Decklid hinge security torx bolt (Page 1/2)
gregr75 MAY 06, 07:55 PM
Hi guys

I tried removing the T40 size security bolt that fastens the end of the torsion rod to the decklid hinge. i ended having to dremel 2 flats on the head and vice-grip it off... the head sheared off and now im left with a piece of the bolt still in the hinge. assuming i can drill out the piece and salvage the M6-1.00 threads, can i just use a normal M6-1.00 bolt to put it back together?

Reason i ask is this bolt appears to have some unusual geometry. It appears to have a length of shoulder under the head before the threads start and some kind of taper at the end of the bolt.

bolt head side:

end of bolt side:
Stingray92 MAY 06, 08:29 PM
At least on mine they are grade 9.8. Standard bolts I wouldn't trust them/think they would hold up to the cycling of the decklid.

FYI mine are M8 x 1.0 x 30
Stingray92 MAY 06, 08:33 PM
Oops, sorry you're talking about the security strap retainer? If so it's probably at least a 9.8. Sail area can be a real pain at times. Mine are in a box can't get to them at the moment.
gregr75 MAY 06, 08:57 PM
yes its the smaller bolt, 1 on each hinge, that you have to relieve torque rod tension on before unscrewing.

drivers side hinge and decklid are currently off car.

[This message has been edited by gregr75 (edited 05-06-2024).]

fieroguru MAY 07, 06:56 AM
You will want to replace it with another shoulder bolt. Shoulder bolts are designed to allow the bolt to be fully tightened and for the part contained on the shoulder part free to rotate slightly.

McMaster had a bunch of options, but you will need to know the thread length, shoulder diameter and shoulder length. If the threads are too long, you can cut off the excess. If the shoulder is too long, you can add a washer.
https://www.mcmaster.com/pr.../?s=m6+shoulder+bolt
gregr75 MAY 08, 06:33 AM
OK thanks, Unfortunately the shoulder measures .350 inch diameter or 8.9 mm which is non-standard shoulder diameter in the mcmaster catalog. I looked a couple other places too.

I may have to turn down a larger bolt on a lathe. Or maybe slide a custom bushing over a normal bolt.

[This message has been edited by gregr75 (edited 05-08-2024).]

Mickey_Moose MAY 14, 02:48 PM
...or just buy a set of good used ones from someone on here?
cartercarbaficionado MAY 14, 07:15 PM

quote
Originally posted by Mickey_Moose:

...or just buy a set of good used ones from someone on here?


or he could find some off the shelf stuff to help figure out how to remake a bunch of the weird rare bolts. I'm still working on making the tail light bolts for a notchback because it would be nice to buy new ones and know they are obtainable, also working on decklid screws that aren't 30 bucks from the fiero store.
cartercarbaficionado MAY 14, 07:16 PM

quote
Originally posted by gregr75:

OK thanks, Unfortunately the shoulder measures .350 inch diameter or 8.9 mm which is non-standard shoulder diameter in the mcmaster catalog. I looked a couple other places too.

I may have to turn down a larger bolt on a lathe. Or maybe slide a custom bushing over a normal bolt.



I think a brass tube might work over a standard bolt, might need to do a Russian nesting doll approach to make it tight but it should work, turning a bolt down is definitely the easiest though
cartercarbaficionado MAY 14, 09:24 PM

quote
Originally posted by gregr75:

OK thanks, Unfortunately the shoulder measures .350 inch diameter or 8.9 mm which is non-standard shoulder diameter in the mcmaster catalog. I looked a couple other places too.

I may have to turn down a larger bolt on a lathe. Or maybe slide a custom bushing over a normal bolt.



I made a bolt for this like 20 minutes ago for my 84, I took a oil pan bolt and made a bushing out of a thick wall copper tube available at home depot and it worked to fasten my terrifying torsion springs to the hinges (they broke the pin like 5 minutes later and tried to self disassemble)