Axle/CV Failures on Road Course

[Robjan]

Hi All! I've read tons of threads on axle/cv failures on these Gen5's. I have a 2010 SS. I do have some performance mods pushing about 492RWP. I'm destroying CV's at VIR. I'm on my 4th set.....

I've trashed a set of DSS Road Course Upgraded OEM axles. All others have been stock OEM half shafts. I've cooked both drivers and passenger sides and have had both inner and outer boots fail during my events. I have only "broke" one axle. It sheared the outer splines after the grease leaked out.

Here are some the suspension mods I've made:

- Ridetech HQ Series Coilovers
- Rear Toe Links
- JPSS Rear Sway Bar
- Delrin offset Diff bushings
- z28 control arms & bushings
** I have not replaced the OEM subframe bushings yet.

The options I know are DSS or GForce axles BUT I can't get my head around having to buy a 1000HP rated axle when I'm really not breaking axles. My CV's are overheating which causes the grease to breakdown. What's causing my CV's to get so hot??? I don't think i'm too low. I've pasted a pic of my measurement from ground to middle of the drivers side rear wheel well.

The last event was run with the delrin offset diff bushings and the OEM's shafts still failed. Can it be as easy as just buying the 1000HP rated axles? I'd really like to know why i'm generating so much heat back there. I have a feeling something is off in my suspension setup but I'm not sure what it could be.

Any thoughts would be appreciated!!

[olblue75]

Have you looked at the axle angles from the back should be as parallel to the ground as possible is my understanding.

[VR Baron]

Measure from wheel lower lip, not ground to be accurate. The rear wheels shouldn’t be any lower then 26” with 20” wheels, 25.5” with 19” wheels. At least according to Pete who used to be at Pedders. Or don’t lower it more then 1 to 1-1/4” from stock. The lower you go from stock the more heat builds up do to more severe axel angle.

[hammdo]

He does have the offset bushings for the diff to help with the angle of the axles. Must be some serious heat... I’d ask DSS if there is a better grease to use for road course work or, maybe change the grease more often...

FYI I do have the DSS 1000 hp axles, Hendrix offsets, completely replace all bushings, and upgraded all suspension components. TruTrac upgrade. Have solid subframe bushings also...

-Don

[Robjan]

Originally Posted by VR Baron

Measure from wheel lower lip, not ground to be accurate. The rear wheels shouldn’t be any lower then 26” with 20” wheels, 25.5” with 19” wheels. At least according to Pete who used to be at Pedders. Or don’t lower it more then 1 to 1-1/4” from stock. The lower you go from stock the more heat builds up do to more severe axel angle.

Measuring from the bottom lip of the wheel up to the bottom of the wheel well is 25 3/4". So, according to your numbers it seems too low. I know Pete well....he did most of the suspension work including installing my coilovers. You'd think he would have caught something as simple as ride height since he did set them up in the first place. Perhaps i caught him when his work started to go downhill.

[VR Baron]

Originally Posted by Robjan

Measuring from the bottom lip of the wheel up to the bottom of the wheel well is 25 3/4". So, according to your numbers it seems too low. I know Pete well....he did most of the suspension work including installing my coilovers. You'd think he would have caught something as simple as ride height since he did set them up in the first place. Perhaps i caught him when his work started to go downhill.

Yeah he helped me to. But different day different answer. He always says 26”(660 mm )height no lower. No matter what the super coilovers were not great. Drove me nuts trying to get a good street setting for good ride.Most companies seem to say just don’t go more then 1 to 1-1/4” lower then stock, which seems to end up about 26” with the factory tolerance.
And he said that’s with a 1/4 tank gas.full tank Mine sits 1/8” lower.
And still others have had issues like yours at stock height do what is good is up to us I guess and take the risks

[Mgizzle]

Just FYI the z/28 has special boots and high temp grease you should give those a try. The only difference over a 1LE part number is the boot and grease used on them. Your probably killing them in the corners because angles are too high. Usually its the outter due to angles during cornering and its the driver side.

[SS Performance]

Originally Posted by Mgizzle

Just FYI the z/28 has special boots and high temp grease you should give those a try. The only difference over a 1LE part number is the boot and grease used on them. Your probably killing them in the corners because angles are too high. Usually its the outter due to angles during cornering and its the driver side.

Do you happen to have the part number for those boots?

[Mgizzle]

PNs in red for entire shaft, not sure if boots are servicable.

[VR Baron]

Yeah temp grease that doesn’t turn to water and run out seems to be a fix an option. In autocross I have had several friends had this happen being at the alleged 26” max drop height and lower. But this took eight to ten years! Obviously a roadcourse issue

[olblue75]

The half shafts are 300 a piece on rock auto.

[SS Performance]

Are the ZL1 boots a higher quality than stock?

[Zombie killer]

I am very curious to figure out this axle boot mystery myself. I am running 19” rims and when checked according to the measuring setup above, I am dead on 25.5”. However I started developing axle grease slinging out the drivers side after I installed a factory 1LE rear diff in my SS. So I installed new GM axles on both sides the day before NCM at CFest9. Guess what? One day on track and I can see evidence of fresh axle grease. So what gives ? I wonder now if I am generating heat thru the rear diff for some reason that gets the grease in the axle boot hotter some how. The drivers side is my only bad side, which of course has the less diameter half shaft to dissipate the heat. I guess I will be watching this issue more and try to figure it out. Might start checking temps with a infrared gun back there more often.

Anybody experience similiar issues that they have pinpointed the culprit ??

[olblue75]

I have 1LE axles and was running 3.91's on a stock diff and never had a problem, then I switched to a Z28 still running the same axles and did a track day in May with no issues. I have bought a set of Z28 axles and the lines to make the diff cooler functional that's the next project on the books after cam and head swap.