Vibration/shuddering - could it be the driveshaft?

[hayythere Lurker Find all posts View Profile Close hayythere]

My 2014 Diesel Prado has a issue that happens when I'm coasting around 70kms. When up to speed and coasting more or less on flat or a slight hill (not pushing the engine hard) a shuddering vibration happens from what feels like the gearbox area.

If I push the accelerator then it goes away or when I travel more than say 80kms (or under around 60kms) it goes away. It seems to only happen when travelling around 70kms and in 5th gear. If I drop back to 4th gear at 70kms it goes away.

I suspect it might be the driveshaft, maybe the uni-joints. Hoping it's not the gearbox.

FYI my Prado has done around 240,000 KMS and with the previous owner was towing a caravan. I only just brought it and in ever other respect it's well maintained and serviced regularly.

If anyone can guide me on what to look at next it would be great. Cheers.

[carco Advanced Member Find all posts View Profile Close carco]

Prop shaft speed is the same at 70kph irrespective of your gear.
I think you should take her to an auto trany specialist. They’ll do a test drive and give you a report.
My gut feeling is torque converter.

[hayythere Lurker Find all posts View Profile Close hayythere]

Update. I did a part flush of the transmission oil, did about 3-4 flushes and took out about 7 litres. Shortly after the shuddering went away (didn't go away immediately but maybe after 30 mins or so of driving).

I think it was the torque converter and this has helped. Looking to change more oil soon and the transmission oil filter.