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21K views 62 replies 42 participants last post by  garfin 
#1 ·
I’m Ed Piatek and I’m the Program Engineering Manager on the CTS-V. I recognize that this forum represents the thoughts and experiences of some very passionate owners and enthusiasts, and appropriately many of us on the engineering team periodically review this and other forums to keep our finger on the pulse of this important group.

While we cannot respond or comment on every post or question, the number of comments and degree of inaccurate information around supercharger shaft wear merits an engineering response to set the record straight, and assuage any concerns of our V series owners. Here is the response from our engine experts:

The torsional isolator is used in the CTSv LSA engine to isolate potential gear rattle noise during idle. The isolator contains a torsional spring that fits over the shaft. Purpose of the shaft is to distribute the stresses in the torsional spring. As the spring goes thru its travel, the inside of the coils can contact the shaft. The spring material is intentionally harder than the shaft which by design results in visual witness marks and/or limited wear on the shaft. The witness marks and/or limited wear is expected and has been observed on all the Eaton component durability tests, GM engine and vehicle durability tests and on customer vehicles with no impact on the functionality of the spring and isolator. The shaft and isolator are in a sealed cavity, separate from the rest of the supercharger and engine.


Q: Will this shaft wear harm my engine?
A: No. The visible wear will not damage the engine. The supercharger and the engine were tested and successfully validated to meet all GM durability requirements…which are much more severe than any customer usage.

Q: What causes this wear?
A: The isolator contains a torsional spring that fits over the shaft. The purpose of the shaft is to better distribute the stresses in the torsional spring and prolong its life. As the spring goes thru its travel, the inside of the coils can contact the shaft. The spring is a harder material than the shaft…so that when there is contact, the spring will not potentially break. If the spring breaks, then the torsional isolator function is lost.

Q: Can the shaft wear all the way thru and broken pieces get into my engine?
A: No. The travel on the spring that is contacting the shaft is limited. It cannot wear all the way thru the shaft. The shaft and isolator are in a sealed cavity, separate from the rest of the supercharger and engine. It cannot be ingested into the engine.

Q: Can worn bits or wear debris from the shaft get into my engine?
A: No. Again, the torsional isolator is in a SEALED cavity inside the supercharger. The seals on the bearings have not been compromised and wear debris is fully contained in this cavity.

Q: Why is the isolator design better than a solid coupling?
A: The torsional isolator does precisely that – it isolates an even more objectionable gear rattle noise that was being heard inside the vehicle cabin at all times during idle. The solid coupling will not eliminate this noise.

Q: My car is now quiet after I replaced the isolator w/ a solid coupling…how do you explain that?
A: If the ONLY modification was the replacement of the isolator w/ solid coupling…then it’s unlikely that it’s completely quiet. Most likely, you WILL have the timing gear rattle noise inside the cabin. Initially, it may sound better because the random “knocking” noise outside the vehicle is reduced…but you’ve now traded that noise for the gear rattle noise. Now…if you also replaced the induction system and exhaust system w/ louder aftermarket/performance parts…then it’s no longer an accurate comparison because you may not hear gear rattle over the increased exhaust and other noises in the cabin at idle. By the way, the torsional isolator is not a serviceable part…and removing the front inlet to replace with another part has warranty implications.

Q: Will GM be releasing a service fix for the shaft wear?
A: No. The current torsional isolator design does not diminish or compromise the durability or longevity of the supercharger or the engine. It has been fully validated to that effect. It also provides a benefit to the customer in terms of reduced noise at idle inside the vehicle…where the driver and passengers will be located during vehicle operation.
 
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#2 · (Edited)
Hi, Ed. Welcome to the forum, and thank you for your response on the torsional isolator issue.

I knew you guys checked out these fourms but this is the first time I've seen a post. I hope this is something that can continue in the future, as there are always other issues.

It's also invaluable to hear from the program engineering manager involved in the creation of our car(s). :thumbsup:
 
#4 ·
The part who captures my eyes the most is: ""By the way, the torsional isolator is not a serviceable part…and removing the front inlet to replace with another part has warranty implications.""
That shouldn't come as a very big suprise to anyone....

Thank you for posting Ed.:welcome:
 
#9 ·
Thanks for the response Ed. May I ask that GM educate the dealers as to what is going on also? I serviced my car last week and they were taken aback a bit by the isolator rattle....they thought it was engine knock, I had to inform them what the noise was.

Again, thanks. If I can push the envelope, any word from engineering on the wheel click issue?
 
#10 ·
Welcome to the forum / site, Ed, and many thanks for the invaluable information regarding the torsional isolator potential issues. I know that we will all sleep somewhat better knowing that we have GM engineering to aid us through our queries. Many thanks again to both you and MReiland for not only being members of the forum but addressing our potential issues and questions.
I hate to be rude, crude, and socially unacceptable but I would like to second the query regarding the wheel clicking issue / potential issue. And ideas, thoughts, suggestions, and / or comments regarding the wheel clicking would be greatly appreciated by all. Care to comment on whether or whether not the polished '09 CTS-V wheels are clear-coated for protection. I believe that most forum members, including myself, believe that they are, but there are some members that won't believe it until they hear it from a Cadillac or GM representative.
 
#11 ·
Thank you, Ed, for your response! HUGE thumbsup :thumbsup: :thumbsup: and a plus to me, being a new GM customer.

Frankly, the bigger problem is the wheel clicking. I would like to add to the chorus requesting information on this issue as while it's a minor one to me, it is pretty significant for others.

Other than that, can I say you guys have fashioned us a fabulous car? :thumbsup:
 
#17 ·
I must say that it seems like the "new" GM is way more customer oriented than the "old" GM. I have been a GM vehicle owner since 1994 and I have never seen GM to really care about customer vehicle issues at this level until now. With the "Tell Fritz" website, you are able to ask top GM brass officials questions and they actually respond, which blows me away. Now, I see this thread started by a GM Engineer to address an issue that really worried me.

All I can say is WOW! After seeing all this, I can actually say that I am even happier to be a GM supporter now. I feel that GM is on top of things now and I think the future looks bright for the General!

KEEP UP THE GREAT WORK GUYS!!!!

SG
 
#19 ·
Thank you Ed for posting. I do enjoy the fact that there are alot of GM engineers here and they are looking and answering some of our questions.

However. Nothing is getting solved. A loud noise that sounds like engine knock That CAN BE HEARD both inside and outside the car is not ok. I have recieved 100s of complaints on people hearing my car at idle even while sitting inside it saying something sounded broken.

By replacing that issolator with a solid piece does fix the engine knock sound. It makes it 100% quiet with no knocking anymore. As for inside noise, The teeth count on the rotor packs are smaller now with the tvs series so you dont have the gear mesh noise that you are talking about inside the car.. Im not sure where you are seeing that from???

Im close to you guys and would gladly show you a before and after in person of the difference in "Noises"

Even if i did get a little more gear whine inside at idle "Which i have yet to hear", that noise would be MUCH BETTER than a solid TAP TAP TAP TAP TAP TAP TAP..

The isolator design you have is only active during NON LOAD situations, which is idle and tip in from a decelleration. So it plays no other part in anything. WE ALL WOULD LIKE TO HAVE A QUIET IDLE..

So, i dont see what is the big deal of just putting in the solid ones, "That have been used in these eaton blowers in every other make" and making the idle conditions quiet for the consumer...
 
#21 ·
Jesse's knowledge and first hand experience with these cars is invaluable. Does anyone really think a GM engineer is going to come on the internet and in writing say something is wrong? I mean seriously...
Anyways, I'm not doubting what he says about pieces not destroying the motor as they are sealed off and that the shaft won't wear through, etc. I'm sure it won't. But doesn't mean they got it right.
I just hope they hurry up with the V coupe. Then I will start "tricking" that car out and make it super powerful like some of the guys have already done with the current model.

just my $.02
Mark
 
#22 ·
Jesse's knowledge and first hand experience with these cars is invaluable. Does anyone really think a GM engineer is going to come on the internet and in writing say something is wrong? I mean seriously...
Just a quick clarification that Ed isn't just some random GM engineer, (That would be me...) he listed his title in the opening of the thread post which is the Program Engineering Manager on the CTS-V program. While I have never doubted Jesse's knowledge or abilities, neither should be discount the knowledge and abilities of the actual people that designed and built your cars.
 
#23 ·
I don't mean to sound bad in this situation. We are all human and we all make mistakes. It is just easier to make mistakes when alot more than one single person is on a project. When that is the case, you have to trust that the others involved in thier specific duty are correct.

Ive seen first hand ALOT of issues with these cars. Especially on build quality.. Which is funny as ive seen some pretty dumb things. Like missing bolts, missing plastic fastners, missaligned parts, LOOSE bolts, plastic cover pieces left in under the blower cover, leaks in the trunk, Parts not pressed all the way on to the trim peices, VERY SHITTY paint jobs on some, As well as Dents in the panels and lines where it wasnt made correctly on the doors.......

Ohh yeah and differentials that are almost empty....

I could go on, but i think im making my point that just because gm made it dont mean it was perfect...
 
#28 ·
Ive seen first hand ALOT of issues with these cars.

diatribe clipped

I could go on, but i think im making my point that just because gm made it dont mean it was perfect...
Yes Jesse, you're making your point about build quality TO THE ENGINEER that designed the car. Not to the plant manager that should be sticking his foot up the asses of the guys building the car.

You're directing your ire at the wrong guy. Ed can't much change the way the plant is running. Do you think he wants to see his baby built with those quality issues? Of course not.

jas
 
#24 ·
that is very nice to know as well.

Welcome
 
#25 ·
lol, i for one have water leaking through my drivers side door. As after every rain I open the door and see that the dash portion facing the door is wet. Yet when I brought it to the dealer they said they hosed it for 30 minutes and it was fine. How do you argue with that ?
 
#31 · (Edited)
Yes I did, sorry if I came off wrong in my response, and I appreciate all of you guys at least giving Ed a fair shake here. It is my belief that engineering team posted a response here because they actually do care and it seems they feel like they did get it right. My understanding is that the isolator was put in for a specific reason that presented itself during testing. I have read at least one post of a member here who has switched to a solid isolator and reported that the noise was much louder than with the spring isolator. You guys here put alot of money into your cars and we all want them to run right. This is one of the reasons I have offered to help escalate any service issues that haven't been handled to your satisfaction.

Matt
 
#33 ·
The Program Manager for a high performance vehicle posting on an owner's forum doesn't happen every day, guys- this is a VERY cool thing that Mr. Piatek is doing.

I look forward to seeing more posts from you in the near future, Ed. (Can I call you Ed after just pseudo-meeting on the Internet? :D)
 
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