Transmission (or TC) catches gear when cold

[hhy2k]

What could cause this?

When I start the car cold, standing still, brake applied and the transmission (5HP30) is in D, the car jerks, like trying to catch first gear (well it is in first gear, right) so it jerks peiodically as the engine turns. There is also a little whining noise in 1st gear when I start rolling and the car is cold. When the engine (tranny) warms up, it is all gone, the jerking and the whining as well. What could cause this? What's broken?

Thanks

[Timm]

Possibly nothing broken - have you changed your gearbox oil and filter recently? Although they are classed as 'filled for life' they aren't and require regular changes.

[hhy2k]

Thanks. The car is a "new" car for me. I haven't changed anything yet, I'm in the evaluation period at the moment. It really shifts fast and nice when warmed up. She has a faint judder at around 2000 rpm at hard acceleration, but a new flex plate is due so I think that is the cause of that. May be not, may be something is going on with the TC. I came for advice what it possibly could be inside the transmission without any real problems. I read about pressure regulators, but I haven't got my head around what it really does.

[Timm]

Always best to replace the fluid and filter first before worrying about other problems - a judder at 2000 RPM could well be the torque converter - but new fluid and filter usually helps, and if it helps a bit then a friction modifier usually helps a lot - fill procedure here:

https://www.meeknet.co.uk/Gen_BMW/ZF_5HP30_Gearbox.pdf

....and more on torque converter problems here:

https://www.meeknet.co.uk/E38/BMW_E3...dy_Misfire.htm

[rjjablo]

As reccomended Change your Transmission Fluid and Filter
If that does not help Clean out the Valve Body
If that does not help you are into the rebuild or replace the transmission/Torque Converter