Common practice is to replace the exhaust manifold bolts on ’94 – ’96 cars with Grade 8 hardware. They are hardened and will carry the highest tensile load, which seems to help them withstand the heat cycles the bolts are exposed to.
Are Grade 8 and Class 8 bolts the same?
Because there are so many different grades and fasteners all look about the same, medium carbon and alloy steel strength grades are marked for identification….Table 1.
| Grade/Class | Strength |
|---|---|
| Grade 2H Nuts | Strength is similar to Grade 5. Use with ASTM A325 structural bolts. |
| Grade 5 | Medium strength. |
| Grade 8 | High strength. |
What is the breaking strength of a Grade 8 bolt?
150,000 lbs. per square inch
Grade 8 bolts are designated as a 150 ksi. This means its tensile strength or the resistance it has before it is subject to breaking under tension is equal to 150,000 lbs. per square inch. In comparison, a Grade 5 bolt is weaker as its tensile is 120 ksi, placing it at 120,000 lbs.
What is a Grade 8 bolt?
A grade 8 bolt is stronger than the more commonly used grade 5. It is made of alloy steel and has six radial lines on the top of the bolt head. Grade 8 bolts have a tensile strength of 150,000 pounds per square inch.
Can I use regular bolts for exhaust manifolds?
Can you use regular bolts on exhaust? The fastener grade is about strength, not corrosion resistance. We used to use brass nuts on exhaust manifolds so the nut could be easily cut off in the unlikely event it seized. Grade 4.6, 4.8 or 5.8 should be all be fine.
What are the different grades of bolts?
There are several grades of bolts but the three common grades for SAE are 2, 5 and 8. The common class (grades) for metric are 5.8, 8.8, 10.9 and 12.9. Each grade has a specific bolt strength. No matter the system used to grade the bolts, the higher the number means the stronger the bolt.
Is Grade 8 or 10.9 stronger?
Class 10.9 is stronger than class 8.8. It is commonly found in high strength automotive applications. Class 10.9 is similar to grade 8. A low carbon steel for general use.
What is the metric equivalent to Grade 8?
Metric Bolt Conversion
| Metric Nut Class | SAE J429 Normally Used | ASTM Grades |
|---|---|---|
| 5.8 | 5 | . |
| 8.8 | 8 | A325,A449 |
| 9.8 | 9 | A193,B7 and B16 |
| 10.9 | 10 or 12 | A490,A354, Grade 8D |
What is the hardest bolt you can buy?
Commercial-grade 8 bolts are the strongest option available. They’re made from medium carbon alloy steel and have markings that include six raised dashes. The psi of the bolt is 150,000, meaning that it can withstand great deals of pressure because of the way it was quenched and tempered.
What bolt is stronger than Grade 8?
Grade 9 bolts are ideal for heavy-duty applications and are also often used in heavy machinery such as bulldozers. Not only are these bolts considerably stronger than they’re grade 8 counterparts, but they are also considerably more resistant to corrosive elements as they are made with yellow zinc chromate.
Can you replace exhaust studs with bolts?
Super Moderator. I agree, the bolts in place of studs and nuts would be okay. Be sure to observe the torque specs for the bolts, i.e. to be the same as the nuts on the studs. You dont want an exhaust manifold to be too tight – it interferes with the manifold expanding at a different rate than the head.
Can I use bolts instead of studs?
Main studs For a performance or heavy-duty application, the use of studs is preferred whenever possible instead of main cap bolts, in those instances where a choice is available. Studs provide the ability to obtain much more accurate torque values because the studs don’t twist during tightening as do bolts.
What type of bolt is the strongest?
Grade 9 Bolts Grade 9 structural bolts, also known as grade 9 hex cap screws, are one the strongest structural bolts that can be used today. While the typical grade 8 bolt has a tensile strength of 150,000 PSI, a grade 9 bolt has a tensile strength of 180,000PSI.
Are stainless bolts stronger than Grade 8?
Stainless commonly comes in grades 18.8 (304) or T316. Stainless steel bolts are rated for corrosion resistance. A stainless steel bolt has the same PSI rating as a grade 5 bolt (125,000 PSI). A grade 8 bolt has a stronger rating with a PSI of 150,000.
What is the strongest grade of bolt?
The strongest commercial-quality bolt is grade 8, marked by six raised dashes; its medium-carbon alloy steel has been quenched and tempered to achieve a tensile strength of 150,000 psi.
What is the highest grade of bolt?
What type of bolt is strongest?
What is the strongest bolt I can buy?
When should exhaust studs be replaced?
If the OEM studs lasted 15-20 years, odds are your replacement studs will last 15-20 years.
How much does it cost to replace exhaust manifold bolts?
Due to the varying complexities associated, the exhaust manifold repair cost can vary from approximately $150 to $1,000, but most repairs will be closer to $150 to $400.
