would drilling 6mm into chassis rail to fit m4 rivnuts weaken the chassis too much?

[Edited on 28/7/10 by femster87]

depends how many you put in and the distance between them.

Depends on what part of the chassis too.
Im sure ive read 4mm is the prefered hole size.

I cheated - i welded in threaded inserts all the way through instead of rivnuts so as not to weaken the chassis / leave a hole into the box section.

Mcgill motorsport have them quite cheaply on ebay.

about 5 on both top rail along the tunnel for fuel line and brake line

Hi

I intend to weld on small plates to act as mounts for such items - not a fan of rivnuts - too many years in the aircraft industry!

Regards Mick