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5/25/2017 8:49 AM  #1


transmission

I have a 66 mustang with a 302 and 355 gears in the rear . I was wondering which tranny is better for me the c4 or the AOD? I drive it no more  than 100 miles , any one have any suggestions?

Last edited by Wag8142 (5/25/2017 8:52 AM)

 

5/25/2017 9:49 AM  #2


Re: transmission

AOD would be best.


Dan      Presently own: 1965 Coupe, 200cid, 3spd.
 

5/25/2017 11:15 AM  #3


Re: transmission

I my opinion neither one. I would put a t5 in it. That said I had a c4 in mine with 3:55 gears and it was terrible at highway speeds. If it has to be an automatic definetly go with an AOD but consider the 5 speed.


"anyone that stops learning is old, whether at twenty or eighty"Henry Ford
 

5/25/2017 11:29 AM  #4


Re: transmission

C4 will be stronger, but AOD will give you overdrive.
A lot of guys like the newer, electronically shifted automatic 4R70W.  It's an automatic with overdrive like the AOD, but stronger.

Personally, I'm like BillyC and prefer a T-5 over either one but you may not want that if you're set on an automatic.
 

 

5/25/2017 12:13 PM  #5


Re: transmission

What is in it now?


Good work ain't cheap, Cheap work ain't good!   Simple Man
 

5/25/2017 7:31 PM  #6


Re: transmission

I too swapped my 2.73 factory gears for 3.50s and love the acceleration, but the car is unusable on a modern highway.  2,500RPM is 55MPH give or take with my current wheels and tires.  Trying to run 75MPH its turning about 3,500, which is just too much for an engine that's all done by 5,000 RPM. 

Personally I always wanted a stick anyway, so the T5 was an obvious choice.  The AOD is a decent trans, a buddy of mine has one in a 12 second Fox body, but they need to be built properly to stand up to a lot of power. 

 

5/26/2017 8:48 AM  #7


Re: transmission

If you have a good C4 in it, and you never drive it on long trips....100 miles isn't, in my opinion...I just might put the stock 2.78 gears back in an keep the highway speed at <70.  JMO.  Much less trouble than swapping in the AOD or the T5.

BB

Last edited by Bullet Bob (5/26/2017 8:49 AM)


"you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
 

5/26/2017 10:31 AM  #8


Re: transmission

Thanks for the helpful info.

     Thread Starter
 

5/26/2017 5:46 PM  #9


Re: transmission

Bullet Bob wrote:

If you have a good C4 in it, and you never drive it on long trips....100 miles isn't, in my opinion...I just might put the stock 2.78 gears back in an keep the highway speed at <70.  JMO.  Much less trouble than swapping in the AOD or the T5.

BB

Or go down to a 3.25.  I did that for a while with my top loader.  It was my daily driver and the 3.25 got about 3mpg less mileage that the old 3.00.  way too much for a 40,000 miles per year car.  The 3.25 worked ok for my daily 100 mile commute.  And power was still up a lot over the other.


Original owner - 351w,T-5, 4whl disks, power R&P
 

5/26/2017 8:35 PM  #10


Re: transmission

I had a C4/3.25 combo. 60 mph was 2900 rpm. Too high revs for long drives behind a 351W. Sucked gas. Changed to a 4R70W. Now 60 mph is 1900 rpm.


68 coupe - 351W, 4R70W, 9" 3.25 -- 65 convertible - 289 4v, C4, 8" 3.00
 

6/09/2017 6:25 PM  #11


Re: transmission

I have a 302 with 3;55 and a AOD in my 66 . I have 215/65/15 tires
.What could I expect if I go to 4;10 gear .

     Thread Starter
 

6/09/2017 6:32 PM  #12


Re: transmission

I am going with a t5z, 275/40/17 tire, and 3.80 gear, and If I remember correctly I would be running 1800rpm at 65mph with the .63 od.

 

6/09/2017 7:17 PM  #13


Re: transmission

My 65 FB had 3.55 rear and stock 4spd. with a roller 5.0l b303 cam balanced assembly and ran 3200rpm at 65mph but was smooth as silk. it is all about what parts are used and what you want out of the vehicle.
 

Last edited by 70 Coupe (6/09/2017 7:26 PM)

 

6/10/2017 8:37 AM  #14


Re: transmission

How the engine is built does make a difference, but to build an engine to really last at 50% or more of max engine RPM you have to spend a lot of money.  The heavier duty the internals the longer they will last, but this means expensive forged parts, expensive rings, expensive bearings, etc.  There's really no need to spend that kind on money on a performance street engine. 

It isn't a question that the engine is going to blow up from the RPM per se, rather its a case that the engine is going to wear out much faster than it should, and a carbed engine is lucky to get 100k between rebuilds, and less the more performance you're trying to get out of it.  Consider that NASCAR engines turn 9,000 RPM or more, and must be extremely reliable, but also consider that they get torn down after every race, so they really only have to run that way for less than 1,000 miles.  Serious drag racers freshen their engines at least once a year (not talking Funny Car, etc. where they tear down between races), and that's 1/4 mile at a time, where a whole season is probably less than 100 miles total.  On the street trying to push 400HP from a 302 based stroker you're going to be lucky to get 20-50k out of it before the ring seal starts to go.  Sure you can keep running it longer, but then you start to risk a wear related failure.  The harder you run the engine, and RPM of 50% max or more counts as running it hard, the faster it wears out.

Then, if it matters to you, there's the issue of fuel mileage.  Fuel isn't getting any cheaper, and while we may be in a time a more reasonable fuel prices; we all know that's not going to last forever.  The cost of fuel is another hindrance to some guys enjoying their car, so if you can build it on the miserly side that's never going to hurt.  I can't ever remember anyone saying their car got mileage that was too good.  Its also worth considering the environmental impact of emissions per mile, even on a vehicle that is emissions exempt. 

 

6/10/2017 11:26 AM  #15


Re: transmission

What TKO says about how long you want it to last makes sense. I had a 302 carbed engine in my 67 coupe that the PO put in. It was supposed to have been rebuilt. He also had a 4:30 rear end in it with a T5. It ran about 2900 -3000 rpm 65-70 mph.  That engine started using oil so I have pulled it and have a 5.0 roller with EFI ready to go in. Probably be asking a bunch of questions once I start with the EFI. Have a set of 3.70 gears ready to go in also. Hopefully get better mileage, was 13-14mpg. Don't care too much about that, just hoping this setup will last. Just got done rebuilding the tranny, now starting on the engine bay. The Wyatit bug is taking over.
 


67 Coupe, 5.0 EEC IV Fuel injected. T5, 3:70 rear
 

6/11/2017 4:39 PM  #16


Re: transmission

Thanks ,   
You guys are great !!!!!!!!

     Thread Starter
 

6/11/2017 7:20 PM  #17


Re: transmission

Wow, 4:30s, that guy was a lunatic.  Shifting into 2nd at 7MPH.  Yeah, that's just too tall for any street car.  3.70s will be perfect with a T5's 0.68 5th gear and a reasonably sized tire. 

 

6/12/2017 9:04 AM  #18


Re: transmission

I built a custom T5 for one car with a 1st gear higher than a normal 2nd gear. Also has the highest fifth. I could get. Had to grind off the gears from the hubs and countershaft and shrink on new gears with lock welds.
4;30's were just right. It was a really fast road racer!



 

 

6/12/2017 2:56 PM  #19


Re: transmission

At that point though couldn't you just have used regular T5 gear with a numerically lower rear gear?  I mean its the overall gear ratio that matters, right?  If you needed a shorter 5th gear G-Force makes 0.75:1 and 0.90:1 sets.  I used to have a 0.80:1 set from a 1LE Camaro that I sold for a pretty penny since they are NLA. 

Last edited by TKOPerformance (6/12/2017 4:11 PM)

 

6/12/2017 7:34 PM  #20


Re: transmission

Wag8142 wrote:

I have a 302 with 3;55 and a AOD in my 66 . I have 215/65/15 tires
.What could I expect if I go to 4;10 gear .

..........You could expect to make me a "smok'in deal" on those 3.55:1 gears!!
6s6
 


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

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