Auto Trans Shifting Hard
Posted 13 November 2011 - 09:48 PM
Posted 14 November 2011 - 11:12 AM
compatible ATF instead of OEM Toyota WS ATF can cause harsh shifting - but since I'm running the OEM fluid, I can't comment on that yet. I was planning a drain and refill with fresh Toyota WS to see if that helps or not.
Posted 15 November 2011 - 01:58 AM
First time this has happened when passing (that I can remember). Earlier last evening, while on my way INTO town, I passed someone and the transmission shifted into passing gear just fine, with no thuds. But on the way back home, was following a few slow-pokes, and when the lead poke turned onto a side road, I was at a place where I could pass the other two (you know how it is: when people follow slow-pokes, they keep going slow when the lead poke finally gets out of the way). Was going at a lower speed before I stepped on the gas to pass. Could the transmission been on the verge of downshifting as I gave it more gas? Who knows? But what I know is that thuds aren't sounds to take lightly.
Haven't looked at my ATF levels today, as I was down all day with some sort of flu bug or something. Head is still spinning. Will do that before I head out tomorrow. Haven't added any fluids to the transmission, and haven't researched my service records to see if the shops to which I've taken it have, either. Will check that.
Searched for the same problem online, and didn't find anything on it, by the way.
Posted 15 November 2011 - 05:44 PM
No hard shifting occurred today at any time.
Posted 15 November 2011 - 11:28 PM
Default Re: Corolla Automatic Transmission Shifting
"SlyckTom" <email@example.com> wrote in message
> Hi All,
> I have a 1993, Corolla, 4 cyl, 1.8 liter, EFI engine. The car has
> 200,500 miles.
> Here's the situation.
> When I'm driving at all lower speeds and RPMs, the tranny shifts very
> smooth - as if it were new. However, if I'm entering an on ramp or
> otherwise bringing the engine to high speed or high RPM (maybe
> accellerating past 50 or 60)s, the tranny shifts into gear not as
> smooth. I dont want to say it clunks or it shifts hard, because those
> are too strong of words. It just isn't as smooth as during lower RPMs
> and speed.
> After the tranny shifts down in this instance its smooth afterwards
> regardless of speed or RPM...
> Does anyone have insight into this?
You did not mention whether you have an automatic or a manual transmission,
but since you are implying that it is an automatic, I'll give my 2 cents
assuming that it is an automatic.
What is the condition of the automatic transmission fluid (ATF)? Is it red,
brown, or black? What it the level of the ATF?
Assuming that the ATF level and condition are satisfactory, my guess is that
the accumulators are worn. Automatic transmissions have a pump that is
turned by the input shaft, and as engine RPM increases, pump output pressure
increases. At higher RPM, shifts will be harsher due to the higher
pressure, and accumulators act as a shock absorber to reduce shift shock,
kind of like slipping the clutch a little on a manual transmission instead
of popping the clutch.
The increased shift shock is not harmful, and is actually a little better in
terms of internal friction surface wear but if you want to reduce the shift
shock, a competent technician should be able to change the accumulator
without too much trouble, as long as there is good access to the
transmission pan and valve body.
(correct punctuation to reply)
Posted 16 November 2011 - 12:11 PM
As for the difference in the marks - generally it is a quart between the high and low marks. From your description - sounds like there is plenty of fluid in there, I would not be tempted to fill it up to the uppermost mark.
Posted 17 November 2011 - 01:09 AM
After thinking about any other time I've noticed a similar incident, I remembered it happened once as I was heading over to Cincinnati this spring. Was on Rt. 32, and had just started out after a stoplight had turned green. Between 2nd-3rd (I think), the trans shifted abruptly. Kinda gives me a jolt when it happens. These hard shifts only just began this year, and have happened between 3-4 times. Wonder if I should have a chat with my dealer about it? Maybe I will.
Posted 17 November 2011 - 08:10 AM
Posted 17 November 2011 - 04:06 PM
Will let everyone know what, if anything, they find.
Posted 21 November 2011 - 05:01 PM
Took my '09 Corolla S to C&C Toyota Scion today for the trans checkout. Matt, their service tech with 15 years of transmission knowledge and know-how, went with me. Of course, I could not duplicate the hard shifts, which was irritating in one respect, but good in another, since it did not shift hard at all when using the Resume function. Learned a LOT about Toyota electronics in the process. I asked Matt if he could tell me, on a percentage basis, what problems were attributed to parts failures, and what problems were traced to computer/programming problems. He told me just about all problems were software related. THAT was some news which had me believing my transmission was in good shape, and that software was the issue. Matt thought the same, and performed the checks to discover what codes popped up.
As it happened, no codes emerged, and he could find no software problem. He also said there was no known issue or TSB covering the issue, either. He told me he would submit my experience in some sort of knowledge database, in case some information came along which could confirm a problem.
So, nearly $44 in service fees later (because no problem could be found), I'm a little more at ease about my transmission. And just to play around, I took the opportunity to pass a car at the same spot along the road on the way back home today where the last incident occurred Sunday a week ago. My transmission shifted beautifully, and I sailed past that car like I had a tailwind. To be honest, I felt like my car had a bit more power! It could have been due to the fact it had been raining, and that the oxygen molecules in the air were a bit more compact, but am uncertain. Anyway, I'll just keep driving like I've been doing, and hope for the best.