does it matter for sva how far the harness bolts go into the threaded tube mounts.
the bolts are about 35mm long and the mounts are around 55mm so when you look from underneath the bolt does not go all the way thru

no, 35mm is more than enough thread engagement

most production car seatbelts mount through a bolt in the bodywork that is around 10mm thick…




[Edited on 7/1/09 by Mr Whippy]

CHEERS WHIPPY

make sure the harness bolts have a Grade stamped on them need to be 8.8 IIRCC.

During my sva the examiner commented on the MK Indy top mounts as these are a weld on boss welded onto the side of box rather than through it, but he did pass them.

A rule of thumb for length of engagement into threaded holes is that it should be one and a half times the bolt diameter as a minimum. This is the case for steel anyway, if it is into something like brass or ally it should be nearer two diameters.

I don't know how this compares with the SVA minimum requirements, I should probably check!



[Edited on 7/1/09 by andylancaster3000]

Worth checking out this link.

Page 66: Seat Belt Ancorage Strength Assesment
http://gtslocost.locostsites.co.uk/documents/pdf_files/sva_manual256742.pdf

it seems to me if you are bolting the seatbelt through a tube (roll bar)
the bolt needs to be threaded all the way through.



[Edited on 7/1/09 by dogwood]

Whether you are going through the roll bar or through a tube welded to the roll bar or through a plate with a welded/captive nut or even just through a thick steel plate with a nut which is accessable by one person to both ends of the nut and bolt, the bolt must pass through and out the other end with the minimum thread showing

We failed out SVA 6 months ago as the examiner at Mitcham said we did not have enough bolt length going into the threaded inserted tube in our cross rail on the roll bar. We had 38 mm bolts of the correct grade so i had to hunt around to get 4 different types from stainless of the full length 50 mm, others i took with me were to 8.8 grade that were 45 mm and two others with no markings. We fitted the stainless and he passed it on the retest. Seems crazy when you consider what tin tips have. But as it was not the only point to fail on it was not worth getting ito a row over and any easy fix.
Richard.

so for SVA purposes id better get some 55mm - 60mm 7/16th bolts