I recently purchased a 2001 Sonata. However, during the first week, the transmission went, and had to be replaced by the dealer (with a used one). Silly me, I did not find out what transmission he replaced it with - the 3 speed or the 4 speed (It had had the 4-speed).

It seems to me that the car is running at higher RPMs during highway driving than I remembered it doing before. When I drove in to work today, it was doing about 2750 RPM @ 75 MPH?

Does anyone have a table of the RPMs a motor should be doing at a given highway speed, and would a different speed transmission change that noticably? Is the 2750RPM @ 75 MPH excessive?

Ineed to make sure everything is right with this transmission before I accept this repair.

A little background history:
The original problem was detailed here - https://www.hyundaiforum.com/m_12051/tm.htm. They ended up replacing the transmission speed sensor, and the problem seemed to only get worse after that, until the car became undrivable. It was jerking/jolting into gear at far higher than normal or reasonable RPM, and refused to shift out of 3rd gear. A transmission shop said there was something physically wrong with the transmission and it got replaced.

 

What engine do you have? 4 cyl. or 6 cyl.?

 

That's not bad for 75 MPH.

Two things you should be able to test:
--manually shifting the automatic, how many gears can you select?
--there should also be a lock-up torque converter. To tell if this is operating correctly, look for a double-drop in RPM as the transmission first shifts into top gear and then locks up the torque converter. Also, if you accelerate moderately in top gear, you should see the RPM jump by a few hundred as the torque converter unlocks.

 

It sounds totally, 100% correct. It's simple math.

Let's start with the known facts:

2001 Sonata automatic:
- 1st gear ratio = 2.842
- 2nd gear ratio = 1.529
- 3rd gear ratio = 1.000
- 4th gear ratio = 0.712
- Final gear ratio = 3.770

So when in 4th gear at 2750 engine RPM's the wheels are turning 1024.5 RPM.
2750 / 0.712 / 3.770 = 1024.5

Original tires:
- 205/60-15

The diameter of that tire is 24.7" and that tire has 817.4 rev per mile.

So if the wheels turning1024.5 revs per minute, multiply that by 60 and you get61,470 revs per hour. Now divide that by the tire rev per mile (817.4) and you get the Miles Per Hour. 61,470 / 817.4 = 75.2 mph

For the record, speeds in 4th gear at indicated engine RPM:
1500-rpm = 41-mph
1600-rpm = 44-mph
1700-rpm = 46-mph
1800-rpm = 49-mph
1900-rpm = 52-mph
2000-rpm = 55-mph
2100-rpm = 57-mph
2200-rpm = 60-mph
2300-rpm = 63-mph
2400-rpm = 66-mph
2500-rpm = 68-mph
2600-rpm = 71-mph
2700-rpm = 74-mph
2800-rpm = 77-mph
2900-rpm = 79-mph
3000-rpm = 82-mph

 

Just wanted to comment that I visit many forums, yet rarely do I come across such an excellent response.