99-04's engine/Auto tranny

[Makdaddymac]

hey all i am a 5.0 talk regular,
but I'm looking into getting a 99-04 mustang..I want a auto for this cause i have no intention of modding it, just want the mod motor exhaust note and some power.....but i was wondering what are the limits of the 2v gt motors and trannys if i were to slap on a supercharger on it nothing to serious just like 350-380whp??? i have a fox 5 speed with more intent to mod but i think the price of 99-04 gt autos are getting tempting...thx

 

[deftsound]

hey all i am a 5.0 talk regular,
but I'm looking into getting a 99-04 mustang..I want a auto for this cause i have no intention of modding it, just want the mod motor exhaust note and some power.....but i was wondering what are the limits of the 2v gt motors and trannys if i were to slap on a supercharger on it nothing to serious just like 350-380whp??? i have a fox 5 speed with more intent to mod but i think the price of 99-04 gt autos are getting tempting...thx

Well most people would agree on here that much more than about 430rwhp is starting to really push it for the stock blocks. The trannys im not so sure about but i know that ive never had a problem with mine and ive been pushing 375+rwhp for a few years now although its a 5 spd.

Now, there are plenty of exceptions on stangnet. Theres a couple guys around here pushing 475rwhp and even a few over the 500rwhp mark...including someone who just dynoed at 540ish i wanna say...all on the stock block

 

[Makdaddymac]

yeah my golas would not push the limits of the block. but im trying to see the input on the auto 4r70w trans i hope thats what in the 99-04gt!?!!?!?

 

[Deleted member 38176]

The 4R70W's are underestimated as far as their strength. They are tough trannies and will easily handle 400rwhp on a daily basis for quite a while.

 

[Red35th]

I can second 4r70w's strength. I've been using a NX kit jetted at 100hp for years.

If you put a trans cooler on it, it'll last for a long time at 400hp. I'd imagine that's especially true if it's a centrifugal (less torque and smoother power band).

 

[hotstang_46]

It's strength may be ok but jeesh....it's behaviour clearly makes it the worst acting tranny in any car I've personally owned/ driven for any length of time. The wandering between gears is the worst. If you get it, at minimum do the JMOD, do a search, you'll probably find a ton of info, that will help.

ps...I'm one of those with big hp on a stock block. Just an FYI... If you ever wanted to upgrade that blower and go over 400-430+ meth will help that keep everything in one piece.

 

[68stang351]

The way I've read is that the 4R70W means 4= 4 speed, R=rear wheel drive 70 = 700 ft/lbs torque capability, W= wide ratio.

They say it's a pretty tough trans. I read that explanation in one of the Mustang mags, they were swapping a 4R70W into a very heavily modded 05+ GT because it was stronger than the 5R55.

 

[wmburns]

The way I've read is that the 4R70W means 4= 4 speed, R=rear wheel drive 70 = 700 ft/lbs torque capability, W= wide ratio.

They say it's a pretty tough trans. I read that explanation in one of the Mustang mags, they were swapping a 4R70W into a very heavily modded 05+ GT because it was stronger than the 5R55.

FWIIW, the 70 is not 700 ft/lbs of torque. It is 700 Nm which is about 516 ft/lbs.

If a 4R70W could support 700 ft/lbs, there would be a lot of happy hot rodders out there. Not to mention the market for upgraded transmissions would be much smaller.

The 5R55 is 550 Nm or 405 Ft/lbs.

 

[Deleted member 38176]

FWIIW, the 70 is not 700 ft/lbs of torque. It is 700 Nm which is about 516 ft/lbs.

If a 4R70W could support 700 ft/lbs, there would be a lot of happy hot rodders out there. Not to mention the market for upgraded transmissions would be much smaller.

The 5R55 is 550 Nm or 405 Ft/lbs.

WHAT???? So the autos in the 05+ cars can only handle around 400tq??

 

[bhuff30]

So what is the torque rating of a C4?

 

[scupking]

It's strength may be ok but jeesh....it's behaviour clearly makes it the worst acting tranny in any car I've personally owned/ driven for any length of time. The wandering between gears is the worst. If you get it, at minimum do the JMOD, do a search, you'll probably find a ton of info, that will help.

ps...I'm one of those with big hp on a stock block. Just an FYI... If you ever wanted to upgrade that blower and go over 400-430+ meth will help that keep everything in one piece.

+1 its a very strong tranny but you must do some things to make it fun and last a very log time.

1. tranny cooler
2. jmod
3. stall converter (3,000-3,200rpm stall)
4. 3.73 or 4.10 gears
5. SCT Xcal III tuner

If you do the above you will have a very fun auto mustang.

 

[stang06girl]

FWIIW, the 70 is not 700 ft/lbs of torque. It is 700 Nm which is about 516 ft/lbs.

If a 4R70W could support 700 ft/lbs, there would be a lot of happy hot rodders out there. Not to mention the market for upgraded transmissions would be much smaller.

The 5R55 is 550 Nm or 405 Ft/lbs.

If always read the code as ft-lbs, Where did you find out that it is in Nm?

 

[Deleted member 38176]

If always read the code as ft-lbs, Where did you find out that it is in Nm?

Just did a little searching and found this:

4R75W is a torque upgrade from 4R70. The numbers in Ford's auto trans nomenclature refer to torque levels which can be accomodated, I believe on the downstream side of the torque converter (i.e., turbine side), in Newton-meters.

 

[bhuff30]

I forgot about the multiplication effect of the torque converter. Normally, manual transmissions, like the T5, TR3650 and T45 have torque ratings between 300 and 340 ft*lbs, which isn't that much. So I was very surprised to see a torque rating of 700N*M (500 ft*lbs) on the automatic. However, you have to remember that the torque converter has a multiplying effect at very slow speeds. You can even get a 2x multiplication of torque if you slam on the gas from a dead stop. Keep that in mind when considering how well your transmission will handle the power.

 

[stang06girl]

WHAT???? So the autos in the 05+ cars can only handle around 400tq??

I guess it's a good thing my Nitto's don't hook worth a crap. At 520 RWHP and somewhere like 460 ft lb of torque I should have snapped the 5R55S in two by now.

Just to throw another tranny into the loop, thr 6R80W trans that they are putting in the 2011's (currently it's in the larger trucks and expeditions) might be worth looking into as well.