hard shifting after downshifting on the freeway

[Billha]

I recently created a new topic thinking that my '02 Buick Park Ave Ultra with 89,000 miles was having tranny hard shifting problems that were related to tranny temperature...
But yesterday the car had only been driven for 15 minutes and the coolant temp was 180 degrees and the outside air temp was 65 degrees, and while in overdrive on the freeway I accelerated to pass someone. From that point forward, every shift was abrupt. The engine light did not turn on at all.

A little while later I pulled over and shut off the engine. I waited only a few seconds and then started it again and continued driving. Shifting was normal the rest of the way home. How does that make any sense? Whatever the problem is, it doesn't appear to be heat related.

When I got home, I checked for error codes using my Actron scan tool and my Innova scan tool. There were no error codes.

The hard-shifting behavior has occurred twice since I've owned this car - once almost a month ago when I was stuck in traffic for more than an hour, and then again yesterday when traffic was clear. So it's not a frequent problem (yet).

I've been contemplating installing the Transgo shift kit and scuffing-up the walls of the accumulator as recommended by others, but it now seems like the cause of the problem may be downshifting, and installing the Transgo kit will only affect 1-2 and 2-3 shifting, right?

Any ideas?
Thanks.

[01bonneSC]

I suspect your PCS is going out in your trans. It resets after you shut the car off.

[torero500]

My car has had this exact problem for the past 30k miles. Tried different type fluids. I replaced all the internal sensos, pcs, 3 in fact. New filter and fluid. That cost $550. Still hard shift. Basically, we need new transmissions or a complete rebuild.

[Billha]

Interesting. I haven't seen any other posts that seem to be for this same problem.

How many miles are on your transmission?

If you've already had the PCS replaced, then I wonder if the TransGo shift kit would help. Several members and several posters on the web have reported that the shift kit helps; but others have reported that it hasn't helped, or only helped temporarily.

Another thought is that someone on another forum said he fixed the problem on several transmissions by roughing-up the walls of the accumulator with fine sandpaper. If I decide to install the TransGo shift kit, I'll rough-up the walls of the accumulator while I've got the accumulator apart.

My car has had this exact problem for the past 30k miles. Tried different type fluids. I replaced all the internal sensos, pcs, 3 in fact. New filter and fluid. That cost $550. Still hard shift. Basically, we need new transmissions or a complete rebuild.

[01bonneSC]

There are a lot of threads on the subject of hard shifting, very common problem. The shift kit is a band aid fix because it basically over rides what the pcs does.

[torero500]

Yeah in these early 2000s cars, honestly these transmissions tend to start going at 75k miles. My car has run about 35k on the hard shifting transmission, and it's just slowly progressively getting worse even with the full service job on it about 6 months ago.

So really I need a new transmission. Also need the upper and lower intake manifold gaskets replaced. Car slowly starting to use coolant, and engine oil starting to get a little sludgy. Also new valve cover gasket, and new hoses and belt while we're at it. Need new tires, old ones are getting bald and dry rotted. Need new windshield.

Like that show on HD Net, Wheeler dealers, where they fix up modern cars that are kinda classics in their own way, the car needs about $4,500k. It's worth about $2500. There certaintly isn't anything like the Bonneville's size being sold on the market today. That's probably mostly good but perhaps some bad to it as well. I do like the extreme comfort of my cloth bench seat.

[myfirstbonnie]

Also need the upper and lower intake manifold gaskets replaced. Car slowly starting to use coolant, and engine oil starting to get a little sludgy.

You better get this done or you might as well add a new engine to the list.

[00Beast]

I had 145k on my SSEi trans before it was replaced, with me buying it with black fluid at 138k. Did you already get your PCS replaced?

Trans rebuild: $2k maybe
UIM/LIM Gaskets: $300 DIY.

Not sure how that adds up to $4500 unless you need rust repair or something...

[LeSabre in Buffalo]

Try a TransGo shift kit. It helped with me for a long while, until the PCS finally got bad enough to need replacing.

[myfirstbonnie]

I wouldn't even do anything to the transmission yet. He has coolant loss with sludgy oil?

The UIM and LIM gaskets need done now before the coolant takes out his bearings. I have been down that road when I just had the transmission rebuilt and did not even have 5k on it when a bearing spun.

I did not have the coolant in oil issue, but the transmission did not shift hard when the motor was out of the car.

Bill, however can start with the transmission. I did not notice the thread jack here.

[Billha]

This post is belated, but if anyone's interested, I bought the TransGo shift kit and installed it several months ago. While I had the accumulator apart, I also lightly scuffed the cylinder walls as recommended on another car site. I also replaced the filter and fluid at that time. The work took about 1 1/2 hours and was relatively uneventful, but a tip for those of you who do this yourself in the future is to make sure that you pay attention to which shift piston is which when you open the accumulator, and also pay attention to where the 3 metal lines connect to the accumulator. The pistons and the pistion bores look identical (but the springs are different), and the metal lines only go back together 1 way.

I'm happy to report that I haven't had any shifting problems since that time.