trany goes into o/d by itself
 

ok a little more detail about the tranny..
its on a mustang not a truck but since every time i did a search you guys came up. i thought this would be the right place to ask.

tranny was oem tranny that came on the gt. 4r70w car is making 600ish rwhp. 4v turbo 4.6..
transmision wiped forward clutch pack. to the point of making actual clutches in the pack into wavie plates an ****ing the piston in the bore into a permanent sideways posture.all the other clutch packs had burned clutches/steels in them but not to the extent of the forward clutch..

i cant complain as this trans has lasted for 5 years of heavy abuse.. maybe 400-500 8th mile passes on it on transbrake..

it has had a pa manual vb on it for those 5 years. reason for this post is.

before tranny took a dump it started going into o/d by itself. meaning i would shift 1-2 all ok. 2-3 all ok.once 3rd applied in about 3 seconds or so i would feel the car binding up and 4th would kick in without me hitting the button. just before it finaly gave up the gost it started to lock the converter up on its own once shifted into second gear.. couple of weeks after that started happening tranny lost all forward gears..

rebuild time..after taking tranny appart i decided to leave it n go find another donor, as bushings n bearings in the tranny were done. found a 5.4 truck in the j/y that had an engine fire but tranny was not touched. bought tranny and rebuilt it without using any of the old gt tranny parts. with the exeption of the tailshaft housing,output shaft,t/c,and transbrake. heres my question

why is my tranny still shifting into od by itself..it has not locked up buy itself yet ,but im afraid it will soon. any help would be appreciated.. its not the solenoids as ive left them with no power. not the vb as its not the one that was on when problem first showed up. case and all internals are different. remember this is full manual control no more computer.

help.

My only advice would be to wait for Darrin or someone else that builds the 4r70w's bud. (see sig for Darrin contact info, but remember he builds these trannies, not diagnoses)

You're over my head, I grasp what your issue is but not how you engage 4th without solenoids.

sounds like there was a wiring malfunction as well

I don't know what the issue is yet, but I have a customer who has an almost identical transmission with the same valve body that is doing the same thing. We know that it isn't the solenoids or the wiring. Ours has to be in the valve body as near as we can tell.

I mean the problems are identical. He has burnt up 2 transmissions now and we know it isn't the transmissions calling for 4th and lockup.

Darrin

Do me a favor and give me a call at 317-541-0816. I want to kind of join forces on this if we can.

i thought maybe something grounded out or solenoids were bad.
took it all apart redid wiring even though i found nothing wrong with it
also put in new solenoids and l/u solenoid as well.orings were in perfect shape.
remember i did say i finaly left them without power at all. no grounds no power wire.i thought maybe i had toasted the vb gaskets or cross leaking somewere but the gasket itself showed no signs of it. no internal rubber or teflon seals apeared to be leaking.. all rubber seals were still soft..every valve in vb moved freely no binding..but still decided to go with the one of the newly aquiered trans. right now the trans works perfect with the exeption of the overdrive dilema. im thinking something in the transbrake..
i have to apply transbrake to go into reverse.that works fine..when i apply transbrake to build boost also works fine.no slips no movement.converter is a 1 disc l/u from precision.never been locked up during a run.

overdrive kicks in weird..if i am quick and apply the od button before it engages by itself. i can feel it give me a nice crisp exchange between 3rd ond od...... but if i let it shift into od by itself it sorta feels like the car is loosing power , sorta like most of the timing is being pulled or something is holding the car back loading it up. then it frees up n od is engaged.once od is there i cant shut it off, unless i down shift into second or first.am i the only person in the world that gets car problems no one has ever heard off?????
lol.

I'm tellin ya, we have another car that is doing exactly this.

Darrin

Darrin when is a good time to call? I was thinking maybe get a stock 98 vb, take of the transbrake vb and swap them. This will eliminate the vb if it keeps doing it. My tune still has full computer comand over tranny if I hook up the oem harness...can the converter cause this? I can't see how.

I think Darrin is EST?