Structural Question, crossmember bolts in sheer or tension? Options

[cooler]

hello 914 structural experts,

I am planning to create a new crossmember to stiffen rear suspension and support engine. The 914 rear suspension console is well known to flex under racing stress and was reinforced by factory racing teams. I intend to address the flexing issue and create engine (Audi V8) mounting locations with a new crossmember and diagonal tension members. The attached photo shows the location of crossmember (red) and diagonal tension members (blue).

The crossmember spans between the suspension consoles, on center with the trailing arm pivot axis. The diagonal tension members span also from rear suspension consoles to firewall, near center tunnel. This assembly will need to be removable to facilitate engine removal and is intended to stiffen the entire engine bay/rear suspension.

I am struggling with detailing the crossmember bolted connections at suspension consoles. I assume each connections should include two bolts each but, should the bolts be loaded in shear or in tension? What size should the bolts be?

Thanks in advance

[PatMc]

Not a vehicle structural expert...but I know a thing or 2 about fasteners. Bolts are never (or should never be) in shear.

Regardless as to how you design the joint, if the fastener is sized and torqued correctly for the loads at hand, and your joint has sufficient purchase, the clamped joint should deal with all the loads and the bolts won't know whether it's under load or not.

If the bolts in a joint were subjected to cyclic loads, they would all experience fatigue failures, and they don't....most of the time.

Bolts that are in applications where they act more like pins can and do wear. Bolts used in applications where the are used as bolts should not experience any wear or cyclic loads whatsoever.