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Discussion Starter · #1 ·
No doubt there are Ford guys who have their early Mustangs running with 5 speed tremecs. I have a C4 coupled to my 347 in my 67 coupe. It has travelled 1001 miles now since it hit the road and on the highway at 60mph it is turning over at 3000. With the torque this engine has 3.55 gears are wasted so i found a guy who imports american driveline gear, diffs,gearboxes etc. including 1985-1987 Mustang V8 5 speeds. With 5th gear an overdrive somewhere between .6 and .8 it would cut the 3000 RPM back to about 2400 RPM and allow better mileage.
I heard early 5 speeds had some issues but i am not sure about the boxes between 85 and 1987.
Any input welcome.
Cheers
Al.
 

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Now I must say Im not a Ford guy and I have no idea what it takes to put a T5 into an early Mustang; however, from a gearbox standpoint, you want a 'World Class' T5 which has tapered bearings in the unit. These were used in Fords much earlier than GM. Parts for these gearboxes are getting harder to find from the OEM; so if a core presents itself, you may want to grab one.

The T5 is really only good to 300-350lbs of torque so have a conversation with your right foot. If the rear end plants hard, you're probably going to hurt that trans eventually. Shock loads are what kill these
 

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Discussion Starter · #3 ·
T5

Thanks for your reply. So the good boxes are called "world class ". I am not sure how much torque this 347 puts out never having dynoed the thing, but its heaps. Sounds as if i bought a non-world class box i would be pulling it out sooner rather than later. I will try and track down a web site to find out the difference and when they were made. The c4 at the momont is changing well and has been fitted with a shift kit for snappy shifts , its the high revving on the hwy which is annoying with a 1 to 1 3rd gear.
Thanks for that.
cheers
Al from downunda.
 

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Discussion Starter · #6 ·
Thanks for your input. From rwenuts link i found the following info very useful with the Z spec of the T5 to have the better power handling. Getting the 347 at its most efficient RPM range is educated guess work so i installed an air/fuel sensor and led readout in the exhaust to watch how it is burning the fuel. It varies only slightly from 1500rpm to 3500 running on two of four v's at constant speed.
Sounds like the importer of American trans stuff here is selling World Class T5's as he claims they are 1985-1987. But then again buying a second hand box opens a whole new can of worms. Condition of bearings, synchros, gear teeth etc. etc. More homework required.
Thanks guys
Cheers from downunda
Al.



The more popular world-class units were used in these original vehicles:
Late 1985-96 Mustang/Cougar/Thunderbird
· 1988-96 Camaro and Firebird
· 1993-95 Chevy/GMC S/T series trucks
· 1994-96 Honda Passport
· 1991-97 Isuzu Rodeo
NOTE: 4-cylinder Ford 2.3-liter Turbo units as well as 1993-96 Cobra “Z-Spec” T-5s do not interchange directly, due to difference in the input shaft bearings.

The most important difference between non-world class and the world-class transmissions is the torque rating. Later is better (or the higher the tag number). For example, 1983-89 Mustang units, both world class and non-world class, were rated at 265-lbs.ft. of torque. The 1990-93 versions were rated at 300-lbs.ft., and the 1993-96 Cobra “Z-Spec” T-5 was rated at 330-lbs.ft.
 

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AutoGear said:
Now I must say Im not a Ford guy and I have no idea what it takes to put a T5 into an early Mustang; however, from a gearbox standpoint, you want a 'World Class' T5 which has tapered bearings in the unit. These were used in Fords much earlier than GM. Parts for these gearboxes are getting harder to find from the OEM; so if a core presents itself, you may want to grab one.

The T5 is really only good to 300-350lbs of torque so have a conversation with your right foot. If the rear end plants hard, you're probably going to hurt that trans eventually. Shock loads are what kill these
AG,

Not to completely change the subject, but have you got any experience with the G-Force or Astro Gear conversions for the T-5? I'm looking for a small, lightweight gearbox for my Maverick (which is soon to be upgraded to around 600 FWHP) because I really don't want to cut my tunnel all to h$ll. Either of these kits will handle that power, especially in a light car.

Russ
 

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Either one will work. Ive never had either gearset in the shop.
Tony at Astro (the owners son I believe) is on the ball and his customer service is great. We helped him with a Muncie for a real finicky guy overseas. I have customers who deal a LOT with G-force and have all had good things to say.
I'd GUESS the G-Force is a bit more hardcore; go to the UMTR North website; in the trans section theres a guy named Nate (not me) with a Mustang that did a G Force T5 write up and he seems pleased with it.

Id also look at Medatronics (5speeds.com). Paul over there has forgotten more than I'll know about T5s and might have some insight. If you have any questions about what they say, George and I would be happy to translate for you.

I would avoid going to a TKO or a Richmond 5spd for what you're doing.
PM me directly and we can get more indepth
 
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