Grinding Noises After Replacing Clutch

[kaleb412]

2025 Honda Civic Si
We recently replaced my clutch ourselves. We did everything right. The car shifts fine, starts fine, idles fine. We made sure the clutch disc was lined up correctly.
There is no other variable that contributes to this noise that I now hear other than speed. Over 30mph the car makes very loud braking noises. Please see the attached videos
Check Brake system light is on
Brake light flashes while driving
The car runs fine shifts fine, idles fine everything, steers fine. The only problem is the 2 engine codes for neutral position sensors a & b & the grinding noise over 30mph. The more the speed increases the more the noise increases. Clutch activity/brake activity does NOT change the sound at all.

I can not find any unplugged sensors in the enginebay. We had to remove the subframe, axels, intake, battery,

Engine codes after job:
P08af
P086c



I would appreciate any/all info regarding this!
Trying to save myself spending hundreds at dealership

Thank you for your time!

 

[jtlctr]

For the noise: I would inspect all the rotating parts from the axles to the brakes, could even be as simple as a bent backing plate. Make sure the axle nuts are tightened properly. Does the noise change if steering hard left or right?

For the “check brakes” light: Possibly one of the ABS sensors got whacked? Though I would think that would trigger an ABS light. Is your brake reservoir full? Not sure if the clutch shares the same fluid reservoir.

For the codes: maybe the neutral switch has a bent pin, or the connector isn’t fully seated?

 

[kaleb412]

I appreciate your response.
Steering does not seem to have affect on the noise at all. It’s just when the car gets above 35mph+ even while coasting

 

[tacthecat]

As the clutch and brake share the same reservoir there is likely a special procedure to bleed them when changing components. This could be a simple as air in the lines. Why was clutch replaced?

 

[kaleb412]

Car started slipping after being tuned for 2 days lol. I will for sure try bleeding the brakes. Would air in the brake lines cause a engine code tho?

 

[jtlctr]

Car started slipping after being tuned for 2 days lol. I will for sure try bleeding the brakes. Would air in the brake lines cause a engine code tho?

As long as the reservoir wasn’t completely emptied when you bled the clutch (if you even had to), I doubt you have air in the lines. You would most likely feel a spongy brake pedal if there was. If you did bleed the clutch, make sure the reservoir is topped up, if not, there’s a fluid level sensor that would cause a brake warning light.
In any case, this wouldn’t cause your neutral sensor codes.

 

[kaleb412]

Appreciate your response again. Please provide me with any and all advice I’m about to work on the car right now

 

[kaleb412]

Look at left side of subframe

 

[kaleb412]

And the right

 

[jtlctr]

Wow! What happened there?

 

[kaleb412]

Hey man I found a sensor on the back of the tranny unplugged which fixed every engine code.

What do you think could be rubbing with my suspension?

 

[jtlctr]

Man, it’s hard to say without experiencing it in person. Listening to the videos, the frequency of the noise increases so rapidly when you're accelerating that it sound more related to engine speed than wheel speed. I also don't know why it would start and stop at 30 mph if it was wheel speed related. I'd be curious to know the noise changes at that speed, but in different gears.

Did the brake system warning light also go away after reconnecting that plug on the transmission?

 

[kaleb412]

Yes the brake system went away too.
I need to make sure I know it’s wheel speed related rather than engine speed. Rpm does not change the sound at all.
It is only speed
I have tested on a hill

 

[jtlctr]

You could jack up the front and have someone run it with the wheels off the ground while you go underneath and try to pinpoint the source. Obviously this is potentially very dangerous, so be super careful about securing the car. Also, this will probably freak out the stability control system, so research what to do about that. Maybe just turning off the VSA is enough. Whatever the procedure is to run on a dyno should be the same.

 

[AZCWTypeR]

My FR-S threw wheel sensor codes when I had it running in gear on jack stands to troubleshoot a bad wheel bearing. Code was easy enough to clear.

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