NemesisC5

I change all fluids before every track day so I will take the fluids out of the equation. While driving to an HPDE I started hearing a humming-whining noise that I thought was comming from my diff. On my 4th session I had the DIC message "Transmission 279*" appear on the last lap so I thought this issue may be related to the humming-whining noise that still persisted. The car cooled in the pits while the other groups ran and when my group came up I ran again being the last session of the day. I was having the fastest day of my life when 3/4 through the session I noticed the DIC displaying "Transmission Hot". I pulled into the pits and let the car cool. Talked to a few people and some said it was possible that a worn/mis-aligned diff may be causing my tranny to overheat since they are connected. Something I noticed while driving the car home was that turning right and loading the driver side the sound would greatly diminish, almost going away. Turning left it sounded a little louder than just driving in a straight line. I assumed the torsional stress on the diff may be the reason.

FAST FOWARD: I purchased a new diff from RPM Transmissions with a cooler pump and after install the sound is still there. I'm thinking it may be the wheel bearings. Is there any way to check them or is the "tell tale sign" the loading and unloading (turning right or left) of the wheel while driving indication enough? What else should I be looking for. I purchased the car from a gentleman that tracked it 5-7 days total and the car has 50k miles on it so I know it may be due for wheel bearing replacement.

I see that Pfadt and LG have some HD wheel bearings for almost $400 or I can purchase $130 replacements from GMPartsdirect.

First: Any suggestions on if this is a wheel bearing issue. How can I check?

Second: If this is a wheel bearing needing replacement should I purchase a GM part or HD aftermarket that may last alot longer?

Opinions will be appreciated

sothpaw2

Others can help more but what I know to check for is "tightness" of the wheel w/tire when you jack up the car and have said wheel in the air, suspension unloaded. You should be able to grab the tire/wheel firmly and pull/shake it and in doing so you should not notice any play or give in the connection. The tire/wheel should resist you always.

longdaddy

transmission overtemp message in not unusual in our cars during HPDE, it is unlikely that it caused damage, especially if you came off the track as soon as you saw it.

also, I doubt that the wheel bearings were cooked after "5-7" HPDEs - they may be a weaker link but from what I have heard you would have to do a good amount of really agressive driving with very sticky tires to start doing real damage there.

couple of theories you may want to look into:

diff fluid - was the slip additive used last time it was changed? if not, you might want to do a fluid change and add the slip additive.

power steering - it is not uncommon to overheat and damage the pump.
you can start by changing the fluid to synthetic and seeing if it quiets things down.
mine has been noisy for about a year, and changing the fluid quieted it down a bunch - I also have replacement pump sitting on the bench ready to go when this one gives out

J.R.

If it turns out to be the wheel bearings - which is not uncommon then definitely go with the HD SKF wheel bearings. They are worth the extra cost, especially for a car that is tracked with DOT tires (i.e. more grip equals more stress).

I get about 10-12 events out of the Autozone or Timken bearings. I just switched to the Pfadt SKF. My understanding are that these were raced in the European GT2 series and lasted the whole season.

The additional problem is if the front wheel bearings go bad at the track. Possible big time problems or major time to swap out bearings.

Note: You can use the rear bearings for both front and rear.

davidfarmer

just run the car on jack stands and see where the noise is coming from. It could be trans, torque tube, diff, or possibly wheel bearings or brake related.

If the noise is "speed" related, it is the diff or bearings, if it is "rpm" related, it is probably the trans/clutch/torque tube.

NemesisC5

I will go check this now, thanks

Diff fluid was changed by me after I purchased the car & after every event. Red Line 75-90 lightweight synthetic.

Power steering is quiet as I have had issues and would recognize the sound. I actually have some synthetic fluid on the bench to replace this week

And, 5-7 one day events I was told....could actually have been more

Thanks

Thanks for qualifying the longevity of the Autozone units. I assume they are fairly equal to GM units?

I definetely want the HD units but cash is tight now and Uncle Sam may be asking me for more soon

Thanks

The noise is definetely speed related and definetely not rpm related. I can coast from 80 mph on the highway or any speed and it gradually gets quieter, or accelerate at any pace and any gear and it is directly proportional to speed. Being that I have a new diff in it now from a reputable shop (RPM Transmissions), I believe the bearings sound like the likely problem.

Thanks David

RAFTRACER

I hate to spend money to fix something .......and it doesn't fix it. You more than likely have a wheel bearing that has deteriorated. The tell tale sign is the difference in noise when loading /unloading the suspension turning left/right. If turning left the noise goes away, it is probably the left front bearing. If you turn right the noise probably gets louder because it is loaded. I have had wheel bearing make noise and it is kinda vice-versa, depends if the inner or outer bearing in the hub is bad to which one will make noise turning left/right. If you jack the car up and there is any play at all that is is good sign that the bearing needs replaced. One that is making noise may/may not have any play. If this is the case, you can disassemble down to the hub assy and spin it buy hand vs. the other and you will probably find it.....

jcmbird

I would think a bearing would grind more than whine, could it be fuel pump? I get a whine also after hot laps, thinking its fuel pump.There is some indication that these cars have noisy fuel pumps.

NemesisC5

Disappointing that I did not diagnose the problem correctly, and I missed a track event on top of that.

It sounds like the noise is comming from the passenger side rear. I went for a drive and the sound gets noticeably louder turning hard to right beginning about 45 mph and at speeds below 20 mph I notice no difference in sound at all when making the same apex which is making me believe it is the passenger side rear. I do not have a partition in my C5Z and I can hear the sound resonate making it difficult to tell from which direction the noise comes from. I jacked up the rear and I have zero play on the two rear wheels. I did not think about the front because the sound is resonating so much in the rear compartment that I did not consider the front.

I went to Advance Auto Parts and the rear wheel bearing assemly with sensor and wheel studs are $181.99/ea.....the fronts I believe were $219.99/ea. It takes them 1 day to arrive.

JohnD60

My rear wheel bearing failure felt like I had a tire extremely out of balance but only when I turned right. However, there appears to be several failure modes that manifest themselves in different ways.

NemesisC5

The sound is worse when hot but is absolutely there when at ambient temp, in the case todat 45*. Rethinking my choice of words it seems like the sound more of a wherring noise (if that's a word), although now it seems to have the beginnings of a grinding noise.

doje

I am curious to see what the problem is and wil be watching this thread

Kanmer

Put the car on jack stands. Remove all wheels. Make sure the car is in neutral. Remove brake calipers and rotors. Now spin each hub paying particular attention to feel and sound. Each hub should spin smoothly and quietly. Any grinding there and you have an issue that needs to be addressed. The condition you are describing by loading and unloading is indicative of a wheel bearing. That would be my first guess by the symptoms you describe. Not a ***** on accurate diagnosis, but a starting point.

HTH
Bob

NemesisC5

Tomorrow I will get it on the jackstands and run it hoping to isolate the corner where the sound is comming from. Then go from there to check for irregularities with the wheels and brakes off.


Are all the SKF bearing assemblies heavy duty compared to the Autozone Timkens? I can get a deal on the SKF units NIB from another member that is selling for $400/pr plus $15 shipping

J.R.

My understanding is that SKF makes two sets of bearings one being the HD with recessed wheel studs and the other being regular with non recessed wheels studs. I believe Pfadt's website has a photo of the HD hubs. NAPA etc sells the regular SKF which is priced higher than the Timken bearings. I do not know whether they are better or not but definitely more money.

NemesisC5

Thanks J.R.

R Mackow

Are you running the same tires on the track and street. i've had tires that hummed when I turned the wheel slightly to the right. No noise straight ahead or left.

NemesisC5

No, I have R888's for track and T1R's for street. The noise is equally noticeable with either set. I planned on getting it on the jackstands tonight but opted for some scanning with my new HP Tuners software.....very cool stuff