1. Welcome To GMTruckClub.com!

    The #1 Chevy Truck Forum Online
    Online since 2004, we are the #1 Chevy Truck & SUV forum and user community. If you have any questions about your Chevy or GMC Truck, SUV or Crossover, or just want to connect with other GM owners and enthusiasts around the world, you've found the best place on the internet to do that.

    Join Today ~ It's Free
    Registering is Free and Easy! Hope to see you on the forums soon!

1985 S-15 Shift speeds?

Discussion in 'GM Powertrain' started by b717doc, Apr 4, 2013.

  1. b717doc

    b717doc New Member

    I've just purchased a 1985 GMC S-15 pick-up from a neighbor...says it has a freshly rebuilt engine and transmission, 2.8 litre automatic....Im not sure the transmission is shifting properly...all is good until I reach about 5000 rpm, and she just doesn't seem to want to shift into overdrive....It's like Im driving around town at 5000 rpm all the time...She will shift on into overdrive at about 67 mph, which seem high to me...downshifts to previous gear at 54 mph....Is this normal for the S15? Or should I have it adjusted, and is this something I can do?
  2. b717doc

    b717doc New Member

    First 70 mile drive to work today, she seems to be shifting okay now, around 55 mph, depending on grade...She'll downshift around 58 going up a slight grade on the interstate....Still would like to see a shift into overdrive a little sooner....
  3. b717doc

    b717doc New Member

    Taking truck to AAMCO tomorrow...manager says he's familiar with the truck and transmission, says the valve body either needs repair, or replacement...maximum cost worst case scenario is $375, guaranteed fix.....previous owner (seller) says he'll pay half the repair bill for me....
  4. b717doc

    b717doc New Member

    Located TSS sensor after O'Reilly auto parts showed me a picture of it, attached a vacuum hose that actually had suction on it to the sensor, transmission shifting perfect now, goes into 4th or overdrive at 45 mph, and cruises on the interstate at 70 mph! TSS sensor HAS to be connected with good vacuum for this transmission to shift properly, contrary to what I've been told by 2 separate people.....

Share This Page