I had my truck on the dyno sunday and the guy running the dyno said that my torque coverter was slpping. is this something that anybodyelse has experienced while getting there truck dynoed. it could also be because i have a predator tuner and it made 770 pounds of torque and 363 horsepower.

I just need to know if this is something i need to woory about. thank ya'll for any info you might have.

 

What type of Dyno were you on? How heavy was the roller?

 

have you been running the truck easy lately?

 

I think he's referring to the fact that the torque converter was unlocked, rather than locked during the run. To obtain a correct reading, the truck must be manually locked into torque converter lock up and 5th (direct drive) gear. With just a Predator, there is no way to force either one of these conditions while on the dyno- running unlocked or in a lower gear will cause the torque to read high, while the horsepower will read low. This is due to steady state slippage (not harmful, just a characteristic of fluid lock in a torque converter)- from this you will lose overall horsepower due to frictional losses, but gain torque from TC stator torque multiplication.

You will either require a custom tune to force the truck into lockup and 5th gear at lower engine/vehicle speed (someone at Diablosport will have to help you with this) or a similar truck in a 6 speed manual will need to be dynoed instead.

Most trucks with a Predator turn out around 380rwhp and 680rwtq.

 

Actually, you want a 1:1 on the Dyno...in the Auto's you need 4th Gear.

 

i'm not sure what the dyno was. i think it said dyno dynamics but i'm not sure if that is the brand. i am pretty sure that it was a friction dyno though. i did think that my torque numbers were kind of high so that does make sense. thanks guys

 

ACtually, you want 5th gear. 4th is a 1.1 to 1 ratio, and isn't used. Keep in mind its actually a 6 speed- when you command 5th in the PCM, you get direct drive. 6th is overdrive.

 

So "6th" is 5th with converter lock up then. Interesting! Thanks!

 

No- there are 6 "hardware" gears, not including converter lockup.

The torqshift has multiple sets of planetaries, unlike a normal 3 speed or 4 speed automatic. There is a low/reverse gearset, an intermediate gearset, and a direct drive gearset.

1st gear is obtained by locking only the low/reverse set, resulting in a 3.09:1 drive ratio. 2nd is actually "first over", using both the low/reverse gearset and the overdrive gearset, resulting in a 2.2:1 ratio (if you multiply the low/reverse of 3.09 by the overdrive ratio of .7, thats what you get). 3rd, a 1.538:1 ratio, locks the intermediate gearset only, whereas 4th (1.09:1, not used unless PCM is in cold strategy) is actually 3rd-over, locking both the intermediate and overdrive gearset. 5th is 1:1 using only the direct drive clutch, and overdrive locks both the direct drive and overdrive gearsets.

Just picture it as a 3-speed transmission with another 2-speed behind it- for all intents and purposes thats how it operates. 4th is used when the TOT is extremely cold to lower the amount of time the direct drive clutch sees before operating temps are reached- the direct drive is the weakest unit in the transmission.

 

GOTCHA!! Amazing thing is, I understood exactly what you just said too. w00t!!