_grunt coming from clutch discs_

BMW i3 Forum

Help Support BMW i3 Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
D

DocRush

Active member
Joined
Feb 18, 2015
Messages
36
Location
İstanbul / TÜRKİYE
Dear all,

This is my first ever message and I have to confess that I took so many precious i3 related information on account of you.

Our BMW i3 is nearly 1.5 month old and has 900 kilometer on the odometer so far. Mostly my wife drove while commuting; I occasionaly made short trips with pleasure. Undoubtedly we are one of the Turkish frontiers in İstanbul since I did not encounter another i3 on the streets.

I wonder if there were also some people suffering the high volume grunt arising from clutch discs.
Especially on the downhill breaking and at the very last moment arriving standstill we unfortunately hear this noise since the first day of possession. :evil:
This noise (sth like grooaannncchhh) is so high that other drivers on the right or left side of us can easily hear and look at our i3's wheels behind the window glass of their cars. :oops:

I do appreciate any thought, experience and/or advice regarding this issue.

kind regards
 
The symptoms you describe match the commonly raised problem of a small rock being caught between the brake rotor and the thin metal 'shield' over them. Most of the time the small rock falls out after a few miles or when reversing, though sometimes a larger rock or one that is 'perfectly' shaped will stay trapped.

The thin metal 'shields' over the rotors can be pulled away from the rotor to free the rock.

If this isn't the problem, then definitely take it into the dealer.
 
If you drive the i3 as efficiently as you can, you end up not really using the brakes much, if at all. That can allow them to get some rust on them. That can cause some noises. Every once in awhile, I try to remember to actually do a hard stop using the brakes to help clean the rotors off. The transmission really doesn't have any clutches like a normal vehicle...it's a one-speed transmission - direct drive, and when you're stopped, unlike an ICE, the motor is not turning at all, so no clutch required. Not exactly sure how it does the hill-hold function, so there IS something in there, but it could be done electronically rather than mechanically. That may be the issue if it is mechanical.

If you are stopped, and on the level, does it do it as well, or only while not level and the hill hold function is working?
 
Schnort said:
Sounds like it needs a trip to the dealer?
Click to expand...

Dear Schnort,

I have already paid a visit to the competent service center and demonstrated the sound to the dealer on a steep downhill area during our test drive.

They made several observations and (so to speak) checked all the bulletins originating from BMW AG concerning the issue.
Result: No intervention but some explanation. :cry: :!: They explained the situation by saying sth like this: " This vehicle occasionally needs braking which causes the formation of a thin layer covering discs' surface (exact technical name = pah). After a single deep braking attempt the layer will be brushed (scraped) and the noise will eventually disappear at that day."

I still doubt if our i3 is generating excessive pah when compared yours' vehicles. :?
 
The explanation that you received seems to be describing the same situation that
jadnashuanh described: a thin layer of rust on your brake discs as a result of little use of your brakes. My i3 has the same problem. When I leave my apartment parking garage, I must descend a steep ramp with concrete walls on each side and a stop sign at the bottom. Regenerative braking is insufficient to stop my car, so I must use my brakes which I do not normally do while driving. The sound of the rust layer being ground off echos off the ramp walls and sounds really terrible. But I now know what causes this noise and that it's not a serious problem, so I don't worry about it. Neither should you.

Congratulations on purchasing your i3 in Istanbul! My wife and I have enjoyed visiting Istanbul twice during the past two years. We have read that Istanbul has been receiving so much snowfall recently that snow chains were required for driving in at least parts of Istanbul. I hope that your i3 handled the snow well.
 
jadnashuanh said:
If you drive the i3 as efficiently as you can, you end up not really using the brakes much, if at all. That can allow them to get some rust on them. That can cause some noises. Every once in awhile, I try to remember to actually do a hard stop using the brakes to help clean the rotors off. The transmission really doesn't have any clutches like a normal vehicle...it's a one-speed transmission - direct drive, and when you're stopped, unlike an ICE, the motor is not turning at all, so no clutch required. Not exactly sure how it does the hill-hold function, so there IS something in there, but it could be done electronically rather than mechanically. That may be the issue if it is mechanical.

If you are stopped, and on the level, does it do it as well, or only while not level and the hill hold function is working?
Click to expand...

...
Dear Jim,

I am not familiar with mechanics and could not discriminate a clutch or rotor, theoretically. Being a poor physician is my excuse who appreciate your well-established competency on i3, cordially.
Please forgive my ignorance but IMHO hill hold function assists us on uphill position rather than downhill.

Anyway, as my wife exclusively uses the aforementioned deep braking on a steep downhill coincidence (eg. due to a traffic light at the bottom of a downhill turnout while approaching a crossroad near our home) in the mornings she ably experiences her first irritation over there.
On her return way at the evenings she does drive half a kilometer downhill along with the grunts (several times) whenever a deep braking is necessary.
So, the advice of our service dealer which denotes a deep braking in the morning will scripe the pah is a nonsense explanation; isn't it... (?) :roll:
 
alohart said:
The explanation that you received seems to be describing the same situation that
jadnashuanh described: a thin layer of rust on your brake discs as a result of little use of your brakes. My i3 has the same problem. When I leave my apartment parking garage, I must descend a steep ramp with concrete walls on each side and a stop sign at the bottom. Regenerative braking is insufficient to stop my car, so I must use my brakes which I do not normally do while driving. The sound of the rust layer being ground off echos off the ramp walls and sounds really terrible. But I now know what causes this noise and that it's not a serious problem, so I don't worry about it. Neither should you.

Congratulations on purchasing your i3 in Istanbul! My wife and I have enjoyed visiting Istanbul twice during the past two years. We have read that Istanbul has been receiving so much snowfall recently that snow chains were required for driving in at least parts of Istanbul. I hope that your i3 handled the snow well.
Click to expand...

...
Dear alohart,

I am not happy but a bit relaxed after reading your personal (resembling) experience. I just started thinking "this unpleasant situation is our destiny" which had never been disclosed/declared :cry: :twisted: . Maybe, there won't be a remedy for this illness. :x

Nice to hear about your İstanbul visits and continued interest, really :) . Nowadays we do struggle with snow here; I am 47 and have never seen such a hard/harsh winter. I have more empathy with polar regions' folks, from now on ;) .

On the other hand, we have a two years old X3 in our garage which serves to my wife instead of our new i3 during these hard days.
PS: Personally, I always walk into my workplace since it is only 150 meters away from home (door to door) :p :roll: .

with my best regards...
 
HIll hold works to prevent you from rolling opposite the setting of the transmission, so it will stop you from rolling backwards when in drive, and forwards when in reverse...but, at least on mine, I've not heard any clutches engaging when it does that. I often use the electronic parking brake when stopped to keep me from rolling, and when that engages, you can hear the motor pulling the (what I think is a) brake cable. And, when it releases, you can both hear and feel something, but I don't find it annoyingly loud or obtrusive. Without hearing yours, can't say. I do not know if the cruise control will apply the brakes on a downhill section if regenerative braking is insufficient to keep your speed in check. I know on my other BMW, it will downshift, rather than brake, to try to accomplish the same thing, but on the i3, there is no lower gear, so they might. I highly doubt it would switch into neutral, and, switching gears is (I think) the only reason the transmission might have any clutch in it.
 
jadnashuanh said:
HIll hold works to prevent you from rolling opposite the setting of the transmission, so it will stop you from rolling backwards when in drive, and forwards when in reverse...but, at least on mine, I've not heard any clutches engaging when it does that. I often use the electronic parking brake when stopped to keep me from rolling, and when that engages, you can hear the motor pulling the (what I think is a) brake cable. And, when it releases, you can both hear and feel something, but I don't find it annoyingly loud or obtrusive. Without hearing yours, can't say. I do not know if the cruise control will apply the brakes on a downhill section if regenerative braking is insufficient to keep your speed in check. I know on my other BMW, it will downshift, rather than brake, to try to accomplish the same thing, but on the i3, there is no lower gear, so they might. I highly doubt it would switch into neutral, and, switching gears is (I think) the only reason the transmission might have any clutch in it.
Click to expand...

...
Dear Jim,

Please do not focus on "clutch disc" or "clutch" and "disc" detail concerning the issue.
The matter is "our cars produce an undesirable noise while deep braking". This occurs especially on downhill positions where regen braking is insufficient to stop the car; maybe, a declination ratio which exceeds 10% is necessary to demonstrate/notice this bad behaviour of our cars.

I count on your curiosity; please consider testing your own car (on a near ramp) just after a period of 8-10 hours of parking interval.
Maybe you will hear the sound which resembles to our cars (Art's and mine) proven grunt. :?:
 
DocRush said:
jadnashuanh said:
HIll hold works to prevent you from rolling opposite the setting of the transmission, so it will stop you from rolling backwards when in drive, and forwards when in reverse...but, at least on mine, I've not heard any clutches engaging when it does that. I often use the electronic parking brake when stopped to keep me from rolling, and when that engages, you can hear the motor pulling the (what I think is a) brake cable. And, when it releases, you can both hear and feel something, but I don't find it annoyingly loud or obtrusive. Without hearing yours, can't say. I do not know if the cruise control will apply the brakes on a downhill section if regenerative braking is insufficient to keep your speed in check. I know on my other BMW, it will downshift, rather than brake, to try to accomplish the same thing, but on the i3, there is no lower gear, so they might. I highly doubt it would switch into neutral, and, switching gears is (I think) the only reason the transmission might have any clutch in it.
Click to expand...

...
Dear Jim,

Please do not focus on "clutch disc" or "clutch" and "disc" detail concerning the issue.
The matter is "our cars produce an undesirable noise while deep braking". This occurs especially on downhill positions where regen braking is insufficient to stop the car; maybe, a declination ratio which exceeds 10% is necessary to demonstrate/notice this bad behaviour of our cars.

I count on your curiosity; please consider testing your own car (on a near ramp) just after a period of 8-10 hours of parking interval.
Maybe you will hear the sound which resembles to our cars (Art's and mine) proven grunt. :?:
Click to expand...

Every morning as driving along our street I gently left food brake as I am accelerating.. This gets rid of rust daily and I have no noises from my disc brakes.
 
I have to add that our other car (see my below written signature) have never caused such a grunt (=noise) at the same road piece till now.

I want to kindly ask :
If a car may produce this grunt due to the said excuse why other car does not grunt after an interval of 3 or more days of parking duration?

I suppose there is a fault in terms of braking instruments' quality level pertaining our i3s.

If anyone of us who has strong contact with decision makers of BMW can hear me, he/she should remind them about this issue.


with my best wishes...
 
DocRush said:
I have to add that our other car (see my below written signature) have never caused such a grunt (=noise) at the same road piece till now.

I want to kindly ask :
If a car may produce this grunt due to the said excuse why other car does not grunt after an interval of 3 or more days of parking duration?

I suppose there is a fault in terms of braking instruments' quality level pertaining our i3s.
Click to expand...
My guess is that because the i3 driver typically uses brakes so much less than drivers of other cars due to the i3's very strong regenerative braking that uses the electric motor to brake rather than the friction brakes, rust that forms on the friction brake discs of all cars isn't cleaned off of the i3's brake discs as well compared with other cars. Another factor might be that the i3's brake pads might not rub the brake discs continuously in order to reduce rolling resistance; I believe that brake pads are always in contact with brake discs on most cars.

I don't believe that the i3's brakes are of lower quality than those on other cars but that the i3's brakes are used much less than those on other cars which results in brake discs with more rust that make more noise when used. I noticed the same brake noise on my previous EV due to its rusty brake discs, so I don't think that this occurs only on the i3.
 
FWIW, at least from looking at the parts diagram, on the i3, there is no additional mechanism to pull the pads back from the rotors. On a typical disk brake pad, it relies on the resilience of the rubber seal and imperfections in the rotor to push/pull the pad slightly away from the rotor. If it were more than a very small amount, you'd notice that in excess brake pedal throw before they activated.

I notice the same brake noises on my ICE, especially if it sat out in the rain for awhile. I do not know if BMW has the same brake drying functionality on the i3 as it does on some of the other models...if it did, that would lightly apply the brakes periodically when it sensed it was raining, but would do nothing for the other operational times, so it would not likely perform that function on a regular basis. I'm sure they could with some programming. Since it only does this for the first significant use of the brakes, I consider it normal....and, certainly not unique to BMW.
 
Hi,
After nearly 11 months of my initial post regarding this topic I may delightedly declare that we did not hear that noise for about 3 months. :D
IOW, it has persisted in the first 9 months of our i3 ownership and we finally got rid of those rust. :roll:

best regards from İstanbul
 
Good stuff. Maybe there was something such which worked its way loose.

It's not a problem I've ever had, and suspect rusty components is much more of a problem here than in Istanbul.

Glad you're enjoying it.
 
displaced1980 said:
It's not a problem I've ever had, and suspect rusty components is much more of a problem here than in Istanbul.
Click to expand...
Rusty brake discs is a significant problem here in salty, humid Honolulu, especially for those of us who rarely use friction brakes. When I depart from my parking space on the second level of our apartment parking garage, I descend a ramp with a stop sign at the bottom forcing me to brake to stop (the ramp is too steep for a regen-only stop). The grinding sound of the brake pads rubbing against the rusty discs echoes off the walls on either side of the ramp. Sounds pretty terrible, but I know the cause, so it's not a concern.
 
i got the same problem with the brakes, when deep braking the sound comes. i dont use the brake much but in my parking space i need a deep brake to stop downhill.. :( dunno what to do.. and on high winds the windows make sound, a fresh air comes in.. i know this is the first generation so there may be problems.. but bmw türkiye dont have an explanation for these small & mainstream problems...
 

Similar threads

I
Taking Control of your Range Extender - Mike Mas
Replies
15
Views
28K
bryanmsi
B

Latest posts

Back
Top