Corolla Automatic Transmission Shifting

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?

TIA!!


Tom

"SlyckTom" <tom@slyck.com> wrote in message
news:vim5d293sspm1m2lbm6cnnl4v56af2b0vq@4ax.com...[color=blue]
> 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?
>
> TIA!!
>
>
> Tom
>[/color]

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.
--

Ray O
(correct punctuation to reply)

Hi Ray,

Yes, it is automatic. The fluid is in good shape, and its always been
changed every 35-40,000 miles.

Just some further info,it happens only when in third gear. There also
a noticeable, but slight "bump-bump" when downshifting (and a quick
"bump-bump" when accellerating).

These patterns have all fix the discription of 'shift-shock' I've read
about, and otherwise the car drives great.

Tom

On Fri, 4 Aug 2006 10:52:57 -0500, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:
[color=blue]
>
>"SlyckTom" <tom@slyck.com> wrote in message
>news:vim5d293sspm1m2lbm6cnnl4v56af2b0vq@4ax.com...[color=green]
>> 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?
>>
>> TIA!!
>>
>>
>> Tom
>>[/color]
>
>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.[/color]

"SlyckTom" <tom@slyck.com> wrote in message
news:kignd2l3te24deoqf5qfc5b841k4ct4uu5@4ax.com...[color=blue]
> Hi Ray,
>
> Yes, it is automatic. The fluid is in good shape, and its always been
> changed every 35-40,000 miles.
>
> Just some further info,it happens only when in third gear. There also
> a noticeable, but slight "bump-bump" when downshifting (and a quick
> "bump-bump" when accellerating).
>
> These patterns have all fix the discription of 'shift-shock' I've read
> about, and otherwise the car drives great.[/color]

Keep an eye on the condition of the ATF, and if it doesn't bother you, don't
worry.
--

Ray O
(correct punctuation to reply)
[color=blue]
>
> Tom
>
> On Fri, 4 Aug 2006 10:52:57 -0500, "Ray O"
> <rokigawaATtristarassociatesDOTcom> wrote:
>[color=green]
>>
>>"SlyckTom" <tom@slyck.com> wrote in message
>>news:vim5d293sspm1m2lbm6cnnl4v56af2b0vq@4ax.com...[color=darkred]
>>> 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?
>>>
>>> TIA!!
>>>
>>>
>>> Tom
>>>[/color]
>>
>>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.[/color]
>[/color]