Replaced 1997 3800's 4T60E due to TCC shudder, still there!!
 

Hi guys, I spent the last few days replacing the transmission in my 3800 Series II powered 1997 LeSabre. The car had just over 70,000 miles on it when I pulled the trans and replaced it with a 31,000 mile unit (I took the pan off the low mileage trans, the magnet showed far, far less metal shavings than my 70k mile original trans, and the torque converter bushing on the 31k mile unit had almost no wear on it at all). The reason I replaced the trans in the first place is that in the last 1500 miles, when the car is very warmed up (at least 20 minutes of driving), ascending a hill, if you let the car get into o/d and tc lockup and held steady throttle, the trans would occasionally start banging very harshly and repeatedly. I attributed this problem to a failing TCC clutch assembly. The fluid that came out of my 70k mile trans smelled like it had been overheated. AND, I have been having coolant evaporate at the rate of around 1" in the reservoir tank per month. I attributed this also to the trans fluid getting too hot and cooking some coolant out of the rad. Anyhow, after going through the huge hassle of replacing the transmission myself, I still have the intermittent transmission banging when ascending a hill in o/d and lockup. The problem is most pronounced at lower speeds, ie 40-45 mph, dogging it at 1200-1500 rpms up a hill. Tonight under this case scenario, the transmission began repeatedly banging so hard I thought it was going to blow up on the spot. It appears that the cause of my problem is not the transmission itself, but something else that is malfunctioning A) When the car is very warmed up B) When the car is bogging down in o/d and t/c lockup ascending a hill, at low rpms and usually between 40-50 mph

Any ideas? I am so furious at this car that I don't know what to do at this point. No current or stored codes. Car runs excellent, very smooth and strong.

BY THE WAY, I was reading the 6 page long thread on all the problems people are having with the 1997 model year 4T60E's surging while going up hills, warmed up, in tcc locked overdrive. My problem is not surging (I had this problem with the original transmission at 25,000 miles and the valve body was the culprit). My problem is repeated mechanical BANGING that occurs in TCC locked overdrive. Sometimes its slight banging, sometimes I feel that the car is going to fall apart. I can't believe that these 1997 model year transmissions, and/or what is controlling them, are such incredible pieces of junk. I have an Intense standard PCM on the way for this car, but now it looks like it was a waste of money, since the transmission still sucks.

hmm. strange one there. i've never heard of a mechanical banging from the tranny.

in any event, your coolant loss is completely unrelated, and is likely due to failing lower (and possibly upper) intake manifold gaskets. i'd worry about that before I'd worry about the tranny.

as for a mechanical banging, it's really hard to go on just that - is it coming from one particular side more than the other? how loud is it? make some comparison for noise, perhaps something like:

or

...

My 97 does the same thing under load. I usually just accelerate a little faster....to bring it out of lockup under these conditions. Otherwise my tranny is fine. I wouldnt worry about it.

Every car I have driven with the 4T60 has had a least a minor shutter under load. None of the 4T65s seem to have that problem. My 97 LSS is the first year for the 4T65 (S/C only) trans and it smooth as butter. I think 98 was the first year for NA cars to have the 65.

A transmission that does this is definitely not fine. I worry about it because the car only has 70k miles on it, and I have an Intense PCM on the way, as well as a new 2.5" mandrel bent exhaust, intake, and new KYB struts, which allow the car to be driven quite aggressively. I'm going to see if Scott at Intense can program the TCC to unlock much quicker under load so I don't have to keep dogging it up hills in lockup, which is when the banging happens.

I had a simliar problem but got rid of the car instead.

I'm gonna through this out here just as a shot in the dark but are you sure it is the trans? I ask this because I just had a similar problem (different car & trans) but the symptoms were the same and I was thinking tranny. It would buck and kick under slight load with the TCC locked up but WOT would run fine. It also was more pronounced at lower speed and ran fine on the highway. It turned out to be as simple as plug wires.

Ranger, after installing a 31k mile transmission and having the same bucking/kicking in TCC lock that you described, it does appear that the trans was not the cause of the problem. I changed plugs tonight, and in doing so found that the #3 plug wire has been in direct contact with the exhaust manifold for quite some time now. It wasn't burned through, but was discolored from the heat. It is definitely possible that this was causing a slight intermittent miss when the engine was hot. I have a new set of wires and will change them tomorrow. Oh man, if I changed a front wheel drive transmission because of a faulty spark plug wire, that will really be something.