Surprised by my TC!

[Strick-9]

I was playing around on the way home from work today and was totally shocked by my torque converter. I had a DTT 91% for over a year and switched it out for an 89% in December.



You'll have to understand that I don't have a locker yet, so tire spin is quite easy in my truck. I pulled out onto the highway and stepped on it with a little propane flowing and OD off. The right rear tire spins through second and kept spinning completely through 3rd as well. My tach was stationary at 3100 rpm and my speedometer read 78 mph. It was frozen like this for several seconds as the vehicle speed catches up to the spinning tire.



What shocked me was a few seconds later I locked up my TC clutch at 78 mph and the tach read 3000 rpm.



Could this be right? Full power and only 100 rpm difference between lockup and fluid coupling? I know TC's get 'tighter' as rpm climb, but under a heavy load with several hundred ft-lbs of torque I thought there would be a bigger difference.



Just thought I would share that tidbit.

-Chris

 

[Cummins Corvette]

Is it possible that your pump was beginning to defuel?

I have the 91 and I get about a 400 rpm slip when the converter (engine rpm) is at 3000 at full power (stator/transmission input at ~2600), and I have nowhere near as much power.

 

[Animal]

Stick-9,



The only thing I can think of is the engine is not at full power while the wheel is sliping, there is less TQ required to keep it slipping verses a wheel that is not slipping. Therefore sense the engine is producing less TQ the transmissions TC is coupling better do to the lesser TQ requirments of the slipping wheel verses a none slipping wheel. I hope this makes sense.

 

[Jim Fulmer]

My 89

I doubt mine will lockup while I have it on the wood, I have tried this some but run out of road or get in to fear factor. If I take off onto the highway at 1/2 to 3/4 throttle keeping the EGT's say at 1150 it will lockup in O/D but not till 80+ but when it does there is a bigger drop then when under no load (as expected) kinda like a 5th gear, all I need now it a smart controller.



Jim

 

[Strick-9]

Chris,



My pump doesn't defuel. No governor. How long ago did you buy your TC? This 89 feels tighter on top than my 91 did that I bought a year and a half ago. I wonder if something was changed in them?



Animal,



Without the propane, it usually spins through second and just a little in third and then the engine is bogged down because it doesn't have enough power to keep it spinning as the vehicle speed climbs. That made me think it was using ALL my power.



But I could be wrong. Thanks for your viewpoints.

-Chris

 

[jimk]

torque convertor

At what rpm is the 89% convertor rated for. At 3000 rpm this might be a little better. Now this may be wrong but my stock convertor seems to be better at 2500 than 1700.



JIm

 

[JIM S.]

I just installed Piers govener spring kit and in testing it with my foot on the floor in "drive" the tourqe converter lock up is not hardly noticeable. . light throtle is the same as before the GSK(400 -+ rpm drop). so I have kinda the same question, my TC is stock... as far as I know! but is it slipping or being more efective now that I can use power at high RPM. ????

Jim

 

[Cummins Corvette]

I got mine last august.

 

[Jim Fulmer]

Both Jim's..... My stock converter worked allot better after the GSK but the EGT's would sweep like heck with the #8 plate, If you take your stock converter at 60,70 or whatever MPH and unlock it via switch and put it on the wood it will go to 2800 or so, my 89 will flash 250 RPM or so then start covering ground in a hurry, but there is a hitch, it will spool instantly at say above 1500 RPM. The test I use for folks is power break a little of the line then at 20 MPH roll into the throttle, it goes in to 2nd shakes the tires then hauls a$$... ... . Chris I need you smoke at times to get people off my tail I do find myself using the unlock(dimmer switch) allot and now it is normal operation without thought, If I never jam on it there are two places going to work were I need to gain speed and the converter locks at lower RPM than I like, so I unlock it and drive like I want then lock it later.



JimK... I do come down that way at times as Quanah is home to me and Medicine Mounds is were our farm is, when I go to the farm I travel down 240 which is close to you, but I warn you it will cost you a transmission update to drive mine as it did when I rode in James's truck... . word to the wiseOo. Jim... . Sat I will come down to Lewisville for the Dyno session as long as it is still on!



Jim