No reverse, seems stuck in a forward gear

[Phreakish]

'72 swinger. 318, 3500 stall converter, 904, 8.25 w 3.91s. Kick-down is adjusted to be bottomed out at WOT, shifts pretty soft at low/part-throttle and shifts 1-2 and 2-3 north of 5500.

I've been tweaking my carb throughout the day - had been running very rich - leaned it out and took it for a spin. Tons more power on take-off (11.8 AFR vs 8.5~9, go figure), might have (ok, did) gotten carried away on at least one launch and spun up the tires (255-55R15 street tires, nothing fancy). Got it back into the garage, did some more tweaking and when I went to back out, no reverse.

Reverse acts like neutral, no movement AT ALL. Rev engine, nothing, revs free. Here's the thing though: I have all 3 gears (starting in 1, then going to 2, then going to D) but neutral creeps forward, and in park if I rev the engine it wants to pull (engine feels loaded and body will torque a bit like a brake-stand) but doesn't go anywhere. In the past, I had it lurch on me when in park without the brake applied and revving the engine. Didn't think too much of it at the time, other than to be careful if idling in park with me under the hood, and to see if it might be a case of bad adjustment. I've had other issues to suss out first though.

I know only enough about these trans's to be dangerous, so I'm not even guessing at the cause. Could this be as 'simple' as a band adjustment? Fluid is full, red, no indications it's burnt but there was a few bubbles on the stick (more than 1-2) when I re-checked the level.

NO idea if there's a shift kit in it. Power has been lackluster until today, so it caught me off guard and I'm hoping I won't have to throw dollars into this auto because I'd planned to do a manual swap in the future (once it was actually running/driving somewhat normal.

 

[Woods74]

Pretty common on a tight rebuild front clutch pack to do the creep in neutral.

Double check your linkage at the trans, it may be tweaked.

 

[Phreakish]

Pretty common on a tight rebuild front clutch pack to do the creep in neutral.

Double check your linkage at the trans, it may be tweaked.

How do you mean tweaked? What should I check for? The shift linkage moves, there's nothing binding or blocking.

The kickdown linkage moves freely and maxes out at WOT also with no binding.

Should I start by adjusting the band? Would this cause reverse to not work?

 

[Woods74]

I mean, downstairs make sure that 'neutral' is REALLY 'neutral' and not 1/3 reverse or drive. Just had this problem. Was driving in neutral, till I found out my linkage was pushing and not riding the 'groove' for each gear.

 

[Phreakish]

I mean, downstairs make sure that 'neutral' is REALLY 'neutral' and not 1/3 reverse or drive. Just had this problem. Was driving in neutral, till I found out my linkage was pushing and not riding the 'groove' for each gear.

I'll put it on the checklist. Thanks.

 

[DusterW2]

After reading your description and the fact you have an Automatic valvebody, ALL forward gears operate OK. If Reverse is not working and 3rd is OK, the low/rev band sounds suspect. Have to remove the pan to inspect. Could have bent the spring retainer and the piston is hanging down. If the lip seal is not sealing pressure, it could explain why your shifts are soft. A tight forward clutch (Drum with input shaft) will cause creep in Neutral. If piston is cocked in bore it could cause the trans to work fine in ALL forward gears, and reverse (locked up), neutral, park to feel like it wants to drive forward because the forward clutch is applied at all times. Either way, the pan needs to be removed to inspect the low/rev band servo.

 

[AJ/FormS]

^^what Duster said

 

[Phreakish]

After reading your description and the fact you have an Automatic valvebody, ALL forward gears operate OK. If Reverse is not working and 3rd is OK, the low/rev band sounds suspect. Have to remove the pan to inspect. Could have bent the spring retainer and the piston is hanging down. If the lip seal is not sealing pressure, it could explain why your shifts are soft. A tight forward clutch (Drum with input shaft) will cause creep in Neutral. If piston is cocked in bore it could cause the trans to work fine in ALL forward gears, and reverse (locked up), neutral, park to feel like it wants to drive forward because the forward clutch is applied at all times. Either way, the pan needs to be removed to inspect the low/rev band servo.

So a leaking servo or cocked piston can explain it wanting to move forward all the time?

Got the pan off and VB out, so far nothing looks blown up.

Looking at the servo, to get the piston out will require the tail housing to come off, right?

 

[AJ/FormS]

No.
The pivot pin can stay in the arm. You just back off the adjuster, and flip out the strut. But you shouldnt have to go that far.If the apply arm is centered on the piston its probably fine. Grab the L/R band and attempt to rotate it around the drum. If its a single-wrap band and rotates more than about 1/2 inch, it may have spit out the strut. But you said everything looks fine, so it may just need adjusting. But your 72 teener,should have a double-wrap band. On these the band anchors are part of the band and cannot be spit out, so we go straight to adjusting. And you might as well do the front band too.

With the VB off, and the bands adjusted, its time to do an air pressure test.Between the two servos is another pocket for the accumulator.Around its perimeter are a number of holes, some threaded, some not.There are two round non-threaded holes. These are the band apply passages. the front-most goes to the front band, and the rear-most goes to the rear. You will need to pressurize those with a quick blast of about 80 psi shop air, using a rubber tipped blowgun. You will be watching the servos to see them clamping the bands. And releasing. Try it several times to be satisfied that they're working.
Then up along the front pan-rail next to the bellhouse, are another series of holes and slots. The two long slots go to the pump. The next two non-threaded holes go to the clutch-packs. The first one,nearest the pump slots, goes to the front clutch. The second goes to the rear clutch. Give each of those a full 2 or 3 second blast with about 80psi, and listen for escaping air. Then release. Repeat several times. After several applications, you will begin to get an idea of the sounds, and the movements, they make. They should both be doing the same little dance on application and making a nice clucking noise, with no escaping air sounds. The pistons that you are energizing,only move about .050 to .100 inch, and its impossible to know how far they are moving, in the assembled state. But if one clutch (the rear one) is packed up,(And it sounds kinda like it is) it likely wont be making the same noise nor the dance. So, be observant.
If a pack is just worn out, it will make the same noise and dance. If a lip-seal is gone it will leak air.

I tried to figure out a way to test for a packed up rear clutch, but came up with nothing.

 

[Phreakish]

Well, I'm impatient and how have the tail shaft off and the servo apart and piston off. I couldn't see any way that lever was going to move out of the way enough to let the piston out.

The piston isn't/wasn't stuck and shows no obvious signs of damage. No cracks, seal is intact.

It is definitely the double wrap band and I can see the anchor firm against the case. The lever has some play, and the band will move a bit but then tightens up (hand pressure). Same with the front band.

Guess I can be satisfied that my servo piston is A-OK...

I'll do the test you describe and see what there is to see.

 

[AJ/FormS]

Wow, that was fast!
The air pressure test would have netted the same result.
The FSMs list many different band adjustments, for different applications. I have found that about a quarter of an inch of servo travel seems to work well. I think they make it out to be way more complicated than it needs to be.

 

[Phreakish]

I get 'thunks' with both clutches, and a little 'thunk' when I remove the air.

I grabbed the output shaft and spun it by hand while playing with things, and notice I CANNOT turn the output shaft if I push (index finger, maybe 20 lbs) on the reverse band. No idea if that means anything. I tried a few times, and at one point I was able to hold the reverse band and the hub just ahead of the reverse drum spun the opposite way, but then it seemed to 'lock up' again. Again, no idea if that's significant.

 

[Phreakish]

Wow, that was fast!

Pays to have a lift in the shop attached to your office ;)

 

[Phreakish]

Well, it's out now. Parts are on their way. Figure one way or another something inside has to be broken for it to work and then not... At least I'll know the trans is 'fresh' by the time its back in, and I learned it's got a 9.5" PTC converter, all I knew before was that it was "3500 stall". Hopefully I'll learn what cam is in it at some point too.

 

[AJ/FormS]

I woulda pulled it too. The signs are all there. Proving stuff just delays the inevitable.

Yeah so if you're a first timer, take pics. Especially note how the over-running clutch goes together.I almost always put new springs in there. There are several ways to put those springs in there, only one of which is correct. If you're sharp you can figure it out, but its a whole bunch easier to follow a pic. The rest is easy if you take it apart as sub-assemblies.

 

[Phreakish]

I woulda pulled it too. The signs are all there. Proving stuff just delays the inevitable.

Yeah so if you're a first timer, take pics. Especially note how the over-running clutch goes together.I almost always put new springs in there. There are several ways to put those springs in there, only one of which is correct. If you're sharp you can figure it out, but its a whole bunch easier to follow a pic. The rest is easy if you take it apart as sub-assemblies.

Definite first timer, but not my first time in a complicated piece of equipment.

That was my line of thinking: something is broken, and I'm not going to assume it fixed itself after removing a few bolts and blowing some air. Even if it did, it would be on borrowed time. Everything I've found shows a bone stock trans that's been drag raced a bit, so it will be interesting to see what I find.

 

[Woods74]

Cool bro, good idea, I did the same thing with mine. Wittrans will have all the extra parts you need.

 

[Phreakish]

Yanked the pump and clutch packs today. Two steels welded together in the rear clutch. It's actually a relief! I would have hated to find 'nothing' wrong and be wondering WTF to do.

Once my parts arrive it should be a snap to get this thing back together. Far simpler than I was expecting. It's also been gone through more recently than I imagined after looking closer. The only thing with actual wear on it are these clutches. I should have known it would be a problem when the guy I bought it from pointed at the kickdown and said "yeah that wasn't even bolted on when I put the new carb on, figured it should be attached to something". d'oh!

 

[TrailBeast]

Yanked the pump and clutch packs today. Two steels welded together in the rear clutch. It's actually a relief! I would have hated to find 'nothing' wrong and be wondering WTF to do.

Once my parts arrive it should be a snap to get this thing back together. Far simpler than I was expecting. It's also been gone through more recently than I imagined after looking closer. The only thing with actual wear on it are these clutches. I should have known it would be a problem when the guy I bought it from pointed at the kickdown and said "yeah that wasn't even bolted on when I put the new carb on, figured it should be attached to something". d'oh!

Two steels or two plates (as steel and a clutch disc with the material burned off) welded together?

Should be the latter, but it doesn't make any difference if you are rebuilding it anyway
Just curious is all.

 

[AJ/FormS]

Two steels shouldnt be running side by side. But even if they were its no biggie. They will just act like one. Sometimes, you just have to put that last one in there to take up space.
Again, two same steels,back to back, will not cause your problem..

But if those two welded ones are not the same(as TB suggests), and they were in the forward-drum(rear clutch), then you will have this problem.

 

[Phreakish]

Should have said two steels welded together BY a clutch. Had to hammer my pocket knife between them to split them apart. Literally a hammer, too; not just pried apart.

They were in the forward (rear) clutch pack, I haven't taken the other set apart yet - my kit won't be here until monday so I'm waiting for it to be on-hand before I mix a bunch of parts together on my bench! I didn't bother with looking into the direct clutch, because I wouldn't (shouldn't) have still had all three gears if it was that one. I'm sure they're toast too, but probably not quite as bad.

 

[AJ/FormS]

So the two steels were the same outside lugs, and no inside splines?

The thing I'm trying to figure out is this; the lined plates are a steel plate with friction materials bonded to it. So when the material burns off you are left with the sorta naked steel plate. but its a different steel plate from the non-lined steel plates. The non-lined steels have outside lugs,all around the perimeter . The lined plates have splines all along the inside diameter.
For the life of me I cant figure out how 2 exact same steel plates can become welded together.

 

[Phreakish]

So the two steels were the same outside lugs, and no inside splines?

The thing I'm trying to figure out is this; the lined plates are a steel plate with friction materials bonded to it. So when the material burns off you are left with the sorta naked steel plate. but its a different steel plate from the non-lined steel plates. The non-lined steels have outside lugs,all around the perimeter . The lined plates have splines all along the inside diameter.
For the life of me I cant figure out how 2 exact same steel plates can become welded together.

It went like this:
Steel/clutch/steel.

The clutch in the center was welded to both steels, thereby 'welding' the two steels together. There were teeth inside and out on the 'weldment' within the pack. Bit more clear? They weren't just two steels, I just assumed that the only thing that could 'weld' these two steels together was the clutch (friction) in between them and so omitted it in my previous post.

I've never been in an auto trans before, but I've played with plenty of wet clutches - I get lined vs non-lined. The lined part was no longer lined. Kaput, toast, crispy, burnt, scorched, galled, trashed, destroyed... but not lined (any longer) ;)

 

[AJ/FormS]

All right. Now I get it.

Yeah so thats the problem right there. Now, the why of it.
Guess we'll wait til you get the piston out.

 

[Phreakish]

All right. Now I get it.

Yeah so thats the problem right there. Now, the why of it.
Guess we'll wait til you get the piston out.

Piston looks fine. I think the PO ran it with the TV rod disconnected (by his words). Wasn't sure how much or how long when I bought it, so I didn't worry too much since it drove.. Turns out I should have worried.