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THUMP on acceleration


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Hey guys, been a while.

Have a long standing issue that I'd like to resolve - hope you can give me some pointers.

More often than not, when I take off from either stand-still, or simply having slowed for traffic lights (in 2WD), there's a delayed 'thump' felt coming from the driveline. Seems more noticeable when already moving, maybe due to not using clutch.

It's not audible as far as I can tell (over slightly noisy intake, exhaust, and tyres), but it's very clearly felt 'in the seat'. 

It only happens once on acceleration, within a short delay of punching the gas pedal. ie car first starts moving, then it happens. I'm pretty certain it's not just lash in the gearbox/diff therefore.

If I slow down really gently, on the gears or just coasting, and then accelerate again, it's often not felt.

It almost feels like the clutch slips a turn, then bites aggressively... But clutch seems pretty good. Not slipping in 5th, up hill, etc... Doesn't hardly slip when dumped with revs.

I did wonder if sticking of the slip joint in the main driveshaft could cause this? ie torque from motor makes it adjust length slightly, but it's binding up.


Vehicle details:

JDM R3M Urban - LBYD21 (thats a TD27T diesel model)

31" ATs

5 speed manual

H233 read diff with LSD (fitted from a higher spec vehicle years ago) 

2" raised rear springs, and wound up torsion bars (no panhard drop bracket, or longer swaybar links)

Good HD shocks (issue predates replacement anyway)


Thanks for any suggestions!


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I'm thinking that the u-joints in the driveshaft might be shot. That's mostly because my Xterra is doing the something similar. Mine u-joints are so bad that it's like I'm driving down a rutted dirt road at speeds between 80-100 km/hr. I gave my driveshaft a wiggle while I was under there to replace the front wheel bearings and the thing shakes up and down almost 6mm and you can get it to make "kilcky-klincky" noises just like that.... clearly the u-joints are done on mine!


The other thing that occurs to me is that there might be a loose mount or something, but I would think you would feel that in both loaded directions (accel. and decel) with a stab at the gas pedal.


And last but not least: front suspension bushings?? But I'm throwing that out there as a wild one just trying to keep ideas coming!!

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I also have the same thing - most accurately fits with this: "It almost feels like the clutch slips a turn, then bites aggressively... But clutch seems pretty good. Not slipping in 5th, up hill, etc..."

Also a manual with TD27t.

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  • 4 weeks later...

Check the motor and trans mounts. also check the rear suspension bushings. I am going to bet it is the link bushings in the rear. Simple check, with trans in first(manual) or park(auto), parking brake off on hard level surface, rock a rear tire back and forth while watching the axle housing. If the yoke moves more than 1-2 inches up and down, you have worn bushings, Any side movement there is another sign of worn out bushings.

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