Saturday, February 19, 2011

Porsche Axle Repair - Diminutive DIY






My son’s Porsche suffered a rather dramatic front axle failure while undergoing some high-speed, high-stress testing in our living room. Just look at the damage. My wife and I, and Graham as well, are just lucky he was able to walk away unscathed. Our wallet, however, had to bear the brunt of the damage as we attempted a repair.

Looking at the damaged parts in detail I was surprised to see that the front axle was made up of uni-directional pine, milled to less than 1MM diameter. This seemed like a feathery piece of engineering, one I wondered if had been superseded by a new factory part.

Calling the factory in Stuttgart, I was soon forwarded to a member of the competition engineering department. A Dr. Peter Wolfhensler. He was well aware of the front axle failure on my son’s Porsche. “Unfortunately, the pine used for that production run had some core instabilities that showed up under extensive testing. We ourselves experienced a dramatic failure while testing on the Nurburgring. The right front wheel shearing off and the driver being slammed into the Armco at 200 kmh. But overall, we are still pleased with the performance of this equipment. It is within factory failure rates.”

I asked if they had fixed the problem. Here the doctor paused, “Not quite. We are still looking for a suitable pine-based axle assembly as it has the desired weight/cost/performance ratio but have not found an adequate solution. Yet.”

Carbon fiber seemed like a good material for this use, so I asked Dr. Wolfhensler about that as an option. “It is too costly for a customer car. We have learned our lessons from ceramic brakes. Until the costs come down, the customers cars will need to be optioned only with the pine.”

About to hang up the phone, Dr. Wolfhensler tossed another option at me. “I hear The Racer’s Group, TRG.”

“Of endurance racing fame?” I asked.

“Yes, of course. I hear that TRG is developing a fix that uses a ferrous material. They have found the additional weight is not a handicap in their particular type of racing. Maybe they have an option for you.”

So once again, when it comes to my Porsches, I had to turn to a private entity to find a satisfactory repair. The LN engineering fix for the M96 IMS comes to mind. I quickly rang up TRG.

I didn’t even fully explain the problem when the young man on the other end of the line interrupted me. “I know the exact problem. We have developed a kit to upgrade to an extruded, air-rolled, nickel-lined, honeycombed center steel axle.”

“I’ll take it.” I said.

Gulping after the young man quoted me the price, I took a breath and was hit with more bad news. “You are handy right? The kit comes as a you-cut-to-fit and epoxy yourself kit. This allows you to change the track of the car if you wish. We find an extra 2mm track in the rear helps with braking stability.”

The kit arrived and I set to work. First, I had to re-bore the wheels. Thanks Porsche for using an adhesive instead of a center-lock. I used a 1/4 inch bit and made sure to hone it perfectly true. I don’t want my son to suffer any high-speed vibrations.

Next, I leave some things as the factory intended and did not alter the track. I used the stock width of 11.5mm. And with no other alternative, I also used a quick-setting, multi-material epoxy. The fellows at TRG suggesting I ensure thorough coating of the parts because if their steel comes into contact with the wood wheels there would be galvanic corrosion due to minute metal particles in the wood stock. Who knew?

So, did Graham notice any difference in the ride quality of his Porsche after my lengthy repairs? In a word, no. He just grabbed it and pushed it along the floor - on its roof.

Of course the above is fiction. It is the way I handle how poorly this toy was built in the first place. Kinda like Boxster motors.

2 comments:

gary said...

You Sir need a new project!

longrooffan said...

That is a fantastic write up!! BTW, I saw TRG's Andy Lolly driven Impala on the grid at the start of the Daytona 500 on Sunday. The TRG guys were real pleasant to speak with and Andy ran a good race until he got punted off the track. Again, a great write up, thanks for sharing. john