Shifter guide plate, an often ignored small part

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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YLG80
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Shifter guide plate, an often ignored small part

Post by YLG80 » Tue May 04, 2021 6:48 am

In 1983, when I've restarted for the first time since years the jeep of my father-in-law (now my jeep :D ) there was an annoying problem.
The second gear was always shifting out to neutral when accelerating.
I have disassembled the gear box cover and to me the guide plate was worn and was the cause of that problem.
At that time, I've bought a NOS gearbox cover, and the problem was indeed fixed.
Now years after, I've decided to restore my GPW F-marked gearbox cover and replace the guide plate.

I take that opportunity to show you the difference between a worn plate and a new one, side by side.
I have also spent some time to make a drawing that would help you when inspecting your gearbox cover.

I believe that this small hidden part is very important and needs more attention.

What are we talking about?

Shift_gearbox_top_view_GPW.jpg

And more specifically that part on the other side:

IMG_0005s.JPG

Here is the side-by-side comparison to show how worn was the shifter guide plate in my jeep gearbox cover
It's difficult to see, but the top side of the plate has also many burrs and the two rivets had been hammered during the previous jeep life.

WORN_PLATE.png

You can also see that the gap between the ears had grown a lot....

Here is the drawing that I have made by measuring two different brand new plates. It's even in fraction of inches for you !
For some reason there are slight differences with the JeepDraw drawing, but I believe that its not very critical.

GPW-7214_WO-A-635859_GUIDE-PLATE-SHIFTER-rev4_fracinches.jpg

I would advise to carefully de-burr the new plate, to make slight chamfers in the plate cutting area and to improve the surface finish where the shift lever will touch the plate.
It will help to preserve the shift lever tip.

Yves
[Edited on May 7th, 2021 - incorrect dimension +missing slot width on drawing - drawing replaced in rev4]
Last edited by YLG80 on Fri May 07, 2021 12:51 am, edited 2 times in total.
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Tue May 04, 2021 7:18 am

And here is the drawing in metric, for the people in the tiny part of the world using the metric system :wink: .

GPW-7214_WO-A-635859_GUIDE-PLATE-SHIFTER-metric_rev4s.jpg

Yves

[Last edited on May 7th, 2021 - drawing in metric updated to rev 4 - added missing slot width of 7.9mm]
Last edited by YLG80 on Fri May 07, 2021 1:36 am, edited 1 time in total.
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Re: Shifter guide plate, an often ignored small part

Post by sjalbert » Tue May 04, 2021 7:49 am

Thanks Yves,

I'm going to have to inspect mine. I occasionally have experienced that problem. replacing a worn plate is a lot simpler then r&r'ng the transmission for a full rebuild if it'll solve the problem.
Seth
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Re: Shifter guide plate, an often ignored small part

Post by '42 Peep's Motorpool » Tue May 04, 2021 10:23 am

Hi Yves,


Great drawings! Yes a vital piece to a properly shifting T-84. Certainly overlooked by many (as it is not a mechanical part, it tends to get overlooked).
"Peep" was the name used by the Armored Force for the 1/4 Ton truck early in WWII.

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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Tue May 04, 2021 2:11 pm

Thanks Seth and "42 Peep",

Yes that little part is often overlooked also because it's riveted.
That's also the reason why I didn't restore the gearbox cover earlier :oops: .
Although I've seen a perfect repair with two screws with countersunk head.
With the next macro photo, it's more evident to understand why the second gear was getting out during acceleration.

IMG_2719s.jpg

Riveting is also the reason why I didn't restore my gearbox cover earlier :oops: .
But now I have to go forward with the two rivets :) !

Yves
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Re: Shifter guide plate, an often ignored small part

Post by bryanbdp » Wed May 05, 2021 6:51 am

Can someone explain how being worn affects popping out of gear? Mine pops out only under deacceleration. The plate was replaced with a new one, the theory right now is the slots aren't deep enough for positive engagement of the shift rail balls.
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Wed May 05, 2021 7:01 am

bryanbdp wrote:
Wed May 05, 2021 6:51 am
...theory right now is the slots aren't deep enough for positive engagement of the shift rail balls.
And the guide plate slot slope helps the shifter can tip to get out ...as shown on the macro photo.
I don't remember if the problem happened also during deceleration. Sorry, it was in 1983 :)!

I'm pretty sure that the shifter cane tip has also to be inspected and perhaps repaired.
Here is a picture showing how it should be:

s-l1600-8s.jpg

As usual there are two parts playing a role in that game.
Yves
Last edited by YLG80 on Fri May 07, 2021 2:02 pm, edited 1 time in total.
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Re: Shifter guide plate, an often ignored small part

Post by 17thAirborne » Wed May 05, 2021 7:55 am

Yves,
Excellent information. THanks.
Oz

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Re: Shifter guide plate, an often ignored small part

Post by FUBAR » Wed May 05, 2021 9:20 am

Nice drawing Yves!

I'd be happy to offer my initials for CK once DRWG. COMPLETED. :D

Best, -=BK
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Wed May 05, 2021 10:28 am

FUBAR wrote:
Wed May 05, 2021 9:20 am
Nice drawing Yves!

I'd be happy to offer my initials for CK once DRWG. COMPLETED. :D

Best, -=BK
Thanks for Check and Approval :) !
Yves
Last edited by YLG80 on Fri May 07, 2021 1:34 am, edited 2 times in total.
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
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Re: Shifter guide plate, an often ignored small part

Post by Bill H. » Wed May 05, 2021 11:21 am

Thanks Yves! Excellent post and great information. :D
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Thu May 06, 2021 2:09 pm

The first published guide plate drawing in fraction of inches was incorrect
However the same drawing in metric is correct.

There was some problem with the Trimble Sketchup conversion from metric to inches.
It seems that it was converting the displayed value and not the stored value which is exactly 9.5250mm or equal to 3/8in.
There is an error in the distance between the two fingers, ½’’ should be 3/8’’.
Likely a rounding issue on the displayed value…don't know.
What is strange is that the 3D perspective view on the right is OK with the 3/8’’ inches distance between the fingers :shock: .

The drawing is up to date in the first post (rev4). Added also the slot width (5/16') which was missing.

Thanks to the attentive reader for his remarks :wink: !
Yves
[Edited on May 7th, 2021 - removed new drawing from this post and updated the drawing in the 1st post]
Last edited by YLG80 on Fri May 07, 2021 1:33 am, edited 1 time in total.
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
ACM I body#198443
Restored as 1st Army 759th LT B21
ON6YD(ex YB1AUH) MVPA38444

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Re: Shifter guide plate, an often ignored small part

Post by sjalbert » Thu May 06, 2021 3:06 pm

Yves,

They just changed the editing time limit to one week. If that's retroactive you might be able to edit that post.
Seth
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Thu May 06, 2021 11:57 pm

Hi Seth,

Thanks for that information. I wasn’t aware of that.
But that’s a very reasonable decision. Many thanks addressed to the board!

I have tidied up my posts! (drawings in rev4)

Thanks.
Yves
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Re: Shifter guide plate, an often ignored small part

Post by YLG80 » Fri May 07, 2021 3:48 am

Found on eBay.
Why not, if it works? :lol:

It was the common fate of our jeeps: it had to run with no waste of time.
My jeep was no exception to this rule.
The "useless" and annoying parking brake lever, w/o cable and all that stuff, was welded in order not to fall on the ground under the jeep:wink: .

For sure, this guy was afraid to loose the guide plate.
found-on-eBay-2s.jpg
Found-on-eBay-3s.jpg

Yves
Ford GPW 164794 1/4T 12-7-43 - Frame# GPW*239762*
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Restored as 1st Army 759th LT B21
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