Q. Are the spacers the type which bolt to the hub and the wheel to the spacer..or the type which requires longer bolts to pass through the spacer and into the hub?
The best spacer is the one which bolts to the hub, with the wheel bolted to the spacer...Obviously, this requires the spacers to be sufficiently thick to accomodate the full length of OEM wheel bolts.
It is a fact that the greater the number of "faces" which are being held together by a single fastner, the greater the torque required to keep the faces stable.
ie. Under OEM conditions, you have 2 faces mating...the hub and the wheel rim. Fit a spacer, and you have doubled the number of faces to 4...Technically the bolt torque required to maintain the same stability as for 2 faces is 8 times normal torque.
If you choose to use spacers with longer bolts, it is advisable to have the spacer and hubs drilled with at least 3 hole triangulated accurately and the hub holes threaded internally. Then fit flush coutersunk bolts to the 3 new holes, and then you can safely use longer bolts which pass through the spacer and into the OEM bolt holes.
Fortunately, there is already 1 hole in the hub into which a scew is fitted...this holds the brake hub / disc onto the car...you will need a longer similar screw and the spacer drilled and the hole countersunk to accept the head, plus at least 2 more new holes drilled etc as described above.
This is especially important if you're the type of driver who enjoys pushing the envelope through the corners !!
Finally, if you read the manual, it gives you the correct OEM torque for wheel bolts...This is important because a bolt which is over - torqued. is under huge stretch stresses...it will be more inclined to snap than one with less torque applied. With less torque, the bolt is able to flex without breaking. As you corner, the stress on the bolt is to stretch as it approaches and passes the 90 degree position, and then that stress is relieved as it approaches and passes the 270 degree position. That happens thousands of times per minute...so the alternating stretch - relaease etc etc...will cause metal fatigue. It's the same principle as in aircraft bodies which are subjected to being internally pressurised and de-pressurised as it reaches altitude and then lands. That "breathing" effect causes metal fatigue and micro cracks begin to appear, which ultimately result in failure.
Hope this will help you to make some progress to resolve the problem...
With the spacers fitted, they work fine. No bolts have broken off when the spacers are fitted to the front wheels! Also, they are 16" steel wheels compared to my 18" summer alloys.
