Saturday, February 14, 2015

Mount Half Shafts

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Major System Category: Transmission
Task: Install half shafts between rear hubs and transaxle
Parts:
New Half Shafts (Custom Made)
Prerequisite Tasks:
Additional Costs: $1300
Time Requirement: 8+ hours
Date Started: November 15, 2014
Date Completed: February 14, 2015

The governing principles for Super Car Build are quite simple:
  • Failure is not an Option - Unknown
  • Never, never, never give up. - Winston Churchill
I decided that to do this job right it might take longer than I wished, and probably cost more than I anticipated. Okay. I refuse to end up as one of those guys with a half built car and a $50,000 price tag for failure.
This is an assembled half shaft per the Factory Five Manual. Looks good and it certainly would fit a G50 transaxle. But I have been off the reservation  since I went with the 991 transaxle. 
The half shafts should be a simple task. Some grunting, scraped knuckles, a few choice words, but nothing that should take months to complete. In my post on the Cable Shifter, I listed all the things up to that point that had to be adjusted for going with a Porsche 991 transaxle versus a Porsche G50. It is a long expensive list, but the end result is a state of the art, 7 speed transaxle straight from Germany. The kind of transaxle a super car deserves.
The green circles show the shaft stubs on the 991 transaxle. They measure out around 22 inches. I know you're supposed to get this stuff down to the 1/4 inch. However, there is enough play that you have some room to work with.
I assembled the half shafts with the Corvette CV joint on one end and the 930 CV on the other end. It took a little time, but it was a straight forward task. The next day, I planned to install them. I slid the Corvette CV into the Corvette hub and tried to get the other end of half shaft to connect to the transaxle. Guess what, when the shaft is several inches too long, it just isn't going to happen. The problem arises that the width of the G50 between the shaft stubs is 10 inches. The width of the 991 is 22 inches. At the time, I didn't know what the width of G50 was. I know now it is 10 inches.
This is the half axle from the Drive Shaft Shop. No, it isn't made out of gold. My buddy Brian commented that it was a beautiful unit. It is - these guys do good work.
I sent an email to Factory Five support and asked them for that dimension. They didn't know the answer. Then I asked them for assistance in specing out new half shafts. They buy their shafts overseas and couldn't help either. What about the spline count. They thought it was 28. Ever count splines by hand - you might go cross-eyed. The only thing they said was figure out the difference and divide by 2. Duh, I ALREADY KNEW THAT!
I ended up taking off the caliper, rotors, tie rod and shock absorber to get a enough room to work. My buddy Charlie chided me that I was supposed to be putting things together. In this photo, I was doing the heat - tap - heat  -tap process to get the CV splines through the hub.
If Shane (Vraptor SpeedWorks) had had a G50 sitting on the floor of his shop, he would have measured it for me. I ended up getting the dimensions from GBox. Trust me, wherever they have the dimensions posted on the web is well hidden. There are diagrams, but they are so distorted that you can't read any numbers off of them.
This bolt is the correct size and that is the Torx head I needed to install it.
I don't know what caused me to check, but I decided to see if the bolts fit. Of course not. Porsche in their modern transaxles have switched to a M10 x 1.0 mm thread. These are about as common as the proverbial unicorn at the end of the rainbow. I tried finding these on my own, and finally called Carousel Porsche Audi in Golden Valley, MN (where I had the Boxster serviced). They ordered me 12 bolts designed for the 991 transaxle. And I thought I was home free, I was just getting in line for another smack across the head.
My weapon of choice (eh, I mean tool) to get this monster assembled.
The assembled half shaft with CV joints on both ends is smidgen over 30 inches long. The actual shaft if 23 inches long. This means I needed a half shaft that was 17 inches long before I added the CV joints. I probably double checked this measurement 100 times. I knew this was not going to be cheap. I ended up ordering custom half shafts from the Drive Shaft Shop. It is a good thing they knew their business, because I certainly was swimming in the deep water. He told me how much it was going to cost. I swallowed hard and gave him my VISA info. They were on the door step in two days. These guys do really good work.
This is a beautiful sight. Normally, it takes about 20 minutes to get here. I had a minor 4 month detour.
So now I have the bolts and the half shafts. Everything should work - right? The first problem I run into is that the splines on the Corvette CV joint are new (versus the ones I got from Fparts on the donor pallet - that seems like a million years ago). The spline is correct, but these buggers are really, really tight. There is a new hardware store 3 miles down the road from the NSMC. The dog and I ended making two trips that day. The first one was to buy a torch.
Installed! I was on top of the world, and greatly relieved that it finally worked.
I used the torch to heat up the hub and heat up the end of the Corvette CV that goes through the hub. It took about 15 - 20 minutes on each side to heat, tap lightly with a hammer, heat - tap -heat - tap. The Corvette CV joints that came with the donor pallet use a 34mm nut. I had purchased a 34 mm socket. The nut required for the new CV uses a 36 mm socket. No, I didn't have one of those behemoths handy. This precipitated trip #2 to the hardware store. The pup was beginning to think I was insane.
Bracket installed on the chassis to reinforce the area that I had to remove material from.
Back at the NSMC, I believe I see light at the end of the tunnel, or it could be an in bound train. It was a train. I get lift to the proper height, I position CV and I can't get there from here. The problem  is the cradle I built for the transaxle to keep the drain plug safe. I did this, because I didn't want to cut into the chassis. <Sigh>. The only way to make this work is to cut into the chassis. Out comes the cutting wheel and angle die grinder.
Another look at the channel brace I built.
A long time ago, my dad was faced with a similar problem. A building inspector decided that two 7 inch logs was not sufficient to support a structural truss. This was a bunch of hooey, but dad was also driven to get this house built. A few days later he showed up with channel braces that distributed the load else where. I adopted this idea, and created a sleeve to reinforce the area where I cut away material. My dad was a brilliant engineer. I'm just a kid using his idea. I built the sleeve and removed the cradle. Now the everything should fit - right? Nope.

Those bolts that I special ordered from Porsche -  they were short. However, I had one thing that I never had when I looked for those bolts on my own - a Porsche part number. I maintain an office at the NSMC. So I sat down and brought up Pelican Parts. I found the bolts for the 991 transaxle (M10 x 1.0 x 46mm). I also saw in the related listing transaxle bolts for 997 transaxles. A different part number. I clicked on that link and discovered that Porsche changed the bolts when they went to the 991 transaxle. The older bolts are M10 x 1.0 x 50mm. Well what did I have to lose, I ordered 12 bolts. (I have  acquired several sets of bolts that do not work in this application.) I was already a gazillion bucks over budget on this task, what's another $20. My dad was driven to build a house; I'm driven to build a car.

The new bolts arrived. I tested them in the transaxle and they were the correct thread and pitch. They were long enough going through 930 CV. I hooked up the air ratchet and attached the biggest Torx bit I have. Literally, 20 minutes later I had everything attached!

"Never, never, never give up!"
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