humming noise from rear of 90

Hi guys, I have posted this topic many times and still my problem persists so any additional info will be greatly aprechated, i have a defender 90 200tdi convesion, when driving at approx 40-50 mph and I let off the accelerator I get a slight vibration and a humming noise for just a few seconds, i get it when I start to accelerate but again only for a few seconds, right the bits I have replaced, rear prop (with new uj's),rear axle (disco 300tdi one) rear trailing arms, the fault has been there before I replaced all of this, I have had centre of seat box out and don't seem to be gear/transfer box and seems to come from rear of vehicle, swapped front tyres to rear but still remains, the fault is intermittent sometimes really bad and sometimes sweet as a nut, i noticed this when I put 235/85r16 insa turbos on and 2 inch lift blocks, what could it be, im going insane now. Lol

you can try running with one prop off at a time in diff lock , or removing t/box sump plate and checking for end float in gears

have you allways run insa turbos? would it be possible to "borrow" a set of more road biased tyres and see how the vibrations is.
i run insa turbos and there very noisy and send vibrations through the truck varying at different speeds. when i swap over to bfg at all is well.

I am going to try and swap wheels just to ellinamite but don't think it is as is very intermittent, it never happens at an exact speed or on a specific road, makes no diffrence if it's wet or dry, if there was a slight pattern then maybe I could point to tyres, will try though as another illumination.

Ok, so I have increased tyre pressures to 40psi, and fault still there but not as bad ( ? Not as much resistance), it's like the rear wheels are not as free running and braking the vehicle slightly, i checked wheel bearings and seem ok, only other thing I noticed is there is slight play on a fame bushes, and propshaft seems to have a lot of play (not uj's) transfer box end, any suggestions??

phippsey27 said:

Ok, so I have increased tyre pressures to 40psi, and fault still there but not as bad ( ? Not as much resistance), it's like the rear wheels are not as free running and braking the vehicle slightly, i checked wheel bearings and seem ok, only other thing I noticed is there is slight play on a fame bushes, and propshaft seems to have a lot of play (not uj's) transfer box end, any suggestions??

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Is play at transfer box end rotational or up/down?
Did you try removing each prop in turn and running in diff lock as suggested?

aaronmorris said:

Is play at transfer box end rotational or up/down?
Did you try removing each prop in turn and running in diff lock as suggested?

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Not yet going to do prop removal on tuesday as james said, no play up/down side/side play though

Ok, so I have been reading quite a few threads and have found one which states a rumbling noise and rear braking on over run, these are the exact symptoms I have, James Martin said pinion bearing as I have also been told, question is what are the chances of me having the same problem with two different diff's, i did have to change the flange as the donor diff was from a disco, could this be a contributing factor and would the 2 inch lift be putting undue pressure on diff? I have put a 15mm prop spacer on to counteract the extra trave length