About DTM Power
Why not to use titanium for wheel nuts
Titanium, whilst lighter than steel, has a lower tensile strength and a lower modulus of elasticity, so for correct design the part
would need to be larger to perform the same job as a steel part, and that’s just for mild steel. If the replaced part is any
type of high or very high tensile strength steel, the titanium part would need to be much larger, and the weight saving has gone.
BUT the big problem that has triggered this article is corrosion. Many think that titanium does not corrode, wrong. Recent experience
with Porsche wheel nuts proves that it does. I have just spent a whole day taking one wheel off a 993 with some damage to the wheel
itself resulting from the process. All the wheel nuts on this car, (apart from the 4 locking ones bizarrely!) were badly corroded
to the extent that the corners fell straight off the hex when removal was attempted. A couple came off with a single hex socket,
but most of them just rounded off into shards of corrosion. Next step was to hammer on a smaller socket, which got all but one
off after a few attempts.
The last one failed at that point and the nut itself snapped off leaving half of it in place still holding the wheel on inside the
spherical seat area of the wheel.
So the animal tools came out... First the left hand threaded scroll tool designed for removing damaged locking wheel nuts. This
removed some more material but did not loosen the remains of the nut. Then the hammer-on left handed damaged bolt remover,
still no luck. Eventually the only option was to drill the stud out and this took a while! The wheel stud is a tough high
tensile steel so quite a few drill bits got used up in the process. It got out to a 10.5mm hole down the middle of the M14 x 1.5 stud,
a bit off centre, and some load on the wheel snapped the remains of the stud off, and the wheel was free at last!
Some more reasons not to use these Ti wheel nuts:
Titanium is particularly bad at galling and brinelling so good lubrication is vital and usually ignored with wheel nuts.
Seizing or cold welding is the result.
Differential metal corrosion (a bit like the way Land Rovers dissolve as they are steel and aluminium in close proximity).
What is the answer? We have used VW campervan wheel nuts on racing Porsches and Ferraris for 30 years with no problems, they are cheap and
easy to find, at 14 x 1.5 thread with a spherical flange face they are just the job. If appearance is important they can be plated,
bright nickel is the best as it is more flexible than chrome and lasts longer than zinc. Or use plastic covers, but be sure to coat
them in silicone grease (not sealant) first as the covers hold water and speed up the corrosion...
The weight saving found by using them is so small as to be insignificant, how much quicker are you going to go with Ti wheel nuts?
You won’t even measure it let alone feel it!