Hey guys,

I have a friend that is interested in maybe purchasing a C5 pretty soon. He was looking at some automatics and was asked me some questions about how much the stock automatic transmissions can hold.

What kind of power can a stock auto transmission hold up to?

What are some upgrades, if any, that need to be carried out to keep the transmission together if he plans on modding it quite a bit (blower, nitrous, etc.)?

And how much do these upgrades usually cost?

Thanks guys,
Harshil.

 

The stock trans is good up until about 400 RWHP. It's not worth trying to modify your stock transmission and if you leave it stock, with that kind of HP, you will fry the clutches, 3rd gear always seems to go first. I went with an RPM stage IV, and didn't look back. Besides, you are going to have to remove the transmission, (which entails lowering the whole transaxle) to install a high stall torque converter if and when he does decide to do that. My advice would be to wait until he decides on what exactly he is doing to the engine, then match the trans and stall (and maybe even gears in the differential) accordingly. I decided to just install a new torque converter and transmission cooler. Then my stock transmission went.

So........when I got my new trans, I installed the new 3.42's. If I knew then what I know now, I would have done it right the first time and done the trans, trans cooler, torque converter and differential all at once. Hope this helps.

Costs:

Transmission: $1,700.
Torque converter: $450.00
Trans cooler: $100.00
Differential (new GM assembly): $1,100.00
Fluids: $70.00

P.S. If you're going to go that far, you may as well flush all the lines while you're at it. A can of transmission line flush is $10.00. That's what I did.

 

cbx is right on and for those of us who have replaced a trans, RPM transmissions is the only place to go.

 

I am adding a shift kit, billet super servos, and readjust the band with a longer servo pin and installed a trans cooler, plus a deep pan. This is as much as a person can do to extend the life of the tranny without dropping it. The main reason any transmission goes is usuaslly a seal failure. Keeping the fliud cool will extend the life of the seals. Adding a shift kit and better and bigger servos will help reduce band slippage. And a shift kit will help eliminate some other problems. But it still wouldn't come close to a fully built tranny. I am just doing this hoping it will last the rest of the year. I am hoping Santa will drop me off a RPM level V

 

I've got a mostly stock tranny (has a Transgo shift kit) and am running 423 rwhp and 392 rwtq with a stock torque converter in my 2004 C5. I've heard a few people comment that some of the 2005 tranny enhancements went into the 2004 for durability reasons. Seemed to make sense, but I don't know for certain whether or not that is true. I did feel that keeping the stock TC might help the tranny last longer.

So far about 7,000 miles and no problems. I don't abuse my car, but I certainly don't baby it. So, a couple of different factors seem to affect durability and longevity.

 

I've a 99 A4 (stock tranny & engine) with shift kit, with 8,000+ miles on it... Running great... Recently added 3.42's...

 

Are you guys still running the Torque managment? I would think that that probably has a lot to do with the tranny life too.

 

400 rwhp is on the high side in my opinion. 350 rwhp at the most. The 4l60e is a weak transmission at best with no mods at all. Heat just kills these things especially if you live down here in Texas. 4-5 hard runs in 100 degree Texas heat will have your stock tranny up to 230-240 degrees no problem.. If you live up north somewhere in a cooler climate you may be able to get a litttle more torque /horsepower to the tranny without overheating it Not sure where CBX lives but its probably somewhere way up north if hes getting 400rwhp and not frying the transmission.. Get another trans cooler where ever you are..

 

Turned off via tune.

 

Fried mine at 350 RWHP

 

How? How many miles on it? Did you have a cooler?
I have 61K on mine and have 349.31 RWHP 351.11 RWTQ.
Just installed a tranny cooler also use Royal Purple transmission fliud. So far all is well.

 

Thanks for all the information cbx. You pretty much answered everything that my friend needed to know.

Thanks to everyone else as well. This information was very helpful.

Harshil.

 

Hi sleeper C5.. Not to hijack the thread or be rude but I had to laugh at your Birthday on your public profile.. It looks like you are 9 years old.. I'm sure its just a typo error
Damn children on this Forum!!! Just kidding man. What the heck sometimes I feel like I'm a 9 year old in a grown mans body