: Engineering Response -Wheel Clicking and Diff Cooling



Ed Piatek
12-18-09, 11:35 AM
After my initial post on the subject of the supercharger torsional isolator wear concern, I received several requests for further information on wheel clicking and diff cooling. Here is our engineering response to each of these questions:

Wheel Clicking

We acknowledge and regret that some CTS-V customers experience this "clicking sound" from their wheels in low speed, tight turn parking lot maneuvers. We've studied this phenomenon fairly extensively; it is the result of interface of the aluminum wheel to aluminum rotor hat configuration. We have released a technical service bulletin that prescribes a very high degree of cleanliness in the wheel-to-rotor mounting, and our experience to date is that the TSB, if followed exactly, is very effective in eliminating the noise.

Some customers had been concerned about this being a noise from brake system interference to the wheel under high steer angles. It is not. The noise emanates from the mounting surface of the wheel on the hat of the rotor at high steer angles. If you have this noise, the cleaning process and re-torquing is fully covered by your warranty at our dealership. If you choose to dismount wheels on your own, please follow the service bulletin pasted below and carefully follow the instructions on cleaning and torquing wheels.

GM has tested the integrity of wheel attachment on the CTS-V. The "clicking noise" is not indicative of any concerns or compromised performance in wheel attachment integrity, or in the wheel itself.

Differential Cooling System

Regarding the rear differential hot message, the CTS-V has a high torque capacity cast iron diff, and a physical property of cast iron is that it does not dissipate heat as effectively as aluminum. Coupled with the high out of the LSA engine, the differential fluid can reach operating temperatures during race track type useage that begins to break down the lubrication properties of the fluid, reducing the fluid’s effective service life.

As we have done on the previous generation CTS-V and the STS-V, we intended to offer an differential fluid cooling system through our Service Parts Organization for owners who exercise their car in track type use to prevent the need for frequent fluid changes – unfortunately a component availability issue prevented us from initially stocking the intended quantities of the system, but that issue has been resolved and we expect the system to be available in sufficient quantity very shortly. As commented elsewhere on this forum, the cooler is installed as original equipment for countries with significantly higher ambient temperatures or have typical vehicle usage speeds that are much higher than in North America. The info recently posted by MReiland on the part number and system description is accurate.

I look forward to your comments and questions going forward, and thank you for your continued interest and support.

Ed Piatek
CTS-V Program Engineering Manager


Subject: Clicking Noise From Front Wheels
Models: 2009 Cadillac CTS-V
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A clicking noise emanating from the front wheels. This condition is noticed at low speed (walking speed) during full wheel lock turns on dry clean pavement (Full lock parking lot maneuver). The clicking noise is generally noted as approximately 1 to 4 "clicks" per wheel revolution. The cause may be an interaction between wheel mounting face and wheel mounting surface on rotor.
Recommendation/Instructions:
Complete the procedure below on both front wheels.
Note: It is not necessary to clean the rear wheels for the "clicking" condition.
1. Remove the front wheels.
Important: Be careful not to use the Brake Cleaner on the painted or clear coated surfaces of the wheel.
2. Clean the wheels as follows.
• 2.1 Use a clean cloth dampened with GM Brake Parts Cleaner 12378556 or equivalent.


• 2.1 Wipe the mounting surface of the wheel to remove any residual grey or black material that
has accumulated on the wheel mounting surface.


3. Clean the rotor top hat as follows.
• 3.1 Use a clean cloth dampened with GM Brake Parts Cleaner 12378556 or equivalent.


• 3.2 Clean the wheel mounting surface of the rotor (rotor top hat) to remove any residual grey or
black material that has accumulated on the rotor. During cleaning process be sure to clean the
rotor near the wheel pilot at the center of the rotor.


4. Reinstall the wheels.
• 4.1 Be sure to thoroughly dry the wheel and rotor prior to installation on vehicle.


• 4.2 Tighten wheel nuts to 215 N•m (158 lbs ft).


Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

neuronbob
12-18-09, 11:38 AM
THANK YOU AGAIN, ED! Very useful information about the wheel clicking (gone since I changed wheels for winter, thankfully). The track hounds will also be extremely happy to hear that a diff cooler is still planned.

:woot:

Mods, can we sticky this?

Krug Ford
12-18-09, 11:41 AM
Great. Thanks for explaining.

Looks like a easy fix

Razorecko
12-18-09, 12:12 PM
Thanks Ed ! quick question though, do you believe that if an owner lightly scrubbed down the hat of the wheel with some high grit sand paper would it effectively get rid of the noise as it would change the level of friction and possibly create a little "slip" ? Just in case owners didnt want to clean wheels on a consistent basis and were looking for a more long term solution.

CTSVeee
12-18-09, 12:31 PM
:thumbsup:Wow! This is what I call service! Thank you for posting!!! :thumbsup:

Florian
12-18-09, 12:46 PM
Ed,

Thank you for your informative, "from the horses mouth" answers. There is tons of misinformation and speculation on the Web, and your presence here with the facts is wonderful. Thank you for perusing Cadillac Owners and our forums and being available to our members...GM is certainly stepping up to the plate.

Best,
F

dvandentop
12-18-09, 01:13 PM
Awesome job again Ed thanks for the thorough explanation of this and it will come in handy for owners to know the procedure.

Z06ified
12-18-09, 03:16 PM
Thanks for the info Ed. Quick question: if the issue with the differential under track use is diff oil temps getting too high and losing its lubrication qualities, what about using a full synthetic differential oil that has higher temperature tolerance, such as Mobil 1 gear oil? http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_Synthetic_Gear_Lubricant_LS_75W-90.asp

I'm not promoting Mobil 1 - just citing an example of a synthetic gear oil available that may provide ample protection from high diff temps.

I assume the factory fill is non-synthetic diff oil?

ewill3rd
12-18-09, 03:53 PM
The factory fill is a 75W-90 Synthetic gear oil.
We have been using synthetic lube starting in 1999 with the Silverado and almost everything else has followed suit.

Z06ified
12-18-09, 04:49 PM
Oh well, so much for that idea then. But I find it amazing that the diff gets so hot as to cook a fully synthetic oil. I don't know about the gear oil, but I know Mobil 1 motor oil is good for 600F.

dpchamp87
12-18-09, 05:42 PM
Ed, many thanks for the insight into this issue. My 2010 has not clicked yet but at least now I know what to do when (if) it does

GM-4-LIFE
12-18-09, 06:59 PM
Ed,

Thank you for offering the information on the wheel clicking issue. I think I am the only one here on the forum that has had the problem repeatedly return. My local dealer with the assistance of the local GM field rep and GM engineers were on site and they all inspected my car and made sure the tech performed the recall correctly and the problem still persists. My car has had the TSB done at least 5 times with no success. They even replaced my wheels, front rotors and front lugnuts.

Because of this, GM is buying my 2009 CTS-V back.

Am I the only one that has had the problem come back with no relief in the country? It seems so!

SG

thebigjimsho
12-18-09, 08:39 PM
Thank you very much, Ed! By the way, were you at the Cadillac Driving Labs at Monticello last year??

GMX322V S/C
12-18-09, 09:00 PM
Am I the only one that has had the problem come back with no relief in the country? It seems so!I've had it done 3 times and its returned all 3 times. The first time was right after Short-Throw posted the pre-released TSB about a year ago.

RapidRob
12-18-09, 11:01 PM
Thanks very much Ed! Good info., and I will have my own wheel clicking issue looked into during the next dealer visit.

Rob

chopmeat
12-18-09, 11:54 PM
When I hear 158 lb ft of torque, I wonder if the wheels will be stressed and possibly eventually crack?

Tony407
12-19-09, 01:31 AM
Ed,

I can't give you and GM enough Kudos for your posts. Unheard of!! THANKS!!

Tony

cbloveday
12-19-09, 11:11 AM
When I hear 158 lb ft of torque, I wonder if the wheels will be stressed and possibly eventually crack?

I have a question. Why does the manual state on page 5-134 that the
specification for wheel nut torques is 140 lb ft/190 N-m?I have seen this 158 ft lb in previous posts. So now I am unsure which is the proper torque.

Could it be if you are having clicking issues then 158 ft lbs, else 140 ft lbs?

6104696
12-19-09, 12:34 PM
ed,

thank you for your informative, "from the horses mouth" answers. There is tons of misinformation and speculation on the web, and your presence here with the facts is wonderful. Thank you for perusing cadillac owners and our forums and being available to our members...gm is certainly stepping up to the plate.

Best,
f


+1000

Nutz
12-19-09, 01:19 PM
This thread, :golf clap:

Many are listening (451 views in the last 24 hrs.). Well done Ed.

liqidvenom
12-19-09, 04:43 PM
its always good to hear that the maker of the vehicle is willing to offer a solution to questions people might be asking.

jvp
12-19-09, 08:01 PM
I have a question. Why does the manual state on page 5-134 that the
specification for wheel nut torques is 140 lb ft/190 N-m?I have seen this 158 ft lb in previous posts. So now I am unsure which is the proper torque

The manual and the shop manual are both wrong and out of date. Per the TSB: 158ft-lbs.

jas

Short-Throw
12-19-09, 09:12 PM
The manual and the shop manual are both wrong and out of date. Per the TSB: 158ft-lbs.

jas

Thanks Jason,

I'm hoarse from trying to set the record straight for way too long.

Mike

cbloveday
12-19-09, 10:26 PM
The manual and the shop manual are both wrong and out of date. Per the TSB: 158ft-lbs.

jas


Thanks Jason,

I'm hoarse from trying to set the record straight for way too long.

Mike

Thanks guys, I just bought a Husky Micro-adjusting torque wench that goes from 20 to 250 ft-lbs. I also bought this protective socket set from Griots for $69.99

Since most wheels are painted these days, it's easy to damage their finish when removing lug nuts. These 1/2" drive metal sockets are surrounded with a soft protective plastic that won't allow the metal of the socket to come into contact with the wheel. There is even a plastic insert so it won't hurt the top of the lug nut. Color coded and large size markings make grabbing the correct socket easy. The set contains eight sockets. Four Metric Sockets in 17mm, 19mm, 21mm, and 22mm, and four Inch Sockets in 13/16", 7/8", 1" and one 1 1/16". You'll have a socket for any application. Now for the good stuff: the 6" Extension bar has a free-wheeling, spinning sleeve which allows you to steady the socket instead of having it rotate in your hand. P.S. Anyone working in a tire shop should have a set of these. (And if you take your wheels in, take this set with you. You'll thank me later...)

http://i183.photobucket.com/albums/x99/cbloveday_bucket/sockets.jpg

There were instructions with the wrench that discussed whether these sockets would require recalculation of correct torque. It indicated that regular (concentric socket extensions which extend directly under the drive head along the axis of the drive do not affect the calibration of the torque wrench.

4gear70
12-19-09, 11:24 PM
Thanks Jason,

I'm hoarse from trying to set the record straight for way too long.

Mike

LOL
I have not had the wheel clicking issue but even so I did re-torque my wheels from the factory setting of 140 ft-lbs to the new 158 ft-lbs spec when you first posted the pre-TSB way back in March. Still no clicking yet.

http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2009/165703-service-procedure-wheel-clicking-official-tsb.html

TSB's are written for a reason. I'm sure your posts are read and respected by more than just me.

Innisfree
12-31-09, 05:48 PM
Hi to everyone in the Forum. I'm a new member, with a new 2009 CTS V since September. I've 3500 miles on the car - it's a beauty, great to drive! Yesterday I read this Engineering Response. Imagine my surprise when I go out to the car, back it out and hear the clicking noise for the first time! Today it's still there. Forward, reverse, not even at full lock. Worrying!

Any ideas why it should suddenly start? Could it be the very cold damp weather here in SC?

Apart from the Dealer fix is there anything I can do myself? (My Dealer is 1 hour away.) Anything I can squirt on the wheel assembly? And, most of all, do you really believe this is safe as is now?

Thanks for any advice/opinions.

Nutz
12-31-09, 05:53 PM
whoa... Welcome to the forum.:thumbsup:

Low_ET
12-31-09, 06:12 PM
Hi to everyone in the Forum. I'm a new member, with a new 2009 CTS V since September. I've 3500 miles on the car - it's a beauty, great to drive! Yesterday I read this Engineering Response. Imagine my surprise when I go out to the car, back it out and hear the clicking noise for the first time! Today it's still there. Forward, reverse, not even at full lock. Worrying!

Any ideas why it should suddenly start? Could it be the very cold damp weather here in SC?

Apart from the Dealer fix is there anything I can do myself? (My Dealer is 1 hour away.) Anything I can squirt on the wheel assembly? And, most of all, do you really believe this is safe as is now?

Thanks for any advice/opinions.

I had the wheel clicking noise really bad. I did the TSB myself. I pulled off the front wheels and cleaned the back side of the wheel and the front side of the hub with "Brake Part Cleaner". Then I re-installed the wheels and torqued them to 158 ft-lbs. My wheel clicking has been gone for months.

Good luck.

Gary Wells
12-31-09, 06:36 PM
N514864:
welcome to the forum. Hope that all gets well on the wheel clicking issue.

Gary Wells
12-31-09, 06:38 PM
I had the wheel clicking noise really bad. I did the TSB myself. I pulled off the front wheels and cleaned the back side of the wheel and the front side of the hub with "Brake Part Cleaner". Then I re-installed the wheels and torqued them to 158 ft-lbs. My wheel clicking has been gone for months.

Good luck.

Time is not a good common denominator on this issue, miles are. How many miles since you have done the TSB?

Low_ET
12-31-09, 08:00 PM
Time is not a good common denominator on this issue, miles are. How many miles since you have done the TSB?

3,000 to 4,000 miles since I cleaned and re-torqued the wheels. Still nice and quiet.

Innisfree
12-31-09, 09:33 PM
Hi everyone!

I'm a new member today- and got my new CTS V 2009 in September. What a car - a great drive.

Ref this wheel clicking - I read Ed's post yesterday and, surprise, I heard the wheel clicking noise for the first time when I backed out, though not on full lock. Today, I got it again. Why should this start all of sudden? Could it be the cold damp weather here in SC? Is it safe to drive? Is there any easy fix - like something you spray on?

Happy New Year everyone!

RBM

Hondarrr
12-31-09, 10:28 PM
I took mine to my local dealer and they replaced one front hub and clicking it's gone......

Gary Wells
01-01-10, 09:52 AM
Hi everyone!
I'm a new member today- and got my new CTS V 2009 in September. What a car - a great drive.
Ref this wheel clicking - I read Ed's post yesterday and, surprise, I heard the wheel clicking noise for the first time when I backed out, though not on full lock. Today, I got it again. Why should this start all of sudden? Could it be the cold damp weather here in SC? Is it safe to drive? Is there any easy fix - like something you spray on?
Happy New Year everyone!
RBM

N514864:
Not necessarily enjoyable reading, but it will give you some good insight into the wheel clicking issue. If you do a search under the therm "clicking" there is quite a list of threads with other info on this problem.

http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2009/178922-v2-wheel-clicking.html

Gary Wells
01-01-10, 09:55 AM
I took mine to my local dealer and they replaced one front hub and clicking it's gone......
You are very fortunate to have a good dealer. Most dealers do the TSB and then send you on your merry way. Less than a handful have been reported on the forum as having replaced any of the hubs. Maybe with a little luck, yours will not return.

Gary Wells
01-01-10, 10:00 AM
3,000 to 4,000 miles since I cleaned and re-torqued the wheels. Still nice and quiet.
Thanks for the info. You might be one of the fortunate few that the issue went away forever, as far as known, as there are less than a handful that have had total success with the TSB.

Innisfree
01-03-10, 03:05 PM
Thanks for the input. Another surprise - on Friday I cleaned the wheels and really hosed down the brake assemblies. Saturday morning, I backed the car out - and no noise! It's still OK today. Note that I didn't take the wheels off to clean them, just hosed them down in place. And it's still freezing cold in SC.

Can anyone make sense of that? Of course the noise could come back again.

I'll keep you posted.

Gary Wells
01-03-10, 05:07 PM
Probably. Someone under the user name "Prof" that generally posts on here advises that he pulls his wheels off every week and cleans them and then installs them back on the car has never had any clicking problems and he is up to about 13K miles or so, I believe. Probably some type of tie-in there regarding cleanliness and / or removal of anything between the mating surface of the wheel and the hub.

Mike 09 V
01-03-10, 08:12 PM
Never had the wheels off, never had a click. 7300 miles so far, took delivery in June and build date was 4/09. Real dry out here in AZ and not too cold.

thebigjimsho
01-04-10, 12:49 AM
Can someone confirm this for me. My wheels click when making a turn. I will bring it to the dealer for the first time and have them try the fix. However when I backup I noticed more when the ground is damp the back wheels jerk and it feels like a ran over a person. (not that I know what that feels like) my passengers often look back and ask what was that.

Is this a seperate issue then the wheel click or the same??
Totally separate...

GMX322V S/C
01-04-10, 04:12 AM
... However when I backup I noticed more when the ground is damp the back wheels jerk and it feels like a ran over a person. (not that I know what that feels like) my passengers often look back and ask what was that...It might be the differential contributing. I used to get a kind of faint groan/slight "crabbing" during my first turn (forward direction, left or right turn) after a cold start during cooler conditions (under 60 degrees). I had the diff fluid level checked and it was reported fine; it went away after I had the fluid changed.

Palagius
01-06-10, 01:15 AM
Thanks for the info. You might be one of the fortunate few that the issue went away forever, as far as known, as there are less than a handful that have had total success with the TSB.

I haven't posted in some time, but I had a recurrence of the clicking after Moore Cadillac in Chantilly, VA applied the TSB at 2900 miles on the ODO. I failed to follow up here, but I took the car back in at around 4k miles (I don't have the paperwork handy) for the wheel clicking again. My service adviser indicated that the technician very carefully applied the entirety of the TSB. He also offered up his opinion that the previous time they only re-torqued the wheels and didn't actually clean them--at least not adequately.

In my case with the TSB completely and correctly applied I have now gone another few thousand miles without any more clicking--and it returned after only a few hundred miles after the first (mis-?) application of the TSB.

My suspicion is that the cleaning of the mating surfaces on the hub and wheel is not viewed with adequate gravity by some of the shop technicians and that is the source of at least some of the recurrences owners have experienced. I realize that I have only my case as a single sample but I could certainly see it as representative.

I will also say that Moore Cadillac was extremely responsive to my concerns on both visits and I felt well-cared-for through the process.

Thus far at least I've had a happy ending to the wheel clicking. Now I just need to decide on a solution to my complete absence of cold-weather traction. :-)

JFJr
01-06-10, 01:09 PM
Did the TSB for wheel clicking at 6,800 miles and it hasn't returned (currently 18,200 miles).

GM-4-LIFE
01-06-10, 05:59 PM
Did the TSB for wheel clicking at 6,800 miles and it hasn't returned (currently 18,200 miles).

I have had the TSB done every 2K miles and I currently have 10K miles on the car and the clicking keeps coming back. It only goes away for a few hundred miles.

SG

tedcmiller
01-07-10, 01:45 PM
The "crabbing" or "jerking" (one poster described it like running over golf balls) of the wheels when making tight turns during cold weather is a fairly common compliant associated with the 2009 and later CTS-Vs (I never detected this with my 2004 or 2005 CTS-V). It has nothing to do with the "clicking" issue and, like the "clicking" issue does not represent a problem.

Regarding the clicking issue, many people have had parts replaced with the same part and reported that the clicking as disappeared. It is my position that replacing non-defective parts (hubs. etc.) is a waste of time and money, and the real reason the clicking went away is because the wheels were removed and reinstalled when the parts were replaced. Torqueing the lug nuts to the higher value now specified (158 rather than 140 lb-ft) also contributes to longer driving intervals with no wheel clicking. Engineers from GM have commented on this problem and think that it is caused by slight slipping between the wheel-hub interface. Cleaning this interface combined with the higher lug nut torque will eliminate the clicking for a mileage interval that varies from car to car. As stated before, in any case, the clicking is an annoyance, not a problem.

Patriot
07-02-10, 10:32 AM
I am presently considering the 2011 CTS-V and i am wondering what GM has done to address these issues. I wish to thank all of the feedback good and bad that members have posted it is really very helpful.

Z06ified
07-02-10, 10:54 AM
I am presently considering the 2011 CTS-V and i am wondering what GM has done to address these issues. I wish to thank all of the feedback good and bad that members have posted it is really very helpful.

Wheel clicking has just recently been fixed with a new wheel design:

http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2009/202022-front-tires-clicking-again-new-solution-6.html

Differential cooler may not be needed. More and more people are taking their V's to the track and not having any problems with the diff overheating. It seems key is making sure the diff fluid level is full.

ruben
07-02-10, 03:27 PM
GM is making sure we are happy with our cars don't be afraid.