1990 Super Seven roll bar bolt question

[greasymonkey]

I just noticed I'm missing both bolts that hold the standard roll bar hoop to the mounts behind the seats.

 

I'm looking to buy replacement bolts, spring washers, and flat washers. 

 

I want to make sure I understand correctly, with 4pt harness, I should get 7/16" UNF x 1" screws, NOT the 5/16" UNF x 1" screws that would be used if I had standard seat belts. 

 

The Assembly Guide says the following, which, is confusing. (note: I have 4 pt harnesses installed)

 

"6.11 Standard Roll bar
This is best fitted after any work required in the boot and before fitment of the boot cover.
The roll bar attaches on top of the seat bulkhead and inside the rear of the boot.

 

a) 5/16”UNF x 1” set screws and spring washers are used into the seat bulkhead,
tighten to 20-25 lbft. The rear legs locate into the chassis brackets in the boot and are
secured using 5/16”UNF x 2” bolts, washers either side and nylocs, again tighten to 20-
251bft.

 

b) Fastening of the forward ends is dependent on the type of seat belts being fitted.
Static three point lap and diagonal belt:

 

The rollbar is secured using the same bolt as used by the top seat belt mount. The roilbar
is fitted underneath one of the thinner seatbelt spacer bushes. The seatbelt bolts are
tightened to 40-45 lbft.

 

Static four point harness:

The rolibar is secured at the front by 7/16” UNF x 1” set screws and spring washers.
Tighten to 20-25 lbft."

 

Thanks!

[IamScotticus]

If it helps, my 95 chassis was built as a racing Live Axle (makes a difference) chassis so i have 4 point bungs installed which are directly behind the headrest.

 

If I didn't have these, or didn't use them,  the roll bar mount bung (pointing) would be used with the top seat belt strap attached to the top of the roll bar mount.

My chassis was built for an FIA roll bar so the bung is 7/16-20 tpi.  If it was intended for a "standard" road bar, it would have a 5/16 bung.

 

I wouldn't let the build manuaI throw you on the threading.  These cars can have a variety of variations.  Your friend is a set of thread sizers like the one in the bung. 

https://a.co/d/09u6gMPR

Check everything to know what sizes and thread pitches you have.  Use a set of thread chasers to clean and deburr threads.

 

The bolts you buy to use should be high quality and never plated steel.  Never stainless steel for safety applications like this.

 

Know that most threads come in at least two different pitches

Edited Monday at 02:27 AM by IamScotticus

[IamScotticus]

On harness mounts there are center standoffs to keep the buckles off the frame and swiveling.   Also eye bolt and gate latch types.

 

 

 

If you can, I would follow the bottom of the bolt with a nylock nut and washer as a safety against shear and walk out.

Not tight. 20 lbs ft is 6" wrench snug.

 

Edited Monday at 03:24 AM by IamScotticus