Auto trans problems
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
Auto trans problems
I'm having constant problems with my 4L60 trans.
From the first day when I bought the car, five years ago,
it wouldnt shift into 4-th under WOT.
Last year when I was doing 155+ mph trans shifted back
to 3-rd and everything went to little pieces.
I had trand rebuilt but after rebuild it still won't shift to
4-th under WOT but it's even worse.
I rev 3-rd to 5500 rpm and let go off acc pedal and itr shifts
to 4-th, but I have to accelerate really slowly in 4-th.
If I hit WOT it shifts back to 3-rd even if revs ae much
too high for 3-rd gear.
What could be the problem?
I'm thinking of installing full manual shift kit ( with TV cable )
anyway, but I'm not sure if this would solve the problem.
Edit: signature inserted
From the first day when I bought the car, five years ago,
it wouldnt shift into 4-th under WOT.
Last year when I was doing 155+ mph trans shifted back
to 3-rd and everything went to little pieces.
I had trand rebuilt but after rebuild it still won't shift to
4-th under WOT but it's even worse.
I rev 3-rd to 5500 rpm and let go off acc pedal and itr shifts
to 4-th, but I have to accelerate really slowly in 4-th.
If I hit WOT it shifts back to 3-rd even if revs ae much
too high for 3-rd gear.
What could be the problem?
I'm thinking of installing full manual shift kit ( with TV cable )
anyway, but I'm not sure if this would solve the problem.
Edit: signature inserted
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
If the trans was replaced before you bought it, it may be a non vette trans. The vettes and cop cars were the only cars that got the wot upshift valve in the valve body. The valve can be purchased through the aftermarket and General motors. Price ranges from 40-70 us bucks.
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
Thats an interesting info.
I had no idea about this.
I'm sure that trans on my car is not the one
that came with car original so this could be the
problem with WOT upshift.
But why does it downshift when it shouldn't?
I had no idea about this.
I'm sure that trans on my car is not the one
that came with car original so this could be the
problem with WOT upshift.
But why does it downshift when it shouldn't?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
It is more than just a WOT up shift problem. The valve Pete K talks about is actually to prevent WOT in overdrive. Therefore,
besides not allowing WOT to be applied in 4th gear, it won't allow a shift into 4th at WOT. As you ease down on the pedal in 4th, at some point the trans senses full throttle, and the down shift is forced.
RACE ON!!!
besides not allowing WOT to be applied in 4th gear, it won't allow a shift into 4th at WOT. As you ease down on the pedal in 4th, at some point the trans senses full throttle, and the down shift is forced.
RACE ON!!!
Burning Brakes
Joined: Nov 2000
Posts: 855
Likes: 0
My buddy's S10 Blazer with 4L60 does the same thing you described, but I was the one that rebuilt it. I told him I believed it was bad solenoids in the valve body or bad Computer. I've confirmed the line pressure and fluid level and everything else is fine. Plus this is only intermintent. I rebuilt my 700r4 and no problems. I really don't like computers. Computers are the Devil.
Instructor
Joined: May 2005
Posts: 162
Likes: 0
From: Lady Lake FL
Something you may want to look into is the replacement throttle valve that prevents downshifting to 3rd until like 2/3rds throttle, B&M makes something like that. My '85 Iroc has something similar to this, and at high speeds it won't shift out of overdrive at all. It was in there went I bought it so I don't know for sure exactly what was done to the trans, I know it's got a shift-kit of some sort, but none that I've put in have reacted this way (affecting 4th gear shift points). I'm not too fond of it though, as it upshifts to 4th too soon at part throttle, but that's what the shifter is for right?! 
KC
KC
Advanced
Joined: Oct 2004
Posts: 92
Likes: 0
Not all, but many of the Corvette transmissions have the 4-3 part throttle passage eliminated. This will allow WOT 3-4 shifts. You can block these holes in the TV plunger sleeve, by using 2 $0.17 Allen plugs to block the 3-4 part throttle passages. This will in most cases solve this. I do this upon request on my performance build ups.
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Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
I would really like to do that but it's a PIA to find ZF-6
trans with all other parts needed for conversion in Europe.
And it's really expensive.
If I could find everything for ~$2000 I would take it, but I'm
sure that shiping to Croatia would be at least $1000 more
plus customs, plus taxes.........
I think that I'll have to satisfie with full manual shift kit
and 2400-2800 converter.
PBA, how difficult is it to do this? Do I have to pull the
trans down, or can it be done with just removing the pan?
trans with all other parts needed for conversion in Europe.
And it's really expensive.
If I could find everything for ~$2000 I would take it, but I'm
sure that shiping to Croatia would be at least $1000 more
plus customs, plus taxes.........
I think that I'll have to satisfie with full manual shift kit
and 2400-2800 converter.
PBA, how difficult is it to do this? Do I have to pull the
trans down, or can it be done with just removing the pan?
Drifting
Joined: Jun 2001
Posts: 1,997
Likes: 1
From: Lake Ozark MO
You've got something wrong with the transmission or the PCM.
Even when I had 2.59 rear gears the tranny shifted when commanded (2nd to 3rd at 111mph... 3rd to 4th at 172mph)....
Now with 3.07s it does what it's supposed to... 2nd to 3rd at 94mph.. 3rd to 4th at ~147mph.
Mine is electronically controlled. If you've got the "TV cable" then I'd bet that's the problem.
Hopefully someone with experience on the non-electronic tranny will chime in.
Even when I had 2.59 rear gears the tranny shifted when commanded (2nd to 3rd at 111mph... 3rd to 4th at 172mph)....
Now with 3.07s it does what it's supposed to... 2nd to 3rd at 94mph.. 3rd to 4th at ~147mph.
Mine is electronically controlled. If you've got the "TV cable" then I'd bet that's the problem.
Hopefully someone with experience on the non-electronic tranny will chime in.
