distributor functions & bench test (advance mechanisms etc). No doubt, my job won't match the quality or service these places can provide. If I were keeping the 3.0 and it was a permanent fix - I wouldn't hesitate.

I found a couple of great threads from other Pelicans who have refurbished and/or re-bushed their dizzy's (links are repeated in pertinent locations of this thread):

Distributor service (Clean and lube) real easy without removing the pinion gear!

DIY Distributor Repair

SC distributor bushing replacement

Equally as important, I found a place that sells the distributor bushings, shims and other dizzy parts online (sorry, would source via Pelican as a first choice if they carried the parts - hint...).

Disassembly

I removed the spark plugs (to allow the engine to rotate freely), and used a ratchet/socket to rotate the alternator pulley (clockwise rotation - the alternator belt should have sufficient tension to rotate the crank pulley with the plugs pulled). Rotate the alternator pulley until the bottom pulley "Z1" mark is aligned with the mark on the bottom of the alternator housing. This should also center/align the rotor with line/notch on the distributor housing (indicating Top Dead Center - TDC for piston #1). Setting this up before you remove the distributor allows you to T reinstall the distributor by pointing the rotor at the notch which provides the correct position for basic timing/correct spark order.



After TDC for # 1 was lined up, I removed the 13mm nut that holds the distributor in place (the nut also allows distributor rotation for timing adjustment). I was fortunate - my distributor pulled out of the case without much of a fight (some are really stuck).

A few pictures before I disassembled to show how much play there was in the distributor shaft:

Up/down shaft play (the exposed shaft to the right of the pinion gear allows excessive up & down shaft movement - indicating the need for new bushings and shims)


Side-to-side play:



Once the distributor was removed and on the bench, I followed Tim Hancock's process for disassembly DIY Distributor Repair

I ground down the end of the pin with a small, hand-held flat file (for sharpening chainsaw blades). The pin is very soft metal allowing the ends to be ground off pretty quickly. Unfortunately when I tried to punch out the pin, it just mushroomed and wouldn't budge. I ended up center punching the pin and drilled it out.

I think there is little risk of going off center and damaging the pinion pin hole or shaft - the pin is very soft and the pinion gear is obviously hardened (it's very difficult to scribe an alignment mark on the pinion gear and shaft - I ended up using a Sharpie).

Once the pinion gear was removed, I had a bit of difficulty removing the vacuum advance. With the screws removed, I found that I needed to really wiggle the advance body back and forth to get the arm to release from the pin inside of the distributor. Once it let go, I tilted the advance mechanism and remove it.

Not sure if this is normal (doesn't seem right to me...), but the vacuum advance had a bunch of oil in it:



Once the screws, pinion gear and vacuum advance unit were removed, the entire shaft was able to be pulled out of the top of the distributor body. The bottom bushing appeared to be in decent shape, but the top was clearly worn out.

Disassembled parts:



From here I will be cleaning and ordering new top & bottom bushings, shims & pinion gear pin.

I may provide the new bushings & disto body/shaft to a local machine shop to have them pull the old bushings, insert the new ones and ream the bushings to fit the distributor shaft.

Will update as I proceed.

For those who have replaced bushings on their own (Tim H. and others) - has the distributor held up well?

Gordo

[James Brown]

good for you, some special tool but you can fabricate them for installing the bearings. The oil gets sucked up from a worn seal, that should be replaced as you rebuild it. keep us posted

[Gordo2]

Update,

Ordered new top and bottom Oil-lite bushings, a shim kit and new bottom o-ring: $55.00 shipped - should arrive in the next couple of days. I called a local machine shop and described what I needed done (remove/replace bushings and ream to ~.005 of the shaft diameter) - "no problem". Will see what they charge but I can't imagine its over $75 ish.

I also cleaned up the parts, before (just plain filthy):



After hand cleaning the internal parts & vacuum assembly and washed down the body and hit it with my cheap HF soda blaster:



Looking pretty good.

Here's a shot (pre-clean and blast) that shows how badly the top bushing was worn (should be a tight fit):



Finally a few questions:

1. Does a shim go on the shaft to cover the area that is showing wear? Seems there ought to be some sort of bushing to act as a bearing between this part and the distributor body/top bushing:



I guess the wear could be due to the worn out bottom shims. Is there a diagram that accurately depicts where each shim goes?

2. Should the part at the bottom in the above picture wobble freely on the shaft (magnetic pulse generator)? I don't think it will once it is installed with the new bushings and shims, but it seems odd that it is loose on the shaft.

Thanks, Gordo

Side note on the HF blaster - works good if you have a good size compressor (I do) and you shake it frequently. I made an outdoor table to blast on (screen top) and bungee chorded the tank to a leg. Kicked it frequently to keep the soda flowing.

[timmy2]

Great write up, i'll be watching this one as I think it is a job I need to do in my near future.
Please PM me the information on the bushings and shims.
I can tell you where to buy a reluctor kit if you want one.

[LM3929]

Could you PM me the name of the bushing supplier and the part numbers of the parts you used, I have to do the same job on my SC shortly

Lorne M

[Gordo2]

The place I ordered my bushings and shims from contacted me and recommended I also install a new "distributor shaft seal":



I think this is inserted directly below the top bushing - to help stop oil migration up into the distributor upper assembly.

The representative said they would send me an assembly digram that depicts where each replaceable shim/washer and seal is positioned. Will update post with any new info they provide.

Gordo

[LM3929]

I may need a copy of that info, I bought the seal and bushings last night.

lorne m

[Gordo2]

My parts arrived so I did a quick test fit before I dropped them off to be installed:

Upper bushing:



Lower bushing:



I found a great machine shop just a few miles from my house. No idea the place even existed - the guy has 2 shops, the one I went to in his residential garage (about 1600 sqft of pretty nice machines) and a heavier, off-site commercial shop. He specializes in restoring, repairing or replicating old, hard to find parts for collector cars.

The machinist planned to heat the distributor body some to help coax the old bushings out (he has a bushing remover, but thought heating would be safest).

Although the bushings fit the shaft nicely pre-installed, he thought they may need reaming once they are pressed into the body of the distributor. Will see what he thinks in the next day or so.

Gordo

[Gordo2]

The machine shop that I dropped the distributor off with got it back to me the following morning - $75.00 labor (right in line with what I thought it should be):

- Removed old bushings from distributor housing
- Pressed in the new oil-lite bushings
- Reamed the inside diameter of the bushings to fit the shaft

With $50 in parts (inclusive of shipping) - total cost to rebuild was $125

The machinist said the bushings I provided were "a good fit" and really only the bottom bushing compressed enough to warrant reaming.

Photo of the new top bushing installed (the shop installed the shaft seal in the distributor housing, directly below the top bushing)



The place that I purchased the bushings and shims from replied to an e-mail explaining that the oil-lite shim in the shim kit goes directly below the spring plate:



I measured this shim - it's 1" with a .5" diameter shaft hole. I didn't think to measure the thickness. Makes sense that a bronze shim goes there to act as a bearing surface. No sign of a shim there when I disassembled, but that would explain the wear on the spring plate and the up/down shaft play (I believe it originally had a shim, but it disintegrated over time).

Note the wear on the shaft - this is actually below the area that comes in contact with the top bushing. Not sure what caused wear there - possibly the old style internal seal (I think they had a spring in them).

I played around with the various new and old shims attempting to find a combination that provided up/down shaft play within ~ .004" but after removing and reinstalling the shims & pinion gear a few times, I gave up on trying to measure with a feeler gauge and went by feel (play and rotation). I'm fully satisfied that I have it set up right - no noticeable up/down play & shaft spins freely. I ended up using a combination of old and new shims (various thickness) to get it just right.

The pinion gear crush pin fit perfectly as well. Same for the exterior oil seal.

Another note: before reassembling I put a light coat of lithium grease on all moving metal parts that experience friction. Intent was to lubricate and provide corrosion protection.

Here's the finished product - just waiting the new cap & rotor to arrive from PelicanParts before I can op-check.



Will update the post once the cap & rotor arrive and I get my car up and running again.

For the other guys working this same project - might be worthwhile to measure the bushings; I'm sure they can be found for a couple bucks if you had the measurements...

Gordo

[Gordo2]

The cap and rotor arrived yesterday so I reinstalled the distributor.

I set initial timing @ 950 RPM to 5º BTDC. Checked advance @ 6,000 RPM and came up with ~23º, which is right in line with the spec.

Snap-On timing light lets you monitor RPM and check timing advance:


The timing and idle are now stable and smooth and the car is running great again.

Gordo

[James Brown]

great job Gordo

[timmy2]

Gordo,
Did you ever get the assembly diagram?
Could you post a picture?
I have all the parts in hand from the same place but no assembly diagram.

[timmy2]

Never mind, All done rebuilding and shimming it.

Didn't need the bushings as it was tight side to side. (Guess I'll keep them for another 50 thousand miles...)

Shimmed it with the oil-lite shim up top replacing 2 steel and one fiber washers, changed the thickness of one bottom shim and it is tight vertically and the car runs great.

I think most of what I thought was too much vertical movement was the play in the center advance mechanism piece.

I had .010 thousandths of vertical play at the base of the shaft. With shimming it is under .004

[john walker's workshop]

who sells the kit?

[timmy2]

I bought everything from parts klassic dot com.

[ionaetp]

The oil gets sucked up from a worn seal, that should be replaced as you rebuild it.

[john walker's workshop]

Originally Posted by timmy2

I bought everything from parts klassic dot com.

it doesn't come up on a search.

[timmy2]

Pick a year and then go to engine, then engine distributor, then pick all the parts like bushings, seals, shim kit, oil-lite etc. 11 pages of stuff to choose from in the link below, page 2 shows the shim kit.
Put it all in a basket,,,
Or just call them.
Porsche Engines Ignitions Distributors Parts - Porschetechnik Vintage Porsche Engine Parts

[ARCSinAK]

Kurt is unreal.

[john walker's workshop]

Originally Posted by timmy2

Pick a year and then go to engine, then engine distributor, then pick all the parts like bushings, seals, shim kit, oil-lite etc. 11 pages of stuff to choose from in the link below, page 2 shows the shim kit.
Put it all in a basket,,,
Or just call them.
Porsche Engines Ignitions Distributors Parts - Porschetechnik Vintage Porsche Engine Parts

i did that for 911, SC and carrera and all show as no items available. i guess i need to call them.