It’s no secret that bolts come loose in the engine compartment; we’re always wondering why seven of the eight bolts are tight, but that one bolt seemed to magically spin and loosen up even though we know that we torqued them all down equally.
Stage 8 Locking Fasteners
Hex head – steel
American grade 8
Metric grade 10.9
12-Point – 4140 alloy steel
American grade 9
Metric grade 12.9
Stainless steel by customer request
Standard – aluminum
High heat – stainless steel
American grade 8
Metric grade 10.9
E-clips – nickel plated spring steel or stainless steel
One of those problem areas is the exhaust system. The constant temperature change from hot to cold to hot again causes metals to expand and contract. Add to that the vibrations of the engine, the jolts from hitting bumps (and sometimes just Murphy’s Law in general) and you have a need for a bolt kit from Stage 8 Locking Fasteners.
Stage 8 has been around since 1985 when President and Founder Bruce Bennett was trying to figure out a way to keep the bolts on his Harley from backing out – especially the exhaust pipe bolts. Vibration is just part of the package when you have a Harley, and Bennett went to work to fix the problem.
After several different designs, he finally came up with the locking fasteners you see here. It was a simple, yet very effective way to make sure that bolts stay where they’re supposed to, and that they don’t back out due to vibration.
The Harley was eventually sold to raise money for his new company, as he saw there was a dire need for this new product. Bennett decided to name this new company Stage 8 Locking Fasteners in honor of his late canine companion, Eightball, who had faithfully supervised the project in Bennet’s garage.
These days, Stage 8 Locking Fasteners are a household name and very well known in the automotive industry; fasteners include performance, off-road, industrial, railroad, and military applications. Bennet had even developed a screw used for eyeglasses that was so effective it negatively impacted sales for the glasses company. This new fastener more than quadrupled the life of eyeglasses by keeping them from breaking, so the company reverted back to the more defective screws so they could sell more glasses when they broke after a few months.
No matter how you lay it out, Stage 8 Locking Fasteners perform a much needed function that keep bolts torqued down and components in their place.
Tighten, Torque, Lock It In
The concept behind Stage 8 Fasteners is one of those “why didn’t I think of that” ideas. It’s simple, yet very effective in keeping bolts where they need to be, without worry of them loosening up – or worse: backing out completely.
The bolts install like typical hardware, but they have a unique groove on the head of the bolt. With the bolt torqued to specification, a locking retainer is slipped over the head of the bolt and an external E-clip is snapped into the groove. The retainer rests against any fixed part of the engine to keep the bolt from turning.
The locking retainer is designed to rest against any fixed component to prevent the bolts from backing out due to vibrations or temperature differences. It is easily installed by simply rotating it until it lines up with a fixed stop point.
The locking retainer can rest against the header pipe for header bolts, or against anything that can be used as a stop point. Some of the bolt heads are a 12-point design, while others are a 6-point design, however, the locking retainers have a 12-point pattern that is slightly rotated.
The 12-point hole in the locking retainers is rotated 3-1/2 degrees like a box wrench. -Glenn Thompson, Stage 8 Fasteners
This idea of rotating the 12-point hole was ingenious, because we noticed a couple of times that the locking retainer couldn’t rotate to the next position. We asked Stage 8’s Glenn Thompson if it was acceptable to turn a torqued bolt slightly further to accommodate our need.
Thompson told us that it would be okay to turn the bolt a little further if needed, but enlightened us about why that 12-point pattern is slightly rotated. It’s all part of the plan and made perfect sense.
Left: After the bolt was torqued, the locking retainer didn't line up with the header tube to lock the bolt into place. Right: Simply flipping the retainer over changed the position of it and now it sits up against the header tube. This was done without putting a socket to the bolt, it stayed in the exact same spot.
Thompson said, “The 12-point hole in the locking retainers is rotated 3-1/2 degrees like a box wrench. We do this so that you can actually have a total of 24 positions, done so by simply flipping the retainer over on the bolt head.”
If those bolts look familiar, you’ve likely installed a starter on an SBC or LS. Stage 8 has locking bolt kits for many popular applications, both foreign and domestic.
Stage 8 Locking Fastener Applications
We had a few project cars around the shop that could benefit from Stage 8, and spoke to Thompson about the various applications on the website. We noticed some kits were not typical problem areas, but are definitely potential problem areas.
“Some applications seem like peace of mind,” he said, “but components like the flywheel do come loose and the results can be catastrophic.” Other components that are not as catastrophic – yet still potential problem areas – include oil pans, transmission pans, and valve covers. “With Stage 8 bolts you don’t have to over-torque the bolts to keep them tight, which is a common practice with these components,” Thompson continued.
Flipping the locking retainer over will offer an additional 12 positions, closing the gap on some applications. Stage 8 suggests that for very tight tolerances, cutting the tab off the locking retainer is perfectly acceptable, as shown in the image on the underside of the packaging.
Many of those areas do get a little more torque, and it often leads to split gaskets and oil leaks. The great thing about Stage 8 is that you can torque a bolt to approximately five ft-lbs and install the locking retainer and it will stay at five ft-lbs.
Of course, in addition to flywheel bolts, some of the biggest problem areas are components that tend to heat up to extreme temperatures and then cool down afterwards. These components include headers, collector pipes, and turbochargers, to name a few.
Turbo bolts are notorious for loosening up with all the underhood heat and vibrations. Stage 8 Fasteners replaces the original fasteners with its locking retainers and bolts to lock them into place.
We had a new turbo upgrade installed on a project car, and Thompson told us that turbo hardware kits are very popular now because with all the temperature changes and vibration, turbo bolts tend to come loose quite often. Stage 8 has several kits available, and even with our custom installation, we were able to provide some measurements to obtain a kit that worked perfectly for this application.
Another area that we tackled out in the shop is on our Project Blank Slate. Replacing the header bolts with locking fasteners gives us peace of mind that we’re able to torque the bolts down and know that they can’t loosen as we put the hammer down on this LS7-powered beast.
Top: The distributor kit on our BBC was a simple remove and install process, and now the bolt will stay in place. Bottom: Even quality header bolts are prone to coming loose, but Stage 8 locks the bolt securely into place.
Project MaxStreet also benefited from Stage 8 with a distributor hold-down bolt kit and a header bolt kit. Since we’ve recently gotten this 1,200+ horsepower beast running, we wanted to make sure that once we set our distributor in place that we wouldn’t have to worry about the bolt coming loose and allowing the distributor to rotate – at all.
Stage 8 Locking Fasteners install quickly and easily, much like the standard bolt. Thompson recommends using anti-seize on the threads, especially when bolting into aluminum. The bolts can be torqued to factory specifications, and the locking retainer is slipped over the bolt head.
The retainer should be positioned so that it’s touching a fixed spot on the header flange, engine, or other component. If the retainer cannot be rotated enough, simply flip it over and try the opposite side. The bolt can be turned a little further accommodate installation, and once the retainer is installed, the E-clip locks everything into place.
For bolts that are not close to a fixed component, like on this BBC header flange, a pre-bent tab on the locking retainer will function in the same manner.
For header bolts that lie in the middle of the header flange, a special locking retainer is used. It will have a 90-degree bend on the end of the tab to allow it to lock in place on the edge of the header flange. These special retainers are pre-bent from Stage 8 and with our LS7 application it was a perfect fit.
We’d love to tell you that we found a way to test Stage 8 fasteners, but when something doesn’t move – under any condition – the only conclusion we can come to is that they work, as intended.
Even if there isn't a direct kit for your particular turbo application, you can contact Stage 8 with lengths and sizes and they'll be sure to put together a kit for you.
There are hundreds of applications for Stage 8 Locking Fasteners, check out the website for your specific needs. If you don’t find your application, give them a call at the number at the bottom of this page and provide details about the bolts you need, and Stage 8 will put together a custom kit for you.