Thread: Disco 2 TD5 Auto box and towing +best for engine

Hi those a lot more knowledgeable than me will be along soon to comment.

My immediate observation is that what you are seeing at 80kph is not going into overdrive but the box locking up. The drop in revs is due to removing the internal hydraulic slippage. From a towing point of view lock-up is good.

I tow a van of just under 2t, except for steep hills I try to be in 4th above 80kph, If I drop back in speed or there is a long hill then I go back to third.

Cheers

Steve

The overdive you speak of is just the auto locking up. The D2 Auto has lock-up in 3rd and 4th.
Old auto's had a certain amount of slip in any chosen gear, which is bad for just about everything, it gives you bad fuel economy, it heats up the trans fluid which will eventually kill the box.
The Td5 box has different lockup points to the V8 due to lack of torque but around 80 sounds familiar. The V8 by comparison will lock up at 50
As to which gear you tow in,,
Td5 auto's have a lower final drive which should help towing in 4th,, but also have a smaller torque converter (less fluid content which means heat, yes no anyone?) which doesnt. Most trans places say put a V8 TC in when rebuilding,,
I'm sure with the right tweak a TD5 will tow 2-3 tonne admirably, but I'd wack a cooler on the trans just to be sure-- it really is cheap insurance.

oh, 3rd is one to one
4th is .728
which is a big jump

Pretty much what Pedro says.
Lock up is at something like 78km/h from memory
A chipped Td5 will tow fine, some people like to put HDTCs in, larger intercoolers, exhausts systems, etc.
But X several million what Pedro said about the trans cooler, if you're towing heavy loads you're mental not to have one IMHO.
Cheers
Muppet

I have a ECU and intercooler upgrade. I tell you this because it changes the way the auto behaves. When towing I use D and sport mode so it kicks down sooner and is more responsive. When towing heavy loads sometimes (mainly when in the hills) I leave it in 3 to keep the TC locked up in an effort to keep the ATF cool. I also have an additional ATF cooler.

The TD5 EU3 upgrade IMHO has an enormous transmission cooler, by appearance some 4 times the size of the RRC V8 one.

IMHO this is because the Torque converter has a high stall point of 2800 to allow the TD5 to spool up into the torque band revs so quite a bit of heat is generated.

If you are driving with the torque converter locked, then very little heat is generated in the transmission, so ensuring that you try to stay in TC lock and then changing down manually if the TC drops out of lock is the best practice to adopt. If you can stay above 2800RPM then the TC generates far less heat than when it is slipping so maybe "s" mode would also help .

I am surprised to hear that people put v8 TCs in as they have a stall of about 2000RPM and this would make the TD5 a relative slug from stop and may really hinder hill starts with a load.

Regards Philip A

I recently towed my Kimberley Kamper with my TD5 Disco for over 3000km throughout WA and only had the torque converter unlock about three or four times on highway hills. Sitting at 100km I use cruise and I can judge when a hill will make it unlock. This is when I take off cruise and allow the speed to drop down uphill while holding the accelerator down just before the point where it would drop down. If the hill is visibly too steep to maintain over 80kmh I just drop the auto down to third and let it find lockup with gentle throttle before keeping the throttle just below kickdown. The Disco(it is remapped) managed 13.6L/100km of while towing the camper which was way over 1000kg. The car was carrying 6 people plus the 60L fridge, along with 200L of water in the camper. I baby my auto a fair bit. 4 litres or so of Transmax Z every 10,000km and strive to keep the torque converter locked.

Ok, well that clears it up.

4th is overdrive.

I was thinking it may have had some other system for overdrive as earlier on this forum a few people said the converter had a set stall speed & I was asking about electronic lock up.

So the converter must lock up due to electronics.

This also now helps make sense of what the trans guy was trying to tell me, but he was giving things in general as he was not that familiar with the box in the disco. What he was getting at is that you want the converter to lock up to avoid heat for reasons most of us understand,

I have been towing and did a lengthy test already, around 5k klms, I tried all modes and things, I have recorded all the info to check on figures etc later, but this means I can use 3rd or 4th as I see fit, probably in sports mode with the aim of always having converter lock up. Thanks for the replies.

Originally Posted by coops71

I recently towed my Kimberley Kamper with my TD5 Disco for over 3000km throughout WA and only had the torque converter unlock about three or four times on highway hills. Sitting at 100km I use cruise and I can judge when a hill will make it unlock.

Hi coops71, I was often sitting around 90, but found in non sport mode in drive 100 was better, but would it not be better at the base of the hill to just pull back to third so it does not unlock at all ?