E39 530i intermittent transmission/drive train harness

[NZ BMW 368]

Hi Guys,

I've had this happen about 2-3 times over the last 4 weeks...

I've got a bit of harshness changing from 2-3rd gear (I'm assuming these cars start in 2nd in city driving? - or could be 1-2nd gear). It's very strange. There is no hanging/flaring or RPM and no interruption of power or forward momentum (like say when your gearbox is gone and it really crashes into a gear). It feels as though a small person has got into the back seat and gives it a kick or the car has gone over a manhole cover.

It does not seem to have a pattern except to be when I'm accelerating away from a stop with moderate power (not engaging the kickdown but getting up to 50-60km/h somewhat quickly) sometimes I will lift my foot off the accelerator to settle around 55km/h.

The history of maintenance on the gear box was that it was serviced last year with a fluid/filter replacement, driven for about 1-2000km and then had the fluid changed again to get the last of the old stuff out/diluted. It was pretty dirty and I would imagine had not be changed before. I would have to check my service history but I think it was at about 125,000km or so.

The car currently has 137,000km on it.

Any comments?

Flex/driveshart bushes? Transmission rebuild? Clogged Filter? Low fluid?

Thanks for the help.