Hi All,

I have been in contact with a well known tuning company regarding a remap, and asking specifically whether their remaps limit the engine torque in 1st and reverse. It has been mentioned on this forum numerous times that the maximum torque on the manual gearbox is about 380nm and the stock map limits the torque delivered in 1st and reverse.

They say they were not aware of the FL2 ECU map having to limit torque in 1st and reverse. They suggested that torque limiting on the stock map may be incorrect, as could the info on the forum regarding this.

Could anyone come up with cited or referenced proof on the gearboxes torque limit and that LR do indeed limit the engine torque in 1st and reverse.

Thanks
Mark BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

Last edited by Spatch on 12th May 2015 9:15 pm. Edited 2 times in total

Thanks Alex,

What document/website/reference material does that come from? Is it official/JLR documentation?

Cheers
Mark BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

Also, reading that again, it implies that the gearbox itself limits the torque in 1st and reverse rather than the engine map. Would you concur?

If this is the case, then surely we would be free to remap the engine safe in the knowledge that the gearbox would protect itself from the extra torque. BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

Yes, it's the official workshop manual.

As per torque truncation, generally speaking, indeed, there are mechanical ones and software ones.

In FL2 case it's software.
A mechanical one, inside the box, will require a special set of wet clutches with special oil in order to "shave" the torque peaks by calculated clutch slip. Not the FL2 manual box case.

Anyhow, engine develops 400Nm. Box handles 380Nm...
Makes you wonder if tuning and increasing those 400Nm is a correct decision, isn't it?...
Can they guarantee that if they tune it and you will exploit it to the limit in 1st and reverse, the box won't suffer?

In contrast, the automatic box can handle 450Nm which leaves a small margin for tuning.

Thanks again Alex.

My thoughts exactly. I do not want to change anything that could be potentially damaging to the car.

Out of interest, you obviously know your stuff. Do you work for JLR, or work on the cars in a technical capacity? BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

Neither... Pure hobby in spare time...
Thanks for appreciation.

Hi Alex,

Regarding the max torque that the gearbox can withstand. I am assuming that (due to the gearing and the fact that the torque is limited in only 1st and reverse) the gearbox can cope with more torque in the higher gears?

Is the max torque that can be handled in the higher gears related to the ratios of the gears themselves, i.e the higher the gear, the higher the torque the geartrain can cope with?

Thanks
Mark BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

From what I've known, a gearbox is a "torque multiplier".
Inside it has some components that could withstand a certain amount of stress. And here I am referring especially to the box's kinematic exit components.
In lower gears (1st, reverse, etc), the demultiplication ratio is greater and therefore the final drive will develop a higher output/torque.
If you "enter" a certain amount of torque, the corresponding "multiplied" torque will be exited.
If you exceed a certain amount of input torque, the exit components on the kinematic path, because of the multiplied torque, could be overloaded and fail.
So, to respond to your question, yes, in higher gears the box will cope better with the torque.

But you could also take a look at the input components, like the clutch system. And the clutch system isn't one of the "brightest" in this application....

Thanks Alex.

Do you know the torque limit for the clutch??

Cheers, BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

Sorry... No.

OK, thanks. BMW X3 30d M Sport - Current (problem free)
2014 SD4 Auto HSE Lux - Gone (too many problems)
2012 TD4 Manual XS - Gone (too many problems)

As someone who has had two FL2s with gearbox problems requiring a rebuild I was wondering whether the unit is actually up to the job. Having to restrict engine torque via the engine management system sounds like an afterthought by the designers when they realised that someone had screwed up. Discuss  3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

It's quite common, lots of manufacturers do it. Nissan Navara is one quick example off top oft head! MY15
Tyre Pressure Monitoring System (TPMS)
Surround Camera System
InControl Apps soon to be replaced with CarPlay (WIP)
Meridian Premium Surround Sound
Digital Audio Broadcast
Timed Climate
Cruise ECO Data
Follow Me Home Reverse
Extra Features Menu
Picture In Motion
4x4i screen (WIP)
Digital Broadcast TV
Meridian Rear Media with WIFI
Factory Powered Tailgate
Blind Spot Monitoring (BSM)
Reverse Cross Traffic Alert (RCTA)
Electrochromatic Wing Mirrors (WIP)

many cars have torque limiters in 1st and sometimes 2nd years, a good many HGV vehicles are the same.
There to protect the drivetrain.
I go through manual gearboxes, I guess I am hard on them, it's why I prefer auto's, if you have gone through two then maybe there is an issue with the common denominator?