: Engineering Response - S/C Shaft Wear



Ed Piatek
11-23-09, 01:39 PM
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.

Vrocks
11-23-09, 01:56 PM
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:

CoOlSlY
11-23-09, 02:05 PM
Very interesting, thank's for having shared this info!

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.""

MReiland
11-23-09, 02:16 PM
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:

Titaniumseeker
11-23-09, 02:26 PM
Wow! Finally, undisputed facts to clear up what was percieved to be a potential problem. Thank you Ed!:thumbsup::thumbsup:

Ziggerman
11-23-09, 02:35 PM
Very much appreciate you taking the time to check the forum and post to help/inform your customer base, Ed :2thumbs:

Florian
11-23-09, 02:48 PM
Ed,

As moderator of this forum segment, I welcome you to our site. I appreciate your candor and your proactive approach to one of the issues that has been discussed here. Please let me know if I can be of any help to you in the future.

Best,
F

thebigjimsho
11-23-09, 03:23 PM
Welcome, Ed! Good to see GM provide a direct channel to the consumer...

Kadonny
11-23-09, 03:33 PM
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?

Gary Wells
11-23-09, 04:32 PM
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.

neuronbob
11-23-09, 04:43 PM
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:

Razorecko
11-23-09, 05:53 PM
Thanks Ed ! I was wondering how this would affect the long-term reliability of the supercharger.

readyact
11-23-09, 06:26 PM
Ed, thanks for the information.

Nutz
11-23-09, 06:45 PM
Very cool information Ed. We REALLY appreciate direct communication here. :thumbsup:

We'd love to hear your take on the wheels clicking someday.




Suggest a sticky for a while on this one.

GM-4-LIFE
11-23-09, 07:23 PM
Welcome to the forum Ed and thanks for the info. I feel much better about this issue now. Now if GM Engineering can just get the wheel clicking issue solved, I would be 100% at ease.

SG

thunder gray
11-23-09, 07:35 PM
Hey Ed welcome and thank you for the information. I would also second the request for information on the wheel clicking problem. Mine goes into the dealership tomorrow (11/24) for the 2nd time on this issue.

GM-4-LIFE
11-23-09, 07:58 PM
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

chopmeat
11-23-09, 10:38 PM
Thank You Ed!
I'd just like to say you guys designed a great car, I absolutely love this V!
Thanks for the info.

wait4me
11-24-09, 09:30 AM
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...

Razorecko
11-24-09, 10:03 AM
^ I was waiting for you to chime in on this Jesse

musclesbmf
11-24-09, 10:58 AM
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

MReiland
11-24-09, 11:21 AM
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.

wait4me
11-24-09, 12:09 PM
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...

Krug Ford
11-24-09, 12:39 PM
that is very nice to know as well.

Welcome

Razorecko
11-24-09, 01:56 PM
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 ?

Gary Wells
11-24-09, 02:05 PM
Sorry, Razor, I can't help but ask, dude, are you sure that it was the car that got hosed?
J/K, but I know how you feel.

jvp
11-24-09, 02:43 PM
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.

Further, you can bet Ed's post was vetted by a bunch of other engineers (and lawyers, probably.. ;-)) at GM before it was posted. He basically just became a public spokesman for GM, which is a dangerous spot to be in. Even if he's among friends here.

I'd be surprised if we hear much more from him. Don't count on it... I'd be happy to be wrong.

jas

jvp
11-24-09, 02:47 PM
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

MReiland
11-24-09, 03:27 PM
I'd be surprised if we hear much more from him. Don't count on it... I'd be happy to be wrong.

jas

I have a feeling you might be happy...... :thumbsup:

musclesbmf
11-24-09, 03:36 PM
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.

Did you read the rest of my post? :confused:

MReiland
11-24-09, 03:46 PM
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

Vrocks
11-24-09, 04:24 PM
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
Thanks Matt.

You're correct about a member complaining about increased noise after going with a solid isolator - I believe it was an LPE snout mod package.

Cadillac Tony
11-24-09, 04:47 PM
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)

tbss08
11-24-09, 07:24 PM
I appreciate the Program Manager for our cars posting on here. After all the headaches and heart aches I went through with two bad Corvette Z06's and having one of them bought back on a Lemon Law because no one would take the time and try to fix it I really am very appreciative of Ed's concern.
As for Jesse's comments about the build quality and such, it falls on the lack of pride at the plant. You can engineer the worlds best car, build it in a state of the art plant, use the best materials possible but all it takes is one person to not give a crap and the build quality goes down the drain.

Thank you Ed for posting the information and I look forward to more words of wisdom. Keep engineering and making these awesome machines.

dvandentop
11-24-09, 08:02 PM
very awesome i have been on the vette forum for a long time and dont think i have ever seen gm brass post on there before.

welcome Ed

4gear70
11-24-09, 08:24 PM
Good to hear from the Program Engineering Manager on this forum.
Welcome Ed!

backup
11-24-09, 08:46 PM
Sincere THANK YOU to Mr Piatek for posting information here for this group. I am completely impressed that the Program Manager and GM are involved that way and care enough to give us some information. It greatly strengthens my confidence in GM, and pride in CTS-V. I hope this is part of the New GM and continues!

Uriel
11-24-09, 08:49 PM
Purchased my car in March of this year. Odo sez 22,815 smiles (happy miles). No mechanical problems nor any deficiencies observed in build quality. Yeah, had the supercharger rattle early on but much quieter now. I accept what Ed has to say about how the supercharger was designed. After all he is the expert and, in my opinion, has credibility and/or credentials beyond anyone else on this forum. Now others have contributed as much as their expertise has allowed, but the highest cred belongs to the most technically qualified. It should be obvious whom those might be.
I have modded my Vee with a D3 cai and crank pulley and tune. Awaiting delivery and installation of Kooks headers and exhaust (retaining stock mufflers) from D3 and another tune. Will add heads and cam early next year. Vee Baby should be stout enough then --- don't you think?

Gary Wells
11-24-09, 09:02 PM
Uriel:
I think that you might have the highest mileage '09 CTS-V on the forum. That's impressive for trouble free mileage for a supercharged *motor* cranking 556 & 551 respectively to begin with.
I don't want to Bogart this thread but I don's suppose that you would mind revealing what your baseline RWHP & RWTQ was before the mods, and what the RWHP & RWTQ was after the mods that you have already done. *Auto* tranny or stick, & whether figures were from a Dynojet or a Dynopack dyno?

Uriel
11-25-09, 01:01 AM
Gary,
My Vee is Automatic. I'll let you all know what the Dynojet numbers are as soon as D3 completes all my mods --- so that you may get the final and complete results. One thing for sure, I love driving this car as you might assume by the odometer smileage. It's a real "boy toy". I read a recent article where it was stated that our 2009 CTS-V is the best American Automobile ever built. But we all know this ---right?

Tedboss1
11-25-09, 08:59 AM
I was wondering if ZR1 supercharger Eaton R2300 has the same clicking problem as our Eaton R1900 blower in the V2.
Or may be the spring isolator is not used in the Vette?

Caddyscat
11-25-09, 07:29 PM
he never touched on the wheel clicking issue? WTF?

Wreckless
11-25-09, 07:53 PM
Ed,

Thank you for posting. Can you please clarify as to the following:

1. What is GM's definition of limited wear.
2. How was this validated?
3. Is there an ASTM specification?
4. What is acceptable limited wear?
5. How was it measured?
6. How was it tested?
7. When was this test specification set in place? Have any changes been made to the system since? ie; Materials, surface finish, hardness, etc.

Gary Wells
11-25-09, 08:27 PM
I was wondering if ZR1 supercharger Eaton R2300 has the same clicking problem as our Eaton R1900 blower in the V2.
Or may be the spring isolator is not used in the Vette?

In particular, response #'s 55 & 60 on page 4, but in general, lots of good info in here on this issue:

http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2009/179364-isolator-issue.html

Tedboss1
11-26-09, 09:12 AM
Gary thanks for your response.
So it looks like ZR1 has the same noise problem as our V2.

"PIP4523A: Marble Type Rattle Noise At Idle From The Supercharger - Potential Noise Characteristic - keywords BQMI - (March 20, 2009)".

"Document ID: 2253881".

"Models: 2009 Cadillac CTS-V"
"2009 Chevrolet ZR1 Corvette"

"with 6.2L Supercharged Engine (RPO LS9 or LSA)"

Short-Throw
11-26-09, 10:48 AM
very awesome i have been on the vette forum for a long time and dont think i have ever seen gm brass post on there before.

welcome Ed

Yes you have, you just didn't know it. ;)

Razorecko
11-26-09, 03:40 PM
^ yep, They prowl around on all the forums. Its the most undiluted, up to date, customer service and "mod" information they can get.

cbloveday
11-27-09, 08:50 AM
Thanks Matt.

You're correct about a member complaining about increased noise after going with a solid isolator - I believe it was an LPE snout mod package.

I believe that member was me. I would like to clarify that LPE contacted me and others that experienced increased noise and advised it may have been from a faulty batch which had improper tolerances. LPE sent me a new isolator, free of charge, which the installer said was "snug". Problem solved. LPE also paid for removal of faulty isolator and install.

This was all done under the "assumption" that my isolator was faulty.

LPE cares about their customers, services, and products.

Gary Wells
11-27-09, 09:25 AM
That is outstanding customer / service satisfaction commitment of LPE.

Prof
11-27-09, 12:46 PM
This blows my mind.

I am so impressed that someone with the stature of Ed cares enough respond. He must have known that there would be some dissenting opinions, but came here anyway.

If this is the new approach of GM to customer service, I am very impressed.

I hope the few with a burr under their saddle, will be taken in stride. Nothing is absolute, so there is always room for different opinions. But I think all of us are incredibly appreciative of the post. Keep this up and I may have to get rid of my MOPARS!!!

Let's see...a V Wagon, a V Coup...how about a V SUV???

MReiland
11-27-09, 08:44 PM
LPE cares about their customers, services, and products.

I don't think there was ever a question about the quality and service of LPE. The thread starting message was to clearly state that the isolator was designed in for a specific reason.

cbloveday
11-27-09, 11:07 PM
I don't think there was ever a question about the quality and service of LPE. The thread starting message was to clearly state that the isolator was designed in for a specific reason.

I just wanted to make sure members were aware that my experience was an "isolated" incident so to speak.

LPE has identified incorrected tolerances on previously shipped isolators and
the future batches should not be noisy.

Jack B
11-28-09, 03:48 PM
Thanks Ed and GM Engineering. This is a special car and it's really nice to see the manufacturer engaged with us the customers. I all of a sudden don't feel alone with just my fellow owners!!

Tony407
11-30-09, 04:32 AM
I too am completely blown away by the graciousness of Mr. Piatek and GMs response to one of our concerns. I am not certain as to WHY he chose to address this particular concern (as opposed to wheel clicking or any of the other myriad of questions we may have) but in my opinion it really doesn't matter because his input is better than NO input at all - which we obviously have all been accustomed to on manyy forums throughout our collective car- owning lives. I only hope he has been monitoring these responses and has been reading about our messages of gratitude. I can only encourage other forum members not to ruin a good thing by inundating him with other requests pertaining to engineering (even though we are all tempted to do so, including myself.) Don't ruin a good thing. This level of customer service deserves to speak for itself and allowed to slowly grow as levels of trust on both sides are fostered. Thanks, Ed.

Tony

x-srtjeep
12-08-09, 02:56 PM
Wow, you guys are easily impressed! Since Ed had the balls to post a response, problem solved! ahhh, except for the rattle noise at idle, hmmm. It's a simple problem with a simple solution, it's a hardened spring wearing a softer shaft, if wear is acceptable then just accept the noise...besides, I will just tell the guys at the track that GM said that the rattle is supposed to be there, and if I fix it, there will be rattle somewhere else. So did GM actually try this fix? Maybe they should have had added a little (or a lot) more exhaust note and problem solved.
So in the end, does the shaft get really worn down to a point where the spring won't grind/rattle anymore? What mileage will this occur, and if that is the case, why not just machine down the shaft in the first place? I say NO wear on "the shaft" is acceptable, enough said

theamcguy
02-06-11, 12:10 PM
My question is what is the advantage of the torsional isolater w/spring and the added expense over the solid isolater which seems to cure the noise problem?

dr.duct_mossburg
05-20-13, 03:01 PM
My question is what is the advantage of the torsional isolater w/spring and the added expense over the solid isolater which seems to cure the noise problem?

Lol, I guess im one of the select few that don't get star struck.

A $75k car with a bunch of "just married" can's under the hood. This is supposed to compete with the M5, E63, S6, etc... It will sure get the attention of those owner's but not in the way we intended for it to.

Chrispy
05-20-13, 04:06 PM
Great information and thanks for joining the board!

Can you confirm if six speed manual V's have the no lift shift feature that enables flat foot shifting (aka powershifting) where you keep your right foot to the floor while you shift at WOT?

Trapspeed
05-20-13, 06:20 PM
They should.

thebigjimsho
05-21-13, 12:14 PM
Great information and thanks for joining the board!

Can you confirm if six speed manual V's have the no lift shift feature that enables flat foot shifting (aka powershifting) where you keep your right foot to the floor while you shift at WOT?

My '09 did...

Chrispy
05-21-13, 12:49 PM
My '09 did...

Yup I tested at the track on Saturday and it worked :)

Zipperator
05-25-13, 01:20 AM
I am glad I just saw this post! I was about ready to change this s/c piece out!

garfin
05-25-13, 08:38 AM
Great information and thanks for joining the board!

Can you confirm if six speed manual V's have the no lift shift feature that enables flat foot shifting (aka powershifting) where you keep your right foot to the floor while you shift at WOT?

It sure does!
http://www.roadandtrack.com/car-reviews/car-comparison-tests/2012-cadillac-cts-v

Are you telling me you haven't tried it yet? :canttalk:

Best regards,

Elie