Transmission shudder- 92 Park Avenue & 94 Lumina

[Guest Shaffer]

My 1992 Buick Park Avenue (146K), as well as my 1994 Chevrolet Lumina (162K) both have a "shudder" when they are in overdrive, in the lock-up torque converter mode. I can tell it is the transmissions causing this, because when they are kicked out of the mode, it stops, or if the accelerator is released, the lock-up disengages and the shudder stops. It has slightly, but progressively gotton worse on both cars. Someone on the GMforums.com (website with forums covering all GM cars) said it was a sensor in the transmission going bad and was expensive to repair. Later on E-Bay I seen a 91 Lumina Euro with the shudder and the seller said they was told the converter was going bad. I am not sure what it is, nor the cost of repair, if I decide to repair, rather than sell both of these cars. It seems to be a common problem with 90s GM cars, as there was several posts there about others 90s GM cars as well as rear wheel drive Astro vans. Does anyone else have any input about what the trouble is with these transmissions, or anyone here have the same problem with their GM car and know how much to repair? I am planning on calling teh transmission repair shop for a estimate, but wanted to see if anyone here had any info on the problem. Thanks.

[Guest Shaffer]

Maybe not as common on Buicks as I thought. <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" /> <img src="http://www.aaca.org/ubbthreads/images/graemlins/shocked.gif" alt="" />

[NTX5467]

There is a Torque Converter Control (TCC) solenoid that attaches to the main valve body. You have to drop the pan to get to it. Seems to be more common on the THM 125s in the Cavaliers and such than in the larger car transaxles.

The shudder you are describing is most probably the torque converter trying to lock up and can't due to worn friction materials in the torque converter lockup clutch. Those things don't last forever as, just like a manual clutch, every time they engage there is some controlled slippage on initial lockup. Just a matter of time.

If you drop the pan and find friction material, with the symptoms you describe, the prognosis of a failing torque converter lockup clutch would seem appropriate.

For starters, you might do a fluid and filter change (using GM fluid instead of another brand) and see if it changes. I read in an automatic transmission shop trade publication that the GM fluid is the primo fluid and can fix some problems that the aftermarket fluid (even of a reputable name brand) DexronIII fluid will not. I don't know if it might in this case, but it's a shot.

You can find a reman torque converter from many sources, but the quality of the frictions and such in the converter can vary. Of course, getting one from GM would be the primo way to go, but with a higher price, even though it TOO is a reman unit. Do some good shopping and ask questions about failure rates of the aftermarket remans. There are some good ones out there, you just have to find them.

Of course, with the miles on those vehicles, it might be advisable to go ahead and get the frictions replaced and the valve body cleaned out and such. DO NOT forget to have the trans cooler flushed as part of the rebuild too!

You might also check with the GM dealer for the price on a Service Replacement Transmission Assembly (SRTA) for those vehicles. You can buy them "carryout" or installed in their shop. Who installs it depends on if the component warranty is "parts & labor" or "parts only" should a failure result (dealership installed and "owner or private shop" installed, respectively). Many times, the dealerships will wholesale them at a price that is very competitive with private shops AND also have a nationwide warranty with them too (at any GM dealer and with proper documentation). These SRTAs have all of the production updates even though they are reman units and operate just as a new trans would.

There are many credible trans rebuilders and shops out there, not to say there aren't or that they all are flaky or whatever, but do shop the deal both ways and consider the side issues of the options. It could well be that a private shop would work a deal with a GM SRTA for a quick turnaround and "easy money". As always, be an informed shopper and make the best decision as it's your money.

In some municipalities, whatever the actual repair bill should not be over their written estimate more than a certain percentage (if not dead on accurate). If they rebuild your unit and find other problems, you should be notified of the extra expenses too. The one thing going for a reputable private shop is that they usually have access to good, used pieces where a dealership rebuild will be only new parts.

Don't forget to figure in the possibility of having to replace worn/aged engine or transaxle mounts when you do this deal too.

Until you get things fixed, when ever you feel the shudder of attempted lockup, back out of the throttle a little so the load on the trans would be less and let things lockup under less stress and then proceed gently to back where the acceleration was previously. The problem is when the converter is trying to lock up, not usually after it has locked up. As the converter friction materials diminish, you can get the same or worse shudder after lockup, but under load or harder acceleration (but not hard enough to get the converter to unlock).

There are vacuum switches or internal pressure sensors to govern lockup and unlock events. There also might be some ECM intervention too. As the lockup is governed by electric means, you might also find the connection on the trans and unhook it. It might set a code in the computer and turn on the Check Engine light, but the converter would not try to lockup either. You might need to get a service manual to see a representative wiring diagram to determine which wire needs to "have an open circuit" in the lockup converter wiring.

Just some thoughts . . .

NTX5467

[Guest Shaffer]

Thanks for the reply and info. Actually, the car is going into lock-up mode, as the engines slow drastically, but after it actually goes into the mode, that is when the shuddering starts. Maybe you mean, that it is in the mode, but not fully in the mode, therefore the shudder. I do release the accelerator when it does this, like you recommended and it stops, or I accelerate enough to get it out of the mode. I have considered just driving with the gear selectors in "drive" rather than "overdrive". I am going to call the transmission repair shop now, to see a estimate on repairs. If too costly, or time consuming, I will probably sell the cars, rather than repairing them. Both have hail damage and I do not want to put a lot of money into them. Thanks again for the info.

[Reatta Man]

I just had the torque converter changed on my '96 Regal GS. It was doing EXACTLY what you described. It is important to get this fixed quickly, because as others have said, the torque converter is wearing out. No biggie yet, but if it breaks apart and gets debris into the transmission, you have to rebuild or replace the torque converter AND the transmission. Big $$!

My car has the regular, not supercharged, 3.8 Series II engine. It has about 115,000 miles on it. I found a shop that will actually fix the problem, not charge as much as they can, and that is what they did.

The torque converter cost about $100, and they charged $250 for installation. It has been fine since the repair in November.

The problem you are going to have is finding a shop that will only try to sell you what you need. ALL, and I do mean ALL of the national chains I know of will try to sell you a rebuilt transmission and a rebuilt or new converter. Some mark the converter up three or four times. I've seen converters going on these cars for as much as $400 for that $100 part! Now you know who pays for those TV ads with the famous liberal spokesman and the full-page ad in the Yellow pages--YOU do.

The transmission is another gold mine for them--prices range from $1,200 to $2,800. The difference should be in whether they are replacing key sensors and many expensive worn out "hard parts." Often, however, the language on the bill will be so vague that you really won't know what they replaced or proposed to replace. It may say something like "Complete rebuild needed" on the estimate, but that could only be a soft parts kit, removal, cleaning the case, installing the kit and converter and reinstallation. What you are getting in that case is a $1,000 job marked up to $2,000 plus that $400 converter.

If you know a good dealer or independent repair shop, ask them who they use. Many good independent repair shops have gotten out of the transmission business because they are extremely sophisticated and require a specialized mechanic, tools and diagnostic machines to work on them. The shop that does the work for me was recommended by a local used car manager at a major dealership that I have known for years. He uses the independent shop that did the work on my car because his own service department charges him more than he can get the work done for at another shop!

Above all else, GET THOSE CONVERTERS REPLACED SOON IF YOU WANT TO KEEP THE CARS AND NOT BUY NEW TRANSMISSIONS!!

Good luck.

Joe

[R W Burgess]

Hey Guys. Had the same type problem with my daughter's 90 Corseca Chevy. It was locked up so bad the transmission would not downshift to first at stoplights. You could start the car and when put in drive the motor would die. Since this is a 140,000 mile car, I'm not about to put a transmission in it. Fixed it simply, by unhooking the electric plug in the side of the transmission body. Converter does lock up anymore, doesn't shutter or anything because it's not working anymore. The little bit of extra gas I use is a lot cheaper then a transmission rebuilt on a $500.00 car. Wayne

[Guest Shaffer]

RW- my 89 Pontiac Safari had that problem. Would not go out of lock-up mode. Our local repair shop told my dad to unhook the plug and it would be OK. He did and it is fine now. Our old 1985 Buick Regal also did that. But with my 94 Lumina and 92 Park Avenue, they are not staying locked up and shifts perfectly, but shudders. The problem is different. The staying in lock-up all the time is a sensor problem. A fairly easy and cheap repair. My problem with the 94 and 92 are more severe like Joe said. The actual converters are going bad. I called the repair shop today that rebuilt the transmission in my 95 Concorde and he said they could not say 100% without driving them, but he said it sounded like the torque converters going bad. Said approx. $300. repair for each. I may have the Buick repaired, but I am going to sell the Lumina. I only paid $700 for the Lumina, with 150K. Since then it suffered a bad hail storm last summer and I paid $200 two weeks ago for a new fuel pump and $20 more for brake pads. I think I will just sell it instead of investing more money in it than it is worth.

This torque converter problem seems like it is VERY common on the 80s and 90s GM cars.

Thanks again for the replies and information.