[eewink]

bolt above had damaged surface area. Will need more torque than factory specs to create enough friction to prevent slippage. That is why old bolts like CortinaD's fell off even when torqued properly.

Bolt thread below is new and has lots of threaded surface area so lots of friction generated by same bolt tension.

[CortinaD]

I thought that a bolt stays in place not primarily from the friction on the threads. That is what I have read superficially anyway.

A bolt stays in place by bolt tension (the force acting along the long axis of the bolt). If torqued correctly, the bolt tension is what forces the threads against the other mating thread screw hole surface. Even with expansion, vibration etc, if there is sufficient bolt tension, the force on the threaded surfaces will generate enough friction to prevent slippage and thus holding the bolt in place.

Measuring torque when tightening is actually a surrogate for determining bolt tension. Not a perfect measure but good and practical enough. Any rocket scientists here in the forum or am I just talking fucking bullshit?

I dont know the science behind that first document makes sense to me because I know the application of goop on nuts for head studs for example, means you must reduce the tightening torque significantly otherwise you will over do it.

[ferrarifixer]

You just gotta keep checking the torque.

The harder you drive, the hotter it all gets, the more likely it'll come loose.

Just keep a torque wrench in the car, and check them after each drive, and try to drive very hard for a while. But of course, that's difficult.

The 430 scuds are prone to coming loose, apparently, although i haven't seen it myself.

I have a few cars with ti bolts, I look after, but I tend to swap wheels a few days before a track day (run track tyres) then swap them back a few days after. I haven't had any of mine come loose, but they haven't been on for long when i check.

I'd be more inclined to have concern after say over ~1000km of running.

I do know that the 355 twin turbo car spits its wheels off if they're not done up to ~120 lbft, rather than the normal ~80 lb ft. And they're std bolts.

Personally, fitting ti bolts to a non ti original car is a waste of time IMO, just buy the Hill Engineering items if you want quality.

BYW, I'm a Hill agent and get superb prices which i pass on

[TiKORE]

Hi everyone.  I just wanted to stop in a say a few things. I am not currently a forum sponsor so if you have additional questions feel free to email me directly jfierman@tikore.com. I was reading over some of the concerns regarding thermal heat expansion and yes titanium does change at a different rate than steel.  This has yet to cause any problems on any of the cars that are running our product.  Some of our clients cars include: vividracing's 200 mph 997TT, BPP Corvette race team, and a brand new 599 GTO.

Here are some additional facts about our product. We only use aerospace certified Grade 5 6AL-4V titanium which has very similar characteristics to a grade 10.9 bolt (most OEM lug bolts).  Titanium is 45% lighter than steel and has excellent corrosion resistant properties (ask the Porsche guys how fast the OEM bolts corrode) and our threads are rolled not cut.  Most people say the weight saved is minimal. This is true but the weight saved in this case is unsprung and that has additional benefits. These bolts are definitely not for everyone, but what we wanted to do is offer a great product that was more affordable that the alternatives. If you have some free time just price out a Titanium Lug bolt from Ferrari and you will see what I mean.  Thanks for your time and here is a pic for your enjoyment.

Justin