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Old 10-29-2011, 07:27 PM
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47RE - 727 Mystery

After over ten thousand miles on a rebuild of 47re (same thing as 727 but with an overdrive) I spent some extra cash I had on hand on a pressure gauge to monitor line pressures while driving. Nothing wrong with the tranny, just wanted an extra gauge pretty much. Plugged it into the accumulator port, only to show no pressure at anytime.

Gauge checks out fine with air pressure. There is some fluid in the clear nylon line, but very little, looks similar to what an oil pressure gauge line looks like with the engine off (oil with plenty of air in between). Then I unplugged the line to see if any fluid would come out at idle. Not one drop came out. How is this possible? This truck should not run with any line pressure? When I rebuilt the transmission, I put a blocker rod in there, is that the cause? Is there any other way to monitor line pressure?

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Old 10-29-2011, 09:08 PM
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which pressure port are you hooking in to?
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Old 10-29-2011, 09:30 PM
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The accumulator port, 2nd port back from the front.
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Old 10-29-2011, 10:12 PM
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main line should be at the pressure tap above the reverse servo port tap at the back of the case.
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Old 10-30-2011, 01:15 AM
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Nope, that port above the rear servo port is the governor pressure port. That port would read would read 0 psi at idle and rise 1 psi for each 1 mph increase in speed. Even at 100 mph, it would be fare below my mainline pressure on this transmission, which in theory should have over 115 psi at idle.

It just doesn't make any sense how the accumulator port shows ZERO line pressure and the transmission is able to move the 6,500 lbs truck at all.
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Old 10-30-2011, 08:32 AM
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Main line on the 47re is not over 115 in forward gears at idle. They run lower in the area of 65 on the low side and over 100 psi at max TV input.

Reverse will run higher at near 250 stock and higher if you install a shift modification kit. The kit depending on how the tension on the PR spring is adjusted will raise all pressures.

You mention a blocker rod. Where and why was this rod installed?

There is a port on the rear servo and front servo. Have you installed a gauge there?
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Old 10-30-2011, 08:37 AM
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Quote:
Originally Posted by 454headache
Nope, that port above the rear servo port is the governor pressure port. That port would read would read 0 psi at idle and rise 1 psi for each 1 mph increase in speed. Even at 100 mph, it would be fare below my mainline pressure on this transmission, which in theory should have over 115 psi at idle.

It just doesn't make any sense how the accumulator port shows ZERO line pressure and the transmission is able to move the 6,500 lbs truck at all.

this is not a 727. this is a 47RE and has electronic governor controls. that pressure tap i mentioned is used to set tv pressure which should also be main line.
this is from PATC, its the best i can come up with for example. http://www.transmissioncenter.net/A5...ssure_Taps.jpg
here is the paragraph that explains it:
A 518 transmission has a throttle valve cable (pressure cable), it must be hooked up and adjusted correctly. You can get the cable and brackets from a junk yard. If you have a 727 transmission now this linkage may work. The correct adjustment on the T V cable or linkage is minimum throttle pressure at minimum throttle. In other words no slack in the cable at idle and it must start to pull immediately off of idle.

here is the link to PATC, they pretty much have everything you could ask for on a 518/46,47,and 48RE.
http://www.transmissioncenter.net/do...FQtrhwodMiI3qg
the info that i put up from the site is near the bottom of the page.
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Old 10-30-2011, 10:19 AM
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The TV cable is set up correctly. Next time around I'm going to look around for a 47RH, which truly is a 727 with an overdrive. The 727 was put in subject because I thought the 47RE and 727 had a lot in common and more people would be familiar with 727's and where to tap them for pressure.

I have not checked the pressures at the other ports yet. Who knows, they might all be 0. The front servo port should only show pressure in 3rd gear or up to 3rd gear? If it shows pressures in D up to 3rd, then I'll use that for my pressure gauge.

The blocker rod is in the accumulator port. I built the thing over a year ago, so my memory is a bit fuzzy, but I'm 99% the rod is behind the accumulator, part of the reason for strong and hard shifts. The mainline pressures should be very high as this is behind a fairly strong diesel engine and there are no signs of slippage or flares. The mainline pressure ranges should be 115-140 idle and 195-205 WOT. Heck, I think in 2000 Dodge even set the factory idle pressure at 95 in order to help these 47re's live a bit longer behind an engine that they were never intended for.
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Old 10-30-2011, 10:35 AM
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Quote:
Originally Posted by 454headache
The TV cable is set up correctly. Next time around I'm going to look around for a 47RH, which truly is a 727 with an overdrive. The 727 was put in subject because I thought the 47RE and 727 had a lot in common and more people would be familiar with 727's and where to tap them for pressure.

I have not checked the pressures at the other ports yet. Who knows, they might all be 0. The front servo port should only show pressure in 3rd gear or up to 3rd gear? If it shows pressures in D up to 3rd, then I'll use that for my pressure gauge.

The blocker rod is in the accumulator port. I built the thing over a year ago, so my memory is a bit fuzzy, but I'm 99% the rod is behind the accumulator, part of the reason for strong and hard shifts. The mainline pressures should be very high as this is behind a fairly strong diesel engine and there are no signs of slippage or flares. The mainline pressure ranges should be 115-140 idle and 195-205 WOT. Heck, I think in 2000 Dodge even set the factory idle pressure at 95 in order to help these 47re's live a bit longer behind an engine that they were never intended for.
Stock pressures run a bit lower in forward gears, even on the diesels. A trans with a shift kit will run higher. I build them and dyno them on a regular basis.

Since you dont remember what you blocked, it may stop the oil flow if the pin was solid.

If you used a TransGo kit, they do not block the acc feed. The pin they provide has a hole in it to restrict flow. there would still be a pressure reading. I hook 4 gauges to the trans during a dyno session and I see pressure out of the center port.

With a diesel that has been turned up, some billet parts are suggested. You also have to watch the main pressures to avoid damage to the forward clutch pack if it is setup a little loose. the piston will over center the bevel spring and tear up stuff.

Shifts with the converter clutch applied usually results in a broken input shaft, even the billet HD shafts are broken.

The internals of the 47re or rh or even the 48re are similar in design to the 727 trans with differences. The controls are greatly different.

The late valve bodies are subject to more wear in the valve bores than the early 3 speed valve bodys
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Old 10-30-2011, 02:57 PM
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It has a Fairbanks shift kit in it. I set it up to their "Competition" specs, which includes the accumulator blocker rod. The blocker rod for the accumulator stops it's movement but it should block all fluid flow, at least I would think.

Then a gain, I do not really understand valvebody modifications, so maybe some step in the shift kit would block fluid flow to the accumulator in order to complement the blocker rod? If that's the case, should I hook up the gauge to the front servo port or are mainline pressures only seen their in 3rd gear?

The only ports that I know are-

Front Servo- sees pressure in D but only in 3rd
Accumulator- sees pressure all the time
Rear Servo- sees pressure in R and 1
Gov Port- sees pressure 1 psi per mph (useless with my 300 psi gauge)

OD Port (on driver's side)- sees pressure in 4th only



The trans has a billet input, billet clutch baskets, billet pistons and better seals to help with leaks, a couple extra clutches and steels throughout. It's built as well as a transmission rookie as myself could build it. I have no complaints other than figuring out a place to monitor pressures and the ever-present stupid pan fluid slight weep.
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Old 11-02-2011, 05:20 PM
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No pressure from front servo port either, What The ????????????
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Old 11-04-2011, 04:36 PM
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OK the blocker rod you are speaking of does just that it blocks the fluid from even entering the acc port that is why you have zero pressure at the acc port

Accumulators are used to cushion the shifts and engagements .. and are usually blocked in performance transmissions , there are several ways to do it .

Hope this clears things up for you ...
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