So obviously a ton of you guys are modding the snot out of your car. Does anyone know what kind of long term impact the major mods have on the drivetrain? I'm talking CAI+tune, s/c, etc... especially on the A/T. Just wondering if anyone has had any long term problems pushing a large amt of power through their tranny.... thx!

 

well, the 5R55S tranny is "rated" to 550 HP. As far as I know, that number refers to HP at the fly. So guys putting down 450 to the wheels figuring a 15-20% drivetrain loss are on the high end of what the tranny is capable of. If you want to go big or just want to be safe, there are plenty of options to beef up the current tranny or switch to a 4R70W. As far as long term, I haven't heard about many daily drivers blowing out their transmissions. Seems mostly concentrated to hardcore racers.

What are your plans for your motor?

 

The tranny is pretty robust, but it all depends on the input. You can run tons of power and be "nice" to the tranny and have it live. There was a shoot-out where on guy was running stock driveline and he had his car in the low 10s.

My recommendation is if you put aggressive gearing and tires in the car, do something with the trans too. If you are going to put down high HP numbers with a S/C you will probably have similar issues.

Everyone I know running either 4.10s or 4.30s or a S/C has done something with their trans to make it "live". I haven't met anyone yet who replaced one because they "had" to.

Our auto tranny car is running a C&L intake and I moved the shift points with a DiabloSport tuner. It's the wife's DD, so it doesn't really see any abuse. I think it is all about how you drive it more than what you got in it.

 

+1 Alot of tranny upgrades are insurance. I hope to someday find the tranny to be my weak link

 

You guys are talking about doing things to make it "live". What kind of tranny upgrades are you talking about?

 

Level 10 has an upgrade kit and TCI was working on or already has a beefed up 5r55s you can buy. I'm not at this point yet so I haven't looked into it much

 

Oh cool. Yea I haven't really looked into tranny upgrades at all so I was wondering what is out there.

 

There was a discussion about this recently on another board, A tranny builder mentioned, as long as you dont change the shift points above 6000 you'll be safe. You might be able to run at 6000 shift points but your running the risk of the clip inside popping off ..

 

The weak point on our transmissions is the input shaft. You can upgrade things like the bands but the input shaft is still weak compaired to the earlier models. As long as you dont beat on a DD I think you would be safe up to 500rwhp.

 

This is extremely helpful information! At the moment I don't have any plans for her, as she's a DD and under the 36k mark... (the fact that someone just T-boned her and in the shop for $4k of body damage just makes me itchy!). I'd love to do a CAI+tune, but I've got other priorities at the moment. Its something that I haven't seen mentioned (on the other board I post on..) and just wanted to know what's been done. Thanks a lot!

 

4R70W tranny torque rating 700, From what I found on internet, you just add a zero to the end to get the rating of the tranny, 5R55S Would be 550 like he said.

 

Mach1mania,
There is no way the Puegot 5R55S is rated to 550 LBS of torque.

These things ar breaking left and right with way less power.
Sorry

 

This is how it is explaned on many sites I found.
.
The 55, 70, 75, and 100 are the torque ratings; 550, 700, 750, and 1000 ft./lbs. which is engine torque multiplied by 2 by the torque convertor. So, 225, 350, 375, and 500 ft./lbs. of engine torque.

So I guess that means (4R70W= 700= 350trq) and the( 5R55S IS =TO 225,) NOW I see why they are breaking..

 

 

Okay I understand the tranny number designation/HP level. However the ratings of the transmissions are based on the torque level after the torque converter. The torque converter multiplies torque from the flywheel when it stalls. So if the 5R55s is rated at 550 lbs of torque that rating level would include the torque multiplied from the converter. Typical converters mutilply 1.8 on a OEM converter to a 2.5 high stall multiplication of torque.
So at 1.8 multiplication a stock GT can make 540 foot pounds of torque at the converter. What would it be with forced induction and a high stall converter? If it is a multiplication factor of 2.0 for a pretty loose converter then a blown GT with 450 foot pounds torque at the crank could have peak torque levels of 900 foot pounds after the stall converter. So relatively speaking the rating on these trannies are pretty low in comparison with a 4r70w.