D40 YD25 Auto Slipping low speeds both directions

[STXMad]

2010 D40 YD25 T/D Auto Trans, done 130,000km bought new from dealer, was a demo car.
When pulling away, or reversing, or going from reverse to forward, there is slippage like a manual clutch slippage. It does not do it at high speed, only at low speed, or after braking into a corner, and accelerating after turning the corner at low speed. Has done this from new and has got worse and worse as it has got older. The dealer claimed it was normal, but clearly this is not normal. Anybody got any idea what it could be? We have done the following:

• Checked fluid levels and okay, then
• We changed the transmission fluid and replaced filter. This made no difference.
• No fault codes.
• Reset ECU, no difference.

 

[Old.Tony]

The dealer was probably referring to the several hundred RPM that are lost because of the torque converter. This is a normal thing. However, the torque converter can be worn/damaged - I've just had mine rebuilt (my TCC wasn't engaging properly).


What needs to be done is a stall test. Normally this is done by the dealer, they have the equipment to issue the commands to the car, but it can be done by any automatic transmission specialist and the amount of actual slip can be measured (the gearbox does report this internally and the dealer could have checked this if they were bothered).


You can get a very rough idea of the torque converter's condition by putting the car in drive, with your foot hard on the brake pedal and rev the car up at a slowish pace as fast as it will rev. It should peak at no more than 3100rpm - if you can get it to 3500rpm, shut the thing down there's something slipping in the torque converter.


I would recommend taking it to an auto transmission place and getting them to test it and provide a report. It will cost you a little to do, but the report will provide black and white "this thing needs fixing" or not and you can hand that to the dealer.


The dealer might not like it - working on auto transmissions is time consuming and expensive. Have the info (keep a copy!) and force the issue.

 

[STXMad]

Thanks very much Tony. Will do.

 

[STXMad]

The dealer was probably referring to the several hundred RPM that are lost because of the torque converter. This is a normal thing. However, the torque converter can be worn/damaged - I've just had mine rebuilt (my TCC wasn't engaging properly).


What needs to be done is a stall test. Normally this is done by the dealer, they have the equipment to issue the commands to the car, but it can be done by any automatic transmission specialist and the amount of actual slip can be measured (the gearbox does report this internally and the dealer could have checked this if they were bothered).


You can get a very rough idea of the torque converter's condition by putting the car in drive, with your foot hard on the brake pedal and rev the car up at a slowish pace as fast as it will rev. It should peak at no more than 3100rpm - if you can get it to 3500rpm, shut the thing down there's something slipping in the torque converter.


I would recommend taking it to an auto transmission place and getting them to test it and provide a report. It will cost you a little to do, but the report will provide black and white "this thing needs fixing" or not and you can hand that to the dealer.


The dealer might not like it - working on auto transmissions is time consuming and expensive. Have the info (keep a copy!) and force the issue.

Well Tony, after having a new duplex timing chain installed, I did the stall test and it didn't fail, so it seems it may not be the torque converter. Sounds like I'm going to have to take it to an auto place.

 

[KevinE]

I'd take it to an Auto place that knows those Jatco transmissions. There seems to be lots of known issues with them. I just had a quick look on the net & was quite stunned!