727 no 3rd gear

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ClassicSnap

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Afternoon all,

727 trans, no upshift to 3rd. Before anyone chimes in and says "Adjust linkage or stuck valve doohickey", this is what I've done.

Have adjusted all linkage, no change. As a test, I Unhooked linkage directly from the trans (yes I know, don't drive fast or for a long distance while like this). No change, still only 1-2 and 2-1 whether going manually or plop into D and go.

Changed out valve body, no change. - both valve bodies are stock forward pattern.

Reverse is as strong as a bull. It's not skipping a gear from 1-3 or 3-1, just no 3 at all

All bands, internal and external,have been adjusted correctly to the right spec (Multiple times for good measure) No change.

Filter has been changed, along with gasket.

Have shifted from N to D and D to N multiple times to see if I can get anything to shake loose.

Only thing that comes to mind is a stuck governor.

Anyone else had this issue whether it's a 727 or 904?

Thoughts?
 
Gov issue, if it has rev. Direct clutch is ok ,changing v/ b eliminates stuck shift valve. Gov is all that's left
 
If it's the Governor, that's out of my range of ability as I'd be working on it laying on my back - no thanks. LOL.
 
Don't drive it too far until it's fixed...

I lost 3rd gear once while on the highway and ended up pushing it too hard and over revved it and dropped a valve which then put a piston through the side of the block... :BangHead:
 
If the 1-2 shift works correctly, it can't be the governor. If the 1-2 shift is at a very high rpm (roadspeed actually), then it could be the wrong gov weight for the rear gear.
If the gov flyweight is AWOL then the upshift would never occur, and worse is the pump would be spewing oil into the tailhouse, and all pressures would be reduced, possibly to the point of slipping stuff.
If the gov is stuck, there's a good chance that the 1-2 still would not occur, but at least it wouldn't be spewing oil,lol.
I offer only that ball #3 is missing. This would prevent the front clutch from energizing,and that would prevent the band from de-energizing. But on two valve bodies? I doubt it,lol. But I got nothing else. This #3 ball is only used in reverse to prevent a small hydraulic pressure loss at the 2-3 shift valve; and then in third, to prevent a total dumping of fluid at the manual valve.
So then the air-pressure test is the go-to.But you say she's OK;SO;

But I noticed in the flow chart that if the shuttle valve was stuck in the rearmost position it would dump the governor pressure and thus no upshifts could occur,at all.And I have no idea how this could occur.SO;

Perhaps the governor pressure just never gets high enough to trip the 2-3 shift valve,as in; insufficient driveshaft rpm, or the line pressure is set too high, or the wrong spring installed on that 2-3 valve. But again,at least one of those, maybe two, would have to be wrong on both VBs. SO;
I guess the governor pressure test is in order. There is a port just under the speed-o gear and forward. You'll probably want to see over 55psi to trip the shift.If it gets to 75psi and still no shift, probably the line pressure is set too high. Or the TV is stuck in full on.

In case you don't know; one of the jobs of throttle pressure is to delay the shift-command coming from the governor. And you the driver can vary the throttle pressure with the gas pedal, and so decide when the trans is to shift. But the throttle pressure is a function of the line-pressure. If you crank up the line-pressure, the TP automatically goes up,too. But the gov. pressure is a function of drive shaft rpm, and the cranked up line pressure does not affect it to nearly the same degree. This is why the the upshift rpms change when thye LP is changed. So,yes, it is possible that when you really crank up the LP, you may get the gov.pressure so far outta whack that the 2-3 shift might be jacked to a very high roadspeed. The solution to that is to increase the gov pressure with a change in the flyweight. This same change must be made when jumping 2 or 3 sizes in rear gear, cuz the pressures get outta sync. The other option is to dial back the line pressure.
So at this point I think a governor pressure test is the thing to do.
 
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The 1-2 shift is what I would call at normal roadspeed, approx 15mph on light throttle.

I think the best bet at this point is to take it to a pro to do adjustments, further testing and possible part replacemts etc. I know my limitations. I would rather have pro do it the right way quickly and efficiently rather than me stumbling my way through, buying extra tools lol. I'm an IT pro, give me a keyboard and a mouse and I'll make your computer do backflips BUT dealing with line pressures in different areas of the Black Magic Voodoo Box of eternal springs and balls, I'll pass.!

Almost wants to make me run manual valve body LOL

Thank you for all the info, appreciate it :)
 
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Ok, I'll give this a shot. Many years ago I had this same problem on 2 different trannys. Sb 727 1-2 shift fine , reverse fine. Turned out it was the inner lip seal in the front drum. I know I know had me stumped for quite awhile. Tranny number 2. Bb727 in a truck. 1 of the 2 sealing rings on the rear of the front pump broke, losing pressure or I guess not being able to hold the pressure.these were my findings after many hours of head scratching and conferring with other wise men Kim
 
After reading that info Kimmer, I think I'm just inclined to tell them to rebuild it anyways as I'm sure there could be more labor involved diagnosing something out of the ordinary than just pull, rebuild and put it back.
 
oldkimmer said:
Ok, I'll give this a shot. Many years ago I had this same problem on 2 different trannys. Sb 727 1-2 shift fine , reverse fine. Turned out it was the inner lip seal in the front drum. I know I know had me stumped for quite awhile. Tranny number 2. Bb727 in a truck. 1 of the 2 sealing rings on the rear of the front pump broke, losing pressure or I guess not being able to hold the pressure.these were my findings after many hours of head scratching and conferring with other wise men Kim
Click to expand...
That would dump pressure in the same circuit as would a missing #3 ball or stuck shuttle. And is a much more plausible possibility. I jumped to the conclusion that this was a recent rebuild. Good call Kim

Manual valve body....in a DD/streeter.....
I tried that for a while,back in the late 70s;with a TRANSGO kit .At that time all three kits came in the same box,namely TFI/TFII/TFIII, and you could choose whichever one you wanted, and even upgrade as you went. You just couldn't go back from II to I on account of some of the mods were not reversible. But from II to III was reversible.
At first it was a lot of fun. But after the summer was over, I flipped that plate (TFIII) over and went back to Semi-auto (TFII). The only difference in the kit was now when I put it into D, it would shift by itself, allbeit at slightly higher rpm/speed and harshness. I was OK with that, cuz I could still manually shift it up/down, at any rpm.
And I was no longer "forced" to shift manually, with an engine that could not pull third gear from a standstill, even with a 2800TC,lol.Well it could but, man getting moving was pitiful.
 
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So question for AJ and Kimmer, would this need to be pointed out to the rebuilder, or would this essentially be part of a standard rebuild? Sorry for such a newbie question, never had to deal with a trans issue on this scale.

Thank you both.
 
A rebuild would replace all the lipseals, and seal-rings. Problem solved. And the rebuilder would spot a missing or swapped ball in a heartbeat; that's what they do, and they look for stuff like that.

But, one thing you can do, is have someone check the gov. pressure prior to pulling it down.This is very easy to do. It could be a cheap easy fix. Governors have been known to fall apart.
While lip-seals usually do not blow out catastrophically,and cast seal-rings I have seen go 200,000 miles and more;but, Kims experiences show that failures do happen.
 
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I would talk to a few guys on ur area that may be able to recommend a good mopar tranny shop. I would tell the builder of the issues ur having even though he should spot anything out of the ordinary.u can ask the builder if he found the problem or is at the very least he is fairly confident it's cured. My experiance with a stuck shuttle valve is a little harder upshift. I personally do not think u have a governor problem. Kim
 
Shall do Kimmer. I take it from your experience that diagnosing a symptom that can have various underlying issues is the challenge. Especially with a trans that has a crazy amount of components. That's a reason I stated what I knew first hand in the first post. Takes a lot out of the guessing game as you can't see the trans in person. :)
 
So was this problem ever answered? I ask because we are trying to figure out a very similar issue right now. All the same issue, only it already has a forward manual valve body in it. Exactly the same otherwise. NO 3RD GEAR. Monster 1 and 2 and reverse, but no 3rd gear from any RPM or MPH.
 
oldkimmer said:
POD, does urs have a TF-3 kit or what MVB is it. Was ur trans built with or u just installed ur. Kim
Click to expand...
How are you Kim? This is Steve P. from dc.com.
The tranny I am trying to help out with here started as a full race tranny with a brake. It is now being used on the street, but the trans brake VB has been removed and a new forward manual VB installed.
 
Hi Steve, I haven’t been over to dc. Com for a long time. So was this tranny rebuilt then the forward pattern put in or just the valvebodies swapped in. Kim. U can message me.
 
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