Torque Converter

[SteveC]

Has any one installed a "Torque Controller Lock-up" in their automatic transmission Jeep?

Any advice would be nice.

[AussieCJ7]

Steve Think you will think your transmission already has a lock up torque convertor :)
Do you mean a switch to manually lock it ? If so I have done it for a AW4 but they are easy because of the way the TCM controls the solenoids for your transmission it would require some researching

[SteveC]

Aussiecj7

Thanks for your reply

Yes I mean a manual lock-up switch so I can hold it in 1st gear on steep descents, to stop the auto from "running" away.

[reyzor]

might be a dumb comment, but cant you jsut put your auto in 1st?

[Steve F]

might be a dumb comment, but cant you jsut put your auto in 1st?

The 4 speed AW4 doesn't have a first position, it's first/second and can, if the RPM's build, change up to second on a long descent. I've never had it happen to mine though it always seems to stay in first on steep descents but I guess that's because the RPM stay low. I've had the opposite issue where I've drop it back to put it in second and the RPM have dropped and it's gone back to first, this will chirp the wheels if it's on the tar which is where I normally do it so I dont have to ride the brakes.

Cheers
Steve

[sbadman]

The 4 speed AW4 doesn't have a first position

Yes and no. Of course you're correct in saying the standard shifter sequence shares 1st and 2nd. If the TCM is disconnected the transmission will operate manually by moving the shifter as 1st, 3rd, 4th (no 2nd). First gear can be locked out electronically by isolating an individual solenoid, Marcus Ohms (GoJeep) has all the details on his website, as well as the manual torque converter lockup. Post 97 models will through an error code if the TCM is altered/disconnected, the pre 97 ECU won't even notice :D

Of course all this info only applies to XJ's (and perhaps some early ZJ's), IIRC SteveC's WJ uses a Mercedes 5 speed, full computer controlled. I'm not going to go there :D

[SteveC]

Sbadman
I did see that link you mentioned but as you say it works pre 97
Mine is a 5 speed more computer controlled system and even has two x 2nd gears, one for up change and another for down change. Funny that!

Mine does however remain in 1st if I keep it there, regardless of steepness unlike some of the modern auto that can up change if revs exceed a predetermined amount. In my case I'm lucky it stays where I thought the lock-up switch keeps the revs in check ?? Perhaps I misunderstand it all.

[Hunno]

Funny,
with the ZJ's turn the AC on & lifts the revs just enough & that it locks up but also loads the engine & stops it running away.

[sbadman]

In my case I'm lucky it stays where I thought the lock-up switch keeps the revs in check ?? Perhaps I misunderstand it all.The torque converter is to an auto what the clutch is to a manual, in that they link the engine to the transmission, but the similarities end there.An unlocked torque converter will actually multiply the torque from engine to transmission due to it's hydraulic operation, but in reverse (ie torque moving from transmission to engine) it will allow the transmission to spin faster than the engine. A clutch that isn't fully engaged will reduce torque transfer, and again allow the transmission to spin faster.A locked up torque converter means the impeller, turbine and housing are all locked together, the transmission must spin at the same speed as the engine, no matter which direction the torque transfer.It is high likely that your 5 speed locks the TC the same way as the XJ's AW4, indeed most modern transmissions, an internal solenoid switching a hydraulic circuit. Working out how to control that solenoid without upsetting the existing computer is the trick. Limp mode for that transmission is 2nd gear only. (Although as I discovered from my father-in-law the 5cyl turbo diesel will still accelerate smartly in second gear when given the berries in anger!)

[glend]

SteveC which transmission do you have? Is it the 545RFE? Because you have two 2nd gears (one used going up and the other going down) it makes me think its the 545 RFE, the same one that I have in my KJ CRD. Yes, it can be held in first with the gear selector. As far as rev limiting is concerned, your really relying on your engine compression to hold it back. Holding it back is always easier with a diesel due to the higher compression ratio. An exhaust compression brake, those annoying noisemakers that you hear when trucks are coming down a steep grade, are available. There are smaller versions that fit some of the US sized pickup trucks, including the Dodge RAM that uses the same transmission. Your problem with fitting an exhaust brake is that due to the lower compression of the petrol engines it will probably stall the engine - not something you want to happen on a steep descent.

Your least cost option might be to just use low range in the transfer case and hold it in first, and try to use the brakes (and anti-lock, or hill descent if ou have it) to hold you back. There's the other option of regearing, to improve crawl performance, but I don't know whether this is best done through a transfer case reduction in low or a general final drive gearing reduction (which will effect your hi range rpms and fuel economy).

[SteveC]

Glen
Yes I have the 545RFE

Mate I think it's all too difficult and probably costly if at all possible AND probably not worth it on my 12yo Jeep

I do appreciate all your input guys

[Wooders]

Steve,
If you do figure it out let me know as I'd be interested to do it to our grand. But at this stage the too hard/expensive for the results is my gut feeling.

[SteveC]

Steve,
If you do figure it out let me know as I'd be interested to do it to our grand. But at this stage the too hard/expensive for the results is my gut feeling.

Dave I think the only answer to this is to install reduction gears. Might be a dumb question but do they just replace the low 1 with a lower gear or is that a higher gear?? Is that all that is done?