View Poll Results: What causes seem most likely?
Differential (humming sound)
0
0%
Multiple Choice Poll. Voters: 16. You may not vote on this poll
When it Rains, it Pours...
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 838
Likes: 17
From: Maple Valley WA
St. Jude Donor '10
When it Rains, it Pours...
Help/insight needed here, folks... I think my car might hate me. It’s a very well kept, low mileage (36k) 2003 Z06 that was babied by the previous and only other owner most of its life. I recently did some mods - Kooks LTs, Halltech CAI, dyno tune, and preventative PAC valve springs. It put down an impressive 399hp/391tq to the rears and runs like a beast.
Prior to doing these mods, I hadn’t really gotten into it due to valve spring failure fears. Therefore, I don’t know if my first issue was pre-existing or is happening because I’m now making more power but, problem number one...
1) The clutch is intermittently sticking to the floor when I upshift or downshift at high RPM only (above 6k). Doesn’t happen every time and it pumps back up pretty quickly after sticking. It’s only actually pinned itself to the floor once, making me pull it back up with my toe. After pulling it up, it went back to normal within seconds. Now, I know there are TONS of posts about this exact issue and it’s relatively common w C5s... But I can’t seem to pinpoint what’s most likely causing the issue in my scenario and would love your opinions/similar experience and outcome. The clutch does not slip at all and engages around the middle of the pedal travel. Seems perfectly healthy other than sticking. **Also, I’ve done the Ranger method four times with Prestone DOT 4 and the fluid has always been clean looking, even from the beginning.
Does this sound like:
-A master cylinder issue? Possibly fixed by going with a Tick...?
-A pedal return spring issue? Assuming not.
-A slave/pressure plate/clutch issue? Praying not because, well, $$$!
At the same time, I noticed another peculiar thing happening... Problem number two...
2) After putting new tires on the car (running 305/35r18 Nitto NT01s at all corners), I started hearing a bit of a humming sound seemingly coming from the rear of the car around 35-45mph. It seemed to get a bit louder and change tones when going through a right hand curve in the road at these speeds. However, I don’t really hear it at higher speeds, like 60+, nor do I hear it at all times at the specified speeds... Given this description, I’m wondering...
Does this sound like:
-Maybe some weird harmonic sound made by these R compound tires? Never heard it before putting them on.
-A failing wheel bearing? From what I’ve read, that sadly seems most likely.
-Something going on with my differential? It’s not the typical “howl” I know being a telltale indicator of diff issues. Again, really hoping this isn’t the case due to $$$!
Bummer when this kind of crap happens after you just dumped a bunch of money into a car. Had I noticed either of these issues prior to doing the mods (aside from valve springs) I likely would’ve held off and reallocated that money to getting the foundation of the car solid. In any case, I’d truly appreciate your thoughts on my situation(s).
Thanks, in advance all!
Prior to doing these mods, I hadn’t really gotten into it due to valve spring failure fears. Therefore, I don’t know if my first issue was pre-existing or is happening because I’m now making more power but, problem number one...
1) The clutch is intermittently sticking to the floor when I upshift or downshift at high RPM only (above 6k). Doesn’t happen every time and it pumps back up pretty quickly after sticking. It’s only actually pinned itself to the floor once, making me pull it back up with my toe. After pulling it up, it went back to normal within seconds. Now, I know there are TONS of posts about this exact issue and it’s relatively common w C5s... But I can’t seem to pinpoint what’s most likely causing the issue in my scenario and would love your opinions/similar experience and outcome. The clutch does not slip at all and engages around the middle of the pedal travel. Seems perfectly healthy other than sticking. **Also, I’ve done the Ranger method four times with Prestone DOT 4 and the fluid has always been clean looking, even from the beginning.
Does this sound like:
-A master cylinder issue? Possibly fixed by going with a Tick...?
-A pedal return spring issue? Assuming not.
-A slave/pressure plate/clutch issue? Praying not because, well, $$$!
At the same time, I noticed another peculiar thing happening... Problem number two...
2) After putting new tires on the car (running 305/35r18 Nitto NT01s at all corners), I started hearing a bit of a humming sound seemingly coming from the rear of the car around 35-45mph. It seemed to get a bit louder and change tones when going through a right hand curve in the road at these speeds. However, I don’t really hear it at higher speeds, like 60+, nor do I hear it at all times at the specified speeds... Given this description, I’m wondering...
Does this sound like:
-Maybe some weird harmonic sound made by these R compound tires? Never heard it before putting them on.
-A failing wheel bearing? From what I’ve read, that sadly seems most likely.
-Something going on with my differential? It’s not the typical “howl” I know being a telltale indicator of diff issues. Again, really hoping this isn’t the case due to $$$!
Bummer when this kind of crap happens after you just dumped a bunch of money into a car. Had I noticed either of these issues prior to doing the mods (aside from valve springs) I likely would’ve held off and reallocated that money to getting the foundation of the car solid. In any case, I’d truly appreciate your thoughts on my situation(s).
Thanks, in advance all!
Last edited by DannyG; Jan 6, 2019 at 04:36 PM.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 838
Likes: 17
From: Maple Valley WA
St. Jude Donor '10
Thanks for reminding me - Will go back and edit.
Instructor
Joined: Jan 2017
Posts: 169
Likes: 22
From: Shelton WA
yikes-sounds like ours last year....and it was (gulp) the slave. i did the ranger mthd several times as well (lots of varying advice about the "effectiveness" of it so don't want to open up that can of worms). The last time i was doing the ranger method the poor girl pee'd all over the shop floor. Praying for you that its definitely NOT the slave....us washingtonians have enough to cry over not being able to drive in the sun for the next 4 months without having to do a slave replacement!
jp
jp
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,069
Likes: 7,387
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
399 rwhp on a stock LS6 cam? That's freak right there! Awesome numbers for the mods.
Also tires can do weird things. My car I thought had a wheel bearing failing at a whopping 29k miles and I changed tires recently and have not heard the noise since.
I can't help with the clutch but I will say my modded 05 GTO always had wonky clutch problems. Hopefully you can get that sorted.
Also tires can do weird things. My car I thought had a wheel bearing failing at a whopping 29k miles and I changed tires recently and have not heard the noise since.
I can't help with the clutch but I will say my modded 05 GTO always had wonky clutch problems. Hopefully you can get that sorted.
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Moving this to C5 Tech.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 838
Likes: 17
From: Maple Valley WA
St. Jude Donor '10
Thanks for the responses, all - My thread subscription hasn't been working so I didn't know any of these were here. Apologies for the delayed response!
I'll check that out and see if removing the spring all together makes a difference. I had a Boss 302 that had this issue and it was a known problem with the return spring... Would be awesome if that was all it was!
To be fair, it was like 45 degrees when the car was dyno'd... But it was also tuned by Tom Wong, so he did his magic. Thing screams!
As for the tires, I think (hope) you may be right... I need to get it back out for a drive to double check but, if memory serves correct, I feel like the "hum" was a little different depending on the road surface. And that wouldn't change the tone of a humming bearing! These NT01s have massive tread blocks unlike any normal radial tires so I could see that being the cause. Ran the situation by Wong too and he said he'd be surprised if the car had a bad wheel bearing at this mileage, having only been tracked once before. Fingers crossed!
For the clutch, I'm going to try the spring removal, as mentioned above. If that doesn't work, next move will be a Tick MC, which I may do anyways. Will be very happy if either of those fix the problem.
I'll check that out and see if removing the spring all together makes a difference. I had a Boss 302 that had this issue and it was a known problem with the return spring... Would be awesome if that was all it was!
399 rwhp on a stock LS6 cam? That's freak right there! Awesome numbers for the mods.
Also tires can do weird things. My car I thought had a wheel bearing failing at a whopping 29k miles and I changed tires recently and have not heard the noise since.
I can't help with the clutch but I will say my modded 05 GTO always had wonky clutch problems. Hopefully you can get that sorted.
Also tires can do weird things. My car I thought had a wheel bearing failing at a whopping 29k miles and I changed tires recently and have not heard the noise since.
I can't help with the clutch but I will say my modded 05 GTO always had wonky clutch problems. Hopefully you can get that sorted.
As for the tires, I think (hope) you may be right... I need to get it back out for a drive to double check but, if memory serves correct, I feel like the "hum" was a little different depending on the road surface. And that wouldn't change the tone of a humming bearing! These NT01s have massive tread blocks unlike any normal radial tires so I could see that being the cause. Ran the situation by Wong too and he said he'd be surprised if the car had a bad wheel bearing at this mileage, having only been tracked once before. Fingers crossed!
For the clutch, I'm going to try the spring removal, as mentioned above. If that doesn't work, next move will be a Tick MC, which I may do anyways. Will be very happy if either of those fix the problem.
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No Hostility Be Happy
Joined: Aug 2018
Posts: 10,069
Likes: 7,387
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
Burning Brakes
Joined: Feb 2013
Posts: 904
Likes: 296
From: Sacramento, California
I believe Lingenfelter makes a helper return spring to help with the problem your describing which is as you know common when high rpm shifting. As far as your humming noise, my guess is the new r compound tires, especially when cold.
Steve
Steve
Instructor
Joined: Oct 2018
Posts: 113
Likes: 21
From: Phoenix, AZ
Scruf makes some really good technical vids, he was having a similar issue, the Lingenfelter spring did not help him.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 838
Likes: 17
From: Maple Valley WA
St. Jude Donor '10
Tom is the man! Won’t let anyone else touch my car.