knocking noise under car while reversing (Update)

[Dim Sum]

I have a little problem, wondered if anyone had experience it or know what is the cause of it.

 

Started about a month ago while reversing I would hear a knocking noise under the Supra. But its not all the time and the knocking disappear and now its back again.

 

symptom are:

 

knocking only in reverse

sounds like its directly under the driver side

( is there something wrong with the propshaft, because the noise it makes kind of sounds like something to do with rotating. It knocks.....then .......knocks again while the car is reversing, I had also tried it with the reserve gear disengage while it was going backwards and it knocks too.)

 

knock...........knock..........knock and etc

 

 

I have been to a mechanic, he said it hard to tell, because sods law it didnt knock when I got there.

Like I have mention this sounds comes and goes but its bugging me.

 

Just wanted members opinion on this.

Edited December 14, 2013 by Dim Sum (see edit history)

[thetrashcanman]

Rear sub frame bolts, or one of the rear shocks maybe? Definitely doesn't do it when your moving forward?

[SPG]

Does it knock when you are reversing straight back or when you turn the wheel and the reverse?

[thetrashcanman]

Does it knock when you are reversing straight back or when you turn the wheel and the reverse?

 

You thinking its the diff maybe?

[Dim Sum]

Rear sub frame bolts, or one of the rear shocks maybe? Definitely doesn't do it when your moving forward?

 

100% don't do it when going forward, because the knocking, sometimes you can feel it inside the car

 

Does it knock when you are reversing straight back or when you turn the wheel and the reverse?

 

When it does knock, its both. reversing straight back and turning.

[SupraLEDrears]

My mate has this problem and some mechanic told him that it's the balljoint collecting energy and then releasing it, thus the knocking noise. IMO that's the most bs I've ever heard. Subscribed

[Camry5Sgte]

I'd check to see that all the subframe bolts are tight for starters.

[Dim Sum]

I'd check to see that all the subframe bolts are tight for starters.

 

Okay I give that a try tomorrow.

 

This problem is so strange, took the supra out today and nothing happening while reversing and last night it was.

[wile e coyote]

Under strain or free wheeling

Ie try reversing up a hill so straining it , then roll backwards down hill

Let us know outcome

[Dim Sum]

okay will do. I will test that out too and I will post the results.

 

Thanks for the suggestions

[Dim Sum]

A little update, well not very much.

 

Bolts all seems tight (subframe)

 

I took the Supra out twice on a little slope to give it a little strain.

The result is nothing, no knocking reversing up the slop or downwards

 

Like I have mention before the knocking will suddenly come back and stop, even on certain circumstances.

It could be a flat road reversing it will knock then maybe ten minutes later I reverse again, nothing.

 

This is driving me nuts

[Big Supes]

I seem to have this problem as well, but it's on the passenger side at full lock (only in reverse). It's like the wheel is catching on something and the knock goes right though the car as if the wheel is ready to fall off....

[Dim Sum]

I seem to have this problem as well, but it's on the passenger side at full lock (only in reverse). It's like the wheel is catching on something and the knock goes right though the car as if the wheel is ready to fall off....

 

my might be a little different, mine knocks for a while then no knocking. Also mine does it on a straight reverse and corner.

[Dazzi]

Classic symptom of engine mounts.

[LOGIE]

Brake shoes not adjusted properly?

[Dim Sum]

Classic symptom of engine mounts.

 

I have no experience about engine mount failing, so is that anyway to check?

 

Brake shoes not adjusted properly?

 

Well the brakeshoes were adjusted two years ago when changing the rear disc. Sometimes the knock can be felt within the car.

[listy]

You thinking its the diff maybe?

 

I'm thinking diff.

I'm sure someone had this a while back, and it was because the internals of the diff were dying.

When they changed the diff fluid, they had metal flake in it.

 

Try draining the diff fluid, and see if it's clean (free of metal) or not.

If it's got metal flakes in there, the diff is screwed.

[thetrashcanman]

I'm thinking diff.

I'm sure someone had this a while back, and it was because the internals of the diff were dying.

When they changed the diff fluid, they had metal flake in it.

 

Try draining the diff fluid, and see if it's clean (free of metal) or not.

If it's got metal flakes in there, the diff is screwed.

 

Sounds like a good shout to me, I would try checking that dude.

[Dim Sum]

Okay. I will try that ASAP.

 

Thanks all for the suggestion, I be back to post results

[Dim Sum]

Okay, a little over due update.

 

 

There is no metal flakes in the diff, when I drained the oil. But lucky for me my friend who's a mechanic was around on the day and so happens the knocking was there when reversing, he confirm it could be diff related, but because the knocking ain't that bad he said. He told me to leave it for now and wait and see.

 

Okay guys I should just start looking for a spare?

[MattP]

Okay, a little over due update.

 

 

There is no metal flakes in the diff, when I drained the oil. But lucky for me my friend who's a mechanic was around on the day and so happens the knocking was there when reversing, he confirm it could be diff related, but because the knocking ain't that bad he said. He told me to leave it for now and wait and see.

 

Okay guys I should just start looking for a spare?

 

I spent two years on my last supra trying to find out what the noise syptyms that you are getting I changed all shocks and top mounts for new,new droplinks all around,checked engine mounts, torqued all subframe bolts and related bushes on anti roll bars etc as mr t specified,checked diff,all 4 calipers refurbed etc the only thing I didn't change we're the rear upper arms which are probably what the problem was.

[Chris Wilson]

If it's a late model car I would suspect engine mounts. I would also check front calipers (and sliders if J-Spec calipers), for any seizing or dragging.

[Cipriani]

I have a similar problem but I know the rear passenger strut top mount is worn badly and the wheelbearing on the same side is poor. I am replacing the coilovers asap and wheelbearings, but I will give the diff a check I will be going for a LSD pretty soon anyway.

[Dim Sum]

I spent two years on my last supra trying to find out what the noise syptyms that you are getting I changed all shocks and top mounts for new,new droplinks all around,checked engine mounts, torqued all subframe bolts and related bushes on anti roll bars etc as mr t specified,checked diff,all 4 calipers refurbed etc the only thing I didn't change we're the rear upper arms which are probably what the problem was.

 

Okay I go and have another check. Well are least you know for piece of mind that underneath the Supra is all good

 

If it's a late model car I would suspect engine mounts. I would also check front calipers (and sliders if J-Spec calipers), for any seizing or dragging.

 

Mine is a facelift 6speed, If it was the engine mount is there anyone to tell besides taking the engine out and changing it?

Also I will check the calipers for any drag marks.

 

 

I don't know if I mentioned the knocking sometimes happen not only in gear but in neutral rolling backwards. Again the knocking comes and goes like this morning no knocking while going backwards

[Chris Wilson]

Yes, you can see if the clearnce between the two halves of the mount are too close together or even touching, on a ramp, with a good light source. If someone posts a photo of an engine mount I will indicate where to look. The late mountings are notorious for trouble. Do you feel a slight tremor through the car and steering wheel when it's idling in neutral?