Thread: Td6 gearbox question

Originally Posted by careyba

I have done another few hundred km since this and not a hint of an issue. No strange sounds and perfect operation.

I have been running the box in sport mode when towing the trailer as I believe (someone please correct me if I am wrong) that this keeps the lockup clutch disengaged. Plus, this gives me plenty of extra power for hills (of which there are crap loads in Tassie!).

I have been checking car sales for the v8 diesel. There is certainly a price jump but there are a few low km ones (under 100,000km) around the 2009 compliance period for about $60k. I should be able to get $30k ish for mine, add $9k to the bucket for the gearbox I will need to do in the future. Just have to come up with $20k extra.

The lock up clutch is what you want to engage. The slip from the clutch is what will cause excess heat and wear that will end up causing the valve body to fail.
When towing, try and try again to keep it above 80kph (Where legally possible) to keep the clutch engaged, 4th and 5th gear will remain locked and produce no slip at this speed. So best put it in manual when on the highway and keep it out of third.
The eco tune for the gear box will change the lock up speed down to 40kph i think, or something around that. I will be getting one soon to try and save my clutch as much as I can.

Where do you get this Eco tune from? Is it a new program for the gearbox ECU?

In terms of the clutch, I was under the impression that when it is not engaged, it isn't slipping as such bit the fluid in the torque converter was being used to drive the gearbox (viscous coupling if you like). By leaving the lockup disengaged, there is no wear on the clutch (but more heat generated in the box from the fluid).

I am no auto trans expert however!

In terms of the clutch, I was under the impression that when it is not engaged, it isn't slipping as such bit the fluid in the torque converter was being used to drive the gearbox (viscous coupling if you like). By leaving the lockup disengaged, there is no wear on the clutch (but more heat generated in the box from the fluid).

The situation is the opposite of what you ( I think) have written above.

The only slip in an auto is in the TC and when it is slipping it is generating heat.
When the TC clutch engages, the drive becomes direct through the planetary gears in the gearbox and there is no heating of the fluid by the slipping action of the torque converter. .
Thus the transmission runs cooler.
You should always aim for TC lock up particularly if towing.
If you cannot get it in 5th then manually select 4th and there should be a speed where it locks.
However it is my understanding only from threads on this forum , that this is not the main problem with the transmission which is a GM transmission.
The main problem is that the valve body material is soft and is worn away by the fluid action with normal operation and that almost all fail before 160KK.
GM uses this transmission in the Commodore high output V6 and they have revised fluids many times trying to fix the problem.

There is a discussion here and if you google you will find a lot of commentary.

Auto gearbox problem

Regards Philip A

Originally Posted by PhilipA

The situation is the opposite of what you ( I think) have written above.

The only slip in an auto is in the TC and when it is slipping it is generating heat.
When the TC clutch engages, the drive becomes direct through the planetary gears in the gearbox and there is no heating of the fluid by the slipping action of the torque converter. .
Thus the transmission runs cooler.
You should always aim for TC lock up particularly if towing.
If you cannot get it in 5th then manually select 4th and there should be a speed where it locks.
However it is my understanding only from threads on this forum , that this is not the main problem with the transmission which is a GM transmission.
The main problem is that the valve body material is soft and is worn away by the fluid action with normal operation and that almost all fail before 160KK.
GM uses this transmission in the Commodore high output V6 and they have revised fluids many times trying to fix the problem.

There is a discussion here and if you google you will find a lot of commentary.

Auto gearbox problem

Regards Philip A

Yep indeed, however I dare say that the material coming from the delaminating clutch most likely causes the pre mature wear. Sensible driving (let the clutch lock as much as you can), oil/filter maintenance and doing a TC swat at 150k will and has proven to a long gearbox life.
Contamination is nearly always the source of pre mature failure in hydraulic systems.

The eco tune will help reduce the contamination.

If you search the forums or even google you can come up with the German site, google translate will be needed.

Another question then on the rebuild, what is the benefit of a "preemptive" rebuild as opposed to waiting until the box completely dies. Do you save any money this way or is it just a piece of mind thing.

Also, I noticed on another forum here that there is a newer type of TC that has been made available recently. Has anyone tried this and is it worth a go?

Originally Posted by careyba

Another question then on the rebuild, what is the benefit of a "preemptive" rebuild as opposed to waiting until the box completely dies. Do you save any money this way or is it just a piece of mind thing.

Also, I noticed on another forum here that there is a newer type of TC that has been made available recently. Has anyone tried this and is it worth a go?

No on the PM rebuild for the box itself. Best money spent is on the TC and if the newer type of TC you are talking about is a heavy duty type one with different clutch material? Then yes, that is what I have fitted. no faults and no slip in 4th or 5th (Full lock up), I was towing an obscurely overloaded trailer from brisbane to melbourne and foot hard down in 4th at about 83kph up a very very steep hill it held up fabulously. this is 20k after it was installed.

Well, spending the last week looking at possible upgrades to my TD6 before the box goes, I have narrowed down to either a tdv8 or a 4.2 supercharged model.

The diesel is obviously better in fuel. However, it is an expensive and complex engine that is not without faults.

The 4.2 is not great on fuel but seems to be quite reliable and was the top of the range so has all the extras. I do about 12000 km per year, part hwy and part city. I expect the extra fuel will be about $600-700 per year ($15 a week).

The models I have found are around the same age (2008), the diesels seem to gave 90-100k on the clock and the 4.2 between 60-70. Both I expect I could get for $55-60k (petrol probably $50k if I push).

Any thoughts from guys on here who may have gone through the same mental gymnastics?

The decision has been made to keep the TD6 and fix the box.

I have a question now on the best torque converter to use with the box. I have found through the forums a brand called "Roadblaster" who do a heavy duty converter.

Has anyone fitted one of these and are they worth it?

Also, is it worth going the lower speed lockup and what benefits/drawbacks are associated with a lower speed lockup?

Cheers, Brad.