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4l80e line pressure

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Old Jul 2, 2009 | 09:43 PM
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Default 4l80e line pressure

What's the line pressure supposed to be in a 4l80e manual valve body transmission? Better yet a transgo stage 3 kit at idle and load?

My 4l80e died out on me after 600 miles. My line pressure is:

120 idle
205 reverse
1-4 gears cruizing 90-120
typically when downshifting to 2nd and doing wide open throttle it's at 90psi and stays at 90psi and slips.

Obviously my transmission pump is out and or the valve body needs some attention.

If need be i can upload a video of the gauge readings

setup: 4l8i0e, manual valve body, forward pattern pull back to downshift, locking converter, stage 3 transgo.
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Old Jul 3, 2009 | 12:53 PM
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You'll see about 160-180 in forward gears with slight throttle. 275-300+ in reverse.
Somethings not right with your kit.
Are you using the vacuum modulator or a dead EPC?
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Old Jul 3, 2009 | 06:32 PM
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Originally Posted by jakeshoe
Are you using the vacuum modulator or a dead EPC?
I am just using the transgo stage 3 kit. Vacume modulator? I have no electronics going to my transmission i only have a vacume line which is supposed to lower line pressure when the car is in vacume. however when disconnected that line i noted no pressure change on the line pressure.
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Old Jul 6, 2009 | 03:42 PM
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2nd gear on my 80e with transgo-3 is much higher, as Jakeshoe says above, the line pressure on mine is 150+ in all forward gears at idle, 220+ in reverse. Light load driving it is 175+ in forward gears. WOT I can't say for sure, my car is too hard to drive and watch the gauge at the same time.

I wasn't 100% happy with my transgo kit at first due to slow 2-3 shifts, but it has held up to several dyno pulls in 3rd with the converter locked, plus 2000 miles on the street, so I don't think it is fair to blame the design of the kit. I did a DIY rebuild, my first 4l80e, so it doesn't require a pro, just need to be careful and check everything twice. I bet my slow 2-3 shift is because I set up a clutch pack too loose, not because of a fault in the design of the transgo-3 kit. I will say that the instructions in the kit are not really very clear, especially if you don't build transmissions for a living.

The vacuum modulator is inside the pan, looks just like one from a th400, but the end is machined off shorter. I assume from your post you didn't do the work yourself, if so perhaps you should take it back to the people who did the work.
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Old Jul 6, 2009 | 03:47 PM
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What shifter are you using? Are you 100% certain that the detent in the shifter lines up with the detent in the transmission? I had both a Hurst and a B&M that did NOT line up correctly, in the end I cut the bracket that goes on a TH400 and modified it to line up with the 4L80E detents.
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Old Jul 6, 2009 | 09:06 PM
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kind of a dump question, but is the fluid level correct-i know when i had my gauge hooked up, it would still build pressure as i poured the last couple quarts of fluid in
i had low pressure with the man. kit, when i switched out to an auto v/b
and compushift controller, i had much better pressure
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Old Jul 7, 2009 | 04:38 AM
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Originally Posted by twinturbo496
What shifter are you using? Are you 100% certain that the detent in the shifter lines up with the detent in the transmission? I had both a Hurst and a B&M that did NOT line up correctly, in the end I cut the bracket that goes on a TH400 and modified it to line up with the 4L80E detents.
b&M shifter i believe it lines up pretty well. I am not able to perform the work as I crashed a motorcycle and still recovering. Yes a transmission builder built the transmission i am pulling it out tomorrow and he said something is wrong iwth it.
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