1-2 WOT Shift Problem

LIVipers

LIVipers

Registered User
Okay I've been noticing a problem with my car as it does a WOT shift from 1st-2nd. Its a 94 Auto with 50k on it. Mods include:

Complete exhaust
70mm bbk throttle body
CAI
73mm MAF with correct sampling tube.

Now, from a stand still it accelerates great, but when it reaches 5100rpm it wants to bounce off the rev limiter (or so i think) instead of shifting right into second. The sequence goes: Bounces off rev limiter (or so it sounds like) and then as it bounces off it shifts into second. I'm lost as to what it could possibly be. Any help would be appreciated.

BTW this only happens in 1-2, 2-3 is perfectly fine at WOT
 
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Your 94 sc utilizes a 4r70w transmission. It has an electronic valve body. How does the car shift at part throttle? Can you post a video?
 
At partial throttle the car shifts perfectly fine, no real problems that I have noticed. Very smooth in all gears. Its just this 1-2 shift that has recently come about that is causing me to worry.
 
Your shift point for the 1-2 shift at wot could be off and may need to be lowered a couple of hundred rpm. Sounds you are hitting the rev limiter before it shifts. Or you could have the rev limiter raised a couple of hundred rpm. :)
 
What would cause the shift point to be off all of a sudden? And lol i know, i plan on tuning the car with QH next year, this year is all supporting mods first! haha
 
In mine it would do that sometimes. What it ended up being was the bearings in the one way clutch got flat spots. So when they were in the right position... no shift. There is an updated mechanical diode one way clutch. Mine finally completely blew up.:D
interclutch.jpg
 
So am I in need of a full tranny rebuild? It's only got 30k on the tranny. (Ford replaced under warranty a while ago)
 
There are dozens of things it could be and impossible to diagnose your symptom properly without test driving, and performing an inspection of the transmission.
 
I can do my best to try and get a video. Unfortunately though it is as intermittent thing, and has been happening just recently. I'll do my best. Blown38, can you possibly send me a link to this upgraded part you speak of?

Thanks guys,

Tom
 
I had a 95 LX v8 (with 64k miles) that had the check engine light on and the same issue. It ended up being the mass air flow sensor. It wasn't reading right and wasn't allow the car to shift sometimes. I thought it was the transmission too. Is your check engine light on?
 
The check engine light isn't on, and I noticed it really happening when I got the exhaust done in September. It happened 2 or 3 times, then stopped, then came back now. So it's not everytime, just intermittent. Thing is I'd rather fix it now, whatever it may be, than wait for it to break and potentially do more damage
 
I gotcha, I figured if the check engine light was on that the mass air flow could be a possible culprit. My car was the 4.6 v8 with a K&N cone filter and mufflers/resonator/3rd cat delete and did the same thing before getting to operating temperature. After that it ran and shifted fine. I hope these other TBird guys on here can help you
 
You could probably check to see if yours has the new style one way. Jack up rear of car put trans in nuetral and spin driveshaft by hand both ways. One way it should have a ratcheting sound. It may be faint with fluid.

Mechanical diode

15286DSCN6096.JPG


Here is my old style installed.

input1.jpg


I think you would be able to just install the new clutch without having to shim anything, but thats a question better answered by a trans guy.
 
Perfect, thank you. I will check it out this weekend and hope for the best. Now, in the event I do have the new one, where would diagnosing go from there? The one way being worn?

And in the event it is the old one way, a new one would be the best bet?

Thanks again for all your help,

Tom
 
I've never seen the new one way break. To me it sounds like you have the problem I had. It is intermitent and only when I was really getting at it WOT. Most of the time I was manually shifting to get the car to kick out in a turn.:D But when at the track in drive it would try to shift and then just free wheel and hit the limiter then I would let off and it would drop into 3rd.

How long ago was the tranny replaced, what year? I don't know if they update them like a performance shop would.

I'm trying to upload a video of the ratchet sound for you.

Video. looking at the tail shaft of trans to front of car I had to turn clockwise for the ratchet.

http://s169.beta.photobucket.com/user/blown38/media/20130226_133351_zpsf965dd96.mp4.html
 
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If I had to guess it was probably replaced from 1998-2000. My dad doesn't remember for sure when it was replaced. I'll see if I can try and get that ratcheting sound this weekend. If not, well, guess the Tranny is getting an overhaul a year earlier than expected lol
 
ford started using the mechanical diodes in 1998. You will also want to replace the retaining ring with the Sonnax spiral style, as the factory retainers are known for popping off under high RPM shifts in second
 
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