Wheel alignment

[Magpie]

http://mx5cartalk.com/forum/viewtopic.php?p=903497#p903497
This is my experience with alignment bolts. Worn out bolts cause alignment NOT to be held, it will move.

Previous experience on the front of my NA6 and not sufficient alignment adjustability was fixed with new lower control arms.

Bolts need to stretch to ‘hold’, this is a given. This is why torque is used, how much will the bolt be stretched. From memory the long bolt is torqued to around 130nm. See how much effort 130nm takes!

A bolt can fatigue when frequently torqued up to high values. This is why alignment bolts fail!

[RS2000]

Steven, does the rear have offset bushes? If so the offset tubes could be located differently either side, & it's possible the mechanic just adjusted the cam bolts without studying the bushes?

[StillIC]

A bolt can fatigue when frequently torqued up to high values. This is why alignment bolts fail!

Fatigue is a term that describes the gradual weakening of a material as it encounters many cycles of loading and unloading or loading and reversed loading.

If steel bolts are designed correctly for an application, and are tensioned correctly, they will last forever. For a correctly designed bolt application, failure generally occurs for one reason: the bolt is under-tensioned, thus allowing the bolt to experience loading and unloading from forces acting upon the bolted joint that it would not have felt if properly tensioned. The extra loading/unloading forces felt by the bolt due to a lack of tension can eventually cause a fatigue failure.

See how much effort 130nm takes!

You betcha!

I believe under tensioning is a particular problem for suspension bolts if they are tightened with the weight of the car on the ground, as they should be, to ensure the rubber bushes are not pre-loaded in torsion. A ramp style hoist helps greatly for this job, but I don't have one. So I find it quite difficult to get full tension on the MX5 suspension bolts when the car is sitting on the ground simply due to limited access and spanner swing space. I bet others do too! I am sure the lack of suspension bolt tension is a major factor in slipping camber adjustment as well as bolt failure.

[manga_blue]

Mind if I ask what specs you're aiming for? I can't imagine anyone wanting less than 2 deg negative at the rear.

[Nevyn72]

"WOW" Iooks like I hit a nerve...

You like to think your the only one on this forum that is 100% correct, the only person that is never wrong, no one dare question your diagnostics...lol

Hmmmm, profile says you have a ND GT......

Is that you Pete?