3 speed automatic

[Oconnellrb]

New TDR Member

Just purchased a '90 CTD with the 3 speed automatic. Is there anyway to change the gears in the rear end or anything to have lower rpm's at higher speeds? Your help would be appreciated.

 

[bgilbert]

Yes an overdrive transmission. You have 3. 07 gears in the rearend and a 1:1 direct drive transmission. Ain't gonna find anything lower than 3. 07's for your use. Welcome to TDR.

 

[SGibson]

You could check your R&P #'s or just jack your truck up and see how many times the driveshaft turns over for 1 rev. of the tire, maybe somebody threw a 3. 54 or 4. 10 in it, my 89 tops out a little over 80mph. If it is 3. 07's take care of it, gear's are hard to find, and look for taller tires.

 

[KMSCD]

so how does the 3 speed hold up as a transmission

 

[SGibson]

It's very durable, cheap to rebuild and simple. It's a purely hydromechanical peice that dates back to the early sixties, has been used and abused in everything from top fuel to cummins trucks almost all of your high performance transmission company's around made thier "name" off T-Flites.

 

[Greenleaf]

It's true. What he said and more.



BTW, to gain a bit more top end/higher speed you can modify the throttle links. Even with the pump turned up and modified the thing topped out @85-ish. That's ok for daily driving. After modifiying the linkages, it will really run now if I put my foot into it.

 

[Oconnellrb]

Green leaf what gears do you have in the rear end. How do you modify the links. would it just make the motor rev higher. My truck will only go about 65 and sounds like it rev high. dont have a tac yet. what is the cheap way to put a tac in my truck. Do i need one with the auto.

 

[Oconnellrb]

Do they also call this transmission a 727? Was a 4 speed a option in my 90 ctd.

 

[Niki]

No there was no 4 speed auto option in '90. I'd love to have another 3. 07/727 truck, I liked my early 91 better than my 93, my 91 did 65 easy, but was about maxed. Greenleaf is referring to backing off your high idle screw and modifying the links to get full travel of the pump lever, this helps a lot. Get some guages and buy a 3200 governor spring and you'll be all set. -Nick

 

[pepecat]

yeah revs would be high at 65 with the 727. I had the same problem... looked into the options... . 3500 for gear vendors o/d unit installed or 1500 for getrag 5sp manual conversion. I have gotten as high as 25 mpg on a tank... 600 miles with 24 gallons of fuel.

 

[Greenleaf]

Yes,



727 w/3. 07 rear gear. I have a 90 model. The linkages are modified to obtain much further travel as well as the gov screw went MIA. I have also had to remove the pump's throttle lever to cut it down and reposition the plate on said lever that makes contact with the slow idle screw. I have had to move them back to obtain a slower idle speed with the pump turned up (which raises slow idle speed) because the slow speed screw wouldn't allow for a further reduction in rpm's.



I mostly use the 90 for trips into town and nothing more. It rarely sees over 2000 rpm's. The tach is wired into the alternator if you feel you would like one. Please see issue #50 in the First Gen section for instructions.