Im going to flip!!!! Knocking noise in reverse

could easily be the rear diff mounts. best to check.

When turning in 4x4 mode the VC will slip. This will cause a judder in the drive chain. Sounds like the rear diff mounts are the place to start as Daft has suggested. Oh, and no, this wouldn't happen in 2WD mode as the rear diff is under no load soit won't stress on its mounts.

hi right ive checked the diff and subframe mounts and they are fine no movement wear or tear on them. what now????

Assuming you are at manovouring speeds when you reverse, how rapid is this knocking? Greater than 1 a second or a lot slower?

i wasnt really doing any speed just taking my time reversing as i had just put everything back together reversed about 2m and heard the first knock so stopped reversed again prob same distance and heard for a second time. pulled back onto drive and no knocks at all.

I assumed you were taking it carefully. If you had a rapid series of knocks I would say the diff was the problem. A single thump is probably on the driveshaft. Either the bearings or the VC itself.

Try the VC test trick. Car in gear, handbrake off (Flat ground it must be on, goes without saying). Now left one read wheel off the ground. Now try and turn that wheel. It will be very tight but it should give with a jump before going tight again. This is the VC slipping. You might hear your knock as well.

If you're unhappy with the VC then get it back from wence it came and get it checked out.

cheers for the advice really appreciate it. ive taken the prop shaft and viscous coupling off as i was going to drive it for work in 2 wheel drive but when i get a spare hour ill fit it back on and try your advice. is there any tests you can do with the prop and vc off?

cracked chassis or subframe mount.

The Mad Hat Man said:

cracked chassis or subframe mount.

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Ah, another well known favourite. My subframe can't move, its welded to the floor pan!!

It could be the CV joint on the front drive shaft by the IRD!!

the lad in the garrage is almost defly right,i had a knock like that,i knew the drive shaft was a bit loose(drivers side)knocked when taking off in left handed lock.i let it go for way too long,now the drive shaft will rattle in the ird when i move it by hand(front wheels lifted).ive ordered 2 new complete shafts from ebay seller for £121 delivered to ireland.now i need to source 2 new oil seals.

so would the drive shaft only make this noise in 4 wheel drive (with prop shaft and vc)? because there is no noise in 2 wheel drive?

is there a test to know if its a cv joint thats the problem? what should i be looking for?

again how would i be able to see if its the cv joint? is it easy to spot?

No, its not easy to spot. The CV joint is all covered up in its protective boot. It allows a shaft to twist slightly and allows the shaft to reach or contract if the two objects being connected move in relation to each other. For the front, central drive shaft, one end is fixed to the body work by virtue of the VCU support bearing. The other end is fixed to the IRD, which in turn is part of the engine assembly. When the engine applies a load its anti torque will twist it on its mounts and as its a transverse engine this means forwards and backwards movement of the IRD in relation to the VCU.

The problem could be only at a certain extension position while on load, therefore if you are underneath the car with no load on the shaft and the engine not running (best conditions really) then you may not feel anything wrong with the CV joint.

I recommend you seek a friendly garage and see if they can fit a different central propshaft to your Hippo. Then give it a try. If the problems gone away then you know its your prop.

jasper the dog said:

again how would i be able to see if its the cv joint? is it easy to spot?

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if you lift the front off the ground,grab the drive shaft in near the ird and see if you can rattle it about,if you can its on the way out.

Im a carpenter and not a mechanic,so you may or may not want to believe what I or others type,but get down on yer back and try to rattle that inner cv joint.