Discovery 2 TD5 Torque Converter Mods

[Robbo]

One area that I think my Disco could be improved in is the torque converter. I believe that the lock up RPM or stall Rpm is too high and that the motor tends to be revving more than it needs to be. I am wondering whether anyone else has replaced or has had there standard torque converter modified. I have been speaking to a torque converter specialist and he agrees with me and believes the lock up on the torque converter on a TD5 is about 1000 rpm more than it should be. My TD5 has been re flashed with nothing to crazy but as I said I believe it is the one weak link that I am thinking about altering. I am very interested in hearing other peoples experiences and opinions on this topic. With me doing all the installation and removal it would be about a $600 proposition.

[George130]

I had mine rebuilt. At the time it was a 3000rpm stall converter but had blown out to 3500rpm. It had cooked the friction material so I had it redone as heavy duty as possible while dialing it bak down. The guess is it should now lock up around 2200rpm.

[stevo]

I thought that the lock up was done via the computer on the DII it will come on at 74 kmh and only once the oil is at a certain temperture, but hey I could be wrong:angel:

[5teve]

80k's on mine.. and yes not until the temp is correct.

i think they mean the stall revs tho which is about 3000 - 3200 if you nail it or waaaayyy above that in sports mode... :D

remember its designed for the normal engine and i think its designed for peak torque / power and as its a small engine thats probably why its so high?

Thanks

Steve

[Tombie]

I thought that the lock up was done via the computer on the DII it will come on at 74 kmh and only once the oil is at a certain temperture, but hey I could be wrong:angel:

Your not wrong... The Lock Up is ECU controlled...

Stall speed is around 2250rpm IIRC (Rave not here at the moment)

And I think you'll find the 'torque converter' guy is more than happy to help this bloke lighten his wallet $600.00 :cool:

It amuses me no end... :D

Yes, it may be worn or need overhaul, but otherwise, why would a large manufacturer fit a sub spec torque converter when it *could* be lower?

[ashtrans]

One area that I think my Disco could be improved in is the torque converter. I believe that the lock up RPM or stall Rpm is too high and that the motor tends to be revving more than it needs to be. I am wondering whether anyone else has replaced or has had there standard torque converter modified. I have been speaking to a torque converter specialist and he agrees with me and believes the lock up on the torque converter on a TD5 is about 1000 rpm more than it should be. My TD5 has been re flashed with nothing to crazy but as I said I believe it is the one weak link that I am thinking about altering. I am very interested in hearing other peoples experiences and opinions on this topic. With me doing all the installation and removal it would be about a $600 proposition.

Hi Robbo,

have a read here :

Ashcroft Transmissions (http://www.ashcroft-transmissions.co.uk/part_18.html)

Dave

[Robbo]

No I am not talking about the electronic lockup I am referring to the stall speed of the Torque converter which I believe to be too high. (around the 2800rpm). I think the TD5 would benefit from having a stall speed where most of its torque is at it peak and that is around the 2000-2200 rpm.


Why would a large manufacturer fit a sub spec torque converter when it *could* be lower?

Well too answer the question Tombie. Why have you had to do so many mods to your engine to get the best out of it??????????????
Transmissions are often something that don't have as much time spent on the design of the vehicle as the power plant.
I can not understand why the torque converters stall speed is above where the motor has its best torque. It just seems to me that the motor is being revved harder than it needs to be in order to gain speed.

[Tombie]

In a nutshell...

The TD5 is a tiny motor... It wont hold 2000rpm under heavy loadings.
And when chipped, peak torque is a little higher....

Also, look at trans behavior as it maintains acceleration. Lowering the stall will reduce this ability.

:cool:

[rovercare]

Yes, it may be worn or need overhaul, but otherwise, why would a large manufacturer fit a sub spec torque converter when it *could* be lower?

The why alter anything?

Why do ashcrofts fit a lower stall convertor?

If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.

:cool::D

[Tombie]

The why alter anything?

Why do ashcrofts fit a lower stall convertor?

If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.

:cool::D

Whoa!!! Where does it say lower? They fit a LARGER diameter unit....

Stall / Lockup is still ECU controlled and goes by the ECUs requests...

[discowhite]

Torque Converter Upgrades
The ZF auto as used in the LandRover vehicles uses three different diameters of torque converter. Small. Medium and Large.Photo here (http://217.34.53.228:9876/uploads/3tc.jpg)
"Small" is used on the 300 Tdi, P38 diesel and the TD5 "Medium" is used on the 3.9, 4.0 and the later 4.6 P38 "Large" is used on the early 4.6 P38"s
The converter has a lock up clutch inside and the smaller one struggles to cope with a stock engine, never mind a tuned one.
When the "stage 2" ZF is being used with a V8 or 2.8 TGV you have the option of using the larger diameter 4.6 torque converter at no additional cost but on a V8 you will also need the 4.6 boss and flexplate assy to match the bigger converter. When using on the 2.8 be sure to order the conversion kit to fit the bigger 4.6 converter. This bigger converter is recommended on the big V8"s and the 2.8 as it keeps the revs and heat down.
If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.

read this like dave said, usefull info.
Ashcroft Transmissions (http://www.ashcroft-transmissions.co.uk/part_80.html)

cheers phil

[Tombie]

OK My apologies...

I'll eat some humble pie on this one :cool:

[discowhite]

he he:D
dose it tase as good as they say??:p

stall speeds are also dependant on the power and torque of the motor in question.
i played around with a few in a powerglide on a 308 torry. outta the box the convertor was 3800rpm lock, on the track it was closer to 4200 lock.

cheers phil

[slug_burner]

if the same torque converter is used for both the diesel and the V8s then there is a good chance that a compromise has been achieved.

When I lived in the UK most of the vehicles were manuals. It has been a few years now so things could have changed but I suspect that the majority of the autos are used with the v8s and the manuals with the diesels. So I strongly suspect that if a compromise has been arrieved at on the TC it would be in favour of the V8. So perhaps there is scope for modifications of the TC when used behind a diesel (as long as the power is there to cope with the lower stall speed)

[rovercare]

he he:D
dose it tase as good as they say??:p

stall speeds are also dependant on the power and torque of the motor in question.
i played around with a few in a powerglide on a 308 torry. outta the box the convertor was 3800rpm lock, on the track it was closer to 4200 lock.

cheers phil

Ditto

[rovercare]

Whoa!!! Where does it say lower? They fit a LARGER diameter unit....

Stall / Lockup is still ECU controlled and goes by the ECUs requests...

Lockup can be controlled but stall speed is mechanical;)

[Blknight.aus]

urmmm lockup is mechanical under either hydraulic pressure controls or ECU and stall is hydrulic... (just to nit pic...)

what I think would be better suited to the discos is the medium stall speed converter (which is a nice compromise) with manual control on the lockup.

[p38arover]

Umble Pie:


he he:D
does it taste as good as they say??:p

I saw it on "The Worst Jobs in History" and it "Umble Pie" - (note Umble not Humble) sounded gross - it's made from offal.

[rovercare]

urmmm lockup is mechanical under either hydraulic pressure controls or ECU and stall is hydrulic... (just to nit pic...)

what I think would be better suited to the discos is the medium stall speed converter (which is a nice compromise) with manual control on the lockup.

Correct, but I was talking control, as in stall speed is governed mechanically;) as in stall is by no means governed by the ECU:D

More HP = More flare in stall speed:D

[Blknight.aus]

yeah thats why I was nit picking....

did you know you can actually get a torque converter with an adjustable stall speed......

you probabley dont want to know about the cost of one.....

its not what its supposed to do but its a bug in the design.

it works by removing the restriction on the oil flow out of the TC thus more or less elimnating the restriction of the movement of the oil in the TC. By slowly applying the restriction you slowly decrease the flow rate of the oil through the TC which inturn increases the flow of oil around the internals of the TC (which is what provides the driving force) The idea behind it is so that you can leave an engine going flat out while its driving something (like a pump) that requires a preset RPM and lower the % of the power output of the engine to the driveline for creeping.

not the most elegant of explinations but for those who are familiar enough to understand the concept its near enough.

[Slunnie]

The why alter anything?

Why do ashcrofts fit a lower stall convertor?

If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.

:cool::D
I had a brief chat to Dave Ashcroft last Thurs. Just a heads up on this mod... The Med 3.9/4.0V8 Torque converter needs to be modified to fit the TD5 engine as the flex plates are different between the two motors.

[markd2]

hi guys
just a quick question on the lock up of the converter my td5 doesn't lock up til 85km/h is this unusual has now done 200,000kms and done some heavy towing could box or converter be getting a bit long in the tooth ? still changes nice any thoughts

thanks mark

[Slunnie]

hi guys
just a quick question on the lock up of the converter my td5 doesn't lock up til 85km/h is this unusual has now done 200,000kms and done some heavy towing could box or converter be getting a bit long in the tooth ? still changes nice any thoughts

thanks mark
80km/h for a D2 is normal for lockup in 4th. Sounds fine to me. :)

[Blknight.aus]

is that 85 KPH indicated or 85 Kph real... (check it with a GPS)

whats on the speedo can be faster than your acutally going.

but even then Id call 5K over acceptable (at least partially cause ID want the auto to leave the workshop so I didnt have to touch it :) )

[Slunnie]

The lockup can be anywhere from just under 80km/h up depending on how its being driven. Tyres etc wont make much difference to the minimum lockup speed, it's whatever the speedo is displaying. The speed is determined by the ABS sensors, nothing mechanical like transfer case drives etc.

[Tank]

Higher (than V8 petrol) stall speeds through the torque convertor on "Turbo'd" diesel engines is to allow the engine and Turbo revs to be higher at take off, which allows the Turbo to Spool up and reduce Turbo Lag, simply speaking, Regards Frank.

[Robbo]

Yes Frank I thought along those lines but 2800rpm is a bit over the top. I think this motor would have enough boost and plenty of torque by the time it reached 2200rpm.

[markd2]

thanks guys

speed is with gps just didn't know if 85kms was high thanks again all for the info

cheers mark

[Trevhoare]

In my DII transmission lockup happens at around 80 Km/Hr in both 3rd and 4th gear. This is the mechanical lockup which turns the Torque converter into a direct drive..
As for torque converter stall speeds .. my reading of this ( as a lifetime manual driver in the process of selling an Auto TD5 which I have replaced with a manual ) is that it is the speed at which the torque converter stops being a torque multiplier with the input and output turning at different speeds to become a more or less 1:1 fluid drive. This speed depends on the input torque and the load.. so upgrading the engine and its torque will cause the TC to slip to higher speeds and raise the "stall speed" so a heavier TC would be appropriate. As for changing the TC on a standard engine.... there must be a good reason and I suspect a lot of R&D that has gone into the selection that LR ( BMW ) used in these rigs.. It is possible of course that it was designed for different market expectations than ours - the USA for instance.
What would be more useful would be manual control of the TC lockup function so that we could pull in direct drive from say 2000 RPM in all gears rather than waiting for 80 KM.... but then it would be simpler and more efficient to get a manual with the extra gear and full control.

Trevor

[haydent]

how do you tell when you get lockup ?

[slug_burner]

revs drop on the tacho

[Slunnie]

Yep, it feels like the transmission has taken another gear.

The other big tell tale is that when the TC is unlocked and you vary the amount of throttle used the revs will vary. If the TC is locked the revs wont vary based on the amount of throttle used aside from that which come from accelleration or slowing down. When you do this, don't come completely off the accelerator as this may unlock the TC.

[haydent]

thanks