A bit of a surprise, what tranny do I have?

35thGTLimited

Active Member
Mar 10, 2007
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The Pocono's
So I was chatting in a Stang group today on FB, and wound up in a disagreement and then profoundly confused. I have a '00 GT auto, it's highly modified, mostly from the previous owner. I bought it knowing very little and I've just been sort of figuring it all out. Anyway, my car is 100% definitely a 4 speed with O/D. I just discovered that my car's OEM trans was a 3 speed with O/D. After a bit of googling, it seems as though I likely have the 5R55S out of a newer Stang (or something?).

So I'm curious, without a doubt new edge Stangs are 3 speed with O/D? And if so, is there any way I can go about figuring the exact trans I have?

P.S. I'm not a super technical guy, but I'll explain best I can. First through third gears are your typical sloppy auto gears, 4th gear locks and it's firm like a manual, and then there's O/D. Hope that makes sense.
 
The automatic transmission from a 1996+ model year is PCM controlled. Which means that the shifting is totally controlled by the car's computer.

The 1996-2004 model year Mustang came from the factory with a 4R70W which is a 4 speed transmission. The top gear also has a lock up torque converter.

If you were to bolt up a 5 speed transmission from a 2005+ model year into a 1999-2004 MY then:
  • the drive shaft would not fit
  • the transmission mount would not fit.
  • the electrical connectors would not fit
  • the PCM would not have the needed programming to control shifting.
Does YOUR car have a transmission dip stick? FWIIW the 5R55S does not have a dip stick.

If you still want confirmation of which transmission your car has then post pictures of the transmission oil pan.
 
So I was chatting in a Stang group today on FB
First mistake :nonono:


and wound up in a disagreement and then profoundly confused.
As if there was another likely outcome :D


I just discovered that my car's OEM trans was a 3 speed with O/D.
Here we go... lol


I'm not sure where you got that other transmission listing from.


Sorry it's not you. bookface is a constant source of awesome Mustang tech. :rlaugh: If you have a chance, check out the, "I'm surrounded by idiots" thread in the 5oh Talk section. There's some whoppers in there. LoL
 
I guess I'm not surprised, but a wiki showed the same thing. Frustrating, numerous sources say 3 speed, I give up.

I feel ya man. I've been on this site for many many years as a direct result of crazy info from Magazine Mechanics. Internet Mechanics are an even more special breed.

"My best friend's buddy's sister's cousin on her uncle's side makes 12 million hp with a hair dryer turbo system running form a 9 volt battery!" :O_o:
 
I guess I'm not surprised, but a wiki showed the same thing. Frustrating, numerous sources say 3 speed, I give up.

Technically Wiki is right because the 4th gear (Overdrive) can be locked out so the trans only uses the first 3 gears. After 2005, and in many modern automatics this feature was dropped in many cars.

So it could be referred to as a 3 + OD, or a 4-spd auto. Both are correct as long as you know what they are talking about. When my car was an AOD, I always drove it around in D which basically limited it to a 3-spd auto. On the highway I would shift to OD on the trans allowing it to use that 4th gear. Modern cars today just have D and usually feature a manumatic mode, so the old designation isn't really applicable today.

But for a 2000 GT stock, you should have a 4-spd automatic. If you hit the O/D off button, the light on the dash should come on and the trans will not use 4th gear as listed below.

1st = 2.84
2nd = 1.55
3rd = 1
4th = .70
 
If you are counting 5 gears, then we'll need pics and such to help try and track down what you actually have.

Is your car a 3V swap? Do you have a trans dipstick?

I'll record a short video and upload to my youtube channel. I'll also try to get it on the lift today, will certainly take pics. Edit: Are the valve covers the same size on a 3V as a 2V? It most certainly looks like a 2V. Also thanks for the assist here.
 
Ignore the RPM gauge, I need to pull the cluster to fix it, reads 1000rpm high. Also battery and engine are fine, I'm messing with stuff and I need to replace my battery terminals. I made a video for now, to clearly show that it's a 5 speed (4 speed with O/D). I plan to jack it up at work tonight and get a few pics of the trans.

The audio is absolute trash, sorry, my phone is awful.

View: https://www.youtube.com/watch?v=NKbniwkTOtk
 
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It would be expected for the RPM's to drop when the lock up torque converter locks up. But that's not a gear change! 4 gears plus lock up torque converted, RPM's drop (5) times.

A car with a 5R55S would shift 5 times and then when the lock up torque converted "locks up" would make (6) RPM's drop.