727 3rd gear feels more like a down shift

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What was the band set at b4 u adjusted it. U absolutely have to have the 5.0 lever in the trans when u run a rmvb. It's adjustment is 11/2 turns. If u adj yes to 2 1/4,that tells me u have some other ratio. I would say the front band is on its way out as it will surely be burned up a little from the wrong adjustment.Ibpresume it was fine b4 u adjusted the front band. Kim
 
oldkimmer said:
What was the band set at b4 u adjusted it. U absolutely have to have the 5.0 lever in the trans when u run a rmvb. It's adjustment is 11/2 turns. If u adj yes to 2 1/4,that tells me u have some other ratio. I would say the front band is on its way out as it will surely be burned up a little from the wrong adjustment.Ibpresume it was fine b4 u adjusted the front band. Kim
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It has 4.2 lever in it and has always been at 2 1/4 turns. I readjusted after it started acting up and it made no difference.
 
When the car slows down, it may be cuz the tranny is trying to engage two gears at once, namely second and third. This is not supposed to be possible, so one of them is out of time. Either the second is late releasing, or third is early engaging. IMO, this would have to be a mechanical issue, broken slip-rings, or a busted VB or even a shattered second gear servo piston. Honestly I don't know how second could stay engaged.
Oh maybe I do;
If the servo retainer system failed and the servo popped out far enough to get cocked ... oh wait that's not it either, then it would also suck power big time in first gear, as two gears would still be engaged, but second and first this time.
Nope, I'm stumped.
But the air-pressure test should help get to the bottom of it.
 
oldkimmer said:
1 thing I've seen b4 was the shift linkage/cable got out of adjustment. Kim
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Winner Winner!!
Got under it and went through the shifter adjustment before I got too deep into it. Found the "throw" of the cable as erratic. Found in the shifter side of the cable the eye was too big so the first part shift was not moving the cable because of the slop in the eyelet. Made a bushing to take out the slop and the problem is solved.
Thanks to everyone the help.
 
oldkimmer said:
1 thing I've seen b4 was the shift linkage/cable got out of adjustment. Kim
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I was thinking about that too, but if the manual valve was between two gears,nothing happens. Plus the second gear oil-circuit is pressurized; in both second and third. It's just that when the manual valve calls for third oil pressure is supposed to simultaneously force the second gear servo piston to the park position which relaxes the band.

Oh I think I know whats going on; Maybe the hi-drum piston seal blew out. That would cause the oil pressure in the hi-drum to be lower than in the servo. The servo might remain engaged while the hi-drum slips. Yeah that might do it. It's the best I got, and the air-pressure test will prove it.
 
Two gears engaged at once equals a locked up transmission.....unless a band or clutch is slipping. Either way it should get opened up and investigated.

To the OP, have you talked to Cope? Does the vb need kickdown linkage?
 
Glad you got it fixed so easy Dave. I've had cables get out of adjustment before but never did what yours did but that's how it goes with these mechanical marvels
 
fishy68 said:
Glad you got it fixed so easy Dave. I've had cables get out of adjustment before but never did what yours did but that's how it goes with these mechanical marvels
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Easy once I figured it out. Funny how that works...
Got lucky and had a cable hanging on the wall and notice how much smaller the eye on it was. The one in the car measured 17/64 and the other one was 3/16. Just enough slop to not let it get all the way in gear. Doesn't seem like much but when I had someone shift and watched the lever and it wouldn't fully engage.
 
I was going through old threads in hopes of finding one that describes the trans problems that I'm experiencing and it sounds like this discussion hits the nail on the head. My issues are virtually the same.
I have a 727 with reverse manual valve body and trans brake. With my car when I shift from 2nd to 3rd gear the car slows just like the brakes are applied. The engine lugs down and if I leave it in 3rd it will stop the car. No burnt fluid smell. I race this car and it seems to grab 3rd properly when making a pass, although perhaps I'm just not noticing a lug at that time. It used to be fine and when going into 3rd it was a dead solid shift, the aluminum leaf bushings would clunk like a bugger.. The other thing is that I did have a stiff cable problem earlier in the year but was able to free it up with lubrication and by re-routing the cable. As I write this I'm wondering if maybe I still have a bit of a stiff cable and the shift valve isn't travelling the full distance when going into 3rd? Any thoughts on this anyone?
 
What happens if you step on the gas pedal?
Make sure;
this is not due to a faulty low-speed circuit,
or that the powervalve is not dumping fuel in response to low manifold vacuum,
or, if you're running the Vcan on manifold vacuum instead of ported, that the timing isn't dropping out.
All of these can reduce engine power when you don't expect it,and thus,slow the car.
Then make sure that the manual valve inside the VB is seeing what the shifter is calling for. IE synchronize the shifter to the manual valve.
So once those are eliminated, then you can look to shift overlap.
In a 727, on the 2-3 shift,there isn't supposed to be hardly any, cuz the same hydraulic circuit that engages the Direct clutch, simultaneously disengages the Second-gear band. If you've eliminated the above,then, it sounds like your trans may have a hydraulic issue.
Just to help indicate how things are; what are your trap speed and car weight?
Is this really your first post since joining, in April/2016?
 
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AJ/FormS said:
What happens if you step on the gas pedal?
Make sure;
this is not due to a faulty low-speed circuit,
or that the powervalve is not dumping fuel in response to low manifold vacuum,
or, if you're running the Vcan on manifold vacuum instead of ported, that the timing isn't dropping out.
All of these can reduce engine power when you don't expect it,and thus,slow the car.
Then make sure that the manual valve inside the VB is seeing what the shifter is calling for. IE synchronize the shifter to the manual valve.
So once those are eliminated, then you can look to shift overlap.
In a 727, on the 2-3 shift,there isn't supposed to be hardly any, cuz the same hydraulic circuit that engages the Direct clutch, simultaneously disengages the Second-gear band. If you've eliminated the above,then, it sounds like your trans may have a hydraulic issue.
Just to help indicate how things are; what are your trap speed and car weight?
Is this really your first post since joining, in April/2016?
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When I shift into 3rd it starts to work against itself and when accelerating I can feel it loading down as it tries to speed up, I've stayed in it and it has let go and then is ok but there's a problem. I wouldn't even think of doing a burnout in 3rd gear the way it is. It's got nothing to do with the engine bogging down. I can only think that 2nd gear is hanging on. It seems fine when I'm making a pass but perhaps there's the same delay and I'm not noticing the condition. From what dgibby found I hope that is my problem too. The car weighs 3600 with me, 129.87 mph @ 10.38 so far. It's my first year racing and a new car. And yes, my first post.
 
Awrigt, now I have a mental picture; nice numbers. Very nice. The trap speed calculates to around 620 crank hp, and the ET is indicating 605 hp! So that's a pretty sweet tune.
I agree with your diagnoses, but am struggling with it being OK under power.
 
AJ/FormS said:
Awrigt, now I have a mental picture; nice numbers. Very nice. The trap speed calculates to around 620 crank hp, and the ET is indicating 605 hp! So that's a pretty sweet tune.
I agree with your diagnoses, but am struggling with it being OK under power.
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Thanks for the compliment AJ. Perhaps it is still hanging on when I'm making a pass but it powers through it, I'm not sure. I did have a shift cable problem early in the year, it got too close to the header and burnt. There was none available at the time this happened but I was able to free it up and re-use it. Perhaps it is still a bit stiff and the shift spool valve is not making it's full detent? I will be checking that. At this point I'm hopeful it's just an adjustment like dgibby found.
The trans came with the car but it was supposed to be fresh, built at Protrans, fully rollerized and 4 gear planetaries, although I haven't had it apart to confirm all of this.
I visit this site frequently and also a member of FBBO. I was in Moparts forum searching for threads on this sort of problem and came across one where it said that in FABO there's some expert transmission members here so I came looking and ended up here.
My dyno numbers are 720HP/677TQ,
 
So thinking more about dgibby's problem and how a slight adjustment fixed him up I had to scoot under the car and check mine out. First of all, that damned trans blanket is the worst SOB a guy could work around, although it's for my own good so.. Anyways I got to checking the adjustment over and I did find that my shift arm was loose and moving on the shaft coming up from the valve body. I was able to tighten it and it's solid now. The cable was then out of adjustment 2 turns to drop straight in when in high gear on both the shifter and transmission, so that may be the issue. Perhaps the shift spool valve was just not completely completing the travel, which was feeding both second and direct? Does that sound possible?
Wish there was as much space as it looks like.
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No the hydraulic circuit on the 2-3 doesn't work like that.
My guess is the KD servo is nor backing up. Could be mechanical, could be hydraulic.
It could also be low pump pressure at low-rpm, but I doubt that.
So it looks like a pressure test is in order.You'll need a factory FSM to figure out what to hook where and what the numbers should be. A Torqueflite hydraulic flow chart will be very helpful.
I assume your governor circuit has been defeated, and the VB is a full manual shift, meaning that there is no longer an automatic upshift mode.

In the meantime, you could try backing off the KD band adjustment. But before you do, you need to see where its at, cuz if you back it out too far, the actuator inside, falls apart and then you have to take the pan off to re-install it. That sux,lol. I don't know what the max looseness speck might be, but I'll guess you'd be Ok at up to 5 turns from snug.The normal adjustment is 2 to 2.5 turns from snug.
 
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AJ/FormS said:
No the hydraulic circuit on the 2-3 doesn't work like that.
My guess is the KD servo is nor backing up. Could be mechanical, could be hydraulic.
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Ok that's good to know just the same. What I'll do in the days ahead is change out that cable and run it through the gears to see how it shifts. If there's no change I'll put my transmission hat on once my garage and I are thru bodyshop mode. Appreciate your input AJ.
 
AJ/FormS said:
Awrigt, now I have a mental picture; nice numbers. Very nice. The trap speed calculates to around 620 crank hp, and the ET is indicating 605 hp! So that's a pretty sweet tune.
I agree with your diagnoses, but am struggling with it being OK under power.
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I could be powering through the shift so not noticing it. I'm good to run a 10.0 and hoping that this fix moves me closer to the mark. Wishful thinking!
 
Good that u found that the lever was loose and not moving the manual valve all the way. Could be in 2 gears at once. With the rev manual valve body the 2nd gear band is set at 1.5 turns with the 5.0 ratio arm. Kim
 
720hp/3600#=.200 P/W which is good for 137ishMPH, at under 10; so you're right on target; good luck.

Judging by your current numbers (posts 40/41), it would seem there's room for improvement. If your foot was in the carb, the trapspeed is down some 6 or 7 mph so it could very well be that the trans is sucking up some power.
Just in case you might be thinking I know anything about racing, tho, I don't. I just read a lotta books and stuff,plus I'm old,lol. Naw, I'm just a 64 yr old street maniac, with 400ish hp.But she traps about right, going 93 in the 1/8th with no tune whatsoever. I drove to the track, ran the number, and parked it. Then spent the day in the bleachers with my 24 yr old son.Then drove home; Good times.
 
AJ/FormS said:
720hp/3600#=.200 P/W which is good for 137ishMPH, at under 10; so you're right on target; good luck.

Judging by your current numbers (posts 40/41), it would seem there's room for improvement. If your foot was in the carb, the trapspeed is down some 6 or 7 mph so it could very well be that the trans is sucking up some power.
Just in case you might be thinking I know anything about racing, tho, I don't. I just read a lotta books and stuff,plus I'm old,lol. Naw, I'm just a 64 yr old street maniac, with 400ish hp.But she traps about right, going 93 in the 1/8th with no tune whatsoever. I drove to the track, ran the number, and parked it. Then spent the day in the bleachers with my 24 yr old son.Then drove home; Good times.
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Being the first year for both the car and myself, there's been steady improvement. I expect to find a couple more tenths and a few more MPH next year. I'm good to run 10.0 so some room to play.
The car will be losing about 120 Lbs over the course of the winter, which is also going to help. Track elevation is 1800' and air has usually been around 3500 + so the guys with weather stations say.
Today I swapped out the old shift cable and that bugger was stiff overall and worse in certain spots. That along with the loose shift arm likely created the same problem that Dgibby started this thread over.
Will add some fuel to the car (drained for winter) tomorrow, up with the back wheels and run in through the gears. If it bangs into high gear then I'll know it's a fix. Before this problem started when going into 3rd it was a instant solid shift. I suspect that with the reverse manual valve body the shift cable adjustment has to be absolutely dead on otherwise a problem like this could show up. We'll find out.. Stay tuned.

New cable - routes around the right side - no more burnt cable on this Mopar.
IMG_1734.JPG
 
Mike Alexander said:
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Being the first year for both the car and myself, there's been steady improvement. I expect to find a couple more tenths and a few more MPH next year. I'm good to run 10.0 so some room to play.
The car will be losing about 120 Lbs over the course of the winter, which is also going to help. Track elevation is 1800' and air has usually been around 3500 + so the guys with weather stations say.
Today I swapped out the old shift cable and that bugger was stiff overall and worse in certain spots. That along with the loose shift arm likely created the same problem that Dgibby started this thread over.
Will add some fuel to the car (drained for winter) tomorrow, up with the back wheels and run in through the gears. If it bangs into high gear then I'll know it's a fix. Before this problem started when going into 3rd it was a instant solid shift. I suspect that with the reverse manual valve body the shift cable adjustment has to be absolutely dead on otherwise a problem like this could show up. We'll find out.. Stay tuned.

New cable - routes around the right side - no more burnt cable on this Mopar.
View attachment 1715099572
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Fired up the Mopar today and ran it through the gears. FIX! Pounds 3rd gear every time. The problem had to be a combination of the stiff cable, adjustment, and the shift arm moving a little on the valve body shaft.
My condition ended up being the same as Dgibby, who started this thread and I'm glad I came to FABO and found it.
It's obvious that when you have the reverse pattern valve body that the shift cable adjustment is correct. It's probably the shift spool valve (for lack of better term) not being exactly in it's right position must allow pressure to get somewhere that it shouldn't be. We'll know next racing season if the fix shows up on the time slip. I'm hoping it does! Thanks again!

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