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#2383193 - 10/06/17 08:59 PM 727 not upshifting, wierd pressures
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
I'm just getting back into a Transmission that I rebuilt years ago, and didn't want to upshift afterwards. Been sitting 5? years. I seem to recall I was not getting any governor pressure at the time.

I took the extension housing off, and sure enough the valve was stuck fast in the governor. I took it all apart and cleaned it up, no debris to speak of inside. Moves freely, put it all back together.

So now, I'm getting into second gear in drive (Can't tell if it is a incredibly soft upshift or starting in second) But not third. I'm doing this on Jack stands so that may be affecting, but getting to 3000 rpm no upshift.

I check my line pressure in Drive at 1000rpm, (again not sure if it is in 1st or second at this point) and see about 100psi line pressure with the thottle lever all the way forward. When I move it all the way back it drops to 85psi or so. I'm guessing this is an internal leak somewhere?

I'm planning on checking Gov. pressure as well, once things cool down.


Edited by jensenguy (10/06/17 09:03 PM)

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#2383292 - 10/07/17 01:45 AM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 18883
Loc: Rio Linda, CA
Originally Posted By jensenguy
I'm doing this on Jack stands so that may be affecting,


Jack stands are the absolute worst place to test a transmission's performance. Put it on the ground and check it.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#2383485 - 10/07/17 03:00 PM Re: 727 not upshifting, wierd pressures [Re: John_Kunkel]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
Check.

Test Drive kind of confirms what I'm thinking.

Stayed in 1st a really long time, wound up to 3000rpm, lightest throttle, backed off and finally got into second. No upshift to third, again went to 3000rpm about 40 mph.

Slowing down to a stop, no downshift felt. Confirmed, started off in second. Eventually found first again but not regularly downshifting.

When checking Governor pressure on the jack stands, I did see pressure going up with speed - maybe 15-20psi at 40mph. But I did notice some pressure at full stop in drive, hard to say but maybe 5psi. I know thats not correct - and probably explains not downshifting - but what about upshifting?

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#2383495 - 10/07/17 03:34 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 18883
Loc: Rio Linda, CA

Disconnect the TP linkage at the trans lever and see if it shifts through all gears and downshifts at a stop. If it does, the linkage adjustment/installation is wrong.

Which carb? If aftermarket does it have the correct Mopar throttle lever extension?
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#2383540 - 10/07/17 05:31 PM Re: 727 not upshifting, wierd pressures [Re: John_Kunkel]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
Alright, I disconnected the throttle linkage at the trans - still not seeing 3rd gear. I think I actually started out in second this time right off the bat. I could manually hold it in first and upshift to second though.

Don't know much about the linkage / brackets, though I don't think it was correct - I could see the rod contacting the back of the head. Though unfortunately eliminating it did not solve my problem.

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#2383922 - 10/08/17 01:29 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
I did some more line pressure tests, with the trans linkage removed. (My previous numbers were pretty different) At full forward, at idle I was seeing maybe 40 psi. Halfway back 50, all the way back 70. At 2000 rpm I was seeing 85 psi all the way forward, Halfway back 100, and all the way back 120.

The one thing I noticed were these numbers were very inconsistent. When I first shifted into D, I got closer to 70 or 80 psi at idle, then it eventually got back. The pressures seemed to surge up and down as I accelerated. After going at 2000 rpm and then dropping back to idle - I saw my pressures drop all the way to 30psi before recovering.

I also have a question about the physical movement of the throttle lever on the trans. It feels smooth and even spring pressure with the car off. When I go into Drive, the lever actually moves a little easier for the first 80% of travel or so. Then the last 20% is really stiff. It moves and returns but with about 10 times the pressure on it. Should it have that for the entire movement?

Thanks again.

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#2384048 - 10/08/17 05:02 PM Re: 727 Governor pressures [Re: jensenguy]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
Redid the test on Governor pressure:

Seemed to be closer to 0psi at rest - maybe a couple psi.

Again inconsistent numbers like the line pressure.

Could get 10, 15, 20 psi matching mph at least close to. Only saw as high as 25psi, then drops off. Went as high as 45mph, and stayed around 20psi. The pressure was not consistently following at lower speeds either.

What else affects governor pressure besides the governor itself and the sealing rings? I did not replace the sealing rings, though they weren't visibly worn or broken.

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#2384062 - 10/08/17 05:40 PM Re: 727 Governor pressures [Re: jensenguy]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 18883
Loc: Rio Linda, CA

At a dead stop 2 psi governor pressure at idle in Drive is considered the max allowable.

Other than sticky valves/weights, the sealing rings are usually the source of governor pressure woes.

The throttle lever movement sounds normal; moving the lever aft compresses a spring so the movement would be expected to increase and, near the end of travel, you're in the kickdown detent so the lever resistance increases.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#2392030 - 10/23/17 07:16 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
Alright, had a chance to get back into this transmission - I took apart the governor and it was stuck again. I cleaned it up more thoroughly this time and replaced the sealing rings.

On retesting it, I'm getting much better governor pressures - getting as high as 45-50psi at 45mph or so, and consistent movement. 0psi at rest. But, still not getting 3rd gear.

However, in pulling the pan I found a mess of clutch material. I know where I am headed next, but I still want to diagnose this, and not just replace parts without understanding what happened.

I am going to air check the clutches and reinspect the valve body next. What else can I look for here before pulling it out of the vehicle? My understanding is this is most likely a front clutch issue right? If that had failed wouldn't I get neutral after a 2-3 shift rather than just stay in 2nd?

Thanks!

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#2392451 - 10/24/17 03:51 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 18883
Loc: Rio Linda, CA

Yes, if the front clutch were inop the trans would drop to 1st gear as soon as the band releases on the 2-3 shift. Starting to sound like a stuck 2-3 shift valve in the valve body.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#2393105 - 10/25/17 07:55 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
cudaman1969 Offline
master

Registered: 01/25/04
Posts: 3741
Loc: fredericksburg,va
Got basically same problem in buddy's trans, first time I found the valve body full of dirt and junk. Put another vb in and still no up shift, second time apart front clutches burnt. Let us know all what you find please. Trans was a new rebuild supposely.


Edited by cudaman1969 (10/27/17 03:01 PM)

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#2393839 - 10/27/17 01:15 PM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 372
Loc: Ohio
Alright, well I found 3rd gear.. Even cruised to the gas station.

It's still not shifting correctly however, and maybe that will change with some exercise. I had to hold in 2nd at about 3400 rpm (50mph) for a second or two before the shift happened. After that it held 3rd gear down to a reasonable speed, and didn't seem like it was slipping or anything. The other thing I noticed was it didn't want to shift back into 1st at a stop. The last several starts I made were in 2nd gear.

What I had found was the valve body was full of gunk. It had one of those brass filters and I learned the hard way not to use those. The 2-3 valve was stuck fast along with some other valves difficult to get moving.

There is still the question of where all this junk in the pan came from.. I had some concerns with the kickdown linkage, so I replaced it, maybe that caused a lot of wear. Or could the governor being stuck have caused a loss of pressure leading to this?

Thanks for your help John, I have learned a lot.

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#2395270 - 10/30/17 09:27 AM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
moparx Offline
master

Registered: 09/03/03
Posts: 7995
Loc: north of coder
it is a good idea to install a magnet in the pan to catch anything that will stick to it during normal use. that helps a lot in keeping stuff out of the valve body.
beer

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#2395913 - 10/31/17 07:59 AM Re: 727 not upshifting, wierd pressures [Re: jensenguy]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 8950
Loc: in a cattle trailer down by th...
Well, if there is nothing obvious in the trans then the debris is most likely coming from the converter and cooler.
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W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67 with a broken converter hub. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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