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Cadillac CTS-V 2009
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Discussion Starter #1
While I was doing a couple of stuff to the engine I thought about replacing the isolator coupler pulley in the supercharger, my car has 42,000 miles on it with stock everything. Below are the pictures of the shaft on the supercharger. I still do not know what is the benefit of that spring on the coupler (ZR1 does not have it, it is connected through a metal bushing and directly to the shaft)

The shaft grinded by the spring


Another view


Residue left by all that grinding


Thats only by touching it
 

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2011 CTS-V Sedan
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392 Posts
That satisfies any question I had about whether I should replace this thing when I mod mine. Thanks for the pics.

Joe
 

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2010 white diamond sedan, 6MT,all options. 641 RWHP/592 RWTQ
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And GM say's this is not a problem!!!! hmmmmmm. Thanks for the pics.
 

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Silver MT CTS-V Sedan - Recaro/Graphite Wheels
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Forgive my ignorance, but what kind of impact would this have on the motor? Were you hearing any 'tapping' noise?
 

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2013 6MT V wagon, OBM, 2009 silver V sedan (traded)
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I'm glad mine was swapped out.
 

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I guess it's hard to believe what GM Engineering says from here on out. Here is evidence that there is long-term damage. I hope they come on and clear this up. I would be very curious as to what they have to say now.
 

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'09 CTS-V, 3K miles & '87 Turbo Buick, 29K miles
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3,435 Posts
Where the spring is wearing / contacting is the shiny part of the shaft, not down in the grooves - I believe.
 

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2009 cts-v
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971 Posts
I guess it's hard to believe what GM Engineering says from here on out. Here is evidence that there is long-term damage. I hope they come on and clear this up. I would be very curious as to what they have to say now.

With all due respect, let's not just "hope they come and clear this up."

Any suggestions as to how we can get them (GM) to view these pics and explain the damage as it pertains to what is seen in these pics before any more time passes?
 
G

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... I still do not know what is the benefit of that spring on the coupler....

Residue left by all that grinding.....
Reviewing what Ed Piatek said:

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.
So if it fails.... just tell your service dept to give Ed a call. :yup:
 

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<-----"Hulk" 2000-2012...He will always be missed :-(
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So the stock isolator damages the shaft. And simply based on the springs travel, it can only groove the shaft so deep, so it's not like it will shear through it. In fact, eventually, it would wear to the point that it no longer contacts it, and the rattle will go away, as will whatever benefit it supposedly has over a solid isolator.

:confused:
 

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2009 CTS-V, 2009 535i
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So the stock isolator damages the shaft. And simply based on the springs travel, it can only groove the shaft so deep, so it's not like it will shear through it. In fact, eventually, it would wear to the point that it no longer contacts it, and the rattle will go away, as will whatever benefit it supposedly has over a solid isolator.

:confused:
The spring-isolated coupling should still be "isolating." My problem with it isn't the wear, for the reasons Mr. Piatek cited--it's when it produces noise as or more objectionable than it's supposed to eliminate. Poor design.
 

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2009 cts-v
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534 Posts
Mine rattled at part throttle,like when passing someone on the highway. It sounded terrible. Replaced it with solid piece and rattle is completely gone. Most people just report the idle noise. Mine was tolerable at idle but NOT at part throttle.
 

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09 CTS-V, Radiant silver, Loaded, Auto
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I see it as humorous when those of you "modding" your engines bring up the isolator noise. Isn't that a bit of a contradiction? Has anyone had their supercharger malfunction because of this? Or are we simply observing the wear thats going on. My brake pads are wearing down! Let's complain to the service manager! Poor design! One of the many reasons I refuse to void my warranty is peace of mind when and if parts fail.
 

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Had 2009 V, Red/Blk 2016 Now
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I see it as humorous when those of you "modding" your engines bring up the isolator noise. Isn't that a bit of a contradiction? Has anyone had their supercharger malfunction because of this? Or are we simply observing the wear thats going on. My brake pads are wearing down! Let's complain to the service manager! Poor design! One of the many reasons I refuse to void my warranty is peace of mind when and if parts fail.
Word brutha!
 
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