How much HP can a stock c5 automatic transmission handle. ?

Happy Holidays

 

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A question I have asked is what breaks? Haven't seen an answer to that yet.
I know a 4L65 has stronger 5 gear planetaries. And they fit in the 4L60. there are other parts that break, and I need to find out what. I have a shop that hopefully can help. RPM is on the wrong coast I'm afraid.

Ron

 

I thought the clutches, specifically the 3-4 clutches, were the first to go. The problem is that you just move down the path of the weakest. If you get better/stronger clutches, then the next weakest thing will break. You really need to know the full chain and what fails when to determine what to upgrade.

At a certain point though, it becomes simpler to replace them all.

 

OP, what mods are you planning and what are your power goals?

 

about 340!

 

it depends on how long you want it to last and how hard you drive it. For this reason, I haven't added too much power to my car. mine is a manual, but the same principles apply to any drivetrain on any car.

if you want to beat the hell out of it with 400whp for 100k miles, i would suggest a full rebuild, or just wait until it breaks and then do the rebuild. Although if you just let it break, then you are probably going to lose some parts that may have been reusable.

 

Agreed. I pretty much know what RPM adds. Ditto for FLP. My shop knows the trans, A1 transmissions builds a lot of stock eliminator stuff. There are HD clutches and bands and sprags etc. I haven't been inside a 4L60, but have built a few TH400's.

I will be street and strip driving the car with drag radials.

 

on street tires round 400 hp really i see more 4l60 failures in 4x4 trucks than f bodys and vettes they have a few weak spots in stock form the sun gear shell breaks and you have no rev 2nd or 4th the 3 4 clutches burn usually from a worn valve in the valve body and i seen a lot of fwd sprag failures in 05 up 4l65 s the aftermarket sprag is far stronger than the gm unit

 

I'm running around 700 at the crank with all stock drive train. A few trips to the strip, but mostly street driving. No drag tires and so far no problems. Tranny was reprogrammed to up pressure, raise shift points and shorten shift time and has performed well.

 

If you want to familiarize yourself with which parts tranny buliders "upgrade" for a higher HP build---Go to their websites and compare the list of parts they change --Then compare the list to (for example) their stage 1--stage 2 and stage 3 bulids---The different parts and upgraded parts they change are typically what fails 1st---
Try RPM's site---Performabulit---Century
Also even a moderate HP boost say up to 350 RWHP can benefit from trans tuning alone---GM in order to please a vast array of customers make the shifts very soft--In order to get soft shifts-they have to "slip" the clutches---This creates them to wear faster and creates heat--all longivity detrimental--
The major cause of trans failures is HEAT---Try to keep an eye on the fluid temps--200* is sort of the key temp---You don't want it to stay much over 200 very long--Adding an aftermarket cooler really helps the trans to live--
Several WOT hits in a row really bulid up the heat---Let it cool down between runs--
On my stock trans with apprx 400 RWHP--it finally let go after 5 years with lots of spirited driving and about 10 track days---(2600 stall)
I went back in and did a stage 3 rebuild and a 3000 stall---upgraded the cooler--my temps even on a hot day in long city driving never gets beyond 190*--freeway mabe 175
now-