powdrhound

When the hub failed I had just over 49K miles on the car with right at 100 track hours. I am also putting about 550+ ft.lbs of torque through the rear drivetrain which is close to 2x that of a GT3. I'm guessing that probably puts more stress on everything. I don't think there is a published replacement interval on any of Porsche's street legal cars. Only the 997GT3 center lock hubs have a published replacement interval, something ridiculously low if I remember.

powdrhound

The left rear upright was damaged by the hub as it broke so I had to replace it anyway. My shop also told me of a number of instances that the uprights have failed in the area of the bearing case. I just figured while in there we might as well replace every rear suspension component on both sides to be safe. We used the stock 6GT2/3 hubs.

cfjan

Got it. Thanks for clarifying. So you put in new 6GT2/3 uprights, but match them with the 997 hubs.

Since you were going to put in new uprights anyway, you didn't consider putting in 997 version?

powdrhound

I considered it briefly but you would need need to change the rear subframes also due to the different sway bar arrangement. Additionally, I would need to change out my rear JRZ pros as the shock attachment is different on the 997 uprights. Finally, the roll centers are different on the 997 versions which would necessitate changing out the fronts to 997s also. All in all, that would have added huge money to the project which was not cheap to begin with and I was under a bit of a time constraint..

cfjan

I see. Didn't realize so many things need to be changed. I'd guess the 996RS (street) upright would fit without the mod on the subframe. But not sure about the shock mount!

powdrhound

The 996RS parts are very expensive and special order from Germany. The RS uprights were around $1700 each in PET if I recall correctly vs. $600 for the regular uprights. Again, if you do the RS rear, you need to do the RS front uprights in concert. It's a pretty involved swap from what I understand and not cheap.. The 997s use a "pitch fork" type shock mount in the rear vs. the traditional mount on the 996..

452gt3

I had a hub failure on my standard 996 a few years ago, that car had factory wheel bolts. I believe the bearing fails and causes the hubs to fail from excessive heat. After that I replaced both wheel bearing in my GT3 for safety, the bearings were ok but I feel much better. I use the bullet nose studs which make life much easier on wheel changing.

mooty

i replace wheel bearing every 25 track days.
every 50 days i replace hubs (2 yrs)
studs i replace every 2 years as well. bull nose and VERY long, 110mm due to very thick BBS wheel centers. when in doubt, time it out.

powdrhound

Since the new 997 hubs failed again within 1 year of install, we decided to solve this issues once and for all by getting new custom hubs manufactured. New hubs finally are taking shape. These are being machined out of 300M which is an extraordinary high strength vacuum arc re-melt steel, the same thing used to make landing gear components for aircraft. Those will provide a tremendous strength improvement over the factory die cast hubs. I addition to making these out of 300M, we were able to slightly increase the radius of the hub at the bearing race. This will further add strength as there will be more "meat" in the failure area. Should have the finished product in about two weeks...

[url=https://flic.kr/p/LFwvnJ]

[url=https://flic.kr/p/LUKV7g]

[url=https://flic.kr/p/LRHBaC]

hf1

How many track days, HP, and on what tires? From your sig, you seem to be running some kind of a track monster.

powdrhound

The left rear (most loaded) 997hub failed after 2402 track miles (110 sessions / 45.8 track hours)

I'm putting down right at 600 hp / 670 tq to the wheels and using 275/335 NT01s. Lot of torque down low though which punishes things. I've stayed away from any tires with more grip until I get the new hubs on the car.

993GT

looks like its coming along nicely John...planning on fitting them with press-in studs or bolts/threaded-in studs?

powdrhound

Thread in studs. We wanted to make it a direct copy of the originals so that they would appeal a broader audience. Press in studs could be done on request however.

993GT

Very nice, saw the pricing on the 6SO thread, expensive but so is potential damage....I see Porsche has just released a revised hub # 99134160502

powdrhound

Correct. The 991 hubs will not fit the 996/7 cars however.