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rear end gears and torque converter numbers.....

5K views 17 replies 6 participants last post by  cougar2 
#1 ·
As I am going through the car right now I had planned on swapping my 3.70 gears for 3.0s. I am running a built 429 and c6 with a 2700 rpm stall converter and don't have the budget for an overdrive trans but would like to improve the road manners. Problem is though, 3.0 gears puts the engine speed right on the edge of stall on the converter at highway speed. I think if I do it I will end up toasting the transmission.

I think I am going to have to live with the gears until I can put together an AODE swap. Any better ideas?

Matt
 
#4 ·
Anything wrong with a set of 3.25 gears?

BTW, there's nothing 'wrong' with having your 3rd gear be below the rated stall speed of the converter. Stall speed is a function of engine TORQUE at wide-open throttle. Since you're not a your peak torque at normal around town or highway speeds, the converter will still function as it should - it just won't be as efficient. 72-74 Q-code 351C-4V automatics had a factory 2700rpm converter and 3.25s, and those worked just fine.

Why an AOD-E? Why not a 4R70W? Or a plain-old AOD? Standard AODs have a simple TV cable hookup (easy for a carb) and Drive and o/d are already in converter lockup for max efficiency. Yes, I know there aren't any factory 429/AODs, 429/AOD-Es or 429/4R70Ws but they do make an adapter if you choose that route.

I have a wide-ratio AOD (4R70W gearset in an mechanically-controlled AOD case - no electronics needed) behind my 475hp 393W. No problems at all. The wide-ratio gearing (2.84 First gear) is 18% lower than the standard 2.40. That means my 3.55s feel like 4.19s off the starting line, yet the 2700 converter is in lockup in 3rd, and the effective o/d gearing is 2.48 for highway economy.
 
#7 ·
Milo I agree with a lot of the things you have said here but with some exception. The AOD and 4R70 are good choices but I am going to want the electronic control of the AODE. The AOD does not have a shift position for second gear (why in hell did they do that?) and I want the ability to control all gears manually. Messing with TV cables isn't my bag either. I really don't like automatics but have decided to keep one in this car for a few reasons mostly I don't want to do the manual trans conversion and it might be nice to have automatic shifting from time to time. It would be a good thing to have when I let the wife drive it, after all this is going to be my touring car. I can do that electronically with the AODE (a paddle shifting kit for example http://twistmachine.com/Paddle_Shifters.html ) using an aftermarket control box. I could even make one myself if I didn't care about not having an automatic mode. I would like to have the choice for both automatic and manual shifting. Now the 700R4 has shift positions for all gears and I could use it if I could get a torque converter that works. Nobody has mentioned it but the E4OD is a no-go. It is a worse power hog that the C6 I have and it weighs more!

I have also considered the 5R55. 5 speeds and fully electronic control! Now if I could just find an install kit and converter.

There are a lot of options out there but I am limited by my driving habits and the fact that I have an old 429 with the large pilot crank. It might be a challenge getting a torque converter for any of these things.

As far as the gear ration goes..... I am going to keep the 3.70s for now. I am not sure if 3.23s would get me enough revs to make the swap worth it for now.

Matt
 
#5 ·
Can somebody educate me on what 4R70W and 700R4's are? When it comes to the motor, no problems, but transmissions are something I have never had much opportunity to dive into. Of the two can you explain the differences and which one is better for what and then 700R4's to and AOD?
Thanks and if it is advised that I start another thread on this subject, just say so, it will be now problem.
 
#6 ·
The 4R70W are an Ford 4 speed automatic, and the TH700R4 is the GM 4 speed automatic, found in Camaro´s, Blazer´s, Van´s etc, if GM is considered, i´d rather go for the TH200-4R 4 speed automatic, it´s considered to be stronger and better than the 700
 
#8 ·
Thanks Jan, If it were you, which one would you go with, the Ford or GM?
Since the AOD doesn't have a 2nd gear position on the shifter, according to "quickcat" What about the 4R70W, does it have all the different shift positions?
Also What make and model and year of car does it come from?
 
#9 · (Edited)
Matt, the AOD-E and 4R70W are the same trans except for the wide-ratio gearing in the 4R70W. Both are electronically controlled.

You can also get a valvebody from silverfoxtrans.com (and maybe others) for a regular AOD that does have a 'normal' 1-2-3 shift pattern and an electronic switch for the o/d. I bought one for my 393W/WR-AOD but haven't installed it yet. Dan at Silverfox will tailor the WOT shiftpoints and firmness to fit your specific application and the shift points are adjustable with a setscrew. I got the SPT-R with a 'stage 3' calibration. It allows both automatic and manual shifting, too...

Anyway, if you don't mind the electronic controls (~$450 for a stand-alone), the AOD-E and 4R70W are good choices.

Tow-MAY-toe, Tow-MAH-toe....

Maybe I did things the hard way, but there wasn't a stand-alone trans controller back when I built my trans (five years ago), or at least I hadn't heard of one that was reasonably priced.

BTW, I agree wholeheartedly on the E4OD/4R100 being power hogs. That's because they're based on the C-6. Not to mention that the E4OD is freaking HUGE! I have both a 460- and 351W-size E4OD laying around. If nothing else they're good for C-6 parts. Oh, and the E4OD/4R100 have a wide-ratio gearset, too...
 
#13 ·
Yes, but it will be from a 97-up 4.2L V-6 truck, or if you're lucky, you can find a 94-97 F-150/E150 with a 5.0 or 5.8, although most 5.8s got the heavier E4OD trans... The 4.6L and 5.4L modular motors use a different bellhousing bolt pattern than those I listed above which have the same SBF bellhousing bolt pattern as a 351C.
 
#17 ·
cougar2 are you doing a big block project? If not and you are doing a Windsor or Cleveland then you need a transmission, an electronic controller of some kind, mount, shift linkage, torque converter and flexplate if the torque converter does not match your original. Be sure to get a flexplate with the correct counterbalance. The factory torque converter will probably not be suitable if your engine is hopped up. There are a lot of moving parts here and you will need to make or buy some custom parts to make it fit.

What are you after? What do you have and what do you want to do?

For a basic AOD swap these guys have a kit http://www.transmissioncenter.org/classic_mustang_to_aod_conversion.htm . If you go AODE or 4R70W you will need a controller like something from Baumann or Twist Machine. If you want to swap in a Chevy trans look around PATC ( http://www.transmissioncenter.com/ )and maybe Twist Machine.

Matt
 
#16 ·
I'm not at all sure what is involved with adapting a 4R70W to a tall-block 429/460, so I can't answer that. You'll have to check with whoever makes the adapter kit.
 
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