ChiDiddy

Hi everyone,

I'm fairly new to the mustang/domestic community. I'm planning to get an auto, but i also plan to boost it. Now i see a couple of ppl have broken trannies from boost.

But from my current boosted autos, i run:
-Fully built auto race tranny+high stall on the RSX
-ATF cooler
-Amsoil synthetic ATF

The cooler and Amsoil will go LONG ways in improving tranny life and heat control.

Also, are you guys running the Brenspeed Deep tranny pan? More ATF=cooler=longer life. Heat is the trannies worst enemy, and the only thing i can think of u guys who are breaking them are overheating the tranny in some way.

Can you guys share experiences in your boosted automatic? ie. shift quality in daily driving, WOT, etc. And also, list symptoms of "broken" trans.

BTW this is my plan if getting a Saleen is not possible

pinoy

Well supposedly the transmission can take up to 430hp. But i only have 300RWHP and my transmission blew up. Im pretty sure if you get the kit from brenspeed it would help out the transmission plus you can do you own transmission fluid flush. (The new stangs dont have a dipstick!) I have the tune from brenspeed and it really awakens the beast under that hood. Good thing the transmission took the beating till 48k miles. And thats really beating it up. Taking it to the track every week and gunning it at almost every stoplight. I read in Modified Mustangs today that there is a right up on how to change our 5R55S transmission to a 4R70W transmission. Supposedly that new transmission can take up to 1800HP.

ChiDiddy

did u run anything with the tranny to reduce heat? cooler, amsoil, etc?

what trans is the 4R70W from?

Thanks!

zkiller

I know of well over twenty trannies that have broken.
Most were stock. afew had TCI converters
Most lost third gear
Some broke the input shaft in half
some had converter fail

Forced induction = broken tranny at some point in many cases.
Puegot makes this tranny for much less power in my opinion.
Pushed my top end to162 MPH and my tranny began to slip the next day.

Brenspeed has a deep pan
Level 10 has a deep pan
Performance has a deep pan
Those may help keep temps down. The 5/8 input shaft is a weak point also.
The stock converter sucks, it unlocks by itself and runs hot frequently.

cheftjpeck

I dont push mine much or race with mine at all. I do have a PI torque converter on its way. for my first change. along with a deeper pan setup. got to get those temps cooler. My tune is a great tune...the stock TC will unlock and create heat that is for sure. I highly reccommend getting A GOOD TC to accompany the supercharger install. if anything it will give your tranny a better chance at survival. honestly whenever you make any mod to a car designed to handle so much regardless of safety precautions, you run the risk of causing damage to your vehicle. it is a risk / rewards factor...I can not speak for anyone else. my supercharger is still pretty much in its infant stage as I have only had her for a little over 4 months...and 3000 miles....I have heard people blowing their trannies very early on and I have heard some who have 20,000 plus without an issue. Now as others have posted, 3rd is your weakest followed by 4th gear. most issues start with these cars going into 3rd....the tune and tuner will have allot to do with your car as well...heat kills trannies as we know....aggressive tunes not so much..also locking a NON locking torque converter is another thing that will assist in the destruction of your transmission...again I am taking steps to prevent this...but again...no guarantees...

ChiDiddy

so i guess its a toss up if u want a boosted auto.

but most aren't running the necessary precautions i presume? i cannot stress enough how important and big difference the basic cooler+amsoil atf upgrades do.

ChiDiddy

so is the stock TC a lockup kind or not? or do you mean the highstall is no longer a lockup convertor?

zkiller

The stock converter is supposed to lock.
It often comes unlocked under load, this has been documented on dyno runs.
It is a pretty loose converter that is weakly made. They have a solenoid in the tranny that is supposed to actuate the locking feature. This solenoid is the cause of it coming unlocked in amny cases.
The high stallaftermarket convertersare also locking converters. They actually stay locked though (at least mine does). The "super solenoid" is one of the upgraded parts Level 10 uses when beefing up the 5R55S in their kits.

ChiDiddy

Is the C4 tranny a straight up swap? would any trans programming be required? (via SCT?)

fordfanboy

You do not want a C4 on the street. Nothing is ever 'straight up' but it is fairly easy. New bell housing, converter, input shaft, and drive shaft and you're good to go. But if you want a street car as well as a track car, you are better off with an AOD or a rebuilt stocker with a solid TC like the PI multi disc.