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Over 300 detail and descriptive articles with thousands of pieces of vital information specifically crafted to help you repair, maintain, modify and improve your Superformance car! We spend a significant amount of time, money and effort to produce this specialized and unique service and support for Superformance owners to increase the value of your car, and value of your ownership experience.   Please Enjoy the complimentary Technical Article Below!

SCOF Tech Article: No. 004 of

SUBJECT: Roll Bar Frame Mount Bulletin

PROBLEM:
On early cars the outboard roll bar leg was not secured to the mount. On later cars a rivet was used to prevent squeaking. Neither will prevent the roll bar from possibly folding upon a catastrophic incident.

WHAT'S NEEDED:
Drill, "F" drill bit (or 1/4" will work), 5/16-18 tap, 5/16-18 grade-5 bolt, washer, black tape, Loctite 271.

DETAILS:
While a 1/4" bolt would probably be strong enough to do the job, the 5/16" bolt provides more shear surface area inside the hole in the roll bar tube to prevent it from "ripping" the metal in a roll over. Even thought the bolt is only affixed to one side and does nor protrude completely through the tube, most likely the force needed to detach the above installation would probably be more than the force required to significantly damage the entire roll bar under those extreme conditions anyway. A 3/8" bolt would remove too much roll bar material in favor of a larger hole to make it practical. Coarse threads are used to make tapping and threading easier than fine threads. Grade-5 bolts tend to have a little more ductility in this type of shear application although Grade-8's can have more material strength. The fact is, most any bolt would work well, and Grade-5 is sufficient.

DETAILED INSTRUCTIONS...

In this unfortunate accident the car was about 10 feet in the air when it landed onto it's driver side which forced the rollbar over to the passenger side, therefore pulling the left side out of the small solid metal stub on the frame. While the other two legs of the roll bar are fastened to the frame with bolts through the tube, this side is  and is not fastened down other than the light duty rivet which was reported to have been installed at the factory to reduce squeaks. Older cars built somewhere in or before 1999 have no rivets at all, but all the cars could take advantage of this simple quick upgrade.

Here is the roll bar mount looking in from the wheel well underneath on an older car. Notice there is no rivet holding this side of the roll bar down other than being just slipped over the solid frame stub.

Take some adhesive tape and wrap it around an "F", or a 17/64 drill bit exactly 1" from the tip of the bit back. This will be your pre-measured drill stop to indicate when you have reached the proper depth and will also prevent you from going too deep.

Drill 1" up from the base where the tube meets the frame rail into the back of the roll bar tubing under the car in the driver's rear wheel well. This will offer the most material under the bolt to reduce the possibility of it pulling out. Drill as straight as possible until you reach your desired predetermined depth as indicated by the tape.  Do not drill all the way through.

Then thread the hole with a 5/16"-18 tap, keeping the tool as straight as possible. Make sure you tap all the way as deep as possible. Most taps are not "bottoming taps", but with a 1" deep hole, and a 3/4" deep bolt with a washer, the threads should allow the bolts to tighten the washer.

With a dap of Locktite #271 on the threads, insert the bolt and flat washer and tighten snugly to approximately 30 ft/lbs.

Here is your finished product! Reinstall the wheel and let the jack down and you have now added security to your roll bar!

SIDE NOTE:

Below another hole was purposely drilled higher up (
in the wrong spot) to illustrate where the top of the solid stub ends, as you can see the gap in the upper hole in the photo below. Drilling 1" above the frame rail should provide you with plenty of  space to avoid missing parts of the stub.