: Will GM Make the mod Available to us???



BeastMaster
06-17-08, 01:47 PM
One of the big stories about the 09V is no wheel hop. GM claims that one of the magor parts of solving the puzzle was to use different diameter half shafts. By doing this wheel hop is eliminated. In fact GM has applied or is going to apply for a patent on it.

So, if this is true, do you think it would be difficult for GM to give us different diameter half shafts to solve our problem. Am I missing something or over simplifying this?


The article link is http://www.autoblog.com/2008/06/11/a...illac-cts-v-w/

The part of the article that I am referring to is

We wrote in detail about the CTS-V's powerplant back in January, but this is the first opportunity we've had to experience the beast up close. With the supercharged 6.2L LSA V8 now officially outputting 556 hp and 551lb-ft of torque, perhaps the single biggest problem is putting it to use. Turning all that power into kinetic energy can easily cause all manner of mayhem at the drive wheels (rear, of course). Since roads are rarely as uniform as we would like, and the vertical forces acting on the tires are almost never equal, one drive wheel usually looses traction before the other. Once that happens, the drive torque gets sent over to the other wheel via the traction control systems and limited slip differentials.
When the engine produces a lot of torque, the half-shafts twist like a spring and then release when the tire looses traction. If the half-shafts are identical in size, the release on one side can cause the other side to wind up and then reverse the process. Exciting the system in this way ultimately causes the wheels to start bouncing around in a phenomenon known as axle hop. When the wheels start hopping, the car doesn't accelerate and, if you're trying to accelerate out of a corner, you can easily get totally out of control.
Most manufacturers try all kinds of fancy suspension geometries and control schemes to get axle hop under control. The GM suspension engineers decided to go back and look at the root cause of the problem and discovered that it was triggered by the half-shafts alternately winding up and releasing. After analyzing the problem, they discovered that by changing the effective spring rate of the axle shafts they could virtually eliminate axle hop by ensuring the oscillation frequency of each side was different, thus eliminating the excitation that was occurring.
They did this by making the left half-shaft (above, left) almost twice the diameter of the one on the right (above, right). The result is that even with all that torque, the CTS-V has some of the cleanest, smoothest launches with no skittering or bouncing around. The system works so well that GM has applied for a patent on the design and the Corvette ZR1 uses the same setup.

rand49er
06-17-08, 01:55 PM
I mentioned doing this in another thread a couple weeks ago.

Just wonder if the alternating storage of energy then subsequent release is wholly confined to our axle shafts and not codependent on, say, geometry, bushings, driveshaft, etc. Poppin' a couple of new axles in there just seems too easy. One can hope, though.

heavymetals
06-17-08, 01:59 PM
Short answer is : NO :thehand:

1st generation CTS-V's are obsolete.

I would really, really like GM Performance Products Div step up to the plate and support the car (not just the motor), but I ain't holding my breath.

The 09 rear swap out is what I am hanging my hat on. :thumbsup:

CtsVrod
06-17-08, 02:01 PM
I brought up the same question in this thread - http://www.cadillacforums.com/forums/cadillac-cts-v-series-forum-2004/142525-v2-halfshafts-no-more-wheel-hop.html

Someone mentioned they had tried to put Bigger Half Shafts one at a time, and they didnt notice any difference.

BeastMaster
06-17-08, 02:03 PM
.

The 09 rear swap out is what I am hanging my hat on. :thumbsup:


That would be sweet. If it were possible, I'd then keep the 05 and forget about the 09 next May.

rand49er
06-17-08, 02:19 PM
... I would really, really like GM Performance Products Div step up to the plate and support the car (not just the motor) ...You'd think this would make sense. Yup, no breath holding going on here. :nono:

heavymetals
06-17-08, 02:32 PM
You'd think this would make sense. Yup, no breath holding going on here. :nono:


At the D3 event there was a cute girl with a video camera recording comments that were "going to the top".

I made this point very clear about GM Performance Products and lack of same for the V.

trukk
06-17-08, 02:42 PM
At the D3 event there was a cute girl with a video camera recording comments that were "going to the top".

I made this point very clear about GM Performance Products and lack of same for the V.

I point blank asked the engineers that were at the Lindsay event, if they had any pull with GMPP, to try and get them to produce a cast iron diff for V1. There response indicated they thought that very unlikely.

-Chris

The Tony Show
06-17-08, 02:49 PM
Someone with a second car to drive for a week needs to take an axle out, deliver it to a driveline machine shop and ask to have a duplicate made that is twice the diameter and hollow. If it works, become a vendor, order a bunch of them from your shop and sell them at a reasonable profit.

If I had the time and money I'd do it myself, but since I don't.....there's an idea that someone can make money with. Now run with it. :thumbsup:

heavymetals
06-17-08, 04:02 PM
Why not just add material to an OEM axel and balance it?

rand49er
06-17-08, 04:27 PM
Why not just add material to an OEM axel and balance it?What is the '06/'07 axle diameter? Thirty-something?

How about make one side, say, 50mm and the other, say, about 60mm? Two different diameters and MUCH beefier.

If that cures WH AND WH is the primarily link in the chain of events leading to diff failure, then voila!

The Tony Show
06-17-08, 04:28 PM
Frankly, I think it has more to do with the effective spring rate of the piece than the mass. A hollow piece on one side must be necessary to create a large enough difference between the two and stop the oscillation, otherwise GM wouldn't be spending the bucks to do so on the '09.

fred's maggie
06-17-08, 04:32 PM
the rear is still a piece of junk and will hand grenade when the wheel hop goes away

The Tony Show
06-17-08, 04:34 PM
Is that your Professional opinion after 6 months and 29 posts? Well, I respectfully disagree. As long as no sudden, violent force is applied to the case, it should be fine. Removing the wheelhop will eliminate 90% of case failures, maybe more.

silverAg
06-17-08, 04:56 PM
the rear is still a piece of junk and will hand grenade when the wheel hop goes away

wow:halo:

BeastMaster
06-17-08, 06:00 PM
I have to agree with Tony here. If wheel hop can be eliminated then it can only help. Is it the best solution - no, but for the bucks it would be hard to beat.

jweymar
06-17-08, 06:01 PM
What is the '06/'07 axle diameter? Thirty-something?

How about make one side, say, 50mm and the other, say, about 60mm? Two different diameters and MUCH beefier.

If that cures WH AND WH is the primarily link in the chain of events leading to diff failure, then voila!

Cadillac says that the diameter is twice as large and someone tried a slightly larger one on one side and that did nothing.

jbss71
06-17-08, 10:36 PM
our big problem is bushings and soft spring rates. Chase half shaft harmonics after you get a solid suspension