727 No forward or reverse

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Bad1Cuda

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I have a project car that I have been working on for about 6 years. It has a 440 with 727 in it. It is a 1977 440 and 727. I rebuilt the 727 a couple of years ago. The car is now running. I have it on jackstands. When you put it in forward or reverse gear it does not move wheels until about 3000 rpms. I put a pressure gauge on the return line and it only reads around 2psi at 1000 rpms and around 12-15 at about 3000 rpms while in drive. I have checked and adjusted both bands. I thought maybe the tabs were broken on the pump, so I pulled the transmission this morning. Tabs are still there nothing obviously wrong with pump. Any ideas would be greatly appreciated. Fluid was checked while in neutral.
 
If you had the valve body apart during your trans rebuild did you check if the tang on the shift detent lever engaged properly in the manual valve on reassembly?
 
Checking pressure at the return line means very little other than it's pumping some fluid in the cooling circuit. First thing I'd check is the manual valve as kickdown mentioned. If it's in place pull the valve body and do some air pressure testing to see if you can locate the problem before you tear it down
 
The tang on the shift detent lever is engaged properly. This is what I have tried so far. Adjusted both kickdown band and low reverse band. Air tested Front clutch and rear clutch could hear both engaging. Air tested kickdown and low reverse servos. Adjusted line pressure and throttle pressure. After doing all of that last weekend, I refilled transmission and it still doesn't move wheels until around 3000 rpms in both forward and reverse. Removed transmission yesterday thinking it may be pump. Thanks for the speedy replies.
 
Bad1Cuda said:
The tang on the shift detent lever is engaged properly. This is what I have tried so far. Adjusted both kickdown band and low reverse band. Air tested Front clutch and rear clutch could hear both engaging. Air tested kickdown and low reverse servos. Adjusted line pressure and throttle pressure. After doing all of that last weekend, I refilled transmission and it still doesn't move wheels until around 3000 rpms in both forward and reverse. Removed transmission yesterday thinking it may be pump. Thanks for the speedy replies.
Click to expand...

How does the pump look? Pumps can get weak if the gears are worn or the pocket they sit in is scored and worn but I've never actually seen one completely quit except when the torque converter tabs break off. Even a weak pump put out enough to make it run through the gears fine when the wheels are off the ground. I'd pull the valve body apart and see if there's debris blocking the line pressure valve. In fact I'd check everything in the valve body since you said both clutches air tested ok.

What about the torque converter? Is it the correct one and known to be good (new doesn't always mean good btw). I've seen converters break internally and when that happens you lose all motion
 
I live in Phoenix Metro. There are some places that rebuild them here. Not sure where NAPA got it from. No odd noises. You can't even really feel or here it engage. Like a transmission acts when it is low on fluid.
 
The pump looks okay. No scores in the pocket and the gears look good. I agree with you on the converter. I grew up buying all our parts at NAPA. Unfortunately, the one where I live now seems to keep getting things wrong. They have given me wrong or bad parts multiple times. I bought the converter there. It was "rebuilt" by someone in town. Can a transmission shop test the convertor or pump? I have never had issues with one before. I will take your advice on pulling apart the valve body. One other factor. I rebuilt it around 5 years ago, it has been sitting with fluid in it since then without ever running. I don't know if this is causing an issue. I will replace the filter while it is out. Thanks again for your responses.
 
.............If the converter was rebuilt by a converter place they could of missed something.........is there a converter rebuilder in town or just a tranny shop, cause almost no tranny shops rebuild converters......but like fishy68 says check the vb over carefully......kim...
 
fishy68 said:
What about the torque converter? Is it the correct one and known to be good (new doesn't always mean good btw). I've seen converters break internally and when that happens you lose all motion
Click to expand...

X2, if all is as said I would have to suspect the converter.
Either the wrong spline, or broken inside.

If one knew what they were feeling, turning the direct drum with the VB off might show something. (maybe)

No odd noises?
 
I wanted to go on with this thread, not to start new one.
In my case I was accelerating slowly and suddenly car acted like it went out of gear, I could press gas pedal without any effect.

I have 727 with manual vb and Hurst shifter. Transmission goes into park and neutral, when I put it in gear and press gas pedal car moves forward a little but not enough to drive.
Also nss works, I can only start the car in Park and Neutrak
All forward and reverse gears dont work and it acts the same on every gear.
Any tips? I will probably take the trans off the car next weekend. Can it be damaged torque converter?
 
Just a question to people that know 727s well.
Is it possible that my problem is due to loose front band?
I pulled the pan off the trans (found some small metal shavings there and smelly burnt oil) and found out that front band (closer to pump) lever is very loose. I pulled the valve body off and saw that strut on the adjuster siide fell off on the valve body resulting in band completely loose.
Trans has manual valve mody with reverse pattern.

Thanks for any tips.
 
It wouldn't affect all gears for the band to be off, as it would just skip second gear and shift 1-3.
Betcha that drum is tore up under the band and some of the metal went through the pump, converter and valve body causing low pressure and slipping of the direct clutchpack.

A little metal in the pan can be normal depending on what metal it is.
If it sticks to a magnet it's not a good sign, and absolutely ANY burning of anything is a rebuild at the very least.
 
Thats what I am ready for, just the way it happened makes me think. Planned to do total rework of it in winter anyway... Still this is wierd. I mean this trans never slipped once, worked normally until this moment. No strange noises or anything like that. I was accelerating slowly in 2nd and then "ding" and no more driving, felt kinda like rolling in neutral. Kinda wierd thats all, usually there are some sings of problems comming soon but not here.
 
TrailBeast said:
It wouldn't affect all gears for the band to be off, as it would just skip second gear and shift 1-3.
Betcha that drum is tore up under the band and some of the metal went through the pump, converter and valve body causing low pressure and slipping of the direct clutchpack.

A little metal in the pan can be normal depending on what metal it is.
If it sticks to a magnet it's not a good sign, and absolutely ANY burning of anything is a rebuild at the very least.
Click to expand...

Can you recommend a rebuild kit? Wanted to overbuild it a bit so it handles my 471 for some time... As there is zero choice of this stuff in my country I need to get something from the US market.

I have no automatic option in my gearbox, its manual shift only.

Also here is a photo of my pan content...

IMG_8608.JPG
 
Also sory for lame questions, this is first "automatic" in my life ;-)
Just manuals so far...
 
Sorry to say, but that looks like band and bushing material mixed.
In any case that's quite a bit of random metal, and if it was full auto probably wouldn't even shift due to that.
It'll need a converter also since all the metal has been blown through it.
Fluid looks burned also.

I get my trans parts from a place online www.transpartsonline.com
They carry good products and have great prices.

You will need to tear that thing down and find out what hard parts need replaced, and since it's very likely you will need a front drum (where the band rides) anyway you can get a billet unit. (so it doesn't explode in a burnout and take your legs off)
A bolt in 16 roller sprag, and almost certainly a new pump.

The rest is a full rebuild kit with bushings, Kevlar or kolene clutches and bands.
Billet servo's would be a good idea.

Rinse and inspect planetary sets as well for damage.

Other than that you'll need some cleaning brushes and a good amount of solvent in a large container to wash metal out in.

OR,,,, you could buy one already built and ready to go.

WHATEVER happens, make absolutely sure the cooler lines get flushed out well or it'll all happen again in 15 min of running.
 
Just an update.
I got a full rebuild kit with red frictions and kolene steels, bolt in sprag, billet servos, new bands, new pump gears, some teflon pump rings and new thrust bearing just in case. I hope Alto is good quality.
I took the valve body off to check it out from underneath the car.
The front drum looks ok. I hope to stay with it. A friend that is bringing me parts from USA could not take more stuff for me into his bag. If it turns out that drum needs replacemen = no more driving this summer. I will need to wait around 6 weeks for it to get decent shipping price so fingers crossed...

I found a big block 727 for parts in Germany, perhaps I will need to get it if my oil pump is trash or another hard stuff broken inside the transmission.

My trans is a 73 big block 280HP model, this is what I managed to find out from the numbers on it.

Anyway I will post info on what happened when I get the trans apart.
Positive info is that I found no metalic stuff in the radiator hoses or the radiator of the trans. I guess filter did the job.
I hope its not the converter. As I wrote before, what happened was very sudden. I had no slips or stuff before. At the same time the band must have fallen off and that was what I heard.
Perhaps I lost oil pressure?
The shavings found in the pan look like bushing shavings.

If my planetary gears are damaged what should I get?
Any suggestions?
 
Unless your running a lot of power or the trans has a bazillion miles on it it's not often that the planetary sets fail in a 727. You'll probably find that your planetaries are 3 pinion design. The older 727's had 4 pinion sets. If your running over 500 hp I'd find some 4 pinion planetaries and put in it. Be warned that the big block trans you found for parts may or may not be compatible because they changed the output shaft spline angle (on the front end)a few times during the run. They also changed the front drum and pump stator a few times so you have to be careful when swapping in parts. If their the same vintage plus or minus 2 yrs. you should be fine be farther than that it may be an issue. You could have popped the seal in the rear clutch pack which would have caused no forward yet reverse would have worked. Alto are real good quality parts IMO. Make sure and change all those bushings and tighten up the planetary end play and the total end play. Do not use the factory serv manual specs, they are very sloppy. To tighten up the planetary end play you'll need some planetary shims (may only need 1 but it might take 2). To tighten up the total end play you change the front thrust washer to whatever it takes to get it down to as close to .020" as you can get it. For me, 99% of the time it's taken the thickest thrust washer available which is .102" and that usually gets it down in the .025-.035 range. If you need any parts (small or large) I'd think www.bulkpart.com would be able to ship to you. I've bought from them a lot with decent luck
 
I am running around 550 hp. Previous owner of the car did the engine and transmission swap. I am hoping that the trans was built to keep up with the motor. There are kevlar bands in it, also not stock ratio servo levers, deep pan, manual valve body etc.
Trans lasted 8 years before this happened.
Will report on findings soon.

Thanks for the tips. Damn they charge 45$ for shipping to europe in the place you recommend and the shims are 16$ ;-)
 
Having lube pressure means the pump and TC are doing something. It varies from about 5 to 30 psi

Just so you know; when reverse is selected, every other hydraulic circuit is shut down, except the L/R servo and the hi-drum(front clutch), and the pump is running wide open, unregulated. Checking the pressure at the L/R servo can see pressures of 235psi or more at 1000rpm. This will prove that the pump is working and the L/R servo is engaged.If it still does not move, I would suspect a problem in the hi-drum or stripped splines on the planetary.But since it also does not move in Manual low,(which uses the same L/R servo but uses the rear-clutch) NOR move in drive-low ( which uses the rear clutch and the over-running clutch),and the air-pressure tests were good, I would have to suspect the stripped planetary or the over-running clutch.
I would be doing a complete oil pressure test, looking for line pressure of 54 to 60psi at 1000 rpm@ oil-temp of 150 to 200*F. Line pressure should rise to near 100 by increasing the TV/KD pressure at the disconnected KD lever.
If you have these pressures, but no output, then it's back to the stripped spline idea, and complete teardown.
To me this looks like a mechanical issue,with a failure of the outputshaft to receive torque from the front end, or a failure of the TC to transmit torque from the crank in the first place.The pressure test can only prove so much, in this case.But you gotta start someplace.........
 
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Hi, here is some update:

I took the trans apart and dont see any aparent damage.
What I found out is that I already have bolt in sprag, billet drum and 4 pinion planets for front and rear.
The planetaries look great, no need to replace them.

All bushings are shut, they look pretty worn, also clutches in drums look really bad and steels are burnt.

Front and rear bands look really good, I will use new but just because I dont want to go back to it any time soon. Especially 2nd gear band looks almost new.

The pump has pretty worn rings, and the gears dont look so great, I will be replacing them with new gears.
Problem is that I do not see any obvious problems that tell me: this was your problem...

I will have my converter checked this week and see what they tell me. Perhaps this is it?
Wierd that It did not give any signs of wear before.

Any suggestions?
 
Take a good look at the sealing ring surfaces for the drums, because between that and worn bushings it can leak enough pressure to burn clutchpacks.
Also if you are referring to pump gears that don't look so great you should probably consider a whole new pump, or a least a good used one.
If the gears don't look good there is a good chance the gear to housing clearances are bad also.
 
Another update after further examination:

I see that actually rear clutch was fine apart for cracked plastic shim(still in the right place). I think it was installed like this. Steels and frictions in it were fine, not overheated, nor worn out. The only problem I found here were piston seals. They were so loose that piston was falling out of place freely.
After putting new seals its holding in place.
I will put this part of trans together after I get new shim.

I did detailed check on the pump. The case seems really fine, there were visible marks from rings in it but they are gone after some 2000 grid sand paper cleaning. There is no apparent damage to where the gears were, I see nothing there on the stator and case side. The old gears have more clearance. They move more freely than new ones that seem to have nice fit. I put the pump on the converter to see if there is any binding. Pump seems to work very smooth and nice. I will give it a shot.

The biggest problem was with front cluch assembly.
Here steels were bent from heat and frictions were totally worn out to the point where steel was s showing on like 30% of the friction surface. Also piston had really worn out seals, it fell out when positioned piston down.
There are 5 frictions in it. I set the clearance to 0,05", is that OK or too little?
I planned to set the clearace in rear cluctch assembly to about 0.03", is that ok?

Please let me know where should I check other celarance.

Thanks for the help. I hope to test the trans after rebiuld this weekend.
 
Plate clearance, I have always targeted a minimum of .010 per friction.The FSM lists the clearances as all over the place from ridiculously tight to ridiculously loose.
For the front clutch; 3discs are .036 to .086, 4 discs are .024 to .125 depending on application. See what I mean
For the rear clutch, the spec is .032 to .055 for 3 or 4 frictions.

I wouldn't be in a hurry to condemn the lip seals, as I have seen the same thing in perfectly functioning trannys.There are at least two different styles of lipseals for those and one of them in particular fits fairly loosely.
Cast rings however need to have plenty of room between the hooks, before you install them.I always prefit them.
I wouldn't reinstall the tranny until I knew why the front clutch burned up.
And you still need to figure out why no forward gears. Since the rear clutch is engaged in all forward gears, that would normally be the go-to. But since you say yours is fine; that points back to the L/R band.And since the L/R band is used for both Low and Reverse, it now becomes the Go-to item. So you will have to pay particular attention to the hydraulic circuit. Or perhaps the servo was all out of travel, due to a waaaaay out of adjustment L/R band
 
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