check old bolts

Just attempted to fasten my drive shafts to the diff flanges. Firstly I dont know which way round the bolts go - one way the nuts are self locking but the other way is shown in the book - anyone know?
Secondly I sheared the head straight off one of them. It looks corroded from the inside - is this a known problem? needless to say I have ordered the new ones but thought this might be interesting to anyone rebuilding.
Incidentally after my disaster with the diff it is now all rebuilt and if you needs parts or info these guys are helpful and cheaper then others for ZF components Andy King [[email protected]]
ps - some members might remember my bad luck with my valve seats falling out - its all rebuilt and running like a dream - keep fingers crossed!
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We'd all be real curious to hear about how the dropped valve seats were fixed. Did the mechanic that fixed it have any comments about why that happened? was he the one responsible for it? It was an interesting thread- glad you are back on the road!!

 

I took an extremely pragmatic view on this event, the one thing I was not prepared to compromise on was being on the road for spring 2011. I spoke to Ron at Superformance and went with his recomendation re machinists. Within 5 weeks of the failure I had the heads back with yet more guides, seats and valves. I also took the opportunity to have it all balanced and a new damper fitted. I spent most weekends on it and eventually took a weeks holiday to work solely on the car with my son, I got it back on the road end of Feb. The original guys did a good job of welding the old head but got the interferences wrong for the seats - they offered to redo it all for free - but I couldnt trust them and I wnated it quickly, they have agreed to weld up another head I have gratis. It cost £2K to get me back were I started and another £1k for extra balancing / damper. To complete the catalogue of disasters I discovered I had assembled the crown wheel in the diff the wrong way round - my mistake and not recomended. Another £2K.
The good news? It runs like never before and I have had a great time with my 16 yr old son getting it back going. However I now have to reintergrate back into the family!

 

I hope this picture help you.
Alvaro
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Wow, I've never seen a fracture like that before...Almost looks it was damaged during a previous installation but didn't fail completely, then you finished it off. But the discoloration is odd too.

Any engineers want to tackle that?

 

Righty tighty lefty losey....looks like it was overtorqued in the past, or crappy steel to start with!

 

Take a piece of black board chalk and twist it - pure torque without pulling (tension) or pushing (compression). It will fail with a 45 degree spiral fracture. This bolt appears to have failed in the same way. A spiral fracture is classic for torque-induced failure of a solid cylinder.

Frequently seen on x-rays of femurs at the base of ski slopes.

Jim S.

 

Seriously recommend ALL the books by Carroll Smith, he explains quite succinctly why things mechanical fail, and why they do not, and Jim.... no bones ;-)
The man, is a myth in racing circles, he really knows his stuff and dispels all sorts of myths and hallucinations.

Google him, and if mechanically knowledgeable or not, there is so much to learn...good writing and entertaining too!
Pegasus Racing (.com) has the whole series.

Regards, Alberto