WHY I ENJOY THE M-38A1 SO MUCH

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Thu Dec 08, 2011 4:49 am

Owning the M-38A1 is never ending fun, they have been a part of my life for over half a century. Part of collecting is having friends with same interests that make the hobby even more of a pleasure. Here's what came in the mail Yesterday. These are Clary Flanges, and were ordered by the Army for installation on Jeeps driven for administrative use. They were not widely used, if at all, as there were plenty of light civilian vehicles to do the job more efficiently.
The Non Driving Flanges made by Cam Tool Co. simply replaced the original WO-A-868 Drive Flange of the MB/GPW and M-38/M-38A1. The Cap off the original A-868 Driving Flanges along with the 6 bolts and lockwashers is saved for installation on the non driving flanges.
Little surprises like these flanges are what make the hobby not only interesting, but exciting.

NOTE:
CAM Tool Co. also made a similar set of Non Driving Hubs for the WWII 3/4 and 1 1/2 Ton WC and later M-37.
I have a NOS set put aside for my my restored M-37B1 should I ever decide to install them.
Attachments
Clary_Flange_&_Dash_U-Joint_003.JPG
Clary_Flange_&_Dash_U-Joint_003.JPG (146.04 KiB) Viewed 1786 times
Clary_Flange_&_Dash_U-Joint_002.JPG
Clary_Flange_&_Dash_U-Joint_002.JPG (163.49 KiB) Viewed 1786 times
Last edited by Joe Gopan on Mon Dec 03, 2012 2:27 pm, edited 1 time in total.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO


User avatar
SB5477
G-First Lieutenant
G-First Lieutenant
Posts: 625
Joined: Sun Sep 07, 2008 12:37 am
Location: Hungary
Contact:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by SB5477 » Thu Dec 08, 2011 10:28 pm

I have a set of those flanges, but never had the chance to try them yet (jeep disassld.) What kind of fuel savings can be obtained with them?

Cuz
G-Lieutenant General
G-Lieutenant General
Posts: 6672
Joined: Fri Feb 23, 2007 10:26 am
Location: Northwestern Wisconsin
Contact:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Cuz » Fri Dec 09, 2011 5:09 am

What kind of fuel savings can be obtained with them?
They offer the same savings on fuel and wear that any of the manually lockable front aftermarket hubs offer such as Warn, Dualmatic and Cutlass. The savings on front wheel drive component wear are the greatest measurable benefit. Minor improvement on fuel consumption is really just a side benefit.
Cuz (AKA Wes K)
45 MB, 51 M38, 54 M37, 6? M101A1, 60 CJ5, 76 DJ5D & 47 T3-C

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Fri Dec 09, 2011 5:28 am

Not as much as one would think, I have serviced jeeps driven by careful operators with 60-70,000 miles that have had a regular scheduled service and the difference in wear on the parts involved with Jeeps having Free wheeling hubs and those not having hubs is hard to detect. The major benefit is to the front propeller shaft. The gears of the differential are hardened and rarely exhibit wear. The front axle shafts rotate slowly in relation to the rest of the power train and exhibit little, if any wear from high mileage.
What caused wear is rough use in front wheel drive, and that is up to the individual driver. The problem is that few owners service the Jeep according to the Factory Service Manual or Lube Order suggested intervals, that is when the water and grime that gets by the steering knuckle seals takes its toll, the upper and lower bearings deteriorate from the corrosion and the components then get pounded from out of tolerance parts. Many are led to believe that their worn out axle shafts, spindle bushings,failed differential components ,and whatever else happens that is expensive inside the transfer, and front axle is due to lack of freewheeling hubs when in all reality it is not and the Jeep was just driven until it dropped.

When the free wheeling hubs are installed and the axle is in free wheeling, the only part in the transfer affected is the Front Axle Output Shaft which is at rest, next is the Front Propeller Shaft, and next after that are the gears in the differential (which are hardened to resist wear) and finally the front axle shafts which endure little wear in two wheel drive anyways. Again, the only time the aforementioned components get any real wear is when Front Wheel Drive is engaged.

Think about it, your rear differential is engaged 100% of the time and can last well in excess of 100,000 miles and still be in adjustment with quiet operation. The benefit of fuel savings is debatable, there is some and that is due to driving habit. Once the Jeep is warmed up and in motion, there is little rolling resistance from the front axle.
Having "hubs" installed is driver preference, they do no harm and there is some fuel savings. The wear? The wear is also debatable as it is difficult to compare wear as it is up to the type of use and the habits of each owner or driver.
What I can attest to, is that Jeeps that have their front axles serviced per the factory scheduled or L.O. (Army) intervals will exhibit little wear if any as all parts are kept clean and lubed, inspected for wear and kept in adjustment by having good service. Those who just drive the vehicle until a front wheel drive component fails will just continue to fuel the debate. Remember, that the upper and lower steering knuckle bearings are always in use and get "zero" benefit from free wheeling hubs.
My Jeeps get scheduled PM and the axle components are always clean and tight when inspected during maintenance regardless of accumulated mileage.
Hubs are nice and do no harm, but front end service is still a must.
The GI Issue Clary Flanges I just received will be installed on my present M-38A1 that I have driven for the past 36 years just for the heck of it as they are a "GI Issue" accessory.
Those of you who take your Jeeps on long drives especially the ALCAN Trip should not hesitate to install free wheeling hubs as there will be some benifit.
Last edited by Joe Gopan on Sat Dec 10, 2011 12:26 am, edited 4 times in total.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

User avatar
SB5477
G-First Lieutenant
G-First Lieutenant
Posts: 625
Joined: Sun Sep 07, 2008 12:37 am
Location: Hungary
Contact:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by SB5477 » Fri Dec 09, 2011 5:31 am

Thanks Ben, but how minor it is, any numbers? With a CJ5 achieved 18MPG with same engine and gear ratios. 0.5-1 mpg is realistic?

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Fri Dec 09, 2011 6:03 am

I have driven my CJ-5 and M-38A1 Jeeps in my former occupation as a highway surveyor on the Interstate Highway System as much as 700 miles per week and noticed little difference in highway mileage when driving my CJ-5's with Warn Hubs. The M-38A1's had no free wheeling hubs. I averaged from 16-20 MPG with and without hubs in both types of Jeeps. The CJ-5's all had the added weight of Koenig Winches and were driven off road to get to the project sites.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Fri Dec 09, 2011 6:11 am

[quote="SB5477"]I have a set of those flanges, but never had the chance to try them yet (jeep disassld.) What kind of fuel savings can be obtained with them?[/quote]
One consideration is the cost of the hubs, if you just drive in parades or a few miles a year, you may not realize any savings.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

User avatar
SB5477
G-First Lieutenant
G-First Lieutenant
Posts: 625
Joined: Sun Sep 07, 2008 12:37 am
Location: Hungary
Contact:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by SB5477 » Fri Dec 09, 2011 7:27 am

I will use it (once its ready) mostly on the road. We'll see. Thanks Ben.

FrankenJeep
Sergeant Major of the Gee
Sergeant Major of the Gee
Posts: 387
Joined: Fri Mar 04, 2005 8:19 am
Location:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by FrankenJeep » Mon Dec 12, 2011 12:18 pm

My M38 has Warn hubs. I haven't tried to do a comparison of ON/OFF to see how much difference it makes---if any. I WANTED an A1 myself for several reasons, but I found "Willy" an' me an him are pals now, so I doubt I'll change. Unless, of course, my "ship" comes in and I can buy SEVERAL jeeps, I would go for the A1. :lol: :lol: :wink:
FrankenJeep

Cabin Fever
G-Sergeant First Class
G-Sergeant First Class
Posts: 88
Joined: Fri Mar 29, 2013 10:04 am
Location: Between Emily and Crosslake, Minnesota

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Cabin Fever » Thu Jul 17, 2014 9:26 am

I'm looking for a set of free-wheeling hubs for my A1. Anyone have some for sale or know where I can purchase a set?

Thanks
1955 M38A1 MD 85388

MVPA Member #35153
Member - Red Bull Historic Military Vehicle Association

Marty, SoCal
G-Lieutenant General
G-Lieutenant General
Posts: 6319
Joined: Thu Mar 09, 2006 10:34 am
Location:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Marty, SoCal » Thu Jul 17, 2014 9:49 am

Used sets pop up from time to time here in the for sale section, same hubs from '41 to '71, 10 spline internal, six bolt hub.

The type that Ben has are fairly rare, but "Motorpool" correct

Many different brands are/were made over the years, some easier to use and install than others. As for new production, I've had good luck off-roading with AVM brand hubs, steel construction where it counts at a good price:
One place among many that sells them:
http://www.ccsurplus.com/content/avm-40 ... dana-27-25

Paint them the same color as the jeep and most people won't notice them (Except the jeep police!)

One nice thing beyond fuel economy and wear benefits is the reduced vibration. Most 50-60 year old front drive shafts have some to a lot of wear in their splines which causes an imbalance, with the hubs unlocked the jeep will drive a lot smoother on the highway.
43 Ford GPW 92098
53 Dunbar Kapple M100
Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
MVPA #8266
USMC Tanker (1811, 1812), 85-93
ASE Automotive Master tech, former Chrysler-Jeep Level 4 Mastertech, CA state EA smog license

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Thu Jul 17, 2014 9:52 am

The Army stocked the "Clary Flanges" There is little evidence of use by the Army. I keep a NOS Set on a shelf just because they were "Army".
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Cabin Fever
G-Sergeant First Class
G-Sergeant First Class
Posts: 88
Joined: Fri Mar 29, 2013 10:04 am
Location: Between Emily and Crosslake, Minnesota

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Cabin Fever » Thu Jul 17, 2014 10:22 am

Ben Dover wrote:The Army stocked the "Clary Flanges" There is little evidence of use by the Army. I keep a NOS Set on a shelf just because they were "Army".
Please sell them to me :)
1955 M38A1 MD 85388

MVPA Member #35153
Member - Red Bull Historic Military Vehicle Association

Joe Gopan
Jeep Heaven
Posts: 49841
Joined: Sun Mar 02, 2008 12:37 pm
Location: Proving Ground

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Joe Gopan » Sun Apr 17, 2016 6:31 pm

Going to bite the bullet and install the Clary Flanges on the M-38A1 to make it easier on the Jeep for the upcoming Memorial Day Parade. A volunteer will be driving and it will be easier on both me and my M-38A1.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Marty, SoCal
G-Lieutenant General
G-Lieutenant General
Posts: 6319
Joined: Thu Mar 09, 2006 10:34 am
Location:

Re: WHY I ENJOY THE M-38A1 SO MUCH

Post by Marty, SoCal » Mon Apr 18, 2016 5:59 am

You will notice the difference! For the parades you can run in low range now since there will no longer be a bind in the driveline!
43 Ford GPW 92098
53 Dunbar Kapple M100
Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
MVPA #8266
USMC Tanker (1811, 1812), 85-93
ASE Automotive Master tech, former Chrysler-Jeep Level 4 Mastertech, CA state EA smog license


Post Reply

Return to “M38a1 Technical Knowledge Base”

Who is online

Users browsing this forum: EMSCaptianG and 36 guests