So last fall i noticed that my Car didnt want to shift under WOT into 4th? So This is the first thing i want to take car of this spring when i take her out of storage. Im guessing this means i'll need a Rebuild or new built Trans? what would you all do?

If the Trans have to be removed i want to change the Stall. Somewheres around 2800-3000 to high for a street car?

 

I don't think the trans is supposed to shift into OD at WOT.

 

i don't believe the car is supposed to shift into overdrive at WOT either. What you should do is first make sure your fluid level is where it should be, then when you are WOT in third, ease of the pedel a little and see if it shifts. I don't believe those trannys were meant to shift because of the ratio of the overdrive. there would be no benefit

 

i guess i didnt realize that it was OD. I just noticed it on the free-way a few times right befor winter. Riding aournd 75mph then when go to pass or what not it down shift'd then hit around 90ish it seem'd like it slip'd or wont shift. RPM's just would keep going up into Red. and id back pedel a little bit then ease back on her & she would shift. It would do the same thing if i would Launch(or Not)from a dead stop and Ride her out to 90mph ish Plus. Just i didnt think it is normal has i havent noticed it befor?

This is something new'er as i didnt notice summer of 05 and most of summer of 06. Car has just under 90k on the clock
Fluid Is Pink/Clear Still freash looking, Not Low, didnt smell burnt. Was last Flush'd and Change around 80k

 

Your car must have really low gears to redline in 3rd at only 90mph. Are your sure it's not holding 2nd gear.
For comparison my car has 4.10's with 26" tires and will go 110 ish in 3rd at 6000 rpm.

 

The 700R4's in 3rd gen F-bodies won't do the WOT 3-4 shift. But the 4L60E will shift in the 4th gens. I've had all three F-bodies pedal to the metal in 3rd gear. LS1 automatics are good for at least 150 mph, not whatever 3rd gear works out to.

 

Actually, they can be modified to make a WOT 3-4 shift.

Frank
CPT

 

A 4L60E should make a 3-4 WOT shift. There are a couple things that may contribute to one not doing it. Pay close attention to see if it's acting/starts acting any different on the 1-2 shift. When the 2-4 band goes, it usually shows up in 4th first.

Frank
CPT

 

Either way, I think a WOT 3-4 shift is HARD on a trans.

 

Not if it's built correctly. We have several customers (as well as my own) A4 making a 3-4 upshift in a quarter mile pass.

Frank
CPT

 

Frank, how hard is it on a stock transmission? I don't see why it's any different than a 1-2 or 2-3 shift. I'm referring to wide open highway and doing a random run to say 130 mph.

Were the 700R4's and 4L60E's built any differently from the factory that would warrant the 4L60E being more able to handle the 3-4 shift?

 

The 700 isn't capable of making a WOT 3-4 upshift because of it's design. It's different than a 4L60E because the '60E is electronically controlled.

The reason a WOT throttle 3-4 upshift isn't the best idea in stock form is because the apply piston (in the servo) for 4th gear is very small, and doesn't offer very much "holding power". We change the 4th servo to a "dual piston" design, as well as make some other pressure changes, and use a better 2-4 band.

Frank
CPT

 

Ya i didnt think it was a good thing but... but i guess i'll have to wait untill spring to find out whats going on. i dont rember about 1-2 shifting. i pland on bank tax return for some fun toys this year but maybe it'll be a built trans buy a good one once not have to worry about it for a while!

 

So in the late 1980's Corvettes, was it the Corvette servo that allowed them to make the 3-4 without doing too much damage? Or was it the better piston inside the servo that Corvettes had as opposed to an F-body 700R4?

I've never heard of a C4 owner grenading their transmission on a 3-4 shift. And those B4C cop car Camaros would handle the 3-4 shift back in the day. Yet my 89 GTA doesn't make the shift, while a previous 88 IROC I had would. (Granted the IROC had something done in the tranny as it shifted hard in every gear...to the point of being annoying at times. Was already like that when I bought it)

Honestly, I'd like to get the GTA to make the shift into O/D. But I don't want something to break at 100+ mph.

How do you modify the 700R4 to get the 3-4 shift? Different valve? Different kickdown opening hole? Something else?

 

To actually make it capable of making the 3-4 upshift, you can replace the TV valve and sleeve, in the valve body. Sonnax makes a copy of the old "COP CAR" sleeve. Yes, most 700 equipped police cars would make a WOT 3-4 upshift.
We use a better 2-4 band and 4th servo (Sonnax "dual piston") to make the transmission withstand a full throttle 3-4 shift. We also make some pressure modifications to keep pressure up at high RPM's.

Frank
CPT