Sup H-T.

I've had this problem for a while, so i thought i'd get some opinions on the matter.

When I'm cruising between 70-80kph the car gets a vibration that comes and goes in rhythm, so it'll be vibrating for 2 seconds, then it'll stop, then back on etc. It fades in and out. It's not rev related, so that narrows it down to something beyond the transmission which was replaced last year with a brand newy.

The thud that i'm getting seems too obtrusive to be something that was designed from factory, but only makes itself known if your not very diligent with the clutch, or you don't rev match your shifts properly.

I'll be replacing the oil in the rear differential today, i'll see if that makes any difference. Any other idea's though? The rear diff mount has been replaced. The service manual mentions back lash as a possible cause for the thudding, but it doesn't say how to adjust it. Any insight?

Thanks.

 

when does the thud occur?
slow speeds like doing a U-turn? if so i would guess that its the rear diff, hopefully new oil will clear it up.
is the clutch cable adjusted properly? mine had a thud for a while when my clutch cable was a bit loose.
that vibration sounds odd, idk what to say, what have you checked? are the wheels balanced, suspention okay?

 

Do you have a Lightend Flywheel? ???

 

The thud is usually when your taking off, or changing gears. The clutch seems to be adjusted fine, no slip.

The vibration feels like part of the drivetrain, although someone else has mentioned a wheel balance, though i rotated all my wheels and it made no difference at all.

No, though i am looking for one.

 

well try cruising along at the speed that the vibration happens and push the clutch in to see if its infact drivetrain related. you might have to try a few times to be sure.

so the thud has nothing in common with releasing the clutch?
i guess i'll wait for you to change your diff oil. let us know if that helps.

and whats with lightened flywheels (and thuds)? i've got one.

 

I'm pretty sure it's drivetrain, it vibrates from the rear. The thud is more from ....'slack' in the drivetrain? Imagine the rear diff has no mounts, it's not nearly that bad, but that's what it feels like on a smaller scale.

I'll be changing the oil soon.

 

sorry i dont know a lot about driveshafts and such but could a worn out U-joint be causing this?

 

I'm sure it could. I'll see if there's any wear signs when i've got it jacked up.

Thanks.

 

Check for your U joints OR, Check all your engine mounts could be that when you push in clutch motor comes shifter forward thus your thudding noise.?

 

i have no idea if the 4wd ef has a driveshaft carrier bearing, but i know my dads truck had a bad one and it would clunk a lot until he got that bearing replaced. The carrier bearing is usually found on the long driveshaft from front to back, somewhere in the middle to relieve the stress/weight of the shaft near the middle. It is a wild *** guess, but something to look for at least.

 

The mounts are all good.

The EF's have a viscous coupler in the middle, so essentially they're a 3 piece prop shaft.

I changed the oil in the dif, and the clunk seems to have subsided, but the vibration is still there. I had a look at the U joint that connected with the dif, and it appeared fine with no obvious signs of wear.

What i did note though, you could turn the prop shaft in your hand. It had about 1/2 an inch of rotational play. I don't know if that's usual or not.

Thanks for the ideas. Has anyone got a how-to to adjust the backlash in the rear differential? The service manual gives the specs but no direction on how to do it.

 

The reason I asked if you had a Lightend flywheel is that they Seem to jitter and Vibrate between 2500-3500 RPM. But if you dont have one? ?

I thought you were pulling our leg when you said rear Diff.. Then I read about your 4wD EF!

Can the Vibe be inertia related? Wheels tires brakes and such?

 

It seems to happen most while coasting, or driving at a steady speed. I can't remember if it gets worse if you accelerate from that certain speed (under load) that it vibrates at.