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- John Barton's -
G503 T 84 GEARBOX REPAIR MANUAL
-DISASSEMBLY, REPAIRING, AND RE-ASSEMBLY OF THE T 84 -
- PART 1 Disassembly -
8:58 PM 8/29/2005
This is probably more for people who have never worked on a T 84 transmission. This transmission is actually pretty simple, and I would encourage you to try it..
The best book is the TM9-1803B I don't know if it is reproduced separately...but it is in the 3-in-1 book, and available on CD's etc.. that manual has everything you need.. but hopefully I'll help with a few things.
I'll show some tricks.. but please send me any corrections or things that you've found..
I don't do everything in same order as 1803B but if you do a few transmissions, you can see how to knock it down quickly
I will post a lot of pictures... not sure how the g503 will handle it, but I'll try
That is the one thing missing in most manuals.. good pics. Mine aren't great, but I'll show more than the manual so it will take more than one page...I have a few transmissions...so the
pics will use clean and dirty parts.. but in the last posts where I show assembly.. it should all be clean..Like I said.. it's pretty simple take out a couple of set screws, punch out
some rails, three bolts, a shaft lock, and a snap ring.. and the T84 will almost fall apart.. but first.. depending on how you get a jeep this is what most transmissions look like.
This one was sitting in a open jeep for years.. rusty.. but look at the actual gears.. not bad!
Or it looks like this.. covered in 40 years of grease, when I strip a jeep...the body comes off first, so I wind up with transmission/transfer together, drain them, take the top off the transmission, and back off the transfer case. I used to flush them.. but a lot of small parts may be there and I want to see how much metal is in bottom before you can work on transmission, you have to separate them there are two transfer case types.. naturally...early and late. pics for those who haven't seen difference.
The late one had a linings, shoes similar to wheel brakes that expanded out into larger drum someone else will have to post changeover dates..
I believe Ford used the same early one throughout production,
but it is not unusual to find late style on GPW's.. from refits or rebuilds..
Willys used both.. The hand brake cable termination- where it connects the lever, was different I will post a photo of each type later.
Five bolts hold the transfer case to the transmission.
Four of these are pretty obvious and go from back thru the transfer case into the transmission...
The fifth one is opposite and not always visible.
Pic on the right shows it going from opposite direction note intermediate shaft.. all MB's & GPW's had this 3/4 inch shaft.. post war, and civilian cases had..1 inch, and later 1 1/4 inch shaft.
That is one way to tell if you have an original transfer case.
After the bolts are out... and you remove the cotter pin and nut, washer, and gear.. sometimes the cases will just fall apart.. note the interlock plunger.. it gets discussed often on g503 as missing etc..?
I have never found a jeep without it? wouldn't know how to tell...most often..
You may need to smack the end of the transmission output shaft.. you'll need a drift or piece of wood through the large hole on back of the transfer case. Usually the rear bearing will stay stuck in the transfer case ..or the output shaft will move back with the transfer case and you will hear little parts falling around inside the transmission...
I will mention that a few times.. rarely does everything stay together so that all the little parts wind up where they belong...don't worry about it..
If it all comes apart easily, the little parts may stay put until you get there. but..... usually they fall about, and they all are coming out eventually anyway, you need to do all this work on a bench with carpet.. pretty soon small pieces are going to be flying out..!
Pic of top of transmission ..
Labelled a few parts on the pic on the right .. note set screws that hold forks on shift rails...in a old goobered transmission... they are the hardest part to get out in a oiled or working transmission.. they usually come out easy, you'll need the correct tool- the Bristol wrench....!! (Available through Ron Fitzpatrick) I have seen the set screws stripped, welded, hammered... someone didn't have the correct tool..!
I have the Bristol wrench but use it for display.. first.. if you have an old one like this.. spray it with liquid wrench over a few days...to get the set screws out.. I use a t27 torx socket.. clean out the recessed heads with a pick tool and air.. I have ground the t27..to put just a little point on it it reaches down further and helps with next step I put it in set screw (with an extension) and smack it pretty hard with hammer.. that and liquid wrench usually works to free them.
I believe the manual says take off the front bearing retainer etc...first
I do the set screws first... parts don't jump around so much when everything is still together
with the set screws out...Rails can be driven out with a skinny drift, the 1803B shows using a screwdriver in the rail notches to drive them out. I believe a lot of shifting problems stem from slop where the shift plate (not in any pics yet) rides in these notches..
I use the drift so I can catch the poppet balls. Now is when you need a little care, under the rails in the two front holes (labelled above) are the springs and poppet balls.. they can be free and will fly out.. or get stuck in crud and not budge..
I hold my hand over the hole to catch them. (Left Pic) and to keep from getting popped into an eye, hold the drift with the same hand.. and hammer them out.. when the poppet ball and spring won't come out.. don't worry ... as you can see in this picture on the right of an empty case.. the hole is thru drilled... you can use a piece of bent coat hanger to push up the ball and spring from the bottom.
The front bearing retainer comes off easily.. three bolts. the third 1/4 inch rail aligns the forks.. push out with a drift also.. top stuff is all free and out now, use a drift to take off the lockplate between two shafts on the rear. (Left Pic) Use a drift to drive out the bearing...it's the long shaft that clustergear rides on.. either way but from front... driving out the back is better so the notch for thelockplate won't catch. The clustergear will fall down into the bottom of the case. The front input shaft may now fall out or be stuck where the bearing sits in the case.. Pic of all top stuff and front retainer removed
As I said by now.. usually one or both shafts has come loose and small parts are free. Wiggle the front input shaft.. light taps with a mallet is OK.. don't hit from the inside.. the shield is not strong enough..
It wont come out until the clustergear is dropped.. but now it should be free. Now if you wiggle the gears on the main output shaft you can get it out of the case.. easier this way to get the snap ring off..
Again- while you're doing all this...the synchro blocking gears, and roller bearings will be flopping around.. just make sure they don't roll away.. the roller bearings will be in the case.. and some will still be stuck inside the input shaft.. take the whole main shaft out the top with gears still on it. Sometimes the gears don't slide well...even on a good transmission.. line it up in original position, use a drift from the front end ..1st/rev gear will hit the back of the case.. this will get gears sliding.. and out.. or not..!
The 1803B shows using a screwdriver to pry this snap ring off.. easier this way, with it out!...and using snap ring pliers. I have this pic of the mainshaft with the synchro on.. and then with it off and snap ring back on to show the position.. it's hard to pry with screwdriver.
If you can't get it out of the case.. the snap ring in front of synchro hub needs to come off..
I have snap ring pliers with compound handles.. and little dimples for snap rings.. works fine.. Then you'll still need to smack it out back so the gears come off..
The snap ring that holds bearing on the input shaft is the same type. But if the bearing is OK.. and the input shaft is OK.. leave it!
Push the small idler gear shaft out back, and take out idler now...on a piece of carpet.. gently turn whole case over, poppet balls, synchro gears, roller bearings, cluster gear, bushings, etc will come out.. the springs that hold snychro plates usually stay in place. it's pretty much apart now..
Here are parts that come out with clustergear. and case is empty there is a internal snap ring that holds the roller bearings inside the 3rd gear on the input shaft, why it ever needs to come out.. I don't know? you can get rollers in or out with it in place..!
I'm going to glassbead and wash the case, photograph some parts of the case that can screw up a transmission, wire wheel all the gears etc.. and then post some more in the second part of this process..
- John Barton's -
G503 T 84 GEARBOX REPAIR MANUAL
-DISASSEMBLY, REPAIRING, AND RE-ASSEMBLY OF THE T 84 -
- PART 2 Inspection -
Again, most of this is for those who have not been inside the T84. I have been cleaning and inspecting the greasy transmission from the earlier post.
It appears to be in good shape but I did not drive it, so really, no sure way to tell for sure.
I’m going to replace a few parts but all the main pieces were very good.
Most of the shifting problems that I’ve seen in T84’s were caused by wear and slop in the
shift plate, shift lever, or top housing- often just switching out one or more, to make a different combination would fix or make it better.
These fulcrum pins are good…I have seen them worn to a V, or down to nubs. This pin can be driven out and replaced. One of the ORD’s gives the dimensions. The bottom ball that moves theshift plate and 2nd/3rd rail needs to be complete and sharp also.. this one looks good. The notches on the top housing for the fulcrum pins need to be straight…this will work, but you can see the rounded surfaces.
The fulcrum pin does not ride in bottom of notch in good housing…ball supports lever..
I haven’t found a worn out ball.. but this one looks like it was repaired…welded on rod..
I can’t always find or afford new top parts.. so I try that swapping first The good thing is you can do that with transmission still in jeep..! But if transmission was really no good.. it was usually the transmission case.. which led to or resulted in other bad things.. Poor lube is probably biggest killer.
I think this transmission is pretty sturdy, and I have taken apart several that worked fine…even though looking at the gears, you would think it was trash. For sake of uniformity with part names.. here’s one page from 1803B-
I’ll try to use correct names.. instead of cluster gear and bearing shaft, etc.
Worn parts may be noisy and grind a little.. but learning to shift a certain way (doubleclutch) can overcome this..
But, getting back to the case..
Both front and back holes that hold the countershaft have to be good. The holes for the front input bearing have to be good. I have not come across a rear bearing hole that was boogered.. the bearing is mostly supported by the transfer case.
Then, the surfaces inside the case that ride against countershaft gear thrust washers and washers have to be good…
If not, they tear up thrust washers etc. Again I have seen these pretty bad but have been able to salvage the case sometimes. Note small index pin.(Left pic) .it fits in the rear countershaft washer. Not important from this side.. but I’ll picture later what needs to be done. I don’t know the technical description.. but the countershaft fit through the case, In these holes- has to be a tight slide fit. You should barely be able to push in or out by hand.. if the countershaft slides with no effort holes are too worn. Don’t have a picture of really worn oblong holes.. but you will know- from the countershaft loose fit and pushed up metal on edges of holes. That I’m sure, lets the countershaft wobble.. it winds up like this.. (Right pic)
This is not the one from my rebuild- it was very good but when you see one with grooves
like these, (not the flat machined area-that for lube) dip on top edge! and discolored from heat, the bushings inside the countershaft gear are probably worn also.
In my experience- worn gears do not seem to cause as much trouble as a countershaft gear that hops around. The transmissions that I found to be undriveable always had a screwed up countershaft..?
When I show the assemble pictures, I’ll show bushings and spacers in countershaft and gear.
When countershaft, bushings, etc. go.. the thrust washers wind up like this- worn into oblongholes like the case holes. Then the transmission has- serious problems!..
and no changing of top parts will fix it. I have seen cases with the countershaft holes drilled out and a bushing inserted. Don’t have a pic…I was told once that this was and Israeli mod.. I don’t know.?
I presume these work.. so a boogered case can be repaired.
Without tech drawings I don’t know how to find center for boring out an oversize wobbly hole.. I’m sure a good machinist could figure it out. This is a pic of the front inside case where front thrust washer rides.
A good case has flat surfaces there, not grooved. Note angle notch.. the front thrust washer has a corresponding punch out that has to fit.
When you assemble. It keeps the thrust washer from spinning. I’ll picture that again later.
It also lets lube flow down I presume..
Here is pic of inside rear of case around countershaft hole.. (Right pic)
The index pin has to protrude into the case.. just enough to fit in the
washer hole and prevent it from turning. In this pic I have pushed it too far so you can see it. It is often worn down.. and you can’t see or feel it.. you punch it in from back with small drift..
It only has to protrude less than thickness of washer. If it sticks out more..
First, you won’t get the countershaft gear in.. and second it will tear up rear thrust washer.
This rear surface is in good shape.. I have seen them grooved also..
Note on this late (H) case there are two notches.. I think they are for lubrication as rear washer has no corresponding tab.. early cases don’t have these notches or only have one.
If either of the thrust washer surfaces are grooved.. I take an angle grinder.. with light grit pad and clean up surface…not to get it machined smooth.. just clean.. I haven’t disassembled one that I have done… so I guess it works??
To prep the case.. I wash well/flush with solvent etc to get all oil and particles out..
I glassbead and clean with air.. wash.. spray etc again to clean.. I put in the drain and fill plugs…with sealant, tape off front and rear holes- then fill with inch or so of red primer.. slosh it all over turn it upside down…spray rest of it.. let it dry for few days.. I do not know if the inside was originally painted. I read once that the cast is porous.. and that engine crankcases, etc. were painted in old engines- I don’t see how it can hurt..?
I then take bore brushes on a drill to all holes, poppet ball holes, and run taps thru all threaded holes. If you don’t clean all the holes.. you’ll have a hard time with rails, countershaft, fork alignment rail, idler shaft, etc.. bearings won’t fit in etc..
I spray a little WD40 on to keep it til I get ready..
Here is another pic from 1803B..shows the transmission from the top.
With this and the next picture I want to show how the shift lever moves rails, When you figure out how it shifts.. you can see how the synchro moves, works, etc. After you play with it.. it all seems logical and you can probably figure out
which part is causing a problem. Now that I have case cleaned.. it was in good shape.. I’m going to start the rebuild..
Like I said earlier.. the 1803B is pretty good.. it is what I started with…
I learned a lot from other collectors.. join a local chapter.. have someone give a demo…get a lot of feedback and different ideas.. and tips.. Assembly date.. have seen other places or not at all? I’m taking pictures of assembly now.. few days I hope.. I hope some others will add ideas or suggestions.
T 84 GEARBOX REPAIR MANUAL
- ASSEMBLY -
- John Barton -
Transmission Assembly Part 1
I have photographed and reassembled a transmission..
There are too many photo’s- so I’m going to have to break it up
I should have covered this first part with my last post..
first thing to assemble is the countershaft gear.. and there are several pieces involved.
Old Worn Bushing, Opposite end, Driving Bushing Out, Bushing partially out.
The front end is a little better, but both bushings and the spacer need to come out. I use a bushing driver from a set with different sizes.. others are needed when working on the jeep.. so the set paid off.. just drive from one end,
And bushings and spacer will come out. Putting them in is just the opposite.. same driver,
The above pics shows some of the different types of bushings I’ve come across.
Some slide in countershaft gear.. some need driving,
Some need to be reamed, some don’t.. I have seen different
Combinations.. it depend on what you get when you buy them.
Pic of countershaft, bushings and spacer, and countershaft gear.. (above) I do not know if it is a Ford/Willys thing there are holes in gear.. and holes in bushings. They do not need to be lined up. I use the same driver to insert.. ( Left below pic) one in one end, spacer from other side, and then 2nd bushing.. I have used an expandable reamer..
and I have taken the assembled gear to a machine shop for reaming, The assembled gear must go in the case..the front thrust washer And the rear thrust washer with spacer must be in place
I do just what the 1803B says..put a good coat of grease on them To hold them in place..(no grease for photo, right side pic)
The earlier section had pics of the index pin and front notches and how to set etc..
tilt the gear so back end goes out rear bearing hole.. ( Above Pics ) Level it off, line it up, and lower… it will probably take a few times…the fit between washers is slim, I usually knock them off a few times before I get it right. Let it drop to the bottom
Sometimes the fit is very tight…I have had to play with different combinations of thrustwashers etc.. I did measure the thicknesses once....there were several variations
I have lapped them down.. and cleaned up the case surface if necessary.
When I do get it to set right.. I test fit everything by using this Sears rolling pin pry bar as a substitute mainshaft.. hold gear with one hand…raise it slightly and slide bar in.. I roll the gear, get grease spread out to hold washers.. From now on…try not to turn case to much…you want the Thrust washers to stay in place..
The manual says put the idler in first…I find it easier to put the cluster assemble in first.
Then idler gear…cone end toward front, Insert shaft from rear…pay attention to notch on
shaft…the notch must line up to accept locking plate.. And this small shaft is harder to turn when all the way in.. The locking plate will do a final line up.. but easier to set it close now.
The next part to go in is output shaft…book says
Insert from rear of case and slide gears on..
It is easier to put gears on and them slide whole assembly in
One of the gears that goes on output shaft is synchro.. the directions in
different places are not quite clear on how to do this..
You need the springs in.. Locking plates in place, outer hub on.. Some instructions use a clock system, or put in one, turn it over And do same thing, etc.. The easiest explanation of springs is this picture above to the left. Hold the plates with your fingers and slide
outer hub over..a little oil helps. Outer hub should slide back and forth.. you’ll see action of plates and springs, the next picture shows various types of locking plates I’ve seen short, curved, long and flat…I have come across many.. I think it is just important to have three matching ones.. You should always buy a new synchro and blocking rings.. the first/reverse gear goes on output shaft, fork channel to rear then second gear. taper toward front.. it onlygoes on a short distance . Then blocking ring..the small brass gear..
Then synchro…. Long end of hub toward front line up notches in blocking ring with plates on synchro.. put snap ring in front of synchro.. slide gears toward front.. tilt and put back end of assembly out rear hole in case.. just let it sit there (Left Pic)
Now is usually when I call my daughter because my fat fingers won’t fit in to install roller bearings in back end of input grease them up.. she doesn’t like the icky grease!!! the last one has to slide in from top.. sharp needle nose… the snap ring that holds them in doesn’t really touch them.. never taken that snap ring out.. I guess if you buy a new input shaft it will come without it.. It's a little tricky to install..pliers.. screwdrivers, etc..again- you need to be careful now.. if you drop or set it down too hard.. the bearings will fall out.. now comes another tricky part… put other blocking ring in place.. use grease to hold in in synchro or put it on back of input shaft and line up notches again..
You now need to slide the rear bearing on to line up output shaft.. after the spacer and oil baffle.. snap ring is already on.. (Right Pic)
If you get fit correct first time.. it will look like this, if not…one of the rollers fell out…they won’t mesh.. you’ll be able to tell.. because you’ll feel it grinding etc.. gentle tapping on the bearing may be necessary to finish.. I try to insert the output shaft tip.. into the roller bearings, and them tap the front bearing into case...keeps the rollers from falling.. hold on to both shafts from now on while moving… if either moves out.. the roller bearing or blocking
ring can fall out of place.. with both shafts in place.. some people wire them ..to hold them..
Just be careful.. you’re ready to raise the countershaft gear.. you can’t get the input shaft in with the countershaft in place.. so don’t try to do that before now..
Here’s what I do…there are other methods
I turn the case on its side with the idler gear down..it helps locate the Countershaft gear..I use the rolling head pry bar again..from the front..
It is sharply tapered so it can usuall get thru the thrustwashers..which settled with gear..I slowly and gently try to get it all the way through..
Turn the case completely upside down..
Turn the input shaft…that helps center and line up the countershaft gear and washers..
Now the trick is to replace the prybar with the mainshaft..
Insert from rear…line up notches for lockplate again..
Some people have a special tool machined..probably easier to insert mainshaft
As you slide the tool out….either way..? you can do it without any tool…
When case is upside down..if you turn the gears..the countershaft will center itself..
Put lockplate in place..leave mainshaft out just a hair..after front end is lined up..tap both shafts with hammer. if notches are not lined up exactly..the lockplate may turn them into position..or you may need to turn the shafts…look at the neat “F” on extra lockplate..
Rotate the gearbox upright, be careful that the gears don't slip out . Now if you have lined everything up…it should look like this.
Slide 1st/reverse gear to this position..neutral..
the input and output shaft should turn independently..squirt a few drops of oil on synchro’s blocking rings etc.. a new, dry,transmission does not turn or shift easily..Last pic is that same gear in three positions
In first-..turn input shaft..output should turn same direction
In reverse-.. the output shaft will turn opposite direction
Transmission Assembly Part 2
The final steps with top end actually go pretty easily. The books and manuals however, don’thave very clear drawings.. most of them are exploded diagrams- you can’t tell clearly what goes in where..
I’m going to try and show the rails, springs, forks, etc…in their relative positions. This picture shows the rails outside..in their relative position.
The 1st/rev is shorter. If you line up the notches for the interlock plunger facing each other, and the cut-outs in rail for shift lever and shift
plate.. 2nd/3rd is on inside..1st/rev is on top…and notches for poppet balls on bottom…it starts to be logical.
The small rail is to align the forks…the large fork rides in the channel on the large gear (1st/rev) at back of the case.. the small fork rides in the synchro groove…slide alignment rail through the small hole in the case, and respective holes in forks. another picture to show rail arrangement on the right.
I push the rails in their respective case holes from the back…through the forks.. up to the holes for the springs and poppet balls…the spring goes in first on the bottom.. then add the poppet ball..
The object is to hold the ball down.. while pushing the rail over it..
It can be tricky.. I tried another shift rail.. a drift, etc.. but I wind up just using the flat of a screwdriver.. inserted from the front.. levering off the top of the hole…and then hitting back end of rail with hammer.. the first few times.. it will pop out.. fly all over the room.. a third hand covering the hole.. or handling the hammer is better.. and.. now that the spring and ball are clean.. it can fly out pretty fast. A brass drift, with a flat surface, the same size as the hole can be used. However, I do recommend that you Use and Wear Safety glasses… or keep it covered! now you wiggle the rail to line up with the notch on the rail.. with a set screw hole on the fork ..the set screw goes in pretty easily now.. Compared to getting them out… but you do need to line up the fork and the notch for it to go all the way in
Next. Finish tapping the alignment rail and the shift rails in.
Now it’s ready for front gasket. NOS one are always shrunken up.. you can put in the microwave, or in a pan of boiling water to loosen it up. It is easy to make them.. use the front of case as template.. the gasket can be inverted.. it should be obvious…but if you make or buy one…make sure the hole for the oil passage is
there, and in correct place..
I also put some sealant on the front end of the mainshaft.. under the gasket. it doesn't turn.. with gasket and sealant, and being pressed against bell housing it shouldn't leak.. more peace of mind..! Oil from inside the case is used through this hole to lube the front bearing.. it is opened to the front-inside the retainer.
And the retainer uses a little splash lube to travel out the rifling inside the bearing carrier.. the input shaft is turning in there to propel oil.. to drip out the hole on bottom to grease bearing carrier.. Not too much oil.. because there is a seal.
I have used the old cork seals..or the new fabric ones.. I have also made them from carpet liner..they keep oil from running out… but have to let a little bit wick out
This picture shows release bearing on carrier, it slips on the retainer.. I put just a little grease on it. The spring pulls the carrier back toward the case..
The ball is the pivot for the clutch control fork.
We almost have a transmission..! NOTE:-The Rail Cap on front of the case, this is usually missing, supposed to keep oil from coming out. Put a little sealant on outside edge before you smack it in place (Left pic) The Top Gasket…and shift plate spring…under the shifter plate..! yes.. "The Spring!"...I have seen the all the discussions.. the math “proves” it doesn’t do anything on top…but if it is under.. it holds shifter plate up against machined surface on inside of top housing.. which acts as a fulcrum and levers far end of shift plate down into notch on rail… (right pic) assemble it without the spring…reach down thru top housing with wire.. you can rattle shifter plate.. assemble it with spring on top of shifter plate.. again reach down with wire.. the shifter plate rattles.. Assemble it with the spring under the shifter plate.. no rattle..
I believe it goes under plate…but then, I didn’t "write the book on transmissions"
All it needs now is to put the shifter plate on..
If I’m not using it in a vehicle right away.. I will wire back bearing in place, just wrap wire around on of the top housing bolts.. put a little oil in.. play with rails.. moving them.. try turning input and watch output..
A new and dry transmission does not shift or turn easily.. you will think it is not right.. when you fill it with oil.. and have it turning with a motor.. it will shift..! Synchros actually require a layer of oil on the blocking rings to function.. Mercedes books have a really good section on the dynamics of manual transmissions… hope this helped a few people.. The transmission is not beyond anyone who can work on this jeep.. it is pretty straight forward..
Comments and tips appreciated... this is just my way of doing transmissions.. I'm sure there are others..