4 spd. pops out of gear.

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I have been hand grinding points on those clutch teeth since the 80s; this is not rocket science. Usually there are 6 to 8 splines on each slider that do all the work, and they need to be back-cut so different undamaged splines come into play. Again, not rocket-science; just zip-zip with the die-grinder, and it's done. There will be 6 to 8 clutch teeth, per gear, that will/may need a similar back cut.
But grinding in all gears is NEVER a transmission problem. Let me rephrase that; In the hundreds and hundreds of many types of transmissions that I have "rebuilt", I cannot recall ever seeing one with 4 worn out brass rings. I mean chances are there was one or even a few, but I just don't recall it. In 40 years I can't recall ever seeing four bad brass rings. When they come to me the second gear is the bad one, the fourth is like new, and the other two are inbetween somewhere.
Grinding in all gears would be one of two things; either slippery oil or a dragging disc. The dragging disc can be one or more of several reasons, namely; Clutch Departure,or a bellhouse out of alignment, or a six-cylinder pedal-kit... which goes back to clutch departure.

Here's the test;
Start it up and let it idle. Depress the clutch pedal to the floor. Wait ~5 seconds , then attempt to put it into first. If it grinds,the input gear is still spinning, and you have either a departure problem, or an oil problem. Repeat but wait 10 seconds. If it still grinds you have a dragging clutch, probably because of insufficient Departure. But if no grind then drop the oil and install 75/90 EP Dyno oil with NO friction modifiers; that is to say NOT rear end oil. Then repeat the test.If problem solved yur done.
But if you have a departure problem with the pedal on the floor, then you got some homework to do.
First;verify that the freeplay is no more than 1 inch. I like 1/2 inch, because I have plenty of pedal left, NO departure problems, and I like the short stab on the pedal to make it happen. But 1" is the factory spec for lazy people, who don't like to crawl under there more than once a year.
Next you must verify that your Z-bar and TO fork are correct for your application. The Brewers site is very helpful.
Next you gotta verify that the Z-bar geometry is correct and stable. The bar must go from frame to bellhouse about parallel to the road and at 90* to the frame-rail in planview from above. And it must not move inboard/outboard on it's plastic bushings, and the frame end ball-stud must be securely welded to the fender/frame. The BH end must be securely anchored so it cannot move. On the stock BH this usually means 2 bolts.
Next; the TO fork must be the correct length, and sitting in the correct location in the window,which is; about centered vertically, and very near to the front edge. To change this, you use the fork pivot bracket, or the release bearing.
If you have a factory BH;
Finally, we get to measuring the departure. But first; with the trans in neutral, have a helper floor the clutch-pedal, then grab a tool and attempt to rotate the disc. It must move freely in both directions.
If it doesn't move at all with obvious departure, it's probably in backwards.
But assuming it moves;
keep turning it watching it wobble from side to side. If it drags on the PP or on the flywheel make a note of it. If it does it in several places make a note of that too. If it become hard to turn at any time, after all these checks have been made, then either the the disc is not properly floating on the splines, or, the departure is inadequate, or the disc is warped or damaged beyond usability, or the trans and crank are not on a common center.
The easiest to check is departure. I grab a couple of .080 feelers or anything about that thick, and with the helper still flooring the pedal jam them in there as far apart as you can and hanging down, then tell your helper to lift off the pedal. Let go of the feelers, then re floor it slowly. When the feelers drop out, yell to your helper to stop. Shimmy out and eyeball the distance from under the pedal to the floor (no floormat). This dimension should be more than 2 inches,and less than about three. Ok let your helper relax. But if this dimension is on or near the floor; OR, if the feelers don't drop out, then you have the wrong pedal ratio for your clutch. The whole pedal assembly will have to come out for inspection and possibly modification or replacement to the proper ratio.
Lessee where was I?.
Oh yeah, but if the departure works out right, then next is to make sure the disc is moving freely on the splines. IDK how you are gonna accomplish this; I always check this before I install the clutch. IDK. But I can tell you this; if you accidentally hung the trans on the disc with the retainer not yet in the BH, then chances are good that you bent the marcel carrier, and the wobbling during the spin test was pointing to that. And that brings us to;
If you have a scattershield, yur in trouble.
I suppose you could remove the driveshaft and insert a dummy-yoke into the tail, and you can turn the trans with that, but now you will have to put the trans into fourth, so the disc will spin, and you can sneak a peak thru the TO fork window. But I don't see how you can measure the departure. You'll have to figure something out.
And finally, when all else fails, did you dial-indicate your BH as to serviceability and make any required corrections? If the crank and the trans mainshaft are not on or nearly on the same centerline, you are gonna have issues. From hard- shifting to burned up mainshaft front pilot to unhappy bearings.
I think I got you covered.......

And here's a red-herring
There are two types of tail pieces, each with it's own Mainshaft bearing ........ and the big bearing, (a type of 308) is Mopar specific as to thickness. If you put a regular 308 in there, the mainshaft can walk backwards and forwards, which drags the gears with it, and so they may not be in the right place at the right time and the brass of course are out of their working range. And grinding in two gears is guaranteed. The only gear that is not affected is fourth/high.
As for the smaller 307 back bearing, I can't recall if it is Mopar specific.
And a double red-herring;
one of these bearings, maybe both, is retained in probably the most horrible way I have ever seen, and it is fairly difficult to properly install the retaining ring. If it was not properly seated, then the bearing is again free to walk back and forth, with guaranteed grinding in at least two gears. Again fourth is not affected, but the struts could pop out, making it impossible to return the trans to neutral.

Happy HotRodding

Very nice! I only have one thing to add, and that is "A" Body 4 speeds only use a 307 rear bearing except the 66-67 small output spline and it uses a 207 rear bearing.
 
AJ, I performed a few of those tests you suggested, with the car still up in the air.
I instinctively bump a higher gear with these old trans before I go for first so as not to get a grind, but waiting the 5-10 sec. before shifting none of the gears ground at slower rpms .
On the road at higher rpms the gears will grind. Help is hard to come by so I try to do every thing myself. With the pedal propped to nearly the floor I can slip a .050 shim all around the airspace, the disc spins freely and no wobble, all new stuff except trans.
Any more air space needed I will have to modify my homemade Zbar. .050 seems plenty? but I`m no expert. The trans installed too easy/nice to think of bell misalignment.
BUT the engine was from an auto 440 car, 72 forged crank newyorker, pilot bearing tapped in nice and snug.
I`m working up the gumption to get it drained ,pulled, and opened up for a look see, and try to restore this thing myself. I`ll post a few up closers and with a new kit from Dan, and hopefully a little help from all you guys, I can get r done.
 
Well this does`nt help nothing. I wondered what that bang was, lol
IMG_20200121_184349.jpg
 
Well out on the bench with cover off I see no obvious damage, but I have an un trained eye.
would these 1-2 slider pics offer any clue to what`s going on? What say you builders?
IMG_20200122_174642.jpg


The only obvious wear I see is on the 1-2 fork.
IMG_20200122_174349.jpg


I can try and get additional pics if needed just ask what with detail.
 
From what I can see, the sync's look like new, and don't see anything out of ordinary. Another thing I didn't mention earlier when I commented is runout. I have taken transmissions apart that were said to be rebuilt, and found the thrust washers not installed correctly. Reach in and grab the lower cluster gear and see if there is movement back and forth. If the trust washer came out, due to not being installed right it would definantly cause grinding, and mis-alignment issues. As I stated before, popping out of gear is generally a worn key or broken spring issue, but it's impossible for me or anyone else to troubleshoot this without taking it apart and seeing it in person. Also, stick an extension magnet into the oil in the case and see what shows up, that's how I've found missing thrust washers before, they will raise hell with gear boxes if they get into the gears.

Jeff
 
Here is a blowup parts diagram if it helps, notice the thrust washers on each end of the cluster gear, they align in slots in the case. Part numbers 47, and 54

19a20600.jpg
 
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