Ok guys Im sure you all have heard of this "Stall wall" problem.. but does anyone know how to fix it or get around it?

Anytime I run a sticky tire on my car it won't shift from 2-3 with out hiting the limiter about 4-5 times. I have heard it a electronic PCM problem, and I really am considering just going with a 700r4 but really didn't want to if i could get around it...

 

I have the same issue but it happens any time it shifts at wot. It dosent matter if is on the street, Highway, or strip.

 

I had that problem when when I was running nitrous only with slicks and I lowered the 2-3 shift point 200 rpm and went up 100 rpm on the rev limiter and took care of the problem.It may not work for you but it worked for me.

 

That didnt work tried that too

 

:banghead:

 

There's a couple local LT1 guys having similar issues....no fix yet that worked in all cases that I'm aware of.

 

in hptuners, there is a transrevs/mile setting that has to be right or it will hit the limiter

 

Full manual valve body fixed mine

 

For as common as this is i cant beleave that no one has figured this out

 

It's a weak 3-4 clutch.....too much clearance, wrong friction material, number of plates, second band release vs 3-4 clutch apply (shift timing). It needs proper transmission modifications not necessarily a shift kit but shift kits provide the basic instructions. FWIW if you install a transgo kit as the instructions you're still only halfway there, the instructions are very conservative. If you still have any torque management you're never going to get it to run right.
You can put a band aid on it with hp tuners by playing with the upshift pressure modifier, shift speed, shift rpm.
People have figured it out. Those who have give free advice but no one ******* listens, the others are selling their product and would rather you get pissed off about your transmission and buy theirs other than give advice on how to fix or build your own.

 

BTW I'm not a 'tranny guy', I wonder if any will post with some advice
There is only one person who posts here who gives good advice for free, even if you don't buy from him.

 

The fix has been around for awhile now. Welcome to this century
http://www.pcmforless.com/

 

You're right that is funny.
Programming can help a poorly built transmission limp along better.
The problem started with 700R4/4L60's , the 3-4 was improved a little from the factory with the 4L60E, then the aftermarket made some improvements. The fix has been around for a while but it's mechanical.

 

Whats mechanically wrong that causes this? I was always told its an issue with shift timing.

 

Hum well i had the trans rebuilt a year a go. When it was rebulit the 3-4 clutch was made stronger with incressed number of clutch packs. Is there any way to adjust the clearance with the trans in the car, I know it can be done on most other transmissions but i dont think GMs have an adjustment. And how else can i adjust shift timeing.

 

Also over the summer i was able to put a scan tool on it and watch the solonids turn off and cause the shift. With the 1-2 shift the solonid would turn off and instantly the car would shift. But during the 2-3 the solonid would turn off but the shift was delayed a half second or so. This was during part throttle. So i would think that the computer programing is fine and the problem is inside the transmisson. I know for certain that the clutches are ok becasue the trans was once again taken apart 4 months ago (to rebulid the pump in an attempt to cure this problem) and at that point the clutches were fine. So with that being said what can be done to fix this problem. I dont want to attempt to fix it with a PCM band aid which i tried also by uping the limiter by 200rpm to no effect

 

Whats the 3-4 clutch clearance in your transmission? You don't know because you dropped the car off, waited for a phone call and picked it up. (No offense intended). Plus the factory clearance range for this clutch is .090-.123, the tighter the better up to a point, and I can tell you even .070 is too loose.
Take the transmission out of the car, take it apart and (among other things) adjust the 3-4 clutch clearance.

A lot of things affect shift timing, this is why there is no universal build or shift kit installation specs, everything needs to be built specifically for your transmission.
Shift timing is effected by the clutch clearance, clutch feed hole size, band release feed hole size, servo size (the release hole has to be matched to the servo size).
Tuning.
It also helps if your builder knows what he's doing or you do it yourself and your not afraid to take it apart several times to get it perfect.

 

im having th esame problem and have been trying to band aid it with computer tuning now for the last month with no luck. If i buy a shift kit and have it installed would that help at all, if so do i need to tell them to do something specific during the install? if it'll help then i'll do that till i can buy a rock-on tranny. thanks for the great info as always.

--Matt

 

There is one guy here who might offer help.
You can't just drop it off and tell them to install the shift kit, there are too many options that effect too many drivability characteristics.
Unless the shop does these kits on a regular basis and you give an accurate description of how you want it to feel when they're done.

 

The "modified" Trans-Go Performance Shift kit can solve the majority of problems of a 2-3 WOT shift, without taking out the transmission. But sometimes you have to go into the 3-4 clutch pack to solve this. You will need to increase the clutch count and reduce the clearance to around .030, add the "modified" Shift kit, and going to a 9.5" torque converter will wonders for this unit.