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hey every1, just wondering how do i know when my differentials are going bad, is there a special noise that comes?
 

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11 CTS Sport Coupe, 2000 Carrera GT3, 2013 Jetta
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CadiKing2006 said:
hey every1, just wondering how do i know when my differentials are going bad, is there a special noise that comes?
You may hear either a "clunk" when your on and off the gas or if the carrier bearings are going - you can also get a "whine" - sort of a supercharger like sound that changes pitch up or down with road speed. Have someone drive your car while you sit in the backseat and listen carefully. Make them vary the speed and turn in different directions both low speed 90 degree corners and higher speed "sweepers". Most dealers will go out on a road test with you to check it - or better yet, get a sales person to take you out in one of their demos to compare sounds.

I had my diff go on an Iroc many years ago and the bad news is that once you hear the noice it's too late. The good part is that you can drive for thousands of miles and the cost of repairs when you do fix it, is not much worse then if you had it fixed as soon as you heard it. One point however: if you do keep driving - maintain the fluid level in the diff and have your dealer confirm it's just wear and is not close to a complete failure. I've seen the result of people ignoring maintenance checks of the diff fluid level to the point where they heat treated the housing before it locked up solid...
 

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Not really much of a road test needed to determine if the rear carrier unit is "going bad". The cause of the differential failure is NOT usually the failure of the ring and pinion gears or failure of the half-shafts.

The above is the "whining or howling" effect that you are now hearing as the ring and pinion gear set is out of "sync".

What is the cause of this? A visual inspection of the differential case will more than likely (99%) of all cases will reflect cracking of the sand cast aluminum differential case caused by drive train deflection at the rear of the drive shaft tunnel.

This deflection is usually around 4% which is enough to crack the case and cause the carrier gears to fail. I know this for a fact as I've cracked at least 6 cases and will actually this time post some photos of the various diffentials and where they crack.

The bottom line is that the differential case is constructed of sand cast aluminum and "hard launching", speed shifting, clutch dumping will grenade that rear-end.

The Ford, Dana and most other rear carrier cases are constructed of nodular iron, but not this piece of crap.

There is no recall, but only a technical service bulletin issued by GM and it is up to the Service Advisor to determine if it is a warranty related claim, so do not suggest for a second you were launching the vehicle at WOT or 4000 RPM's as they will send you and your broken differential out the door!

We are currently working with another Cadillac Forum Engineering company on c0-engineering a nodular iron case for the CTS and CTSV that is constructed of nodular iron to replace this known, defective and under engineered differential case.

The process of creating a tool and die mold alone exceeds more than $15,000 and has a limited service life before the mold itself has to be replaced.

There are NO cradle units that have proven to be effective in managing the rear wheel torque that causes the drive train deflection that ultimately causes this aluminum case to crack and the internal gearing to ultimately fail. That approach has been the traditional "band-aid" and has failed miserably at the costs of the consumer.

What you need is a "permanent fix" if your hard launching this vehicle or exceeding 320 RWHP as deflection is cracking the damn carrier case and eating your ring and pinion gears for lunch.

Your rear end is more than likely history or on it's way there. The dealership will replace it with a 2006 unit with deeper cooling fins, however that will NOT fix the problem as I've cracked one of those just recentley as well.

A Ford 9 bolt nodular iron rear would fix the problem, but your redesigning the entire rear of the car and that is beyond the scope of any DIY'ers; nor will any dealership do it.

Get your hands on a 2006 differential and PM me and I will tell you how to proceed before they install the damn thing; otherwise you'll just repeat the process when the new unit fails based on your driving habits.

Bottom line is that we can cryo-treat the aluminum carrier case along with the entire ring and pinion gear unit (all intact)without any dimensional changes to the unit until a steel case is available from us. No other vendor will provide this fix due to manufacturing costs and we are cost sharing the R&D with another company as we feel that there will be few "takers" on a bullet-proof $3000 rear-end that you will have to pay for as GM does not intend to recall and replace it with the proper nodular iron unit and will simply handle each failure via the TSB on a case by case basis.

This is what you would call a "ROYAL GM SCREWING" by Cadillac as they were made aware of this issue by Getrag before selecting this sand-cast aluminum carrier case and it's high rate of failure probability.

Welcome to the world of CTSV ownership woes!

regards - CMS, LTD.
 

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Black the Darkside
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HiYa Pete,
Some questions for you that would help many of us. I think you own the CTS, CTS-V and an SRX. Are the differentials interchangeable? Do they all share the same degree of weakness? Any change with the new STS?

These Cadillac have different gear ratios too. The CTS-V has I think the 3.91 ratio where the CTS auto has like a 3.42. The 3.91 sure would help launch the CTS 3.6 auto:D I think the CTS-V has a two piece drive shaft.
Does that eliminate the possiblity of using it in the CTS:hmm:
 

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RobertCTS said:
HiYa Pete,
Some questions for you that would help many of us. I think you own the CTS, CTS-V and an SRX. Are the differentials interchangeable? Do they all share the same degree of weakness? Any change with the new STS?

These Cadillac have different gear ratios too. The CTS-V has I think the 3.91 ratio where the CTS auto has like a 3.42. The 3.91 sure would help launch the CTS 3.6 auto:D I think the CTS-V has a two piece drive shaft.
Does that eliminate the possiblity of using it in the CTS:hmm:
Bob:

For the sake of brevity; there is not enough time or space on this Forum to even begin a discussion in answering your question regarding the failure of the Getrag rear carrier except tom make the following factual statements:

  • It is constructed on sand cast aluminum and is grossly underengineered.
  • This was revealed by Getrag to Cadillac "before" they decided to purchase this unit as engineered to GM specifications for both the 3.6 CTS and the 5.7 CTSV
  • GM purchased this unit based purely on "cost parameters" knowing in advance that it would not support more than approx 280 RWHP and Torque.
  • There is NO PROBLEM with the engineering of the Getrag half shafts, drive axles or internal ring and pinion gears.
  • The above mentioned internal items are failing as a "direct cause" of drive train deflection caused by rear wheel torque which is a direct result of drive train delfection of approximately 4 degrees which is enough deflection to crack the egg shell thin sand cast aluminum Getrag carrier case.
  • When the carrier case cracks; it therefore shifts and causes ring and pinion gear grinding and the ultimate failure of the rear differential. That is the whining and howling noise that you hear and most people have no idea where to "look" to see where the carrier case has cracked and therefore shifted from it's position.
  • No cradle or stabilizing unit will repair this engineering problem.
  • GM has refused to recall the rear carrier and has issued a TSB blaming the failure on "hard launches"; which is corporate BS.
What is the fix:

  • A nodular iron carrier case similiar to a Ford 9 bolt rear that is capable of handling the rear wheel torque, wheel hop and deflection that is inherent in hard launching of these perforance vehicles.
  • Cost to engineer a nodular iron carrier case; a minimum of $8000 for a mold and then the cost of removing your existing rear carrier and installing the internal components and half shafts into the new nodular iron carrier case.
Short Term Fix:

  • Removal of your existing rear carrier unit prior to it's failure and the removal of it's internal ring and pinion gears and half shafts.
  • Cryongenically treating the sand cast aluminum carrier case to minus 300 degrees turning the porous, brittle aluminum carrier case weak aluminum deposits known as austenites into much harder, more uniform particles known as martensites. These particles are responsible for the exceptional wear characteristics imparted by the cryo process due to a denser molecular structure and a reduction in porosity. We can't heat temper aluminum as it will literally melt like butter at 500 degrees.
  • Cryogenically treating the internal ring and pinion gears and half shafts and isotropically superfinishing them as well as heat tempering them to plus 500 degrees making them virtually bullet-proof from failure.
The above process offers "no guarantee" that the aluminum case will still not crack, however the ring and pinion gears will still be virtually bullet-proof due to the fact that they are ferrous iron and cryo and heat tempered.

The aluminum case is still brittle thin, underengineered in size and all of the "cooling fins" in the world will never solve the problem when you build a house on a foundation made of "quicksand",

Bob; you know for a fact that at CMS, we do what is right for the CTS client. We would never release a product that jeopardizes the vehicle owners safety or the integrity of the vehicle.

I've "preached" the errors and woes of Eibach lowering springs and 20" wheels and the overall effect that it would have on the CTS suspension geometry when you attempted to add RWHP and torque and I was calledd a fool for that! Now the number of private PM's that I have received from Forum members that have said..."Pete, damn you were right, can you help me?" Let's just say that because I value the privacy of people.....we'll just leave it at that.

You just can't slap something on a vehicle and not expect that there will be an overall engineering effect that will have either a positive or negative outcome. If you want look cool......slam the top, install 22" wheels and chrome the dash board for all I care. But don't think for a second that you can do those things and not effect the suspension geometry of the vehicle, it's rear tracking, contact patch, suspension component wear, scrub radius as well as roll center among another of other items. It just doesn't work that way in the real world; whether you choose to believe it or not!

We have an ESC that I can release tomorrow if all CMS wanted was your money, but we want your total satisfaction. We want to exceed you expectations. If I won't put it on my vehicle; why would I put it on yours?

I have to stand behind it....bottom line means I have to guarantee your rear carrier unit and I can't do that right now.

What I can do is reduce the boost on the ESC to about 3PSI which is where we are right now in final testing and redesign the cold air intake with the revised ESC to operate under WOT at 3500 rpms with no parastic loss and add 40 RWHP and 33 pounds of rear torque to your 3.6 or 3.2 without compromising your rear differential; so that is the approach that we will now take with regard to the ESC for a first quarter delivery with price TBD. The revised ESC will not require any changes to the 160 amp alternator, but would require an upgrade to to an Optima Yellow Top battery.

Along with the ESC, we have a protype Cool Mist water/methane injection system that is good for another 15 RWHP that also cools the intake charge. Again, another CMS fully integrated product for the CTS that our competition ignores as if the CTS was the "red haired step child" of the Cadillac Family with it's 50,000 plus units that are sold every year.

You tell me what vendor other than CMS, Ltd. has stood up for the CTS 3.6 and 3.2 more so than Cadillac MotorSports, Ltd?

Please understand; we're not looking to solicit anyone's business in particular; nor are we looking for accolades or thank-you's.

But it is offensive when members "demand proof" from a company that has NEVER sold a product that has EVER been returned for lack of quality or workmanship, when in fact we stand behind EVERYTHING without condition or reservation. Not one other vendor does this, yet we receive the grief and folks wonder why the aftermarket has ignored the CTS market and will sooner produce products for Scions that cost half the price of a Cadillac.

That is the price you pay when you bite the hand that "attempts" to feed you. That is what I meant in context when I made the reference that "vendors talk among each other".

And truth be told Bob; the CTS 3.6 & 3.2 crowd is a very tough crowd that most vendors would sooner have nothing to do with which is why you cannot find aftermarket products when comments are made on public forums like this that degrade the vehicle and the companies that attempt to serve those customers.

Check out the CTSV side of this Forum and you'll never see the banter that occurs on this side of the forum. Reed made a very wise statement to some members: "GROW UP".

I would add to that one very simple thing: "WAKE UP"

very best regards:
Pietro J. Raimondi
Cadillac MotorSports, Ltd
[email protected]***********************
 

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Black the Darkside
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I totally understand what you are saying Pete. But we are presently stuck with our lousey differentials. So working with what we have. Are there differences and interchangeabilty. Like can a 3.91 ratio CTS-V differential interchange with my 3.6VVT 3.42? Is the V beefier than ours?

I think you own the CTS, CTS-V and an SRX. Are the differentials interchangeable? Do they all share the same degree of weakness? Any change with the new STS?

These Cadillac have different gear ratios too. The CTS-V has I think the 3.91 ratio where the CTS auto has like a 3.42. The 3.91 sure would help launch the CTS 3.6 auto:D I think the CTS-V has a two piece drive shaft.
Does that eliminate the possiblity of using it in the CTS:hmm:
 

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RobertCTS said:
I think you own the CTS, CTS-V and an SRX. Are the differentials interchangeable? Do they all share the same degree of weakness? Any change with the new STS?
Good question. Surely the 460 hp STS-V can't use the same glass-jaw rear end that our CTSs do.

I thought when I sold my f-body I'd be done with under-engineered rear ends from GM. I guess not :(
 

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1500cc said:
Good question. Surely the 460 hp STS-V can't use the same glass-jaw rear end that our CTSs do.

I thought when I sold my f-body I'd be done with under-engineered rear ends from GM. I guess not :(
Yep, the 469Hp Supercharged NorthStar would really put a load on the Caddy differential. I wonder if any changes were made. I know the All Wheel Drive is not available with the 469HP engine.
 

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1500cc said:
I thought when I sold my f-body I'd be done with under-engineered rear ends from GM. I guess not :(
I hear ya...I repaired the diff on my dodge ram twice...after it went out again...I simply sold it...

I guess it's more common than I thought
 
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