Autobox slipping in top gear

[TenaciousC]

Hi,

Noticed a juddering through transmission when accelerating in top gear on the motorway(without using kickdown). Initially I thought it was the road surface but it keeps doing it, so I guess not. All other gears appear to be fine and there are no other symptoms.

I checked the fluid last week (after changing the radiator and by definition the autobox oil cooler). I thought the level was OK, but now I'm not so sure. If the level is low, would I expect this slipping to happen?

Would changing the fluid completely help? Not sure when it was last done. It's still red coloured and not smelling burnt.

Thanks in advance for any ideas.

PS it's an 850 t5 so the box is a Aisin Warner AW50-42LE.

Cheers

C

[5seaterT5x2]

Hi,

Noticed a juddering through transmission when accelerating in top gear on the motorway(without using kickdown). Initially I thought it was the road surface but it keeps doing it, so I guess not. All other gears appear to be fine and there are no other symptoms.

I checked the fluid last week (after changing the radiator and by definition the autobox oil cooler). I thought the level was OK, but now I'm not so sure. If the level is low, would I expect this slipping to happen?

Would changing the fluid completely help? Not sure when it was last done. It's still red coloured and not smelling burnt.

Thanks in advance for any ideas.



PS it's an 850 t5 so the box is a Aisin Warner AW50-42LE.

Cheers

C

if the level is low enough and it wont have to be that low a litre or so it simply wont move and could well give the appearance of slipping

[ChrisMClark]

You'll get slip/drag if the auto-transmission fluid is low. Do the following:

Run the car for 30 mins to get the box to normal ops temp, and park up on a level surface. With your foot on the brake, move the shift lever through all positions before returning to 'P'. Wait two minutes then take a level from the autobox dipstick. The difference between min and max is about 500ml.


Gotta love Haynes manuals

edit: Damn, too slow!

[TenaciousC]

I measured the oil from cold using the cold side of the dipstick otherwise as prescribed above.

I added a litre of Dexron III and now the level is at the top of the range, so I estimate it was 500ml short which would be about right for the loss incurred by the oil cooler change.

Anyway I took it out for a drive, and whilst the gear changes seemed a little smoother, the same problem manifested itself on the motorway. I'll try and describe the symptom a little better, as I'm not sure it is the gear box.

I've experienced a slipping clutch on a manual box, and certainly this is happening at the same time i.e. in a high gear at high boost and maximum power. However, on the manual box the slip was smooth... the engine revs would shoot up and power was obviously lost to the wheels whilst slipping was occurring.

In this case, the revs do not shoot up and there a rigid (but light) vibration felt coming from the front left hand side of the car, almost as if the drive shaft was slipping around on inside the hub.

Admittedly the gear box is in that area too, so it can't be ruled out.

Can anyone make any sense of this?

Cheers

C

[t5 stealth]

just to check............you are checking the gearbox level with the engine running...........not switched off .

[TenaciousC]

just to check............you are checking the gearbox level with the engine running...........not switched off .

Yes indeed. :-)

C