Knock/bang on throttle and brakes.

[Tj172]

Got a bit of a strange issue with my 200. After replacing all ball joints, links, shocks, springs, wheel bearings, inner tie rods and ends, top mounts. Calipers and basically everything else suspension related I'm left with a knocking noise.

It only does it when throttling hard from a stand still, it will only do it once and will not do it under throttle again until I brake hard, when it also knocks once. So seems to be somthing moving back and forth. Will literally only do it when launching from a standstill and emergency braking. It's a very harsh metallic knock.

Going totally out on a whim here, as I've had it in pieces 4 times trying to find the issue. I've had it up on my 2 post lift and bolt checked everything numerous times, I cannot find anything loose and everything is tight.

I've also checked

Lower engine mount
Upper stabiliser
Hub nuts
Wheel bolts
I've even put brand new genuine lower arms on

Absolutely pulling my hair out now (what's left of it after owning this car for 3 years)

I'm open to any suggestions if anyone has any

 

[R20BTG]

Loose item in the car/glove box


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[Maidens1979]

I started getting something like this recently but it only happens under breaking and it’s not consistent, my first thought is a sticking brake pad or calliper piston maybe?

 

[Tj172]

I thought it could be pad knock but it wouldn't explain why it does it on throttle. The sound is definitely under the front somewhere. It can be felt through the floor when it knocks. Think I'm going to have the subframe off today.

 

[Maidens1979]

Keep us updated if you find the issue @Tj172

 

[turkie172]

Is the sound in the center or to the left or right as my thinking is if everything is been done and fitted correctly and the hubs were not cracked then I would say it is the exhaust on the subframe (but this will make noise in one direction) or going over the back axle, Main engine mount sheered, Gearbox mount. Slack off the top torque mount and the lower mount as they may not have been done together then grab the back of the head and rotate the engine forward that will give more clearance between the manifold and subframe with it rotated forward tighten the mounts again so one is holding the other in check, another thing would be check the gearbox mount the holes are bigger than the bolts and can slide


The main engine mount this one has the yellow powerflex bush fitted they can be sheered if the engine is jacked up too much taking the cars weight.

 

[funMACHINE]

can you show a picture of the old outer tie rod ends ?

 

[turkie172]

ah yes

 

[Tj172]

Thanks for all the advice, just done it all including checking the subframe bolts and every other bolt I can get to and still no joy. It does sound as if something is cracked or loose but it was all checked when I did the rebuild. I found a small hairline crack in the top ball joint area on one knuckle which was replaced. Tried many things yesterday all of which didn't work.

Don't think I've got the old ones anymore, if I have they're at the bottom of the scrap bin.

 

[R20BTG]

Are you running wheel spacers?

 

[Tj172]

Yeah, 25mm through bolt ones.

 

[funMACHINE]

Don't think I've got the old ones anymore, if I have they're at the bottom of the scrap bin.

Then have a Look at where the outer tie rod end goes into the alloy hub carrier, there have to be a steel bushing Insert inbetween... It's a common failure that the bushing is removed with the tie rod end and the new ones are build in without them. Dont realize it cause you can tighten the nut, but in driving conditiones, it makes exact what you describe.

 

[turkie172]

sorry funmachine I did not realize you were in the middle of replying


I think what funmachine was asking was the top hat did it come out with the old track rod ends its a steel insert that stops wear it has a habit of coming out with the old track rod ends people miss it and fit the new track rod ends with them missing. They are not officially sold as a spare part as well

 

[funMACHINE]

Thats what I meant, have the pictures not on the Smartphone

 

[Tj172]

Ah yeah I've got those fitted, made sure I put them back in when I rebuilt it. Although I will take the ends out the knuckle and check for wear in the sleeve. It can't hurt

 

[Ciapata]

Try tightening rear lower arm bolts. Torqued them to spec and had the same issue. Gave them some more, problem solved.

 

[Maidens1979]

Interesting find when changing my gearbox mount today. While I was in there I thought I’d check the torque on the two bolts that hold the plate to the chassis. The lower bolt was fine while the upper (circled in red in image) was not. So I started to turn it but it wasn’t feeling right, so I slowly tightened it and then a loud bang just like the sound I get when breaking .
The bolt will not torque up and just gets to the point where it makes this loud bang noise.
Also when I went out in the car after putting everything back together the same noise happened as soon as I lightly breaked.

 

[Matekkr200]

Interesting find when changing my gearbox mount today. While I was in there I thought I’d check the torque on the two bolts that hold the plate to the chassis. The lower bolt was fine while the upper (circled in red in image) was not. So I started to turn it but it wasn’t feeling right, so I slowly tightened it and then a loud bang just like the sound I get when breaking .
The bolt will not torque up and just gets to the point where it makes this loud bang noise.
Also when I went out in the car after putting everything back together the same noise happened as soon as I lightly breaked.View attachment 154326

Did you figure it out?

 

[Maidens1979]

No I haven’t fixed the issue with the bolt. I think it’s probably been over tightened at some point and stretched the bolt.
But I’ve not had the noise again since it happened straight after I’d changed the gearbox mount and took it out for a drive (hopefully I haven’t just jinxed myself)

 

[Ciapata]

In my case the noise came back again, although only under very heavy braking and full throttle. It was lower swivel joint. Also it squeaked like an old wardrobe when maneuvering and wandered at high speeds.