1993 Chevy Caprice, hard 1-2 shift

1993 Chevrolet Caprice, 5.0 8cyl, 4L60/700R4 transmission, 68k miles.



This car gets driven 4 to 5k a year, 20 to 30 miles at a time, generally 50 mph and under. The transmission fluid and filter was first changed at 44k miles in Feb 2002. The car was rarely driven the previous three years before my in-laws gave me the car.



I drove on the highway today, averaging 65 to 70 mph for the trip (~150 miles), after I exited the highway, I noticed the 1-2 shift was very abrupt, the 2-3, and 3-4 shifts were normal. The 1-2 shift has always been firm, but never shifted like it did today. After the car sat for a few hours the shift was better, but still somewhat abrupt. The Service manual refers to it as a “bump”.



I checked the fluid, it was pink, not burned. However the level was about 3/8" to 1/2" high. It was below the bend/crook in the dipstick though. I don’t know if this contributed to the problem, but I will drain some ATF out of the dipstick tube.



Any suggestions what might be causing the harsh 1-2 shift and what to do about it would be appreciated. The manual suggests Dexron IIE, is this still available? I going to have the fluid and filter changed, would an additive like Lubegard Red help?



Thanks in advance,



Ed B.

The high fluid is a definite probable cause, especially if your transmission has a modulator valve which is sensitive to high fluid levels. Worse in cold weather. I see that the others have posted. Never mind this one.

The 1-2 shift on these is usually a little firm due to the big gear jump; 3.06:1 to 1.63:1 from 1st to 2nd. I?ve owned numerous 700?s (all in trucks though), and they all shift a little firm on the 1-2. My current truck will chirp the tires when taking a corner on the 1-2, but that?s not factory:)

Do you have the 700R4 or the computer controlled 4L60?

If 700R4, then I would check the Throttle Valve (TV) cable. Reset it and follow the factory adjustment procedure. If it?s the 4L60 I have no idea.

There is no vacuum modulator on these trannies; TV cable only (700).

The fluid height you describe does not sound too high. I’ve run them a little high before with no problems.

In the five years I’ve had it the 1-2 shift has been firm like you describe. I’m concerned that it got worse after highway driving. It was a little better today going to work, but not back to normal.

According the to shop manual the 700R4 was renamed 4L60, the computer controlled 4L60 is called the 4L60e. It’s confusing.

Thanks for the advice on the TV cable, I will check the adjustment. I will make an appt. for a fluid and filter change (not flush).

Thanks,

Ed B.

Ed,

 This IS a 700R4 correct????  Not a 4L60E??  I ask this because 1993 was the changeover year.  The early 93's were 700R4's, the later was the 4L60E.    Let me know because there are several things which could be causing your issues.

transman

Transman,

There is a TV cable on the TBI, so it is a 700R4.

First fluid and filter change was done Feb 2002 at 44k miles. My mechanic said there was a fair amount of debris including some metal in the pan. I had put in 8 oz of Seafoam Transtune a week before the first change. As pointed out by Loafer the 1-2 shift has always been firm in the 5 years I’ve owned it. After I exited the highway (65 to 75 mph), I noticed the abrupt 1-2 shift. I am getting the fluid/filter change done in late February (earliest appt I could get).

Do you have any thoughts on additives such as Lubegard Red or Berrymans?

Thanks,

Ed B.

Loafer,

I adjusted the TV cable last night, it was too tight. The transmission is very sensitve to the adjustment, I set the baseline using the factory procedure which turned out to be too loose (smoother shifting but no downshift). I then adjusted it tighter 1 click at a time followed by a test drive.

The current setting provides upshifts at 15, 30, and 45 mph under light throttle and a 2-1 downshift at 25 mph. The transmission is shifting better than before this problem came up. I may go 1 click tighter to firm up the upshift, but I’m going to leave well enough for now.

Thanks again,

Ed B.