GM High-Tech Mag CTS-V Rear End Article
11-12-2012, 06:17 PM
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GM High-Tech Mag CTS-V Rear End Article Thought I would share this article to the CTS-V crew, this article was in this months edition of GM High-Tech Performance Magazine and is about the 2004-2007 CTS-V Rear End and installing the BMR Fix for it.
Here's a link to the a scanned copy of the article, I couldn't find it on their website: https://docs.google.com/open?id=0Byi...0xUZllQZW5aSFk
Here's a link to the a scanned copy of the article, I couldn't find it on their website: https://docs.google.com/open?id=0Byi...0xUZllQZW5aSFk
11-13-2012, 02:38 AM
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It doesn't solve the fact that the rear end is weak sauce, but it will reduce wheel hop and strengthen the rear end from flex which will reduce the possibility of gernading the diff. Put it this way, if you're smokin your tires, doing burnouts in the parking lot and launching the car all the time no amount of bandaids will keep the rear end safe.
However if you're just looking to prolong the life, then all of these fixes in the article are a lot cheaper than $5k for a ford 8.8 and will help.
However if you're just looking to prolong the life, then all of these fixes in the article are a lot cheaper than $5k for a ford 8.8 and will help.
11-13-2012, 12:17 PM
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Has anybody installed just the chassis brace that ties the front of the trailing arms together AWK001 and noticed any improvements? This appears like a decent modification regardless of wheel hop concerns for road track duty.
Last edited by garrettg; 11-13-2012 at 12:24 PM.
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11-13-2012, 02:15 PM
#8
Wheel hop is 100% because of the driveline lash and the fact that the pinion is allowed to rise in the car.
Compare the driveline of a vette to the V and you'll see that they use a lot of the same components, the trans is the same, the diff is essentially the same, but there is very little lash in the vette driveline. Also the torque tube acts as a torque arm and basically eliminates the possibility of the pinion rising because the entire driveline is rigidly attached to the differential. That is why vettes don't wheel hop nearly as badly as the V.
The V could be the same, I just need to open up this fabrication shop and start building torque arms for everyone's diff.
Think about it like this: the stock V produces 400ft lbs at the flywheel, and the 2.97 first gear multiplies this to 1,188 ft lbs at the driveshaft. The 3.73 gears in the diff multiply this to 4,431 ft lbs at the axle. So at a full launch, you are subjecting the diff's mounting points to quite a bit of stress. If you have a situation where the differential's pinion can rise (because it only has 1 rubber bushing in the front) and the subframe is allowed to twist as well, you are essentially storing energy in the whole subframe/diff assembly to spring back and forth when the tires lose traction. The mounting points for the differential are less than a foot apart, and the mounting points for the subframe are only a little farther apart than that. What the car needs is a mounting point farther forward or backward to take the torque load and apply it where that 4,431 ft lbs has a little less leverage. Another mount on the carrier bearing would be pretty much the best we could do on our cars. It's either that or we remove all the rubber from the subframe and differential.
Compare the driveline of a vette to the V and you'll see that they use a lot of the same components, the trans is the same, the diff is essentially the same, but there is very little lash in the vette driveline. Also the torque tube acts as a torque arm and basically eliminates the possibility of the pinion rising because the entire driveline is rigidly attached to the differential. That is why vettes don't wheel hop nearly as badly as the V.
The V could be the same, I just need to open up this fabrication shop and start building torque arms for everyone's diff.
Think about it like this: the stock V produces 400ft lbs at the flywheel, and the 2.97 first gear multiplies this to 1,188 ft lbs at the driveshaft. The 3.73 gears in the diff multiply this to 4,431 ft lbs at the axle. So at a full launch, you are subjecting the diff's mounting points to quite a bit of stress. If you have a situation where the differential's pinion can rise (because it only has 1 rubber bushing in the front) and the subframe is allowed to twist as well, you are essentially storing energy in the whole subframe/diff assembly to spring back and forth when the tires lose traction. The mounting points for the differential are less than a foot apart, and the mounting points for the subframe are only a little farther apart than that. What the car needs is a mounting point farther forward or backward to take the torque load and apply it where that 4,431 ft lbs has a little less leverage. Another mount on the carrier bearing would be pretty much the best we could do on our cars. It's either that or we remove all the rubber from the subframe and differential.
Last edited by killernoodle; 11-13-2012 at 02:23 PM.
11-13-2012, 05:38 PM
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What if you did the upgrade on the diff bushings the kit in this article and the axles. I don't beat any of my cars. If I ever race any of them its always rolling on highway. Never do drags. I like twisties more than anything. I live on back roads.
