If you could put titanium lug bolts on a 308, would you?
Do they stretch like the steel? If not what would you torque it too? Are the more brittle then steel? Sent from my iPhone using Tapatalk
They seem to be a option on all new Ferrari models. Titanium is as strong as steel but much less dense. It is therefore important as an alloying agent with many metals including aluminium, molybdenum and iron. These alloys are mainly used in aircraft, spacecraft and missiles because of their low density and ability to withstand extremes of temperature. They are also used in golf clubs, laptops, bicycles and crutches. Power plant condensers use titanium pipes because of their resistance to corrosion. Because titanium has excellent resistance to corrosion in seawater, it is used in desalination plants and to protect the hulls of ships, submarines and other structures exposed to seawater. Feddan is selling a 308 set in the For Sale section, https://www.ferrarichat.com/forum/threads/ferrari-308-titan-wheelbolts-400-usd-incl-shipping.565539/
The question remains: what are the proper torque values? Titanium lugs have downsides as well. Galling, thread contamination... and the weight savings isn't drastic. Cheaper for the driver to lose 5lbs.
Had to look up those. Here is a good explanation of galling. Not sure if its a downside enough side to rust. https://www.fastenal.com/en/72/galling As for the torque values. Here is a nice article on comparison of torque expression if you are really concerned. https://www.ncbi.nlm.nih.gov/pubmed/20578859
I was surprised by the weight of the originals but $400 for a set of Gr5 Ti bolts seemed a bit steep for a couple of kgs saved.
I am not trying to knock anyone that wants to make an improvement on these cars, but I don't get the benefit. No one can drive a car with these bolts and tell it has these bolts. There is absolutely zero performance benefit, frankly you get more out of taking a piss before you drive the car to reduce weight. Only fill the tank 1/4 instead of full, etc. My questions being what part of the factory bolts are causing problems that need to be corrected and why is this a better material to address this problem because there is no performance advantage being brought to the table.
The bolts are unsprung weight so affect the suspension and because of the rotational inertia of the wheel (and bolts) any savings of weight is equivalent to about 1.6x any weight saved on the non-rotating mass of the car when accelerating or braking.... so unless your bladder is a lot bigger than mine, it's a bit more effective than taking a piss
I was thinking about this concept the other night. Since the bolts are close tot he center of rotation (wheel hub) would that effect of (lessening) rotating mass, the 1.6x weight saving be different if they were further from the wheel hub or is that a constant? As an example if I put a weight on a 2" string, swing it around and hit you with it it's not a huge force. If I put that same weight on the end of a 2' string and hit you with it it would be much worse.
The weight savings is negligible. I doubt you'll notice any difference in acceleration nor braking, that could not just as easily be attributed to road conditions. We're talking about a 32 year old, 240ish HP car here. Further, Ti lugs will not be as strong as steel lugs. Ti lugs look nicer, and don't rust. That's about the extent of advantage. If one wishes to spend $400 on Ti lugs - it's your car, your money, your choice... but do be aware of what you're gaining, what you aren't, and what you're losing.
For what its worth in the race car we're running ARP studs and aluminum lug nuts. zero trouble in 3 years. its a non-Ferrari, but we do run sticky tires and have several national trophies. driver can't tell with just the lug nuts, but it is part of saving weight where we can, and overall it makes a difference
I could give you the keys to 10 308's and not tell you which had them and which didn't. You could drive a tank of gas out of all of them and you still couldn't tell me which had them and which didn't. That is my point. But, hey, if people want to hand out $400 for these things, I'm all about the free market. Have at it. More power to them - as long as no harm comes out of it.
Come to think of it, an average wheels rpm is about 1000 (about 75 mph) so, I don’t know the math formula but an ounce of weight spinning of about 1K rpm, the rotating mass or inertia can end up in lbs.
I would never notice and probably nobody would. As Meister pointed out it's probably less than 1.6x as they are nearer to the centre than most of the wheel. Still more than my bladder can hold It did seem a bit strange to me to have magnesium wheels and then those heavy bolts. My '69 911E has lovey light aluminium nuts to match the forged Fuchs. I was thinking of getting the Ti bolts, knowing full well I would not feel the difference... until I saw the cost. I also balanced my internals beyond what is noticeable given the cross-plane harmonics. Some people draw comfort from unproven celestial beings of one flavour or another, I find comfort in illogical attention to detail. If you saw my desk you'd beg to differ.
What would the concern be with using titanium bolts? Is there any downside, including any valid theoretical ones whose problems my only present themselves years and years down the road ? In other words, what is the absolute worst thing that could possibly happen?
Galling is a problem. Even with hard anodising and a good high temp lube, the threads would not last as well as steel/steel. Not an issue if you are not changing wheels often-- if you are changing often due to racing, you'd probably monitor and change them.
