M Series Door Latch Repair

[majortom]

The following information is how to repair the common failure of the door latch mechanism used on M series 2 1/2 , 5 & 10 ton trucks is also applicable to M37 Dodge.

We get many calls for door latches due to internal failure causing the outside handle not to function. The left latch is very hard to find and is not interchangeable with the right hand latch. The latch is the same for all of the above mentioned units except for the length of the arm to the inside handle.
Yesterday the latch failed on my truck. But I couldn't just replace it I had to know why. After disassembling the latch, the failure was obvious. The quick fix was also obvious.
How the latch works: After you rotate the outside handle it rotates a cam, that pushes a lever attached to the striker. What happens with use is the clearances increase enough so that the cam will slide under the lever and the outside handle does nothing. To repair the problem you must remove the latch from the door. With a firm tap on a specific spot with a punch and hammer on the striker lever the latch will work just like new.

Pic 1: Shows Left Hand Latch

Pic 2: Shows The Exploded View From Left To Right Latch, Cam, Cam Retainer & Cover.

Pic 3: Shows a that the cam has slide under the lever (Broke).

Pic 4: Shows the striker held in the open position with a vicegrip to gain access for the bending operation.

Pic 5: Has the cover removed so the part striker lever being bent

Pic 6: Bending the lever using a punch or chisel with a hammer. Give the punch several good raps then insert outside handle in latch checking for proper function, repeat as necessary.

Pic 7: Shows the cam resting against the striker arm in the proper position with the cover removed.

Pic 8: Shows the cam rotated to the open position.

In short you do not have to take the cover off the latch to repair it we did that to give a better understanding of the inner workings of the latch. One of the easiest things I have ever fixed on a Deuce.

Time to complete Procedure: Half Hour
Materials: 0
Beer: 2

 

[drgreg]

Thanks Tom.
2 beers my ass.

 

[Recovry4x4]

Excellent write-up Tom, thanks!

 

[Wolf.Dose]

Very usefull help for all of us. Thank you!
Wolf

 

[Gastrap]

Nice job. Its always a plus when you turn the knob & something actually happens

I just got done with mine too. all the contact surfaces on the cam & hook were so badly worn I had to build them up with weld & grind them back into shape. Then I had to weld an extension on the back of my latch "bolt" to engage what was left of my broken spring. Works great so far & cost nothing.

 

[tomesee1]

good post thanks for the useful info

 

[docfarmall]

Were can you get just the spring

 

[M-37Bruce]

Nice Job , majortom, Thanks for the input!
Bill Lammer in Ocala, FL had a while back? While my was apart, I replaced the spring.

 

[DUG]

Kinda want mine to break just so I can fix it now.

 

[chris10980]

While on the subject of door latches, has any one replaced the door handle with one of the locking versions found in the Grainger or McMaster Carr catalogs? If so which one did you use?

 

[zb39]

Excellent info, I have a couple that need done!

 

[M-37Bruce]

Wasn't Sure

While on the subject of door latches, has any one replaced the door handle with one of the locking versions found in the Grainger or McMaster Carr catalogs? If so which one did you use?

Where they came from, but the locking ones I have seen over the years were chrome, I guess they would/could be etched or bead blasted & painted? Unfortunately, they will only slow the @ss's up a little?

I have always wanted to visit McMaster Carr, I worked @ a hardware store part time after the AF, learned a lot form the owners pappy!

 

[Gunfreak25]

Awesome, and simple! I've seen so many worn out latches on these trucks, this is the quickest and easiest repair I have ever seen done on these. It's an old post, nearly 11 pages back in this section. Talk about a thread resurrection....

 

[nattieleather]

Kinda want mine to break just so I can fix it now.

Careful what you wish for....

 

[steve hendricks]

Thanks For Infomation Bought Bobbed 5 Ton Last Weekend First Thing To Be Fixed Was Door Latch. Greatly Appreciate The Info

 

[cjtroutt]

Thank you very good repair op. and write up.

 

[camoyj7]

Great post! Mine quit working this morning.

 

[M-37Bruce]

Is everyone aware that the entire mechanism is reversible.

 

[cjtroutt]

Thank you Tom for the info got it done other day and made me feel alot better to open my door
with out leaving the window down.

 

[rwbrown72]

The following information is how to repair the common failure of the door latch mechanism used on M series 2 1/2 , 5 & 10 ton trucks is also applicable to M37 Dodge.

We get many calls for door latches due to internal failure causing the outside handle not to function. The left latch is very hard to find and is not interchangeable with the right hand latch. The latch is the same for all of the above mentioned units except for the length of the arm to the inside handle.
Yesterday the latch failed on my truck. But I couldn't just replace it I had to know why. After disassembling the latch, the failure was obvious. The quick fix was also obvious.
How the latch works: After you rotate the outside handle it rotates a cam, that pushes a lever attached to the striker. What happens with use is the clearances increase enough so that the cam will slide under the lever and the outside handle does nothing. To repair the problem you must remove the latch from the door. With a firm tap on a specific spot with a punch and hammer on the striker lever the latch will work just like new.

Pic 1: Shows Left Hand Latch

Pic 2: Shows The Exploded View From Left To Right Latch, Cam, Cam Retainer & Cover.

Pic 3: Shows a that the cam has slide under the lever (Broke).

Pic 4: Shows the striker held in the open position with a vicegrip to gain access for the bending operation.

Pic 5: Has the cover removed so the part striker lever being bent

Pic 6: Bending the lever using a punch or chisel with a hammer. Give the punch several good raps then insert outside handle in latch checking for proper function, repeat as necessary.

Pic 7: Shows the cam resting against the striker arm in the proper position with the cover removed.

Pic 8: Shows the cam rotated to the open position.

In short you do not have to take the cover off the latch to repair it we did that to give a better understanding of the inner workings of the latch. One of the easiest things I have ever fixed on a Deuce.

Time to complete Procedure: Half Hour
Materials: 0
Beer: 2

Perfect... Thanks!