M38 Distributor Rebuild

[Naugha]

I think my IAU4006 distributor needs help beyond a basic ignition kit including possibly the replacement of wiring, bushings, governor weight, ignition coil, internal radio frequency filter, thrust washer and felt wicks.

I have found sources for some but not all of these parts.
I could use advice on my possible choices.

Is there a single source for all the above parts?
Is there a favored rebuild shop that has recently proven reliable?

BTW. At least one rebuild service does not list the governor weight as part of the rebuild.

[wesk]

I would suggest you do a bit more studying of our web sites many old posts on this topic.

Yes the wiring is in poor condition and looks like incorrect gauge.

Yes the rotor is in sad shape & needs replacement.

The only thing usually required for the Governor weights is to clean them, lube them and install new springs.

Just how did you determine yo need a new coil?

Unless you are installing period correct tube type radios in your jeep there is no need to replace the internal radio noise filter (Capacitor). The simple method is shown in several of our posts to modify an old filter (capacitor) to eliminate it.

So you are now left with a thorough cleanup of the distributor and just follow inspection guidelines in TM 9-1825E and the same source for re-assembly.

A simple rule to follow on shopping for parts is to shop by part number and avoid offshore parts.


Here's original radio noise filter and lead to points.


Here's an example of a modified old noise filter used to eliminate the need for one.


Another shot of the modified noise filter with the femal connector housing attached.

I think if you spend some time in TM 9-1825B and in my photo album: http://www.willysmjeeps.com/v2/modules. ... _album.php You'll find most if not all the answers to your questions.

[Naugha]

I got the idea that the ’pivot holes’ on my governor weight were worn from reading section g. Governor / bottom of page 244/ TM 9-1825B. See my last pic to evaluate the slop. Replacing the weight looks ‘easy’ if needed and if I can find the part.

The shaft moves up and down by more than .01” (maybe .02+”) which by the manual suggests adding a .01” thrust washer..... maybe/maybe not?

I had seen how the ‘radio noise filter’ can be eliminated .... but I thought I had also seen a thread somewhere that claimed the filter reduced electrical arcing inside the distributor.... but that was probably something else.

So I don’t need the radio noise filter unless I have a M38 radio onboard.
Maybe I don’t need to dig any deeper into the governor & shaft ?
Old coils may still be working after decades. I will run the test per manual.

Thanks.
Don

[RonD2]

I'll keep my eyeballs peeled for spare parts for you Don. You're going to need them.

[wesk]

I had seen how the ‘radio noise filter’ can be eliminated .... but I thought I had also seen a thread somewhere that claimed the filter reduced electrical arcing inside the distributor.... but that was probably something else.

There are two capacitors used in your distributor. The engineers like to take basic items and give them different names if their assigned functions are different.

You have the noise filter already discussed whose only purpose is to contain electrical noise in the old fashion tube type radios used in these jeeps in the 50's/60's.

You have the condenser that prevents electrical flashover at the contact points lengthening their life.

I got the idea that the ’pivot holes’ on my governor weight were worn from reading section g. Governor / bottom of page 244/ TM 9-1825B. See my last pic to evaluate the slop.

The manuals lack of a specification figure assumes you are a very experienced technician and have a good sense of feel. The photo is no help in determining the amount of play between governor weight and it's pin. If you are unsure use a dial indicator and consider more than 0.002 excessive.

As for the shaft and bearings again the manual is quite clear on how to inspect/check and you should follow it's directions verbatim using the specified testing equipment. In this case a spring scale and a dial indicator,

Old coils may still be working after decades.

Actually unless you see a date code on that old coil you have absolutely no idea how many years it has been in service.

[Naugha]

Ron.... here is a shopping list. I have no idea if this stuff is still around.
If I can get ‘em I will use ‘em. Otherwise best to move on.
I have the IAU4006AUT distributor..... AUT See pics.

Wes tells us in a past post,
“The weights Autolite PN IGC2168L, ORD# 7706790 are the same for both distributors.

“The springs Autolite PN IGB284 or the set IGB284S, ORD# 7376393, NSN 5340-00-350-2288 are used in the IAU4006AUT distributor.”

What I really need is the cam/cam plate because of the worn area.
See above pics.

[Naugha]

37 Ohm reading from the primary windings.
No reading from the secondary.
No grounding shorts found between case and connectors.

Is my Prestolite 24v coil toast?

I don’t think this is the exact testing procedure described in the manual but is the info enough to indicate the coil needs to be replaced?

[Naugha]

Error......“pivot holes’ on my governor weight”

OOps. I should have said that the cam plate holes are worn.
The weights look fine. See above pics.

I am replacing wires and remaking the radio noise ‘filter’.

[Naugha]

Radio Noise Filter Mod (see also pics above from Wes)

As suggested in another post, I cut the 'can' so as to leave enough final length for the O-ring.




But the contact post of the final product extends only halfway up the fitting.


Will this work or do I need to make the post longer?

[RonD2]

Will this work or do I need to make the post longer?

Screw the connector on it and use your ohmmeter to see if contact is made. It looks long enough to me (did you measure the mating distance?), but the meter should tell for sure.

[Naugha]

Screw the connector on it and use your ohmmeter to see if contact is made.

Will do Ron. Uh, connector.... right.

I don’t think I have one of those yet.
Maybe one of the roasted/ toasted wires in my box of old wiring.
Time again to help the economy.

Don

[RonD2]

One of these? https://shop.midwestmilitary.com/produc ... utor-lead/

[Naugha]

“ One of these?”

Ad says. “NOS part. M37 is a direct plug and play. M38 and 38A1 require solder and shrink tube to attach.”

Which sounds OK but..... Ron. You are always talkin’ about checking the fine print.

What are you running?? M37NOS/ M38NOS/ Repo / Home Grown ???

[RonD2]

Don,
Pretty sure I mentioned (in a different post) that mine is converted to 12 volt. I'm running a NOS Prestolite IAY-4401 (CJ) distributor that I got for $220. Coils available at any auto parts store for $25. Cap, points, rotor, condenser also common, available, and reasonable cost.

I admire your fortitude for going down the 24-volt road. It's too steep for me (maybe some day, but not today). Parts are too rare and expensive for my wallet, and not likely to change anytime soon. I always say to myself "If you have to ask what it costs, you can't afford it".

It's not clear to me what MWM means by the solder and shrink tube note. A phone call would solve it. Doesn't sound scary in any case.

You could cut the chase and go Cadillac here? https://shop.midwestmilitary.com/produc ... -assembly/

I'll keep my eyeballs peeled for spare 24V parts. You're going to need them.

Good luck!

[RonD2]

Don,
Are you a Rocky (movie) fan? I can't remember if it was Rocky III of XXIII, but do you recall what Clubber Lang (Mr. T) said when asked what he predicted for the fight?

PAIN