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i30 N Rear Knocking

RawZ05

Well-Known Member
#1
Been away on business a fair bit plus I’ve not needed the N at all for about 3 weeks. It’s been sat on the driveway all that time with all the random weather over the last weeks with heatwaves and downpours.

Thought I’d take it out today just to get some life in her and straight away something isn’t right. Last time I drove the N coming back from London Heathrow to South Wales there wasn’t any problem but today there seems to be a knocking noise every time I’m braking. Apply the brakes and I can here a constant deep knocking until I take my foot off the brake. I’ve had a quick look around the wheels, breaks and underneath but I don’t see anything out the ordinary. I’ve not taken the wheels off yet but it may not be related to that. Could be the suspension or exhaust. I really don’t know.

Could it be that it wasn’t used for over 3 weeks that something has rusted and made loose in some way?

The 250 mile drive back home the last time I used it was completely fine. The weather at the time was mostly dry too.

I can’t get it to Hyundai until Monday at the earliest as their closed tomorrow.

Hopefully whatever it is can be covered under the warranty?
 

R Veloster N

Well-Known Member
#2
No worries, anything like this will be covered under warranty. :)

I'm betting it's a muffler or exhaust hanger has either come off it's hook, been lost or a exhaust heat shield is touching the underbody somewhere.

Grab the muffler tail pipes and give the muffler a shake up and down and right and left. Crawl under the car with a flashlight and check each hanger point on the exhaust system, making sure the rubber hangers are still intact. Grab hold of the exhaust pipe in various locations and give it a shake listening for any contact as well. Don;t be gentle with it either when your shaking. The engine will move it quite a lot.

With the engines movement fore and aft when accelerating and decelerating, the exhaust may be touching a heat shield, the underbody, or a rubber hanger has dropped or come loose.

Is the knock coming from forward of the firewall, mid body or behind the front seats? Try to narrow down the location of the knock. It will help analyze the exact location of the issue.
 

RawZ05

Well-Known Member
#3
I’m losing light tonight but managed to have a look at the exhaust. Everything is fine in that area. Even with some force it’s not hitting the above heat shielding and the rubber hangers look perfect.

It’s hard to say exactly. If I’ve got all windows down, it does seem to come from the rear drivers side. Maybe more central-ish from the mid body onwards. The exhaust pipe underneath doesn’t seem to move so the hooks keeping it in place look intact.

It only happens when braking, no matter if driving at 60 or 20mph. It just seems odd how 3 weeks of none driving had lead to this. Literally within seconds of leaving I noticed it so it couldn’t have happened during the drive back 3 weeks ago. Something must have rusted or seized up during that time.
 

Nomad17

Active Member
#4
It's probably just surface rust where the pads met the rotors, I'm assuming the parking brake was on while it was parked. Should go away after some more braking.
 

R Veloster N

Well-Known Member
#5
Oh crap, I didn't notice right off,you're near the Bristol Channel. I'll say this, salt air is a problem for any motorcycle or auto.

I still think its something on the exhaust banging. The amount or fore and aft movement of this engine is quite noticeable, it causes causes wheel hop as well. There is a flex section of the exhaust aft of the downpipe and it's there for good reason.

I'll find the video of the engine movement. You'll be surprised.

If the wire wrapped flex section were rusting and seizing slightly, it would cause the exhaust to stiffen up and move much more drastically, on accel and decel. Once it breaks loose, the movement would be taken up buy the flex section, as it should. So it would be intermittent.

Rust hits such areas quicker, do to heat and condensation formed from the catalytic converter and exhaust.

If you'll notice the exhaust on most auto is either galvanized steel or stainless. Either will rust in salt air. There is no stopping it.

Being you Brits, drive on the right side even with the windows down, most of the powertrain noise will come from the left of center and behind, unlike us setting on the drivers left. We yanks (yeah, I know the joke well.) :p hear most of the powertrain noise, vice versa.

Our ears are attuned to hear the closest sounds first. This will be your immediate right. So it's difficult to distinguish the true direction. Get your wife or if not married, a friend to set in the passengers side and listen as well. Explain to them, what to listen for but not the direction you think it's coming from.

Hang in there, it will be taken care of one way or the other.
 
#6
Been away on business a fair bit plus I’ve not needed the N at all for about 3 weeks. It’s been sat on the driveway all that time with all the random weather over the last weeks with heatwaves and downpours.

Thought I’d take it out today just to get some life in her and straight away something isn’t right. Last time I drove the N coming back from London Heathrow to South Wales there wasn’t any problem but today there seems to be a knocking noise every time I’m braking. Apply the brakes and I can here a constant deep knocking until I take my foot off the brake. I’ve had a quick look around the wheels, breaks and underneath but I don’t see anything out the ordinary. I’ve not taken the wheels off yet but it may not be related to that. Could be the suspension or exhaust. I really don’t know.

Could it be that it wasn’t used for over 3 weeks that something has rusted and made loose in some way?

The 250 mile drive back home the last time I used it was completely fine. The weather at the time was mostly dry too.

I can’t get it to Hyundai until Monday at the earliest as their closed tomorrow.

Hopefully whatever it is can be covered under the warranty?
I bet this is to do with the dodgy handbrake. Everytime I park for more than a day ( with rain included), the handbrake would not release and there would be a big clunking noise when I force reverse.

I Never know a car that does this. I often wonder did Hyundai used some cheap chinese steel to make the brake discs.
 

Mingy

Well-Known Member
#8
I bet this is to do with the dodgy handbrake. Everytime I park for more than a day ( with rain included), the handbrake would not release and there would be a big clunking noise when I force reverse.

I Never know a car that does this. I often wonder did Hyundai used some cheap chinese steel to make the brake discs.
I have experienced this on VAG vehicles so not only a Hyundai problem.
 
#9
I bet this is to do with the dodgy handbrake. Everytime I park for more than a day ( with rain included), the handbrake would not release and there would be a big clunking noise when I force reverse.

I Never know a car that does this. I often wonder did Hyundai used some cheap chinese steel to make the brake discs.
I don't think it has anything to do with the steel of the brakedisks. The pads that are used contain a certain amount of metal to uprate the frictionpotential, normal brakepads don't have that. That's why they rust to the disks more often than normal pads.
That said, you re only supposed to use your handbrake when you park on a steep slope. You don't use the handbrake on a flat surface, just put the car in gear. No risk of bonding pads / disks.
That's something you learn in drivingschool overhere but everybody seems to forget...
I think the problem of the ts could have something to do with the presence of metal particles in the brakepads and a longer period of being parked in a moist, salty environment. That would be the first place I would look.
Thinking about it I remebered 2 posts on the German forum from the early days of the N where there was a similar problem. That turned out to be a loose fixation of the spoiler above the backwindow in one car ( you can check the screws) and something with the nuts of the rear dampers on the other car (that would be something for the dealer).
 
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RawZ05

Well-Known Member
#10
I’ll have a further look this morning. The handbrake was on for 3 weeks. My driveway has a slight decline where I park the N now since getting the Santa Fe recently.

The brake pad sticking issue I’ve had since day 1 after not using the car for more than 3 days after rain or washing the car. Not had this knocking issues before though.
 
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Davo01

Active Member
#11
The “knocking” is probably the “outline” of the break pad in rust. It only takes a fraction of a fraction of a mm to make the noise as it runs through the break caliper. It will wear off with use (breaking) most likely. If it keeps up though, get it checked.

My moto did it once, and that doesn’t even have a hand break lol. Took a little while to go away.
 

RawZ05

Well-Known Member
#12
All sorted :)

Used some AutoGlym Clean Wheels and Cleaning Mousse for good measure all over the wheel, pads and around the base. Spent a good 5 minutes on each wheel with the pressure washer and everything is fine. Did notice there was a tonne of dirty water coming from behind the wheels, more than usual but I’ve not cleaned the N in near 5 weeks. That and the 3 weeks parked upmust have caused some serious rust build up. Took an hour drive out somewhere quiet and no problems whatsoever.

Moved her to park where I used to with no handbrake, just in gear. Hopefully it doesn’t happen again.
 

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