Transmission lockup gear?

94HeavyChevy · #1 03-08-2008, 09:55 AM

I posted a thread a while back about my transmission on my 95 caprice 4.3L V8 locking up at low RPM's between 45-60 mph or so. i got responces saying that it was my TCC and if i tapped the brake it would disingage or if i gave it more gas it would also disengage. This all worked out fine. i spoke to a mechanic the other day and he said there is a lockup gear before overdrive and the transmission will lock up at low rpm's somehwere between these speeds. Is this a correct statement? Is the transmission supposed to do this? I have a 94 caprice and this has never happened with it.

SLJ2137694 · #2 03-08-2008, 10:09 AM

Some transmissions will engage the TCC in gears other than Over Drive. I can't recall if yours will do it though my guess is it probably does. Does your Owners Manual give you any indication about when TCC engages?

j cAT · #3 03-08-2008, 02:27 PM

Quote:

Originally Posted by 94HeavyChevy

I posted a thread a while back about my transmission on my 95 caprice 4.3L V8 locking up at low RPM's between 45-60 mph or so. i got responces saying that it was my TCC and if i tapped the brake it would disingage or if i gave it more gas it would also disengage. This all worked out fine. i spoke to a mechanic the other day and he said there is a lockup gear before overdrive and the transmission will lock up at low rpm's somehwere between these speeds. Is this a correct statement? Is the transmission supposed to do this? I have a 94 caprice and this has never happened with it.

when towing it is recommended on gm vehicles not to use 4th gear....this is because the transmission TCC will not operate...if you tow in 4th gear TCC cuts in, this causes high transmission temperatures and that is why... on my silverado the tow mode alters the shift points and will not engage TCC but on the older gm vehicles like yours you must not use 4th gear.... on all my vehicles at 43mph level road steady throttle the TCC cuts in after engine reaches normal temp....in 4th... on an older 83 buick 3speed auto 350 transmission i put a switch in to kill the TCC when towing my 4,000lbs boat.....

94HeavyChevy · #4 03-08-2008, 03:20 PM

This is happening during everyday daily driving. I do not use this car to tow anything. i have noticed that it does not lock up when it is cold but as soon as it is warm it does. maybe it is getting to hot. Again ill ask, are the 4L60e transmissions in a 95 caprice supposed to lock up? The mechanic i talked to told me it was normal but it has never happened in my other caprice which is a 94.

96capricemgr · #5 03-09-2008, 10:21 AM

The 4L60E can lockup in drive and overdrive, hell it might even lockup in 2nd if you programmed the computer to do so not that I know of anyone using it like that, the programming software offers the option though.

This tranny is completely computer controlled, a mechanical failure may cause a lack of lockup not not a premature lockup.
94 was not pulse width modulated so maybe they set the lockup a little higher from the factory, 95 they could pulse the lockup so it was less than a complete lockup maybe they set it lower figuring on letting is slip a little so it did not lug the motor.
Was the other car a LT1, if so the extra torque can hide lockup and you just notice it with the L99 because it has to unlock to accelerate?

Bone stock a 95 Impalal SS locksup the TCC at 37mph in 3rd gear at 12.5% throttle and 46mph in 4th if at the same throttle. You would rarely notice the 3rd gear one because you would have to have in in manual 3rd as the 3-4 shift point is 29mph at 12.5% throttle so it upshifts before the lockup if you had the selector in OD.

I don't have an L99 file handy all this is pulled from a 95 Impala file. The computers on these cars are so cheap and easy to modify.

j cAT · #6 03-09-2008, 03:34 PM

Quote:

Originally Posted by 94HeavyChevy

This is happening during everyday daily driving. I do not use this car to tow anything. i have noticed that it does not lock up when it is cold but as soon as it is warm it does. maybe it is getting to hot. Again ill ask, are the 4L60e transmissions in a 95 caprice supposed to lock up? The mechanic i talked to told me it was normal but it has never happened in my other caprice which is a 94.

the 94 caprice should have TCC apply above 43mph in 4th gear...if not have the dtc codes read for that vehicle as there are too many items that could cause this to occur.....on the 95 caprice when you tow do not use 4th gear.. when using 3rd gear the transmission will never have TCC apply.... this is because no slippage will be allowed by the pcm/computer....where as in 4th gear slippage is allowed and this is how the fluid/transmission will over heat....

94HeavyChevy · #7 03-09-2008, 04:53 PM

ya the 94 i have now has a 350 in it but it did have a L99 and i never felt this lockup occur. the 95 that i currently drive to work everyday locks up all the time because when i go to work i am traveling a constant 45-55 mph with my foot barely on the throttle. Is there any way to bypass this lockup? I just find it annoying. i have duel flowmasters on it and when it locks up it sounds like it is bogging down. but i can accelerate through it or tap the brake to disengage so i guess everything is working as it is supposed to.

96capricemgr · #8 03-09-2008, 06:58 PM

Could reprogram it for higher lockup speed or let it lockup but hold 3rd longer. Where are you maybe I know of a tuner in the area?

94HeavyChevy · #9 03-10-2008, 03:55 PM

Im in Columbia, South Carolina. I just talked to the guy who rebuilt my tranny on my 94. I told him the problem i was having with the 95 tranny and he said there is a lock up gear but you should not be able to feel it. When it locks up it is very noticeable so im thinking something is not right??

j cAT · #10 03-10-2008, 05:28 PM

Quote:

Originally Posted by 94HeavyChevy

Im in Columbia, South Carolina. I just talked to the guy who rebuilt my tranny on my 94. I told him the problem i was having with the 95 tranny and he said there is a lock up gear but you should not be able to feel it. When it locks up it is very noticeable so im thinking something is not right??

this TCC lockup is felt when applying... if the engine has problems with this and the engine stumbles it could indicate bad plugged exhaust/plugs also.....maybe this is what your refering to....but this lock up can be felt and because you are going 40-55mph it is constantly going on and off.... try to stay under 40mph or 50mph.....have exhaust checked for restriction,check spark plugs....if going up a small hill TCC lockup is more pronounced....

94HeavyChevy · #11 03-10-2008, 09:59 PM

between 45 and 55 or so it is pretty much constantly locked up. i can disengage by tapping on the brake or pushing the throttle significantly farther. one thing i have noticed is that it does not lock up when it is cold. so maybe it is getting to hot. i dono why it would be getting to hot though

j cAT · #12 03-10-2008, 11:12 PM

Quote:

Originally Posted by 94HeavyChevy

between 45 and 55 or so it is pretty much constantly locked up. i can disengage by tapping on the brake or pushing the throttle significantly farther. one thing i have noticed is that it does not lock up when it is cold. so maybe it is getting to hot. i dono why it would be getting to hot though

when the engine gets to normal operating temperature the tcc then will lock up..... if the engine overheats i don't think it will effect the tcc operation...... when the transmission overheats i believe the tcc will stop operating as tcc operation when towing can cause this to occur....sounds like the 95 is ok but because they put an older engine in the 94 they messed up the transmission wiring.......thats common that people will not hesitate to replace original motor with an older motor that is not compatible with electronics and then it is an electrical mess...remember the tcc is to improve mpg.....that will become more important as gas climbs to 4.oo++++++...

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