*Pics* Why you should do a Solid Isolator Coupler...

[Matt @ FSP]

Originally Posted by joes407

let me know when pick up time is for your car. id love to get an eye on matts shop if you need a ride out & im sure we'd be at high ticket risk on way back though

We are shooting for next weekend (We'll know our schedules as Phil and us collaborate next week).. We'd love for you to come on out here Joe.. Seems like we've missed each other a few times already.

Lunch sounds like a plan...

[Matt @ FSP]

Originally Posted by joes407

so in simplified terms youre saying the wear is unpredictable and varies supercharger to supercharger

Yes.

but that the solid coupler hasn't been around long enough to assess whether or not it might cause a negative effect down the road or less than 100k mile life expectancy?

I can tell you that I have done them in 2009, with daily driven CTS-V's that have a bunch of miles on them and not one failure with the solid coupler. Once again, it's hard for me to give you set condition testing as we have not gone that far. However, I can guarantee you that if something breaks I am informed!

[joes407]

Originally Posted by Matt @ FSP

We are shooting for next weekend (We'll know our schedules as Phil and us collaborate next week).. We'd love for you to come on out here Joe.. Seems like we've missed each other a few times already.

Lunch sounds like a plan...

yes that sounds great. we were sposed to have met when you first moved down here to the other shop for some experimental stuff on my car but seems so much has happened since then that it just hasn't happened yet.

[Al C.]

Maybe someone could answer, So the worst case i leave the spring isolator because i hear not rattle but obviosly it causes damage to the shaft....whats gonna happen? Are there replacement parts for these sc or are we stuck buying a sc.. For some crazy reason I'd think Eaton knows the damage this causes, not GM, and would do something about this..or at least give an factual explanation on the reason they keep using a spring isolator.

[Matt @ FSP]

Originally Posted by joes407

yes that sounds great. we were sposed to have met when you first moved down here to the other shop for some experimental stuff on my car but seems so much has happened since then that it just hasn't happened yet.

Yes I know we were going to look at some dyno test data, I'm still more than open to reviewing data, it can always be a positive any type of testing is productive.

[EVLZL1]

This is mine at about 2k miles...

[OldScoolCamaro]

...there has been much discussed already about this issue, galling/noise <with pics>...GM warranty will R&R the part if it's a major customer complaint. Stay within the warranty untils it's closure, then go with a solid coupling after that time.

[DrkPhx]

This was a big issue with 09-up CTS-V as well. In fact, most thought it was fixed when the ZL1 was introduced because early pics show a solid isolator minus the spring which turned out to be not true. A link is below which includes GM's response. With that said I have a friend with a 09 CTS-V who has tried a few different solid isolators and the noise is reduced, but still there. Those who replace just the isolator risk voiding their warranty if GM finds out because the entire supercharger must be replaced as a unit under warranty.

http://dcautogeek.com/?p=2038

CTS-V owners, like most performance vehicle owners, are very active online. Owners took to the forums to discuss and share their displeasure with ‘the rattle’. They made enough noise that in November of 2009, it prompted Ed Piatek then Program Engineering Manager on the CTS-V to step in and clarify a few facts. Below is the response Ed provided to members of CadillacForums.com:

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.

[ZL1 TIBS]

As an engineer, this is the response I expected. Personally, I am not going to worry about it unless the rattle gets pronounced. I am wondering if it would have been beneficial to install a rubber or polyurethane sleeve between the shaft and spring to avoid contact between them.

[crustychev]

Originally Posted by ZL1 TIBS

As an engineer, this is the response I expected. Personally, I am not going to worry about it unless the rattle gets pronounced. I am wondering if it would have been beneficial to install a rubber or polyurethane sleeve between the shaft and spring to avoid contact between them.

What he said. Was thinking the same thing (sleeve or bushing) as I was reading down the string of posts.

[joes407]

From his response it would seem were worrying for no real reason. Seems they designed it this and if i read correctly the initial wear is the worst

[silverds]

Why has it become so difficult to understand.

The isolator is a coupling. A coupling is simply the connection between the input and output of a drive.

The reason it's called an Isolator is because it isolates the irregular oscillating motion of the engine crank from the rotor timing gears of the supercharger by absorbing shock.

When your pistons fire, they send a violent pulse that is transmitted from the piston head down through the rod into the crankshaft. The pulse is violent enough to actually cause your crankshaft to twist some fraction of a degree. At the end of your crankshaft is a harmonic balancer that has two purposes, to protect your crankshaft from harmonic vibration at specific frequencies and to minimize shock transmitted through your drive belt to your accessories. (i.e. HVAC Compressor, Water Pump, Alternator, and Supercharger)

The harmonic balancer does not completely eliminate vibration from being transmitted through the drivebelt, it only reduces it. So shock is still being transmitted through the drivebelt. External to the supercharger, there is one coupling between the drivebelt and the pulley. Inside the supercharger there is another coupling from the input shaft to the Timing Gears, and then another coupling between the teeth of the two gears.

So there are two "isolators" buffering the violent oscillating torque of the crank shaft and the relatively delicate teeth of the timing gears between your rotors. The Harmonic balancer and the internal isolator coupler.

Removing the isolating (shock-absorbing) coupling and replacing it with a rigid (non-shock-absorbing coupling) only serves to increase stress on the teeth of the timing gears. If you are concerned about the long-term serviceability of your supercharger, why would you do this? To protect a sacrificial part of the coupling whose only purposes are to keep the coupling fixed around a central axis and to provide resistance to the spring in the isolator? To reiterate, this shaft is sacrificial. It is intented to be galled by the spring until it fits snuggly in the grooves just like Memory foam.

[BAD ZL1]

Originally Posted by ZL1 TIBS

As an engineer, this is the response I expected. Personally, I am not going to worry about it unless the rattle gets pronounced. I am wondering if it would have been beneficial to install a rubber or polyurethane sleeve between the shaft and spring to avoid contact between them.

If metal wears down from the spring, wouldn't a poly or rubber sleeve wear even quicker? I am an operator not an engineer and I had another thought. Why not lube the shit out of the part that wears with like Anti seize or something even more modern and exotic?

[580/556 ZL1]

Originally Posted by silverds

Why has it become so difficult to understand.

The isolator is a coupling. A coupling is simply the connection between the input and output of a drive.

The reason it's called an Isolator is because it isolates the irregular oscillating motion of the engine crank from the rotor timing gears of the supercharger by absorbing shock.

When your pistons fire, they send a violent pulse that is transmitted from the piston head down through the rod into the crankshaft. The pulse is violent enough to actually cause your crankshaft to twist some fraction of a degree. At the end of your crankshaft is a harmonic balancer that has two purposes, to protect your crankshaft from harmonic vibration at specific frequencies and to minimize shock transmitted through your drive belt to your accessories. (i.e. HVAC Compressor, Water Pump, Alternator, and Supercharger)

The harmonic balancer does not completely eliminate vibration from being transmitted through the drivebelt, it only reduces it. So shock is still being transmitted through the drivebelt. External to the supercharger, there is one coupling between the drivebelt and the pulley. Inside the supercharger there is another coupling from the input shaft to the Timing Gears, and then another coupling between the teeth of the two gears.

So there are two "isolators" buffering the violent oscillating torque of the crank shaft and the relatively delicate teeth of the timing gears between your rotors. The Harmonic balancer and the internal isolator coupler.

Removing the isolating (shock-absorbing) coupling and replacing it with a rigid (non-shock-absorbing coupling) only serves to increase stress on the teeth of the timing gears. If you are concerned about the long-term serviceability of your supercharger, why would you do this? To protect a sacrificial part of the coupling whose only purposes are to keep the coupling fixed around a central axis and to provide resistance to the spring in the isolator? To reiterate, this shaft is sacrificial. It is intented to be galled by the spring until it fits snuggly in the grooves just like Memory foam.

NOW! i understand ,,,,