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Help with a knock



Ash J

ClioSport Club Member
  Sunflower Ph1 172
Right, hopefully looking for some help with a knocking noise I am getting guys.

It has pretty much been there in some way or another for about 6 months, and nobody seems to have gotten to the bottom of it.

Car went into Rentech back in September of last year, and was told the nearside driveshaft housing was missing one of the three bolts, and the others were really loose, and that was the knocking problem. When I picked it up, knocking was still there. I was asked to bring the car back, and it was found that various bolts on the front end (around the subframe, lower arms etc) were not as tight as they could be, and the engine mount bolts were not quite as tight as they could be. So after having this done, off I drove again, and it was a lot better and the car felt tighter to drive, but there was still a knocking problem.

I spoke to Rentech, and we agreed the next plan of action would be changing the ball joints. So I went back and had these done. Again, car felt tighter than it did before, so it was a benefit having them done, but I still thought I could detect a knocking the same as before, but not quite as loud. Gradually as days/weeks passed, the knocking came back.

This takes me up to a couple of weeks ago, where I booked the car in with Rentech again. I bought a couple of track rod ends, and asked for these to be fitted, along with tracking, and for the knocking to be investigated again. I got the call to pick the car up, and was told the knock was sorted. The steering rack bushes were not as tight as they could be, the gearbox mount bolts were not tight, and the lower arm bolts were not tight, so this was all tightened up. I also had a note on the invoice to say the bushes on lower arms are modified items (powerflex) and that the lower arm bolts were found loose again (these were one of the things that were tightened on an earlier visit).

So I go to drive off, and immediately as I reversed the car up.... knock. It is still there. It seemed to get worse over the next few days too.

So today, I took it to another garage which is really close to my work to have it investigated (means I can leave the car whilst being at work). I get a call later and am told they think they have sorted the knock. I get down to the garage, and am told the following...

Nearside driveshaft housing was very loose. It was missing one of the three bolts altogether! The other two bolts were loose... one was luckily an original bolt, and the other was completely the wrong bolt and when fully tightened would only have had about two teeth being useful (i.e. bolt was nowhere near long enough). I was pretty disappointed with the discovery of incorrect bolts considering this what I was told was the problem at my first visit to Rentech, and they apparently sorted it. And they also found a 16mm socket around the subframe somewhere which they managed to get out with a magnetic rod. They could not really find anything else obvious causing the knock, and said they had taken it for a test drive and the knock was gone.

Picked the car up, took it for a drive, got to the end of the road.... the knock is still there. In fairness they didn't charge me for changing the driveshaft housing bolts to the correct bolts and checking over any other bushes etc for play. But still, they couldn't detect a knock on a test drive... they have asked me to bring it back again this week to have another look over which I will do. And the car did feel better to drive after having this housing tightened so again it obviously needed doing anyway.

But this knock is pretty bloody obvious! And after about 4 different visits to 2 garages over the last 6 months, every time I have been told the knock is sorted, and every time I have detected it immediately after driving away!

It is starting to get me a bit down, so I just wondered if anyone can suggestion what it could be if I try to explain exactly what happens!

Every time I pull away from a standstill, I get the knock. If I am super, super careful and gentle with the pull away, I can sometimes get away without a knock, but I do mean really gentle.

When I come off my driveway, I get the knock. Normally I come off my driveway turning right (not full lock), and where my driveway has a dropped kerb, as I am driving off the driveway heading right, I get the knock just as the front wheels go past the dropped kerb and onto the road (so only a small kerb as it is a dropped one).

There is a little roundabout near where I work which you approach at about 10mph, when I then grab the steering to turn right around the roundabout (fairly sharp I guess as it is a mini roundabout), I get the knock.

I tried a different thing today where I stayed in 2nd gear, then a few times I got on the throttle quite aggressively and harshly then backed off, then do it again, and each stab of the throttle you could hear the knock.

If I am just driving along on uneven/bumpy roads, I do not detect the knocking noise. But every now and then it sometimes does, or maybe more so when I am turning the wheels slightly (either way) whilst going over uneven roads.

If I reverse out of a parking bay right or left, then as I come near to a stand still from going backwards, put it into 1st to drive away.... knock.

My lower arms and anti roll bars are fitted with powerflex bushes.
My dog bone mount has powerflex bushes.
Ball joints have been replaced in last 6 months.
Track rod ends have been replaced in last 2 weeks.
Lowered on Cooksport springs.

Please help me guys! Am very frustrated with this knocking noise!!

Cheers
Ash
 

Louis

ClioSport Club Member
Have you eliminated the knock potentially coming from an exhaust mounting? Probably something you've already done but just thought i'd put it out there! Sound travels weirdly so often you can think it's from one place when it's from another. Can you not recreate the knock anywhere with the car on axle stands? Have you had the front end on stands and had the wheels moving to see if you get the noise, as you say it happens when pulling off.
 

Ash J

ClioSport Club Member
  Sunflower Ph1 172
Cheers for the responses guys.

What would I need to look for in terms of exhaust knocking?

I am pretty adamant it is suspension/driveshaft related or something similar, just from when it does it, particularly coming off my drive. Difficult to explain but it doesn't seem like exhaust knock. Also it sounds like it is coming from around the steering rack/driveshaft area, or near to the bottom of one of the struts.

Could steering rack bushes that are knackered cause a knocking noise? I am going to try and look to see if I have Powerflex ones fitted or not. If not then maybe the standard ones are perished if they can cause knocking?

As for getting the car on axle stands, just not possible for me to do, don't have stands to start and I don't have anything like the driveway space to do so, so unfortunately I generally have to go to a garage to have work done.

Thanks for the suggestions.
 

Davyy

ClioSport Club Member
  Clio 172
Feel free to pop round mine mate if you want to prop it up on stands (I have stands). Could be top mounts? I had a strange very quiet knock from the left wheel area when I came off the throttle, forward and reversing, could only hear it at low speed with the windows down, but it seems to have stopped bizarrely.

Odd/Surprised about the driveshaft bolts!
 

bloke

ClioSport Club Member
  dan's cast offs.
as long as it's 100% on a nut and bolt check then look ad the rack mounting brackets themselves, i had one split that was a right headache to find and everything was tight and the bracket is tucked away behind the rack so not that easy to see plus the split was quite small as well.
 

Pauleds

ClioSport Club Member
  Merc Dueliner sport
Ive never been a fan of Powerflex bushes in the bottom arms after I had them fail rather quickly on my 205's, and I only ever change the bottom arms complete with TRE for genuine items as tend to find they last longer. I would be changing the bottom arms.
 

Ash J

ClioSport Club Member
  Sunflower Ph1 172
Feel free to pop round mine mate if you want to prop it up on stands (I have stands). Could be top mounts? I had a strange very quiet knock from the left wheel area when I came off the throttle, forward and reversing, could only hear it at low speed with the windows down, but it seems to have stopped bizarrely.

Odd/Surprised about the driveshaft bolts!

Yeah top mounts is another thing it could be. If you don't mind then that would be awesome if possible please mate, that's a very nice offer.

Ive never been a fan of Powerflex bushes in the bottom arms after I had them fail rather quickly on my 205's, and I only ever change the bottom arms complete with TRE for genuine items as tend to find they last longer. I would be changing the bottom arms.

I have been thinking about fitting a new pair of genuine lower arms. Partly because these come with ball joints too. I normally only ever replace parts on my car for genuine items, but because I had powerflex bushes in bottom arms, when the ball joints were replaced at the end of last year, I was told TRW were good quality so this is what was fitted. They might be ok, but I do wonder if these ball joints are not great quality and have failed quickly. Either way would be happier with genuine ball joints so I may well try a new set of lower arms.
 
  monaco 172
Knackered dogbone causing the manifold to hit subframe?

I had this when i changed my clutch so I loosened off all the mounts and gave the engine a bit of a shake to centralise it all then nipped back up and the knock was gone.
 


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