OE: The OE Merkur 5 speed transmission is the "T9"
or "Hummer". This transmission was evolved from the
4 speed transmission used in the 60s and 70s Pinto (et al) This
transmission is marginally sized for the stock Merkur. Heavy use
of the trans will cause it to wear prematurely. Modifying the
vehicle for more power will also cause early failure. FORD was
somewhat aware of the problem and specified Castrol SYNTHETIC
The differential on the Merkur 5 spd is 3.64:1 and the auto
is 3.36. By interchanging the diffs, overall ratios may be changed.
Aftermarket: Many owners replace the "T9" with a Borg Warner "T5". Three items on the T5 are critical to installation on the 2.3L: bell housing, input shaft, and gearing. The bell housing was produced in large quantity for the: SVO, Turbo Coupe, and some 4 cyl Mustangs. The input shaft on these cars will work with the 2.3 Turbo clutch. If the input shaft is the 5.0L a different clutch disc can be used with the 2.3 L pressure plate. The gearing is important also; stock engines have little torque so 1st gear should be low. Different owners may want a 5th gear for top speed or good freeway mileage. As shown below there is quite a selection available. Rebuild kits are readily available for T5s. This may be a good idea on a "boneyard" gearbox. Rebuilt gearboxes are also readily available with the correct input shaft and any gear ratios.
Changing the transmission to the T5 is basically bolt in with some MORE PARTS: modified drive shaft, modified transmission cross member, automatic trans speed-O cable, etc.
World Class T-5:
If you're above 225hp...don't settle for a regular T-5. There are many internal differences that are suited for higher power.
The difference between a WC T-5 and NWC T-5.
The WC T-5 had improved bearings throughout. There is a different bearing configuration on the bearings on the cluster shaft also. The WC T-5 has a special bearing cup with an o-ring seal that presses into the front of the case. Could be this o-ring that is leaking (if it is leaking there at all).
The WC T-5 also has caged needle bearings between the gears and the mainshaft vs the gear running directly on the mainshaft in the NWC version. It also has improved two piece syncros. Lots of other small differences and a much better transmission. Both WC & NWC had the same gear ratio's. The later model "Z" spec WC has the 2.95 first gear close ration gearset.
The earily TC & 'Stang had NWC versions, but from about 86 on they were pretty much all WC T-5's.
Outward most obvious sign that was reported to me is:
On the drivers side there is a bolt where 5th/reverse are connected -- on a world class it is either a Torx or Allen. On a regular T-5 it is a standard bolt head.
On the front of the case where the countershaft is in the case: the world class is a flush looking fitting with extra thick case material around it. The non-world class has a beveled edge face and isn't reinforced around that area. Requires the use of RTV or such to seal the case.
Shifter Position: There is a T-5 version that has it moved further back. I am building such a critter for my 3.8 SC motor swap. I have the trans just about assembled & will do a complete write up that will be posted on soon. The Readers Digest version of the story is that you need a GM Camero or Firebird extension housing, shifter shaft, shifter, main shaft & 5th gear assembly integrated into a Ford "World Class" T-5. The GM extension housing does not need to be from a World Class T-5 but the rest of the parts do. All this effort moves the shifter in the middle of the floor cutout. If you want to go the full boat (since you've already got 2 trannys in pieces), use the close ratio gearing from the Camaro also. It's alot friendlier on the track for sure, especially if you've still got the 2.3 turbo.
As shown by the testomonials below, ratios are highly subjective. They also depend on: motor torque, driving style, road conditions, and of course rear end gear.
Hanlon Motorsports or D&D Transmission both offer custom geared T-5's. My father's black beast and my red XR4 both have Hanlon built T-5's with 2.95:1 first gears and 0.80:1 fifths. The other ratios are all within 0.01:1 of the stock ratios.
I've found in 390 miles of mostly highway driving that the taller first gear requires some semi-fancy pedal dancing to get good power off the line.
I think the 2.95 first gear is more useful off the line, as the car doesn't require an immediate grab to second gear at tolls, lights, etc., like a T-Bird trannied car. I'd bet that the taller first gear makes downshifting more practical at the autocross in tight turns.
The 0.80 fifth gear gives slightly longer highway legs. A 5.0 Mustang 0.68 fifth requires more torque than a four cylinder turbo can provide if you want to use the gear below 75-80 mph. I'd bet that 0.73:1 isn't much better.
How much? A Hanlon built T-5 runs about $1300, if I remember correctly. Yeah, ouch, but I think the combo is a decent compromise.
FWIW, I *love* the ratios in my rebuilt TC T-5!! It originally
had ratios of
3.97, 2.34, 1.46 and 1.00 and 0.79. During the rebuild, as there are a
gazillion available gearsets for T-5s, I had 'em do these ratios:
1 - 3.50
2 - 2.14
3 - 1.39
4 - 1.00
5 - 0.70
As I understand it, the 1-4 gearsets are as found in the latest
(and very similar to the 85-86 SVO; possibly the same that Ralph Todd uses in
the Scorch), and 5th is a Camaro (ack!) ratio. In any case, as the 3.50
doesn't sound that different from the 3.97 I started with, I was a little
apprehensive that it would still be too short (3.97 being nearly unusable).
OTOH, I had heard that the "world class" 2.90 (2.95?) was a little tall for
quick launches, so I went ahead with this setup. Couldn't be happier!! The
0.70 fifth might be a little tall for a stock motor, but with the current 65
and 75 mph speed limits in most states, it might work out OK. With my 300+
ft/lb @ 3250 rpm Mannarino Monster Motor, 70 mph roll-ons in 5th are
incredibly fun, and sometimes even frightening. Downshift? Don't need no
I'm running a 3.35 first and an .83 fifth gear. The reason I went with
this gearing is becouse it's a 4 cylinder car. At the the time the care was
completely stock, except for a chip, and the combo worked great. I later
rebuilt(Esslinger built one for me) the engine. I think I would have been
better off with a 2.95 first and either the .83 or .63 fifth. I don't think
there would be much advantage going to the .63 gear except I would have
saved about $75 on the tranny. With the Hp I now have I tend to find the
top end of first very quikly. I will probably have first gear yanked out
and changed to the 2.95 later on. Right now I'll just have to shift a
little sooner. The 4.02 first gear of the t-coupe sounds like something you
might find in a Jeep. I (and someone may disagree) would not go to a higher
gear number than the 3.35 unless you want to pull stumps out. Yes you will
have a whole lot of snap off the line but your tires will thank you later.
I am very happy I threw out the c-3 tranny. I would'nt go back to it for
See the IMON archives for installation details.
Below are charts of: stock, T-5, Tremec, and Richmond transmissions.