Transmission Cooler for Auto

[old Jack]

I'd love to see this thread revisited to find out what people may have done to improve AT cooling - what works, what doesn't. Anyone care to share?

Hi Peter,

The biggest reduction in ATF temps is gained from changing driving style ans using the manual mode rather than "D". Several people have bypassed the radiator and others have installed 2nd ATF coolers but the benefits are not as great as changing driving style as this stops the ATF from getting too hot in the first place.

Optimising airflow if also critical, some bullbars, particularly the split pan design as these restrict airflow into the lower half of the heat exchangers. I recent blocked the "air inlet slots" on my Bushskinz front plate and fitted side gussets to force all ram air through the heat exchangers.

cheers, OJ.

[PeterC51]

Hi Peter,

The biggest reduction in ATF temps is gained from changing driving style ans using the manual mode rather than "D".

Yeah thanks OJ. I was in manual (3rd) when I encountered my first limp at 2500 revs and 24c ambient air towing 1.6 tonne up a long incline (a/c off). Just doesn't add up to me. Should I have held 4th with TC active?? I guess you'll tell me to get a TC lockup Cheers mate.

[old Jack]

Hi Peter,

Unless the AT Temp Warning light was flashing then your limp mode was not triggered by high ATF temps.
If the gear display on the dash was flashing then you had a TC slip "time out" generated limp mode.
The Jatco auto fitted to the Challenger is the same trans as what was fitted to earlier Pajero's but the TC has a higer stall ratio and a different ECU program. In the Challenger, the TC only locks ip in 4th and 5th where as in the Pajero with the same auto it locks the TC up in 3rd, 4th and 5th.

Yes, fitting a Gen 2 TC lockup switch, and using it wisely, will stop the "time out" limp modes and a byproduct of this will be lower ATF temps which is a good thing. Fitting a 2nd cooler or modifying /replacing existing ATF cooler or improving airflow will not stop "time out" limp modes but it will decrease ATF temps.

You do not say what speed you were doing when the engine was at 2500rpm in 3rd but if you were doing less than 66kph then the TC was slipping. Problem is with the high stall ratio TC it is very difficult to tell how much the unlocked TC is slipping except for vehicle speed.

cheers, OJ.

[Dongskie2]

Yes, fitting a Gen 2 TC lockup switch,
cheers, OJ.

I'd love to know how to do this.

So does bypassing the radiator bottom tube do any good? I don't know the flow of the ATF if it goes through the radiator first and into the cooler or vice versa.

[zippo]

Lockup kit

The world has moved on a bit since that comment was posted in 2016.

Search the FORUM for Automate / Lockup-mate and have a read. Automate is the goto solution now. It gives you lockup on 2,3,4,and 5 and is smart enough to unlock, relock or shift down a gear as the need arises. You use the gearbox in manual mode and Lockup-mate takes care of the locking. Fitting the kit is either DIY (it's very simple) or get someone to do it for you. I did DIY. (Automate is the more advanced version. I'm using Lockup-mate)



I tow a 2500KG caravan and only once managed 97 degrees radiator temperature since I fitted the Lockupmate - and I've got a bullbar and bash plates that probably cuts down on cooling air and it was a monster range crossing. Other thing - on the flats you can run some of the time in 5th locked up. That pulls the fuel consumption right down. Up to you to manage the gear changes and not overload the gearbox.

Very happy camper.

[old Jack]

I'd love to know how to do this.

So does bypassing the radiator bottom tube do any good? I don't know the flow of the ATF if it goes through the radiator first and into the cooler or vice versa.

No bypassing the ATF cooler portion of the radiator does very little to improve the cooling efficiency in fact it can be negative. A common misconception is the ATF fluid is surrounded by engine coolant and therefore the coolant adds extra heat into the ATF to assist the ATF in coming up to temperature but also adds extra heat into the ATF when you do not want it. The ATF cooler is a separate portion of the radiator and the coolant and ATF are separated so the heat transfer from either into the other is very minimal. In many vehicles the ATF cooler incorporated in the radiator is the only ATF cooler. On the Challenger there is an additional ATF cooler downstream of the aTF cooler incorporated into the radiator, this is a reasonable size but its location and angle to ram airflow is less than ideal.

Excessive ATF temperatures are caused by an unlocked torque convertor both going uphill and downhill! To prevent excessive TC slip and high ATF temps the Auto ECU is programmed to detect extended periods of slip, when this situation occurs the auto is changed down to 3rd, if the TC slip continues and there is still accelerator pedal input then the Auto ECU changes the auto down to 2nd, removes all accelerator pedal inputs, flashes the gear selected display "N" and the auto is now in "self protect limp mode".
The limp mode normally occurs during or after long uphill drives when towing, normally it can be cleared by removing your foot off the accelerator, shifting the selector to "N" then back to "D", then reapplying the accelerator, however I have had the situation where I have been going downhill immediately after an uphill and have not been able to reset the limp mode immediately, this is because when coasting downhill the TC is unlocked to save fuel.

I have been working with MM4x4, as they have been using my Challenger as a test vehicle for the development of their TC lockup kits over the last 18,000kms and the results are great. ATF temperatures are under control, engine coolant and engine air inlet temperatures are lower when the vehicle is working hard and all temperatures reduce quickly when the load is removed, bonus has been improved drivability on windy roads, steep roads and on loose dirt roads, another bonus has been improved fuel economy especially around the city and suburbs 2-3 litres per 100km and 1-1.5 litres per 100km when touring at GVM+.

Lockup Mate is currently availble and is used in conjunction with the sports shift mode, quite a few of the forum members have these and reports are positive. Lockup-Mate automatically locks the TC in 2nd, 3rd, 4th and 5th when you select any of these gears but only if multiple safe conditions exist, it does not bypass any of the factory self protection programs, it also allows you to keep the TC locked up when going downhill so this provides extra engine braking and quick ATF cooling, ideal for towing and general driving in steep country. It works in low range and even in 1st gear so this improves engine braking as much as possible with the availble reduction ratio of the transfer case.

Auto-Mate should be availble before Christmas, this works in both "D" and manual sports shift mode. In "D" mode, the TC is automatically locked up in 2nd, 3rd, 4th and 5th gears when conditions are suitable rather than just 4th and 5th of the factory AT ECU program, it also changes the gear shift up and down shift points depending on the position of the accelerator pedal and engine load. In manual sport mode it behaves the same as Lockup-Mate so you get the best of both, also like Lockup -Mate, Auto-Mate does not bypass any of the factory self protect functions of the AT ECU.

So rather than fitting additional ATF coolers it makes much more sense not overheat the ATF by limiting TC slip, a TC lockup kit does this and the MM4x4 kits are the most advanced on the market and have been designed and built by a fellow forum member especially for Challenger and Triton with the Jatco auto fitted. I have been involved in the development and testing of both Lockup- Mate and Auto-Mate for about 9 months and around 18,000kms, it has been a long process but the results are impressive and has transformed the Auto Challenger (and Triton) like no other modification or enhancement I have carried out.

I have no financial interest in MM4x4 and my involvement has been out of self interest to remedy the poor Auto programing from factory so the full potential of the auto Challenger can be realised.

OJ.

[whereswes]

Zippo, 97 degrees max towing is outstanding. I can hit that on the Great Ocean Road not towing through the paddle shift and with very little excess weight.

I've got a Lockup Mate sitting on the bench as I've had some issues with power steering performance and more recently dry bearing/bush noise coming up through the steering column and I'd prefer the dealer finishes their poking around down there before I install.

Can't wait to fit it up but sadly, Automate might be available before I even get my Lockup Mate fitted!

OJ, I seem to recall that there might have been a small issue in low speed/low range programming parameters that could be improved (but required further opportunities to test in different terrains). Do you know if these have been updated? Probably makes sense to have mine updated whilst I'm holding back on installing.

And OJ, on behalf of all of us, thanks for your persistence in finding a way to help overcome the Jatco's short comings. You've been like a dog at a bone from day one and I am glad that you never stopped gnawing away.

Cheers
Wes

[Dongskie2]

OJ and Zippo thanks mates

Great inputs!!

[PeePee]

Yeah thanks guys, I am keen on the Automate when it is available.

[m_and_m]

Hi Wes,

Zippo, 97 degrees max towing is outstanding. I can hit that on the Great Ocean Road not towing through the paddle shift and with very little excess weight.

I have a customer who towed a 2.5t van across Australia and reported that the trans didn't go above 70. Certainly no need for an aftermarket transcooler upgrade, because lockup-mate prevents the heat getting generated in the first place.

https://www2.pajeroclub.com.au/forum/showpost.php?p=592894&postcount=133

I've got a Lockup Mate sitting on the bench as I've had some issues with power steering performance and more recently dry bearing/bush noise coming up through the steering column and I'd prefer the dealer finishes their poking around down there before I install.

Can't wait to fit it up but sadly, Automate might be available before I even get my Lockup Mate fitted!

Never fear - If you want to upgrade the lockup-mate to an auto-mate I'll be sending out a special offer.

OJ, I seem to recall that there might have been a small issue in low speed/low range programming parameters that could be improved (but required further opportunities to test in different terrains). Do you know if these have been updated? Probably makes sense to have mine updated whilst I'm holding back on installing.

I made a tweak soon after the first release. If you send me the serial number I'll let you know if it's in your unit. The only other SW improvement will be the LED flashes whilst the trans is warming up, so you know all is OK.


cheers,
Marshall

[itsamitsi]

IIRC mine is serial #11. I'm going to wait for Auto-mate's release and grab that I think. Even though lock-up mate works very well.

[whereswes]

Thanks Marshall. Serial #7 but I'll shoot you an email. Makes sense to just fit once and with AM8 not too far way, I'll head down that track.

Cheers
Wes

[m_and_m]

Thanks Marshall. Serial #7 but I'll shoot you an email. Makes sense to just fit once and with AM8 not too far way, I'll head down that track.

Cheers
Wes

Wes, your unit is v1.2 and the low range tweak was introduced in v1.3. AM8 will solve it

[PeePee]

So when will auto mate be available? I just had a look at MM4x4 site and it is not yet available? I am keen to get this on my Challenger.

[old Jack]

So when will auto mate be available? I just had a look at MM4x4 site and it is not yet available? I am keen to get this on my Challenger.

Marshall is saying before Christmas for the first production batch so send him an email and put your name on the list.

OJ.