Correct M38A1 wiper motors?

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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Old Dog
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Correct M38A1 wiper motors?

Post by Old Dog » Mon Aug 08, 2005 1:40 pm

After being inspired by a fine M38A1 at the Duluth-MVPA, I want to upgrade mine from "parade" to "motor pool". Just for starters, I've always known that my wiper motors didn't match the pictures in the manuals. The parts book lists two different models, so I hoped that mine were of the second type. One of the A1s at Duluth also had this same type. Here is the drawing from the manual, and a photo of my wiper motor. Do I have a proper motor, or is this a CJ replacement? :? Thanks!

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Post by petesilfven » Mon Aug 08, 2005 1:56 pm

The original wiper motors on my A1 were like the top picture. I bought NOS ones to replace them. I think they were about $40 apiece.
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Post by Old Dog » Mon Aug 08, 2005 2:05 pm

Thanks for the quick reply! I guess I'll start looking for a pair of replacements. I didn't see any of the type shown in the manual for sale when I was at the Duluth convention, but I'll keep looking. Thanks Pete. :D
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Post by Terry Roen » Mon Aug 08, 2005 2:21 pm

Old Dog, I saw the M38A1 at the Duluth convention that you refered to. John at Midwest Military has the correct long handle wiper motors. I think he should be able to help you out. :D
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Post by Old Dog » Mon Aug 08, 2005 5:56 pm

Thanks Terry. Good advice. I'll get in touch with John. I appreciate your input, and I wish I could have met you at the convention. :D
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wiper motors

Post by Rich Saylor » Tue Aug 09, 2005 7:54 am

The easy way to tell the correct motors is that the military wiper motors have two outlets, as M38's-M38A1's, & M151's (early ones) all used the same vacuum motor which had an inlet line for vacuum and return line (outlet) that was connected to the air cleaner- because of the need to operate underwater. Never mind that the military never apparently really got them (Jeeps) to actually do this, in any event that's what they were supposed to be able to do.

Military wiper motors have a long bent wire arm, which can be positioned two ways: with the arc of the arm swinging across the top of the round part, or beneath it. The early M151 type is the reverse of the way M38's had it, due to the positioning of the motor itself. The arm is held to the wiper arm shaft by a small splined pin thru the arm base & the shaft, which can be carefully driven or pressed out, the arm position switched (by first removing the mounting bracket temporarily) and replacing the splined pin, etcetera.

The reason for positioning the arms above the wiper motor (in the mounted position, with the rounded part up) is to clear the rifle rack, which is mounted very close to the bottom of the windscreen, which is where the wiper motors are. On the A1, they're mounted on the top part of the windscreen.

Note that the correct motor also has the recessed-type nuts that hold the wiper arms on, rather than large push-on arms that fit onto larg(er) splines on the shaft ends, with no nut.
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Post by Old Dog » Tue Aug 09, 2005 6:27 pm

Thanks for the help Rich! I really appreciate the clear and detailed information! :D
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Post by Star Electric Ordnance » Tue Aug 09, 2005 6:30 pm

A little unknown reason for military wipers to have to be able to work underwater was in case you encountered a dense school of fish, you could clear them from the window much quicker! kevin.
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Post by Old Dog » Tue Aug 09, 2005 6:33 pm

Aha! I did not know that! They thought of everything! :lol: :lol: :lol:
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Post by SteveJ » Tue Aug 09, 2005 11:53 pm

I would not go shopping too fast. Ive seen both styles youve indicated installed in M38 and A1's. I spoke to Brian Asbury in Ontario regarding this and he states that they installed both types and that the superseded part number in the parts book reflects this even though there is no detailed breakdown or picture supplied and that would be the one you have in the 2nd picture you posted :)

WO/674645 Motor Wiper assy. (as the original)

WO/663366 Motor Wiper assy. (supersedes the original)
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wipers

Post by Rich Saylor » Wed Aug 10, 2005 6:25 am

Well,, that's probably because they finally figured out that the underwater system didn't work anyway, so why bother....but having no return outlet, makes it difficult to hook the lot up to the return fittings leading to the air cleaner, doesn't it?

To me the best plan would to get the correct original type, & sell the other ones he already had to someone less fussy, or else is restoring a CJ, for which they'd be fine.

As for my M38, I have no intention of driving around in some river, but then I don't intend to use my rifle anywhere except in parades, either! Nevertherless they both work.
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Post by SteveJ » Wed Aug 10, 2005 10:22 am

If the part is listed in the parts book then it is a correct and original type. So either would be correct.
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Post by Old Dog » Wed Aug 10, 2005 11:01 am

Thanks for the further information Steve! I had wondered if maybe that's why many of the later production A1s had the same wiper motors I have. My A1 does not have the extra venting tubing or fording valves, and according to the parts book, that is correct for my serial number. I appreciate your input from north of the border, as Canada also has a long history with the A1s. Thanks! :D
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Post by SteveJ » Wed Aug 10, 2005 1:14 pm

Glad to be of help Dave.

Have a good one.

:)
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Post by Wes K » Wed Aug 10, 2005 3:26 pm

The military ORD 9's and later parts listings are very helpfull restoration aids. We must remember they are published by the Army. When multiple part numbers are listed for the same part it can mean several things. The most common is a Army supply system supersedure, a serial number specific part or simply identify a second supplier's unit. A quick example is the generator on the M38. In the Sep 55 ORD 9 it lists several Auto-Lite and Delco Remy. Based on additional research of factory data we know Auto-Lites were the only factory installed originals with the GHA4802UT being the early (before the water proof switch with the older bell and small frame starter) and GHA4802BUT was the later (after the switch to the late bell and large frame starter) All this is not readilly apparent in the ORD 9 and there is no reason given in the ORD 9 for the two different Auto-Lite generators. There is also no explanation in the ORD 9 for the 2 Delco generators except they are optional to the Auto-Lites and one Delco supersedes the other. In this example we cannot rely on the data in the ORD 9 to determine which is a correct factory installed unit.

So we must not think of the ORD 9 as a gospel source for factory installed original parts.

As for wipers the early M38 Nov 51 ORD 9 lists only one Trico 63527 WO# 674645 ORD# 7375189 has a built in shutoff valve.

The Sep 55 M38 ORD 9 lists 2 wipers with no serial reference and only mentions that one supersedes the other. Without a serial reference this USUALLY means the newer part was a Army supply system introduced replacement part. In this example the original listed wiper has a G740-7375189 ORD stk # and the superseding replacement motor has a standard Army hardware ORD stk # H017-0500844. The only apparent changes are the kicker valves, gaskets and housing.

The Sep 56 M38A1 ORD 9 lists the same two wiper motors that are in the 55 M38 ORD 9 and lists them the same way.

The Jan 66 M38A1 -20P Org Parts List only lists the H017-0500844 Wiper motor.

The 72, 74M151/M151A1/M718 -20P's and Dec 78 M151 -34P Dir Supp Parts List shows a much later unit with the manual ops handle facing both away from and towards the wiper motor housing and the large splined shaft for the push waiper arm and the tapered splined shaft with nut.

The conclusion one should draw from this is the ORD 9's , -20P's an -34P's are not always reliable for determing original factory installed parts.

In all the above examples the wiper motors all had manual operating handles, facilities for air in/air out and no shut off valve built in yet it is very obvious in the later ORD 7/8's that the Army did add the Trico wiper motor with a very small manual operating thumb type lever and an integral manual shutoff valve to their supply system in the late 50's and many of these found their way onto M38's and M38A1's during the 60's and 70's. I have found quite a few of these on M38's and A1's I have worked on over the years. These were helpful because they allowed the operator to manually turn off one wiper to increase the performance of the other.
Last edited by Wes K on Wed Aug 10, 2005 7:22 pm, edited 3 times in total.
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