ENC
Do you have a suspension lift on your vehicle? If so, it is highly likely the problem is tailshaft vibration because of uneven universal joint angles causing a side shifting wobble of the tailshaft under low speed high torque transmit of engine power. Also if a centre bearing is fitted in the tailshaft then it may be flicked all over the shop by the unis action working out of spec angles.
If it is std, it could be the tailshaft yoke not engaged sufficiently into the rear slide bush of the transfer case rear and allowing the tailshaft to violently flutter sideways as it rotates. That IS A KNOWN FAULT WITH SOME and should be corrected asap if it is the issue.
DMAX shake/wobble/surge under low RPM
Re: DMAX shake/wobble/surge under low RPM
Car is set up with 600kg rear OME lift, vehicle is set up with a full canopy etc. We have been playing with wedges but is very hard to get a correct angle at the rear of the auto transmission with a digital level but best guess is it within 1deg.we also have rotated Rim/tyres and now have replaced all 4 tyres. We also have a Valve body upgrade in the auto and have fitted a rear tail shaft spacer. We have been chasing this for quite some time.
Cheers Ian
Cheers Ian
Last edited by ENC on Sat Aug 26, 2023 2:20 pm, edited 1 time in total.
Re: DMAX shake/wobble/surge under low RPM
Hello ENC
if it is quite a bit higher then the tailshaft engagement may be less than OE. Check for side movement and up and down slack there. It might be flopping about but stabilizes when rotating faster with less torque through it. If it was like it for a while the rear bush for the yoke may have flogged out a bit and still allowing wobble!
Not trying to be smart, but the wedges for pinion alignment are they in there with thick end to rear? I have seen a 3 letter company fit them Frack to Bunt and didn't know they had made it worse and tried other things to fix it.
With a small digital level and 150mm steel rule the Digital level can be paced on flat bits of tailshaft flange to get a reading, straight on tailshaft is easy enough. I presume you have a one piece tailshaft from what you said. If so, the unis should be running at close to the same angle for cancelling of uni torque induced flutter.
if it is quite a bit higher then the tailshaft engagement may be less than OE. Check for side movement and up and down slack there. It might be flopping about but stabilizes when rotating faster with less torque through it. If it was like it for a while the rear bush for the yoke may have flogged out a bit and still allowing wobble!
Not trying to be smart, but the wedges for pinion alignment are they in there with thick end to rear? I have seen a 3 letter company fit them Frack to Bunt and didn't know they had made it worse and tried other things to fix it.
With a small digital level and 150mm steel rule the Digital level can be paced on flat bits of tailshaft flange to get a reading, straight on tailshaft is easy enough. I presume you have a one piece tailshaft from what you said. If so, the unis should be running at close to the same angle for cancelling of uni torque induced flutter.
Re: DMAX shake/wobble/surge under low RPM
Thanks for that. when it is empty(unloaded) it does sit a little high. We will be loading up in 2 weeks with the camper and see if if it better or worse with load. We are also going to drop out a leaf and see if that helps or not. The front of the tail shaft has very little sideways movement and the wide edges of the wedges are to the front as we needed to drop the front of the diff to correct the angle.
Cheers Ian.
Cheers Ian.
Re: DMAX shake/wobble/surge under low RPM
Hello Ian.
You are the first one I have heard of having to lower the pinion flange. Neary all spring packs make the pinion go downward and worsen the uni angle. All I have seen, only ones have seen. need the wedges with thick to rear to bring the pinion up and uni angle near to suitable. Perhaps your spring pack has it's seat area with the flat section aimed upward more than OE and most other packs.
Simply raising the vehicle via spring pack holding it up more means the axle will be left behind and need upward of the pinion, not downward. Who assessed it to need, thick to front? It hasn't got longer rear shackles has it? I find what you said to be hard to believe. Maybe wrong if spring pack is not near OE positioning attitude of spring seat though. If you have out of spec uni angles I would fix it first before a trip. If the rear of the leaves are longer and that area distorts more than the front half then loading it might increase the angle even more. Unis can only tolerate a small difference in constant running before they fail. Just my assessment of course. Unis should run above 1/2 to 1 degree and below 3 degrees in normal operation. No zero angle of either and close to each other as possible. Hope you solve it all.
You are the first one I have heard of having to lower the pinion flange. Neary all spring packs make the pinion go downward and worsen the uni angle. All I have seen, only ones have seen. need the wedges with thick to rear to bring the pinion up and uni angle near to suitable. Perhaps your spring pack has it's seat area with the flat section aimed upward more than OE and most other packs.
Simply raising the vehicle via spring pack holding it up more means the axle will be left behind and need upward of the pinion, not downward. Who assessed it to need, thick to front? It hasn't got longer rear shackles has it? I find what you said to be hard to believe. Maybe wrong if spring pack is not near OE positioning attitude of spring seat though. If you have out of spec uni angles I would fix it first before a trip. If the rear of the leaves are longer and that area distorts more than the front half then loading it might increase the angle even more. Unis can only tolerate a small difference in constant running before they fail. Just my assessment of course. Unis should run above 1/2 to 1 degree and below 3 degrees in normal operation. No zero angle of either and close to each other as possible. Hope you solve it all.