Or direct me to an article where I can learn please. Not sure what the TC does, how it is suppose to lock out, or what to watch for if the the tranny is slipping.


Howoes the tow feature work, what is it suppose to do? I don't even notice a difference when I have mine on.

Once again, thanks for the education.

 

The TC is essentially your clutch between the trans and engine. In fluid coupling it is only about 70% efficient at transfering power, in other word sit has built in slip to allow rpm's to rise when needed. In lockup it is 100% efficient at transfering power. In drive and OD it is aggressively locking for mileage and power transfer. In lower gears it does not lock except in manual 2nd.

The TH on your truck does not lockout OD like the earlier models did, it just uses an alternate lockup and shift strategy that will hold the gears longer for towing and lock the converter more aggressively.

Slipping is a hard thing to track at times. The normal operation for an automatic is to slip a certain amount on gear changes and lockup. This minimizes the shock to the rest of the drive train and provides a smooth transition from gear to gear. The trick is to slip enough and not break things but not so much it starts heating and burning clutches.

The TC clutch and direct clutch pack are the critical areas and where excessive slipping will eventually kill the trans. The TC slipping under power and a load is very obvious and will shake the dust of the headliner if it is bad enough. When somebody talks about TC shudder thats normally what is happening.

Slipping the direct clutch pack, which is on in drive and OD, is almost undetectable. You really have to have gauges and a good base line for the readings to detect when there is a problem. Due to the low stock line pressures in the trans it can and does happen even with no power increase and will eventaully cause the transmissions to quit working, usually catastrophically when it does.

To minimize the problems with slipping clutches a shift kit is a good investment and should be the OEM build. The NVH guys disagree so what we get is what they dictate. To stop the slipping TC, or sloppy fluid coupling, a good TC that is designed to be more efficient is the ticket.

Very high level concepts but thats it in a nutshell.

 

Thanks, that does help alot.....one last question, for now....LOL...... Towing my 5th wheel, about 9000#, on smarty 4, it had some very "hard" shifts, where it jolted the truck and seemed like a very rough shift, on acceleration when going uphill or the rare occasion when needed to have quick acceleration from start, the shifts were "hard" as well.

Is this slippage?

Thanks again. BTW, truck has 72000 miles on it, only last 2000 with a 5th wheel, all other has been relatively easy and towing a couple of snowmobiles.

 

Were you in TH? If so then thats normal, the TH mode is much more aggressive on ramping TV pressure and holds the shift till later so it is much more firm. The lockup in OD is really hard at times because it is a shift then lock immediately with a big rpm drop. With extra power in it and a load it is much more noticable.

 

Yes they can and yes it will. I ran mine hard for 10k towing 10k+ and playing with Smarty on the upper settings, but, I fully intended to replace the TC. When we pulled the trans ALL the TC to flex plate bolts were just barely tight and you could see where the lugs were starting to walk on the plate.

It got rid of the TC clutch slip but you throw Smarty on #4 into the mix and drive it relatively hard and the stock TC has the tendency to warp the cover.

That said, I cranked a lot more pressure into it than some say it needs or will work. It worked fine but there are pitfalls. Running the shift kit in a stock trans is walking that line between fixing the sloppy OEM engineering for a better unit and introducing more problems by over taxing the OEM component capabilities. It can be done but needs to be tempered with restraint.