Joined: Nov 16, 2021 Posts: 69 Location: NE Washington
Posted: Mon Aug 28, 2023 11:53 am Post subject: Speedometer Repair
My speedometer just quit working in my newly restored M38A1.
It's original and I just had a new lens case put on it, so I'd rather repair than replace.
Can anyone recommend a shop?
Preferably, someone with experience with these because of the sealed case.
Thanks _________________ 1955 M38A1 MD 82551
Former owner/restorer of 1977 CJ-5, stock with factory V-8.
Used as a daily driver for seven years.
Joined: Nov 16, 2021 Posts: 69 Location: NE Washington
Posted: Mon Aug 28, 2023 3:11 pm Post subject:
Still checking the cable, my mechanical mastermind is out of town and I'm out of my depth.
But, during the restoration the cable was checked and lubed,
So assuming the worst...
Anyone have a 8376375 or the earlier 7760396.
My G-758 manual says that will fit instrument clusters with different part numbers, I do not know if that means they would NOT work in mine.
Also, since my manual is dated 1956, it doesn't say if there are later part numbers which will work.
45Auto
I thought of Bob's due to their ads in various places.
However, I was warned to stay away from them by a MV restorer/dealer/parts source I trust.
I do not know what his opinion is based on...
I have nothing against them, but I know enough to listen to guys who know more than me. _________________ 1955 M38A1 MD 82551
Former owner/restorer of 1977 CJ-5, stock with factory V-8.
Used as a daily driver for seven years.
Joined: Oct 02, 2014 Posts: 2010 Location: South Carolina, Dorchester County
Posted: Mon Aug 28, 2023 6:18 pm Post subject:
JBJeep wrote:
Still checking the cable, my mechanical mastermind is out of town and I'm out of my depth.
I believe I'll hold off with any troubleshooting advice until your mastermind gets back in town.
If you have to get ready to buy a speedo before knowing what the problem is, I could recommend calling several of our venerable military parts vendors:
MWM, AJP, QTM, BMJP, and several others.
I also see them on fleabay now and then.
Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Which shop did the work on it? I'd be inclined to check warranty first before shopping.
There's not a lot of rocket science in these antique speedo systems. You simply 1 - disconnect the drive cable from the transfer case. Using a battery operated drill connect the drill to the end of the cable. Use the drill to speed up and down while you have someone observe the speedo. If the speedo doesn't work at all 2 - then remove the cable from the back of the speedo and spin the cable with the still attached drill a short burst and see if the top end is turning. If the top end is turning then the speedo is the issue. If the speedo works during step one then the drive gear in the transfer is the problem. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Nov 16, 2021 Posts: 69 Location: NE Washington
Posted: Tue Aug 29, 2023 6:47 am Post subject:
The new case was installed by a shop recommended by John at Midwest Military.
That was my first stop.
He told me the shop was closed, I suspect the guy retired.
As far as a new unit, even just to keep one as a spare,
I checked the usual military Jeep parts vendors (as mentioned by RonD2 above):, three have repros which lack the correct markings...they have the later "MS" numbers,
one has a pricey NOS (unknown markings...I am awaiting a reply on that),
one has a later NOS unit which may or may not work.
My parts manual is a reprint of the original which obviously does not list later units. _________________ 1955 M38A1 MD 82551
Former owner/restorer of 1977 CJ-5, stock with factory V-8.
Used as a daily driver for seven years.
Last edited by JBJeep on Tue Aug 29, 2023 7:15 am; edited 1 time in total
I didn't say which way on the drill because I have way to many different systems on my tray all the time. If any speedo check doesn't show activity in one direction the common sense thing to do is switch directions. Not a lot of choices. Only two.
JB, I noticed you said this in your original post: "It's original and I just had a new lens case put on it"
And the shop retired already! _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Nov 16, 2021 Posts: 69 Location: NE Washington
Posted: Tue Aug 29, 2023 3:22 pm Post subject:
RonD
Thanks, I bought it.
Not a bad price for a new correct unit (albeit an older version). _________________ 1955 M38A1 MD 82551
Former owner/restorer of 1977 CJ-5, stock with factory V-8.
Used as a daily driver for seven years.
Anyone have a 8376375 or the earlier 7760396.
My G-758 manual says that will fit instrument clusters with different part numbers, I do not know if that means
This early gage is correct for M38A1's from MD10001 thru MD70114.
TM 9-2320-208-20P Organizational Parts Catalog dtd. Feb 1959
Speedo is not listed.
TM 9-2320-208-20P Organizational Parts Catalog dtd Jan 1966
The early speedo ORD# 7760396 FSN 6680-776-0396 is only one listed.
TM 9-2320-208-34P Direct Support & General Support Maint. Repair Parts dtd Jul 1966 does not list any gauges. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Nov 16, 2021 Posts: 69 Location: NE Washington
Posted: Wed Aug 30, 2023 11:46 pm Post subject:
Wesk
Thanks.
Looking my manual I was checking the Speedo part numbers but failed to cross reference the gauge numbers a few inches above (duh!!!).
Okay, I bought the early M38A1 Speedo 7760396 as seen in the photo (in fact the eBay page where I bought that had the same photo).
Now my problem is will it fit my late A1?.
The manual says the cluster 7148835 was used up to serial 70114.
My A1 is 82551.
So, will it work?
A very reputable Jeep parts guy offered me the same unit, so he didn't have any concerns, likewise, the various repro units and the later military "MS" marked gauges do not mention a serial range for application.
Your red notes seem to indicate the later (non-luminous Speedos were used as replacements in early A1, so I should be okay.
Any thoughts?
I appreciate your patience. _________________ 1955 M38A1 MD 82551
Former owner/restorer of 1977 CJ-5, stock with factory V-8.
Used as a daily driver for seven years.
Last edited by JBJeep on Thu Aug 31, 2023 10:46 am; edited 1 time in total
Yes it will fit. The various clusters differed more by their components then their own indicator cutout sizes. One obvious example of early cluster vs late cluster are the two gage light units. The late cluster uses the M151 style lamp assemblies.
The top is the Early A1 cluster and the lower is the later A1 and M170 cluster. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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