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What's the difference between transmissions?

Discussion in 'GM Powertrain' started by Rob, Jul 11, 2008.

  1. Rob

    Rob New Member

    I was wondering what are the differences in these transmissions and what application each one is usually used in. Also which one ya'll think would be the best?

    * Turbo 350
    * Power Glide
    * 700R4
  2. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    Since I know some about it, I'll give some details on the TH700R4... It is a non-computerized 3 speed with overdrive transmission that has been used on cars to light trucks. The only way this transmission knows what the motor is doing is by a TV (throttle valve) cable. This cable is NOT a kickdown cable and if is treated as such, transmission failure is almost certain. This transmission also has no vaccuum modulator. It is a fairly popular racing/drag transmission and if built up, can handle a lot of power. It can bolt up to nearly any motor, GM or not with the help of an A-daptor kit. (listen to Johnny Cash and you'll get that joke...) In Chevy and GMC light trucks, it was used up until around 88 in pickup trucks and up to 91 in Suburbans. Its decscendant is the 4L60E, which is the same thing as the 700R4, but with computer control. It's big-brother is the 4L80E. (I don't think there ever was a non-computerized 4L80, but I could be wrong) The most desirable years to get one in is 88 or 89 and later due to pump and case changes. Umm...it has provisions for torque converter lockup.....replaceable tailshafts for different applications....and the speed/abs sensor is in the tailshaft. There, that should be a good amount of info to start you off...
  3. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    Last edited: Jul 11, 2008
  4. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts

    What are you using the transmission in and what is the main purpose of the vehicle?
    Christopher covered most of the important items on these trans already.

    The Turbo 350 was GM's most popular trans since the late 70's and has been built to almost every application you could think of to do almost every job you could imagine (Ive seen one coupled to a Wisconsin Diesel engine running a water pump and a generator at the same time).

    Power Glides were more popular in the early 60's, they saw lots of use in Drag racing, the two speed was a heavy duty trans that usually came behind small block engines (283/327) but could handle the HP of big blocks when built right. They're getting rare and parts are hard to find.

    700R4 was considered a break through trans for GM, it was the start of their overdrive transmissions. Early versions had many problems and were considered weak, minor upgrades made it a respectable trans.
  5. Rob

    Rob New Member

    I was just wondering what were the diffences because i've seen some on craigslist. I was also of thinking of putting a faster shifting trans later on in the future.
  6. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts

    The trans your running now is pretty dependable, replacing it with any of these older models would be a step back. When its time for a new trans either have yours rebuilt by a shop offering warranty or buy a replacement rebuilt or new trans. Depending on the company you choose for your new trans you can get replacements built for anything from economy to big hp.
  7. zippy

    zippy Member

    The smooth shifts of your 4L60E (assuming that's what you have) are something that makes GM's engineers very proud. In the early days, a smooth shift was the mark of a good driver -- any fool can make jerky gear changes. You didn't get a job as a limo chauffeur unless you were a smooth shifting SOB. Later, as automatics replaced clutches it was the same thing, a smooth shift was a luxury not a liability.

    Your truck is capable of abrupt shifts, it's just not set up that way at the factory. Most folks who buy a new truck are looking for smooth shifts. If you want a dramatic demonstration of the 4L60E's flexibility, just retard your engine about 6 or 8 degrees. Yes, it's going to cut your power way down, but you'll see how the computer compensates for the reduced power buy stiffening up the shifts.

    If you want faster (more abrupt) street shifts, it' s well within the capability of your 4L60E. Check out eBay under shift kits, there's many out there for under $50. That's a lot easier than replacing (and adapting) a new tranny.
    Last edited: Jul 12, 2008
  8. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    This is a good background on the TH700R4 transmission. It also has what pressures should be in certain gears and such...

    http://www.hotrodders.com/forum/chevy-th-700r4-transmission-44407.html

    EDIT: After much searching, I finally found a page that CLEARLY indicates where the pressure ports are located on the 700R4, 4L80, and the 200R4 transmissions. It also includes how to attach a pressure gauge and how to test the pressures. For some reason, they state that the gauge shouldn't be connected all the time, anyone know why? I wanted to hook a pressure gauge up permanently...

    http://www.tvmadeez.com/press_gauge/pressgauge.html
    Last edited: Jul 17, 2008

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