FredR

Don,

The job looks more intimidating than it actually is the only caveat being that it is significantly more difficult working from axle stands than a lift. Besides the need for a strong 3/4 inch drive 32mm socket and big lever arm to undo the stub axle nut you need a good 8mm allen key to get the flange bolts which need to be cleaned before attempting to undo them. The best kit for this will be a 1/2 inch drive 8mm impact hex wrench socket and about 3 extension pieces to facilitate manipulation from the side of the car- a single long extension piece about 2 ft long would be ideal if such is available.

Last night I also noted a post from Doc Brown on another current thread advising that the half shaft nuts are a "single shot" affair so I may have to attend to this in due course. I did not pick this up from the WSM or see such mentioned in other threads so a consideration when preparing for the job.

Finally, I would recommend owners to pre-emptively attack this issue based on a time interval of 10 years. I studied the removed boots carefully and one could see the boots were well on the way to splitting in the folds of the bellows with surface cracking of the rubber rampant so do not be tempted to repair only the ruptured bellows- make it your mission to do so before the thing let's go. Do this and the joints will probably last forever but run them contaminated with road crud grinding paste and I guarantee the will go in no time squared.

Regards

Fred

Bill Ball

Small correction: Someone else (Wally?) noted long ago that the conversion from Nm to ftlb for the axle nut torque is incorrect in the WSM. It should be 340 ftlb. BUT I'm the guy that jumps up and down on my 300 ftlb torque wrench a couple of times after it clicks to get the extra ~40 ftlb, so I have little claim to be a stickler about this. I've seen a few loose axle nuts (not on my car), but I seriously doubt this small discrepancy accounts for that.

FredR

Bill,

Interesting observation- Just worked out the conversion factor and indeed 340 ft lbs is the imperial equivalent of the metric version.

Now the question is which number did they start from? One assumes that as the engineers were based in Krautville they would have started from metric but..?

I will give mine a check to see if it is still at 322 ft lbs at the very least.

Sounds as though you need a big *** torque wrench like mine -I think it goes to 370 ft lbs and it was not too expensive all things considered. There again 300 ft lbs and a good wallop with a lump hammer should do nicely.

I purchased a 3/4 inch drive socket set, a 3/4 inch breaker bar, a 3/4 inch sq drive torque wrench, a set of 3/4inch impact sockets and a 3/4 inch windy gun just to make sure I could do that nut and Porsche couldn't get the torque figure correct- durrgh!

Rgds

Fred

Bill Ball

Yeah, it's 340. I corrected my initial post of 341. I use 0.74 conversion factor when actually it's 0.737562149.

Anyway, it's less likely that the error is in the Nm column for 2 reasons. 1. That's the original spec before conversion. 2. If 322 ft lb were correct, then the Nm value would be a strange number: 437 Nm. I wouldn't worry about it. I ran 322 for 10 years and 150K miles before I learned of the error. I finally did buy a 350 ft lb torque wrench. Prior to that I used one extra jump on my 300 ft lb'er to get to ~322 and 2 jumps to ~340. Hah, hah.

Also, it's strange to find, considering how precise the German's are regarded as being, that many other conversions are off to some degree more than just rounding variances. Sometimes the conversion ratio appears to be 0.70 while others immediately succeeding that in a list are 0.72. For MANY/MOST nuts and bolts I am not of a mind that the values are critical, to the precise ft lb, so I don't usually check the math and I never worried that I was at some risk with the axle nut torque approximation kludge I used with my 300 ft lb torque wrench.

FredR

Bill,

Knowing something about mechanical engineering I would think that there is plenty of margin in the design stress range such that at 322 ft lbs the joint is not likely to fail [unless you supercharge ha ha].

Herr Fritz is only human and just as prone to making mistakes as the rest of us! Remember the Volkswagen scandal!

Reminds me of the story about the famous German watchmaker. A chap I knew in England had a beautiful hand crafted watch made in Germany given to him as a present when he left the armed forces stationed there. Trouble was only the company that made this watch could repair them. One day his beautiful master piece developed a very strange problem in that it would only tick so instead of going tick- tock, it went tick tick etc. So he had to send it back to the factory who returned it fully restored to normal about a month later. He was rather intrigued by this and asked them how they fixed it
- they replied "We have vays of making zem tock!"
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Rgds

Fred

Bill Ball

Good one, Fred. Carry on!

Charley B

Are you saying the axle nuts are a one time use?

Adk46

That's the gospel. But if it were critical, there would be many tales of woe. I'm relatively new here - have any failures been reported?

FredR

I take note of anything the good doctor says. Not always possible to follow the mantra given my distance from parts etc so in my case I take the precaution of cross checking. On critical fasteners like the nuts on the con rods I would replace them- no ifs or buts. On the stub axle fastener at least you can check it and if the checks prove it is holding then maybe you can get away with it. These self locking nuts are generally a single shot affair and many re-use them - does not make it right though.

As an owner I can afford to take the risk- the professionals who lose sight of the vehicle the moment it leaves their premises cannot- that is the difference- especially in a litigious society.

I take the position that you might get away with one small sin but committing multiple errors at the same time will be less forgiving thus why I was a bit concerned when Bill pointed out the error in the torque conversion figure in the WSM.

I intend to check the torque this afternoon all being well and if it is still at 322 ft lbs will bang it up to 340 ft lbs.

Rgds

Fred

ltoolio

At ~$5 per nut, following Dr's advice isn't too expensive here. Assuming of course that said part is easy/timely to get give your geographical proximity to a supplier.