My name is KC Moore, and I have a problem...
 

I have a problem with breaking axle shafts on German cars. I just this last weekend broke the left half-shaft of my '74 911. On New Years' Eve, I broke the left half-shaft on my '93 BMW 318i. What's the deal? Are these just like the weakest part of German cars? I haven't driven these cars any different than my previous Honda or Nissan cars, and they never had any problems.

I'm about to order a new half-shaft for the Porsche, but wanted to get some input as to what I can buy that would be more robust for my '74, if anything. Are there any newer, stronger, 930-type parts that will bolt right on? Has anyone else had this problem before?

Sincerely,

German car destroyer.

I wonder if they are designed to break instead of damaging your gearbox. We had 60's and early 70's Land Rovers and they were that way.

Uh, what, may I ask, were you doing when this happened? I'm thinking it wasn't "Pulling out slowly.":D :D

pic...
 

Well, I was just slowing down to a stop sign when it finally gave out, but I have a feeling that the stop-light burn-outs had a hand in it. The sad part is, when it came out, it took the left heat exchanger and throttle linkage with it.

http://www.sunflower.com/~kcmoore/shaft.jpg

http://forums.pelicanparts.com/uploads/he2.jpg

Hmm, shouldn't be an issue. I have heard that BMW's are always in the shop, so that would explain that problem(and the fact that it's not a Porsche), and your other car is almost 30 years old, maybe it was just it's time. These cars are pretty robust, unless you are trying to match the magazines 0-60 times and launching really hard you shouldn't have a problem with normal half shafts. Many people have put much more powerful engines in early cars. I hear more about transmission problems than half shaft problems.

Old age...
 

That's true...this car is old. I guess I should expect some failures, especially after putting in new rings and head gaskets, and a performance muffler. I'm not real worried about replacing the half shaft, because it's pretty cheap, but now I have to get headers sooner than later, and somehow make a bracket to hold the throttle turnbuckle since the other one was ripped out of the tranny housing. Oops.

front wheel drive cv's will click and clack on corners a long time before they break. most vibrate like the dickens when they are worn.

i thought i popped one last night in a loaner 944 (f'in junk mobile).

the guy that works on my cars had the 72 axle cvs machined for bigger balls. (cannon axles which moved from knoxville to nashville).

where are they breaking?


oooh . carnage pictures. tell your insuance guy that you ran over an animal and see what he says.

we used to hulk up on the parking/rear brakes and smoke the tires off the rims on the front drivers in the younger days. $700 bill from the honda dealer for two front half shafts put a stop to all the fun.

Re: pic...
 

There's your answer. These cars are not made for "burn-outs", engine and trans directly over drive wheels provides too much traction for this. The Germans never figured owners like you into their design parameter, something about them being more impressed w/ great road cars than ones that do party tricks. :cool:

KC,
Is it broke or did the bolts just back out? Mine backed out on me and almost gave me a heart attack. I was sitting at a traffic light and got the green. I was actually going to pull out slowly when just as the car began to move, BANG! It let go at the wheel. I was very lucky to be at a stand still or it would have been more like what you encountered.

Warren(Early S man) swears on replacing the washers and NOT re-using them. They are not worth the risk. I bet he pipes up with the part number.

Right Warren?

Hmmmm does the phrase "preventative maintenance" come to mind? You just can't buy a 30 year old car and not expect to give it a thorough going thru before you decide to go out and abuse it. Expect more of the same unless you are willing to put forth the time and money to bring the car up to safety specs.

...
 

Well, after further inspection, it looks like the bolts did indeed back out, but when they did, the drive axle spun around and whacked the heat exchanger and took out the throttle linkage, thereby ripping the boot and releasing all the grease. I'm gonna replace the whole thing anyway, just to be safe.

As for the insurance, I only have liability because no one around here will insure a 28-year-old car with full coverage.

I'm really surprised at some of the other comments concerning my driving. These cars were designed to be driven, and driven like racecars, not Studebakers. For those of you who drive your Porsches slow and cautious, shame on you...you should have bought Mercedes.

Oh, we have guys here who drive anything BUT slow & cautious...Mike Marshall, Jack Olsen, well, the list goes on of guys here who track their cars...TRACK is the key word here...and you know, I doubt any of them like to do "burnouts". But if your car would pass tech, I'm guessing they'd be willing to show you the fast way around places like Mid Ohio, Thunderhill, Laguna Seca, and others. If burnouts is your thing, I'd suggest buying a car designed to do them... rant over...

I deffinately would not replace the whole thing, meaning the half shaft, that would be over kill in my book. i'd replace the CV joint and make sure that you torque the bolts right and make sure that they are the right length.

Paul

Re: ...
 

I've seen lots of loose 911 CV bolts. The threads have to be totally clean and then tightened in a star pattern.

These car were designed to be driven, even raced, but drag race starts on these cars is simply abuse because they aren't designed for it. The clutch will slip before the tires will. In the case of pre-'72 cars with their 901 transmissions, 1st gear hangs off the end of the mainshaft. As a result, drag race starts in first may may snap the end off the mainshaft.

-Chris

Same thing happened to me about a year ago, but two of the bolts sheared off in the trans hub. Now CV inspection and checking the torque is part of my monthly maintenance routine. This just happens all too often.

...
 

Here are some clips of people who disagree with the rest of you.

http://www.sunflower.com/~kcmoore/911burnout.mpeg
http://www.sunflower.com/~kcmoore/911burnout2.mpeg
http://www.sunflower.com/~kcmoore/0-160.mpeg
http://www.sunflower.com/~kcmoore/modena.mpg

"Here are some clips of people who disagree with the rest of you"

Justifying stupidity doesn't make it right. Very few cars were designed for the abuse of a burnout, it appears from your comments about a similar problem with a BMW that you do not own one of them. But what the heck, its your money, abuse away but you may want to migrate towards a Mustang or such

Dude, you need to get a ride in a track prepared 911 by a fast driver on a scary track sometime, that will shut your ass up in a hurry. Without even doing any burnouts. :rolleyes:

I used to judge a performance car by its ability to roast tires, when I was about 16-18, yeah, the less traction the better the performance, right?

Once again, these cars became famous for not breaking in hard core endurance racing situations, like 24 hour flat-out races, but the right idiot can break anything.

We've helped you through some pretty mind-boggling ignorance already on this board, what's the use if you won't listen? :cool:

EDIT: I apologize for the tone of this post, but I am going to leave it up so that everyone can see an example of how not to address a fellow BBS member.

Hey KC....is your car actually *running*?
Last time we heard, I thought you timed it to run on 3 cylinders(?)

Anyway, drill the bolts and safety-wire them.
Enjoy the burn-outs. You'll be asking us about a clutch next.
;)

I repacked my CV's a couple of months ago (okay, only 1K miles). Past weekend I checked the axle bolts and was able to tighten the right side (300+ foot-pounds or me hanging on the cheater bar 2 feet out). All the CV bolts were at torque spec - the G50 bolts are a little bigger and torque tighter.

Like Paul says, it's something on the annual check list...

The bolts backed out on mine a few years ago and did the same thing, a big bang coming out of a parking space, breaking my starter off the motor. I attribute it to pulling my motor and trans out myself a couple of years prior. Speaking to some Porsche mechanics, those bolts must be torqued properly, and really tight, or they will back out. It's supposed to be fairly common knowledge. I just tightened them like normal when I put the whole thing back together. Nevertheless, I just bought all new bolts and washers, and replaced them all, and torqued the hell out of them the second time around. Double check them a few months later to make sure they are still tight.