msd1107 wrote:Look at the fixing torque for the nut/bolt. Calculate the stress on the threads and shanks. If the stresses are less than what aluminum can withstand, use replacement aluminum ones. This saves 2/3 straight away.
If you are using lock washers, use self locking nuts, safety wire the nuts, or use a locking gel or some form of LockTite..
Source nuts 1/8 or 1/16 smaller and tap them out to standard size.
Source 1/2 height nuts (if there are enough threads engaged).
Measure how far the bolt protrudes from the engaging nut. Source a bolt whose length is barely longer than what is necessary to fully engage the nut (or else cut the bolt to length and re-cut the thread).
Source 1/2 height Allen head bolts (or thin the bolt heads and drill the center). (note: for thin headed bolts and nuts, you probably want to use 6 point sockets).
Depending on how the bolt is used, waist the bolt shank (some bolts can be sourced already waisted) or drill the bolt shank so the calculated torque is below the yield strength of the bolt.
David
1968 36/7988
I use aluminium bolts wherever possible.
I will use titanium wheel nuts saving around 40%.of rotational mass. Saving on rotational mass is always good.
Lock washers are usually a waste of time and weight. I use half height nylocks with 1 1/2 threads protruding .
I turn down bolt heads and centre drill where safe to do so. Not keen on wasting shanks as this is where most of the strengh lies. I leave suspension bolts alone apart from slight skimming of head and keeping length to a minimum.
I like to have a bolt thread engagement of a minimum of 1 1/2 times the bolt diameter. EG for a 10mm bolt 15mm of thread engagement. This is nowhere near the recommended minimum but I feel comfortable with this extra margin of safety.
One racing trick I am using, but you will need an understanding MOT man if car is to be used on the UK highways, is to use only 3 bolts on a 6 bolt CV jonit. The other three are replaced with short studs that engage only with the first flange. The stresses are sheer only and you still have 6 sheer resisting points. This saves around 35-40% of the rotational bolt mass.