VT shudder

[Barto76]

I'm having a very similar issue at the moment, bought this VX recently and there was a thumping when taking off from a standing start so I assumed uni joints or diff.

It runs fine around town, idles smoothly, takes off with a heap of grunt but once I get out on the highway, there's a shuddering/surging happening under the following conditions:

• Speed is over 70kmh
• RPM around 1800-2000
• Only in top gear (if I plant it, it changes down and takes off with no issues)
• Only at operating temperature (not a thing happens if the temp gauge is under 1/4
• Only if I accelerate slowly/gently (again, it's all good if I plant the foot)
• It does it on a flat road, up hills, down hills doesnt matter

I assumed coils/plugs or at least something electrical because I had a similar thing with a VS I had. I took it to a mechanic because last time I changed out $400 worth of parts before discovering it because I thought screw it, I'd rather pay someone to diagnose than waste my time again.

Apparently coil packs are fine, they did find a loose lead on one of the plugs and the mechanic said he took it out for a decent drive but couldn't get it to do it again. I took it out last night and same issue.

He did say the thumping at take off is most likely the centre bearing but didn't have time to get it on the hoist to check and there's a possibility a shudder starts up in the centre bearing under certain conditions and I'm mistaking it for a loss of spark/fuel.

Any thoughts? I'll book it in anyway to get the bearing done but in the meantime will change out the plugs to see if that makes a difference.

PS: just noticed it's an old thread that's been bumped, I wish people would come back to their threads and tell us what the problem turned out to be.

 

[Barto76]

Replaced the centre bearing, no clunking during take off from a standing start. Still has a minor shudder from time to time around the 80kmh mark when accelerating slowly, but nowhere as bad or as often. Go figure.

I think I'll just leave it and hope for the best.

 

[VT&VX]

Thumping from rear could be worn bush on diff mount. If a mechanic puts it on the hoist and then checks for movement on the diff mount, they can tell you if they need replacing. Just buy a set of four polyurethane bush inserts.

Shuddering at any speed could be the auto transmission is ready for a filter change. Is it Auto with more than 200,000 kms on it? The old ATF is getting thin when warmed up.

 

[Craig Facey]

A transmission service i.e. filter change, fixed this on my old SV6