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

Registered: 09/22/03
Posts: 370
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: 18764
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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#2383485 - 10/07/17 03:00 PM Re: 727 not upshifting, wierd pressures [Re: John_Kunkel]
jensenguy Offline
enthusiast

Registered: 09/22/03
Posts: 370
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: 18764
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: 370
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: 370
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: 370
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: 18764
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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