Strange knocking sound

[Aaronrichie]

Hi all.

I’ve had this issue for quite some time and cannot get to the bottom of it. There is a knocking sound coming from the rear of my van (‘86 1.9 DG) and it seems to only occur specifically when turning right whilst accelerating. My first guess was the drive shafts since the noise doesn’t occur when turning without pressing the accelerator but I’ve since replaced them and the problem persists…
Any help would be much appreciated.

Thanks,
Aaron

[Aidan]

gearbox mount ? or exhaust touching the body - there is some torque twist applied to the transmission by both the engine and driveshafts, if the engine mounts have delaminated then exhaust more likely

[RogerT]

Is it a single knock, or a repeating knocking when it occurs?

[Mocki]

Is the “knock” road speed related ? Does it stop if you depress the clutch ?

[Aaronrichie]

It’s a repeating knock and only occurs when accelerating whilst turning to the right. So I’ve actually developed a habit of taking my foot off the accelerator when turning right to avoid this knocking. Best way to describe the noise is it’s as if a horse is galloping behind me lol.

[Robsey]

The sound you describes reminds me of tatered CV joints - but I see you said that you replaced the drive shafts.

I always described it as crackling knuckles.
I presume all the bolts are correctly torqued-up.

[Mocki]

Just because they were new doesn’t mean they are good…. A few years ago i replaced all four on mine and had a odd knocking , turns out one of the new “quality” cv joints came from the supplier missing one ball bearing and i didnt notice when i installed them

[Aaronrichie]

I bought them from JustKampers and they certainly aren’t the highest quality drive shafts/CV joints money can buy but I had the same knocking sound before I replaced them so I think that rules out the CV joints being the problem. Having said that, it’s hard to see what else could be at fault.

[RogerT]

The reason I asked whether single or repeating was I had a single knock on accelerating round a corner - outer rear trailing arm mount was letting go of the chassis. Only visible clearly from under the van. Doesn’t sound like your issue tho.

Wheel bearings?

[Aaronrichie]

Ah I see, I’ve actually replaced both rear jacking points/trailing arm mounts so yea that can’t be it either. I suppose it could be the wheel bearings although I’ve been told it’s more of a deep rumbling sound when wheel bearings are worn. Someone mentioned the exhaust could be at fault and it could do with replacing anyway so might get that sorted and see if it fixes this knock.

[shrig1969]

I had a similar knocking noise you describe, that frustrated the hell out of me for over a year. Again only when cornering. Changed CV joints, springs and shocks hoping it would cure it but no.......
Driving home from work one night and the knocking developed into a worrying continuous scraping noise from the rear.
Took a look the following day and it turned out that the rear brake pin/spring had sheared off ( the small one that twists through the backing plate and holds the shoe in position )
Replaced all four and have had no knocking since. I am guessing that the worn pin,over time, was allowing the shoe to rattle under weight distribution when cornering??
Maybe worth a look ?

[Aaronrichie]

I’ve recently rebuilt the drum brakes with new pins/springs so that shouldn’t be the issue, I’ll have a look anyway though cheers. Thanks to everyone on this thread I’ve got a few leads to investigate now… exhaust mounts, gearbox mount or maybe knackered rear springs.

[Oldiebut goodie]

Rear spring turret rusted away?

[Stesaw]

Worth checking that the shock bolts are tight, I had an intermittent knocking noise and after scratching about found that was the cause for me.

[Aaronrichie]

Could well be the spring turret actually. There’s a considerable amount of rust there that I planned on sorting when I come to lower the van. The van is off the road now so gives me a chance to have a look at all these potential issues, cheers guys