T-84 Input Shaft - thrusting problem

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
dinof
G-Major General
G-Major General
Posts: 2860
Joined: Fri Jan 08, 2010 4:32 pm
Location: Arcadia & Johannesburg Ca.

Re: T-84 Input Shaft - thrusting problem

Post by dinof » Tue Oct 17, 2017 6:11 am

I can't answer your last post of questions but I had the same experience as you have here. But when I installed the shafts, bearings front & back, and put the bearing retainer on with the back bearing clamped down, it did not "thread" anymore. My rollers were all spec, and were using all the same parts as my problem was a bad synchro assembly. and the fact that my case was allowing a too far throw into 3rd.

If you put the whole driveline back ( input,main, gears & synchs, front bearing & retainer, and the shims and clamp the back bearing, what happens? Does it bind severely or does it work fine? Mine did not and did not do anything bad when assembled. Maybe my situation was not as severe as yours. Memory also tells me that mine only did it in one direction and not the other.
Dino Falabrino
On the "G" since 1998.
1943 GPW 102310 DOD 3-3-43
1928 Model A Roadster Pickup
1930 Model A Tudor
1968 Taco Minibike


privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Tue Oct 17, 2017 6:39 am

Thanks Dino - when assembled it does not bind severly, but it also does not spin freely in neutral. It's somewhere in between - turning the input counter clockwise there is a stickiness at one point in the rotation, then it frees up for the rest of the turn. I know I add clearance to the blocking rings by taking out thickness in the spacer/shim set but I'm trying to understand first what is causing the thrusting. It seems to be right that there is not enough clearance in the bearings to the "nose" of the main shaft.
Glad to hear someone else has seen the same thing.
And that a thinner gasket will help prevent lateral movement.
Brian

User avatar
Chuck Lutz
Gee Addict
Posts: 26829
Joined: Wed Jun 28, 2006 7:00 am
Location: Jeep Heaven

Re: T-84 Input Shaft - thrusting problem

Post by Chuck Lutz » Tue Oct 17, 2017 8:48 am

1) your bearing retainer is of a correct depth
2) your front bearing snap ring is 0.0644" rather than the original Federal bearing snap ring which is 0.077" so you have about 0.0126" slop there
3) your front bearing retainer is 0.022" rather than the original Ford/MB gaskets which are 0.014 so you have about 0.008" slop there.

Total amount of movement can easily be the sum of those measurements @ 0.0134".

I would replace the new snap ring with the one off the old one if it is in the 0.077" range and get/make a gasket that is 0.014"
Chuck Lutz

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

privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Tue Oct 17, 2017 9:58 am

Thanks Chuck
So if I understand, the retainer recess plus the gasket creates the space for the snap ring.

Ideal is 0.060" + 0.014" = 0.074" space for a 0.077" ring, essentially requiring 0.003" of "compression" when the retainer is bolted down.

My situation is 0.060" + 0.022" = 0.082" space with a 0.0644" ring, which has 0.0176" extra room for the ring to move.

I'll get a new ring and gasket for sure.

Still thinking about getting a new input shaft. I'm going to bring it to work tomorrow and have the bore measured more precisely.


Brian

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

Re: T-84 Input Shaft - thrusting problem

Post by Joe Gopan » Tue Oct 17, 2017 10:05 am

A new M.D. Bearing is usually a good choice as the inner and outer race of the bearings do wear with the miles and will add to the side play at the front end of the M.D. Gear way out at the far end.
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
Chuck Lutz
Gee Addict
Posts: 26829
Joined: Wed Jun 28, 2006 7:00 am
Location: Jeep Heaven

Re: T-84 Input Shaft - thrusting problem

Post by Chuck Lutz » Tue Oct 17, 2017 10:56 am

Brian....measure the "old" front bearing snap ring FIRST...you either destroy them or you don't when removing them so be careful. Sourcing one in the 0.077" range is not easy so re-using them is preferred...same for the other snap rings in the T84.
Chuck Lutz

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

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

Re: T-84 Input Shaft - thrusting problem

Post by Joe Gopan » Tue Oct 17, 2017 11:50 am

Some of your local bearing suppliers may be willing to order the various thickness Snap Rings that go with that series bearing.
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

privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Tue Oct 17, 2017 12:16 pm

Thanks guys, I appreciate it. I don't have an old snap ring, just this one that came with the "rebuilt" trans. I do have a Bearing Headquarters store within 1 mile from me at work, so I can see what they have.

User avatar
Chuck Lutz
Gee Addict
Posts: 26829
Joined: Wed Jun 28, 2006 7:00 am
Location: Jeep Heaven

Re: T-84 Input Shaft - thrusting problem

Post by Chuck Lutz » Tue Oct 17, 2017 12:35 pm

Ask them for a snap ring like this:

2.8346 O.D.
1.3780 I.D.
0.077" thick
Chuck Lutz

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

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

Re: T-84 Input Shaft - thrusting problem

Post by Joe Gopan » Tue Oct 17, 2017 1:03 pm

The bearing Part No. should help as the part number suffix I.D.'s it as being a Snap Ring type and they should be able to give you the options for that particular size bearing.
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

privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Wed Oct 18, 2017 4:30 am

Thanks again, guys.
The bearing OD is 2.835", so I think there must be a problem with the ID and OD sizes shown in Chuck's post. The bearing is NTN brand, #6207N, (also has 62072 on the dust seal) and 141021 on the outer race. I'll take it with me to the bearing store.
Brian

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

Re: T-84 Input Shaft - thrusting problem

Post by Joe Gopan » Wed Oct 18, 2017 4:52 am

27t series will have the same OD and ID, those with snap ring will have suffix S. The greater the snap ring thickness, the tighter the bearing will be secured between the retainer and the case.
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

privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Wed Oct 18, 2017 6:16 am

Thanks Ben.

Changing back to the subject of shaft thrusting, I was able to make a better measurement of the input shaft bore: it changed from 0.975" to 0.9738", making the clearance 0.0027" when the needle bearings and main shaft pilot/nose dimensions are applied.
That is almost exactly the same as what Bantamj measured on his parts that perform normally, without thrusting. So there is still something going on that causes the thrust when the shafts rotate. I'll keep investigating.

Brian

dinof
G-Major General
G-Major General
Posts: 2860
Joined: Fri Jan 08, 2010 4:32 pm
Location: Arcadia & Johannesburg Ca.

Re: T-84 Input Shaft - thrusting problem

Post by dinof » Wed Oct 18, 2017 8:09 am

Here's the dumb question of the day: Do you have the needle bearings well oiled/ greased? You probably do.
Dino Falabrino
On the "G" since 1998.
1943 GPW 102310 DOD 3-3-43
1928 Model A Roadster Pickup
1930 Model A Tudor
1968 Taco Minibike

privatebrian
G-Sergeant Major
G-Sergeant Major
Posts: 191
Joined: Tue Jan 06, 2004 9:22 am
Location: Sothern Illinois

Re: T-84 Input Shaft - thrusting problem

Post by privatebrian » Wed Oct 18, 2017 9:43 am

Well, there is no gear oil on them but they had Dr. Tranny's assembly goo. Most of that I wiped off. It stands to reason that lube would help, at least reduce the force needed to overcome the movement that the thrusting wants to create. At this point, I'm deciding if I should try replacement parts in hope that they will have slightly different dimensions and create more clearance. First an input shaft ($90), then maybe the main shaft ($60)...on the other hand, if everything is "locked down" in place (front bearing held in place by thicker snap ring, and rear bearing captured in the trf case pocket) that it may WANT to thrust/move but it can't, so... problem "solved", or minimized.
Thanks Dino.


Post Reply

Return to “MB GPW Technical Knowledge Base”

Who is online

Users browsing this forum: Gbcygnet, TR BUCK and 47 guests