Building a T-84 transmission!

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Chuck Lutz
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Re: Building a T-84 transmission!

Post by Chuck Lutz » Wed Jul 16, 2014 10:36 am

Carsten....was the snap ring holding the synchro assembly and 2nd gear an original or a replacement? Used ones are often not FLAT from being removed once too often and the repop ones are not always the correct thickness....
You want one that IS flat and that is 0.060" thick so it fits into the groove on the main shaft properly.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947


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Re: Building a T-84 transmission!

Post by Carsten » Wed Jul 16, 2014 11:46 am

Thank you, guys...your advice and help is highly appreciated!

Yes Gindi, the snap ring is good and very tight with no play up and down play in its tapered groove. It is NOS and unused, but not perfectly flat though.
Carsten
Nyborg, Denmark
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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 4:00 am

Hi guys...

I'm in the process of setting up the input gear, synchro, and mainshaft. I looked into Gustl's video series, and decided to do the same. A lot easier to show you what I do, than trying to explain it.

My first try is here: https://www.youtube.com/watch?v=PyQOnopJ3Qg

As the video should show, I think the 3rd gear blocking ring wants to bind a little. It is as if the blocking ring can't make full contact with the synchro hub, thereby releasing the input gear cone completely. Can't see why, I thought the small shifter plates controlled the distance between blocking rings, and you can see there is enough gap left between blocking ring and shifter plates, to release the from cone? Mainshaft spacer is .158" and no shims are present. If I must back the mainshaft off a little, I guess I will need a thinner spacer, right?
Carsten
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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 8:56 am

1) In his video he checks if there is space at both ends of each of shift plate with the synchro in 2nd and in 3rd. Yours appear to NOT bind on the blocking rings so I think they are OK. They should NOT be held tightly between the blocking rings.
2) I also believe you have the main shaft positioned to far FORWARD but did you use the oil slinger between the snap ring and the bearing?
3) I think most of the spacers I have seen are .158" but I found some at .150" and some up to .205" and even up to .251"
4) I assume the spacer is the first type (A-738) and not the second kind (A-15428)?
5) Are you using the original THIN front/rear paper gaskets or the aftemarket ones for a T-90 that are WAY to thick?
6) You DID bolt the box to the transfer case and TORQUE the nut holding the output gear down so it pulled the main shaft to the rear, right?
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 9:20 am

Hi Chuck,

2. No, I didn't use the oil slingers!
4. Correct, standard type. I have a A-15428 I could try out. A little difficult to measure the thickness without a micrometer though...
5. No, not the original gaskets, both front and rear gaskets are even thinner, about .010"
6. Yes, transfer case, output gear, washer and castle nut in place, torqued as hard as I could!

I must say, the more I oil the blocking rings, cones and the synchro parts, the better it feels. I still think 2nd gear blocking ring releases the cone better than 3rd, and I also see more clearance on 2nd, so I guess I will try a thinner mainshaft spacer...
Carsten
Nyborg, Denmark
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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 9:36 am

Hello Gindi,

I get your point, but wouldn't that also bring the 3rd gear blocking ring even closer to the input gear, with risk of it binding?
Carsten
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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 9:38 am

1) adding or removing spacers/shims on the main shaft snap ring will move the hub forward or rearward
2) removing shims on the main shaft snap ring will give more space between the hub and the 3rd gear cone where the 3rd gear blocking ring goes
3) removing/adding shims on the main shaft snap ring will NOT change the distance between the hub and the 2nd gear cone where the 2nd gear blocking ring goes
4) removing too MUCH lenght (sanding it) on the nose of the hub WILL change the distance between the hub and the 2nd gear cone where the 2nd gear blocking ring goes
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 9:59 am

Chuck,

As to your #4 - as I understand it, no matter if you removed the entire nose of the hub (for it to fit between 2nd gear and snap ring), the distance from 2nd gear cone to blocking ring, will remain constant...
Carsten
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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 10:20 am

The amount of space between 2nd gear cone and the hub can be too MUCH if 2nd or the hub are too SHORT as they can then move APART and increase the space alloted for the blocking ring. Removing the intire nose from the hub would add over 1/8" in SPACE even if the snap ring was put on and the hub and 2nd gear moved apart on the main shaft.

Since the 2nd gear is helical cut, it will be driven forward and rearward as you accelerate and then let off the gas....
Chuck Lutz

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Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 10:39 am

Really?

You have confused 2nd gear with 3rd gear....that is plain to see...simply change "2nd gear" and "3rd gear" and that part of your statement is correct. Even Carsten as much as questioned that....read his post!

1) 3rd gear is on the main gear
2) the hub is on the main shaft
3) adding or removing shims on the main shaft snap ring moves the shaft forward or rearward
4) moving the main shaft with 2nd gear fixed onto it changes the "slop" on the blocking ring on 3rd gear

Since the hub and 2nd gear have the blocking ring BETWEEN them and both are held onto the main shaft with a snap ring......moving the main shaft FORWARD or REARWARD does NOT change the space between the Hub and 2nd gear where the 2nd gear blocking ring is.

Carsten just dropped in the 2nd/3rd shift fork but neglected to use the shift rails/poppet balls/forks to move the synchro sleeve so he moved it too far FORWARD. If one wants to know where the sleeve travel is...you must install them. Those components control where the synchro sleeve moves and will not allow the sleeve to move too far.

PS...those who use a front bearing retainer that does not capture the front bearing snap ring/use gaskets that are too thick/use a front bearing with a snap ring that is too THIN.....allow that front bearing and the main gear to move into and out of the case...that will decrease or increase the SPACE between the 3rd gear cone and the hub where the 3nd gear blocking ring goes.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by wo2jeeper » Thu Jul 24, 2014 10:40 am

Thanks Gindi, perhaps you could also post the youtube links here you made of your rebuild ? Where very usefull.

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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 11:18 am

http://www.youtube.com/watch?v=Aww9nF4idCA
http://www.youtube.com/watch?v=uvulGgdFMGY
http://www.youtube.com/watch?v=Zq_6K9WsgJk

Watch all three of the videos gustl posted....as he ADDS shims that move the MAIN SHAFT forward it DECREASES the slop on 3ed gear blocking ring. You can see the slop decrease as he goes from NO shim to adding one that is .016" and then one that is .024" to the snap ring on the MAIN SHAFT where the rear bearing is located.

In the .024" one he has decreased the slop on 3rd gear blocking ring between the 3rd gear cone on the MAIN GEAR and the HUB. While he ADDS those shims, the space between the HUB and the 2nd gear cone does not change.

I think that Carsten has a good fit on the main shaft/2nd gear/hub/snap ring. But if he wants to DECREASE the slop/space for the 3rd gear blocking ring between the 3rd gear cone and the hub, he will have to use a THINNER spacer back on the main shaft snap ring for the rear bearing.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 11:19 am

Chuck Lutz wrote: Carsten just dropped in the 2nd/3rd shift fork but neglected to use the shift rails/poppet balls/forks to move the synchro sleeve so he moved it too far FORWARD. If one wants to know where the sleeve travel is...you must install them. Those components control where the synchro sleeve moves and will not allow the sleeve to move too far.

PS...those who use a front bearing retainer that does not capture the front bearing snap ring/use gaskets that are too thick/use a front bearing with a snap ring that is too THIN.....allow that front bearing and the main gear to move into and out of the case...that will decrease or increase the SPACE between the 3rd gear cone and the hub where the 3nd gear blocking ring goes.
Both the shift rail, 2nd/3rd shift fork, poppet ball and spring is in place in the video....
The front bearing retainer holds the snap ring tightly, also with the 0.01" thin paper gasket in place. I skimmed the face of the retainer on a lathe, so I am sure the snap ring/paper gasket/retainer depth thing is on the tight side by a few hundreths of a millimeter...
Carsten
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Re: Building a T-84 transmission!

Post by Chuck Lutz » Thu Jul 24, 2014 11:59 am

Please read what I posted and respond to what I said in each of those items....

Moving the main shaft forward/rearward does NOT change the amount of space between the HUB and 2nd gear cone since the snap ring holding them on the Main Shaft is not effected by adding/removing shims on the main shaft snap ring at the bearing. Moving the main shaft forward/rearward DOES change the amount of space between the HUB and 3rd gear cone.

If you believe otherwise...please post how exactly that happens.

PS...if the front bearing and the Main Gear move in and out of the case too much, that changes the SLOP between the 3rd gear cone and the HUB. EXCESSIVE movement is not a good idea in that location!

The REAR bearing outer race is tight against the transfer case indent for it and there is no reason that the FRONT bearing can't be held against the front of the case via the snap ring and the front bearing retainer....that prevents the 3nd gear cone from increasing or decreasing the SPACE between 3rd gear cone and the HUB where the 3ed gear blocking ring is located.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947

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Re: Building a T-84 transmission!

Post by Carsten » Thu Jul 24, 2014 2:25 pm

Chuck Lutz wrote:The amount of space between 2nd gear cone and the hub can be too MUCH if 2nd or the hub are too SHORT as they can then move APART and increase the space alloted for the blocking ring. Removing the intire nose from the hub would add over 1/8" in SPACE even if the snap ring was put on and the hub and 2nd gear moved apart on the main shaft.

Since the 2nd gear is helical cut, it will be driven forward and rearward as you accelerate and then let off the gas....
Generally correct, Chuck - but in my situation, there is not excessive space between hub and 2nd gear. Initially, the 2nd gear would bind when mounted on mainshaft under hub and snap ring, so only enough material was removed from nose of hub, to make 2nd gear spin freely, with adequate play for lubrication (0.1mm/0.004").
Carsten
Nyborg, Denmark
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