Maximum gearbox torque before slipping
Posted: Mon Feb 01, 2016 7:37 pm
Hi all - as per the title.
My gearbox was rebuilt a few months ago which included the TC. The company that carried out the work initially put the wrong filter in - it was the right one for the chassis no. but caused some cavitating and they swapped it for one with a different length funnel which cured the noise. Shortly after, my mechanic noticed a slight ATF leak and I took it back to the gearbox people who replaced the O-ring seals (they didn't replace them initially as they weren't leaking.) I asked them about the loss of fluid but they reassured me that they had checked it and there was plenty there so no damage would have been caused. It is still under warranty btw.
Since then it has been fine.
Just recently I had it remapped by MRC due to a new exhaust/pre-cat delete and they advised me that they had to reduce the torque to 782Nm (576 lb/ft) as it was slipping. Doug also said a standard 'box can handle up to 880Nm (650 lb/ft) with their mapping.
I've given it a thorough workout and can't sense any slippage plus it changes gears very smoothly with no thumping into gear or hunting etc. which I would expect from a recent rebuild.
Doug & Ben suggested a full gearbox service as then they can examine the ATF to check the condition of the 'box, TC and clutches. I have agreed to go ahead with this as Ben explained that after a fluid change they will adjust the map and carry out a test drive to check for any slipping.
However, I'm aware that this may not make any difference. The options then would be to a.) live with it or b.) drop £7k+ on a new 'box from Audi (if I entrust it to MRC) which whilst expensive would be worry-free i.e. a warranty would cover any issues. Would the warranty cover mapped 'boxes though, as I'm aware that even strengthened 'boxes from the U.S. aren't guaranteed to handle excessive torque?
Hopefully after the service it will be able to handle the torque, but if not, should I go back to the gearbox company and explain that it's slipping and ask them to rebuild it again? I know from previous conversations that they don't recommend mapping engines due to the additional stress it puts on the 'boxes...
Thoughts/comments welcome
My gearbox was rebuilt a few months ago which included the TC. The company that carried out the work initially put the wrong filter in - it was the right one for the chassis no. but caused some cavitating and they swapped it for one with a different length funnel which cured the noise. Shortly after, my mechanic noticed a slight ATF leak and I took it back to the gearbox people who replaced the O-ring seals (they didn't replace them initially as they weren't leaking.) I asked them about the loss of fluid but they reassured me that they had checked it and there was plenty there so no damage would have been caused. It is still under warranty btw.
Since then it has been fine.
Just recently I had it remapped by MRC due to a new exhaust/pre-cat delete and they advised me that they had to reduce the torque to 782Nm (576 lb/ft) as it was slipping. Doug also said a standard 'box can handle up to 880Nm (650 lb/ft) with their mapping.
I've given it a thorough workout and can't sense any slippage plus it changes gears very smoothly with no thumping into gear or hunting etc. which I would expect from a recent rebuild.
Doug & Ben suggested a full gearbox service as then they can examine the ATF to check the condition of the 'box, TC and clutches. I have agreed to go ahead with this as Ben explained that after a fluid change they will adjust the map and carry out a test drive to check for any slipping.
However, I'm aware that this may not make any difference. The options then would be to a.) live with it or b.) drop £7k+ on a new 'box from Audi (if I entrust it to MRC) which whilst expensive would be worry-free i.e. a warranty would cover any issues. Would the warranty cover mapped 'boxes though, as I'm aware that even strengthened 'boxes from the U.S. aren't guaranteed to handle excessive torque?
Hopefully after the service it will be able to handle the torque, but if not, should I go back to the gearbox company and explain that it's slipping and ask them to rebuild it again? I know from previous conversations that they don't recommend mapping engines due to the additional stress it puts on the 'boxes...
Thoughts/comments welcome
Doug mentioned that with the higher torque it 'jumps' so he's had to reduce it as before.
