Weird Vibration Auto D40 Diesel 80-100km

[JamesChchNZ]

Ok, so Ive googled & searched a few forums incl this one - the TCC (Torque Converter) has me concerned

The symptoms come in around 80+KM/H - comes in under my feet & fully feels RH side wheel bearingish - exactly like driving on rumble edge strip on the road (if anyone else on this forum knows what thats like 8P)
I can kick it out of OD at that speed & the feeling kind of goes away - but not fully
Have not tried it in 4WD yet

New tyres today (was going to anyway)
Good going over of universals & driveshafts
Triple checking of wheel bearings

Other question is :
Is the RH axle & driveshaft supposed to turn all the time?
I am used to Toyota 4x4 actuation sorry - but cant see a good idea spinng the diff full time when not in 4WD?

Hmm - thanks in advance!

Otherwise, been great - finally got away in it for a drive last weekend for an hour or two at highway speed - hence my concern re vibration

Fitted up some 265/70/17 Cooper ST MAXX today - very nice after the nearly buggered Maxxis Buckshots lol

 

[Old.Tony]

If the problem is still evident after you flick overdrive off, it's not the TCC or TC. Those problems are caused by the torque converter clutch attempting to engage, then disengaging, reengaging etc and causing vibration. The TCC won't try to engage unless the vehicle is in D with O/D engaged (and engine load < 50%, vehicle speed > 75km/h) - so we're looking at something else.

Specific-speed related vibration could easily be tyre related but I'd suspect drive shaft more - the big shaft that transfers motion from the transfer case to the diff. A rock striking the shaft and creating a ding will off-balance it.

And yes, the front axles and diff (plus the front drive shaft) are all turning all the time, as the front hubs aren't "free-wheel" hubs like you'd find in a Mishitibus L300 4WD.

I guess the best thing to do is to grab some jack stands, get the whole car off the ground and start turning wheels over. With some ambient quiet, you should be able to hear crunchy spider gears (front axle CVs) and you should be able to nail a worn front bearing (grab the tyre and wiggle it just a little bit *dances*).

Underneath, pay some attention to the drive shafts. Turn them over and make sure there's no damage. Look at the unis - they should be really quite solid.

 

[JamesChchNZ]

Cheers, Ive basically ruled out Tyres / drivehafts but will remove them & check universals for tight spots

 

[ericcs]

does it only happen under load, and does it go away once you get over say 90/95 k/ph, or if it kicks down automatically? if so, mine does the same, and old.tony explains it right in his first paragraph!

 

[JamesChchNZ]

No load - just cruiser 90-100k, kick it down it changes and goes away
One thing I did notice on the way home tonite, it seems worse on different road surfaces!?
Ha ha

If I hadnt just bunged four brand new tyres on yesterday, I'd be blaming the tyres
But its more mechanical in its frequency

 

[Old.Tony]

Okay, very, very specific question to ask here. The answer will tell us whether or not the torque converter is at fault.

At 100km/h (indicated), how many RPM are you doing while cruising on flat ground? Don't be approximate. If the needle is sitting exactly on the left edge of the "2" marker, that's precisely what we need to know.

 

[ericcs]

still sounds like the T/C to me. if it goes away when it kicks down or you back off, it then can't be wheels cv's etc as they are still turning at the same speed.
i can be cruising with very light throttle in O/D and get it to vibrate at will just by loading the throttle.
if it is the T/C in the end, don't worry too much, as i have lived with mine for 100,000k's now, and it doesn't get worse with age

 

[Old.Tony]

Typical issue with the TC is during TCC engagement. Once it's engaged properly, the vibration should go away.

Unless the TCC is engaged, the TC turns over at the speed of the engine (minus a few hundred rpm), so if it's a TC balance issue the vibration should be felt at the same rpm in ANY gear. If it's an engagement issue, it will ONLY happen in Drive, Overdrive ON, speed > 75km/h, engine load < 50% - and it will only happen until such time as the TCC finally engages. At that point, engine RPM should drop between 300-500rpm and releasing the throttle (eg on a slight downhill) should see the RPM maintained.

A slight vibration at light throttle with an engaged TCC might be due to a number of things - a single injector not performing as well as the others, a uni joint that's slightly worn, wheel bearings - there's a significant list here.

 

[JamesChchNZ]

Long time no post so thought I had better pop back in

Wife driving the D40 most of the time & awkward to get it into work to chuck it on a hoist usually, however it was due for a service so at the same time I pulled out the drivers side engine mount - ahoy, metal to metal at times judging by the shiney marks on it
So the Mount Shop only had one in stock on the day - Ive changed that which has in turn changed the vibration considerably - I suspect the passenger mount is as bad as the drivers was, will replace it when possible

There was clear mark you could only see upon removal, if anyone else is having this issue it would be worth a gander

Now I want a V6 one lol, that wee diesel is OK but I miss my cubic capacity of the 80 series under the right foot.....

Cheers

 

[JPMC]

Good to here you've had a bit of a win and thanks for letting us know.

What made you think to check the engine mounts?