Weird Problems With 4 Speed Auto...please Help.

[XR6TBAMK2]

Gday all, Ive had a problem with my 4 speed auto for a while now so I ended up getting it strenghtened.Usual mods done to box, heavy duty clutch packs,bands and line pressure etc.The main problem, apart from the usual slipping clutches was that it was seeming to be getting stuck in between gears,mainly 4th but sometimes 3rd and would start shuddering. To fix the problem, I would either have to back off the throttle and the box would eventually fall back into place or put my foot down and 'sometimes' it would drop back into the lower gear.This would happen without driving the car hard also.I thought after having the box rebuilt that it would go away but it hasnt.The gearbox builder seems to think that it must be something electronic somewhere.Has anyone had this problem happen to them? The car is putting out 330rwkws street and 352rwkws on race. Any help would be much appreciated.Thanx

[our06t]

who's tuning the car , lots of issue's with the 4spd if the tuner can't tune them it's basically 50% of the way the box works .

have you had it retuned since you had the box built

[Rootster]

well I think you should find out what controls the gear change...are they controlled electrically with a solenoid or through the valve body....Mate I'm an old school mechanic and really don't know what controls these new cars..

If the box changes electrically well could be in the tune.....If not did they fit a shift kit to the box.....If so the springs in the valve body may be to hard causing this problem......

[XR6TBAMK2]

A top sydney tuner has done all the work on the car,I was going to wait to run the box in before getting a retune.I had the gearbox settings that were on the capa box taken back to standard,including the torque tags as it was causing dramas for the auto builder.The builder couldnt raise the line pressure on the box unless the all the settings were removed.The box feels stronger and shifts alot harder but it still has that problem....just cant figure it out.

[our06t]

it's all controlled by line and ramp pressures of the fluid wich is controlled by the ecu

[our06t]

c&v maybe ????

[Rootster]

so if its shifts harder he played around with the springs in the valve body??????

[our06t]

maybe but a slipping box takes a lot of line pressure for a good shift if it's been rebuilt and still running the old settings it would be shifting harder

[Rootster]

was the converter replaced......don't they have a pressure regulator valve...

[Adam]

Stuffing about with valve bodies to increase pressure is old hat now.

The best approach is to rebuild them to standard trim with a few little tweaks.

I went through all end of dramas with the 4 speed in my old BA.

Oh, there's no such thing as high friction clutches and bands. OEM parts are the only parts available for these boxes.