FMVB Built 4l80e problems

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Mar 7, 2011 | 06:21 PM

RICE ETR

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From: Virginia

FMVB Built 4l80e problems

I don't have many miles on this trans (under 1,000) and only two passes on it. I've got a FTI lock-up converter fwiw.

In 1st and 2nd (haven't tried 3rd) when I roll into the throttle hard it feels as if the trans clutches are skipping for lack of better terms....seems to grip then let go then grip again, almost like severe tire shake. The lock-up does work (have to flip a switch to engage and I have disconnected it from switch/power to rule it out)
I know these problems are hard to diagnose without seeing the inside of it but just looking for any possible things to check before I rip it out....again. The cable is set correctly and I am running vaccum/one-way valve to the trans for line pressure. It is not overheating and operates great when just cruising around.

Thanks for any input,
-Jarrod

Mar 7, 2011 | 07:21 PM

slow67

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From: DFW

Put a 0-250psi pressure gauge on it and see whats going on.

Mar 7, 2011 | 07:53 PM

RICE ETR

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From: Virginia

Thanks for the response...it's and older style 4l80, which line do I tap into and am I looking for pressure to build and hold?

Mar 7, 2011 | 11:06 PM

Jake's Performance

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Hmm,
Let me get out my magic crystal ball and see....

Did you get this unit built by a vendor on the East Coast?

Does it have delayed shiftfting to 3rd?

Does it sometimes not shift from 1-2 at WOT when hot?

Mar 8, 2011 | 06:34 AM

forcd ind

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From: woodbine, md

lol, i think i know where Jakes going
from my own personal experience, i built a trans with the HD-3 man. kit, had the things Jake referred to, switched to an auto V/B and cured all those things
there is a 1/8" plug on the D/S to tap in for pressure
i also had an FTI converter, it really shined when the trans was right