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General Category >> Rubber Side Down! >> Studs versus Bolts - Exhaust Header
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Message started by NucleaRR on 07/02/18 at 20:43:56

Title: Studs versus Bolts - Exhaust Header
Post by NucleaRR on 07/02/18 at 20:43:56

I recently had to remove my header along with the muffler to do the cam tensioner check. While removing the header bolts, one broke on me. Got it removed fairly easy, not too much cussing. Had to chase the threads with a die once the bolt was out. Seems the PO didn’t know what anti-seize is. The bolt that broke was a stock header bolt and the one that did not was a 10.9 flange bolt. This got me thinking on the best thing to use during re-install, bolts versus studs. After searching on here I found several threads that suggest the use of studs over bolts. I like the idea of studs due to the difference in materials and would prefer to not have to deal with a broke off bolt. That said, I began to search for a stud option but can’t seem to find a compatible solution. I’ve looked at ARP kits, tried Fastenal and looked at options on McMaster-Carr. Found several ARPs that might work but nothing that will be tall enough to get past the exhaust clamp.

The most viable solution I have found seems to be to making the studs. The best candidate I have found is black oxide socket head screws from McMaster-Carr (see link below). They have the tensile strength common with header bolts/ studs (170,000). From this I could cut the head off where I need it to be then thread on nuts. I’d have to double nut them to snug them into the head.

Which leads to the next subject, what nuts to use for final attachment of the header pipe and clamp? Brass has been suggested in many places on the Interwebs but not for our specific application. Also the brass nuts are typically much taller than a ‘normal’ nut. I also can’t find these easily.

So ultimately my questions are, is it worth using studs? What is the best option for studs? What is the best material, considering brittleness, and the aluminum head material? I know the torque values are not extremely high for the stock bolts, so I may be over-engineering this.

My main concern is the periodic cam tensioner check and having to remove the header pipe. I may just feel burnt from the recent bolt breakage, so if flange bolts or stock bolts and anti-seize are the way to go, please say so. But if you have suggestions, pros/ cons for studs and most importantly sources for studs and nuts please help a member out :)

Thanks.

https://www.mcmaster.com/#91290a215/=1djnzgi

Title: Re: Studs versus Bolts - Exhaust Header
Post by Dave on 07/03/18 at 02:54:47

The stock header bolts are chrome plated and durable.....if you use anti-sieze and don't overtighten them, I doubt you will ever have trouble again.

Black Oxide is not durable and will corrode very quickly - it works much better indoors.

Title: Re: Studs versus Bolts - Exhaust Header
Post by batman on 07/03/18 at 06:32:44

Why make this hard ? buy stock bolts and use some antiseize.

Title: Re: Studs versus Bolts - Exhaust Header
Post by elricfate on 07/03/18 at 07:55:02

If you're going to plant studs instead of using the bolts, do yourself a favor and at least get actual studs, not just bolts that you can put in place.

Dorman has a set of studs with a spacer in the middle that would work fine for this. I believe they're like 24mm on one side and 8mm on the other, or something similar.

They would be durable, even in an aluminum block.

Title: Re: Studs versus Bolts - Exhaust Header
Post by justin_o_guy2 on 07/03/18 at 11:18:00

7E7D68717D7228241C0 wrote:

Why make this hard ? buy stock bolts and use some antiseize.

After all
It was a lack of Antisieze that caused the problem.

Title: Re: Studs versus Bolts - Exhaust Header
Post by DragBikeMike on 07/03/18 at 12:55:05

A properly designed fastening system should always set up a condition where the fastener with external threads breaks in tension before the internal threads fail in shear. The aluminum head has the internal thread component, and the stock bolt has the external thread component. If Suzuki designed the system properly, there should be sufficient thread engagement to provide ample shear strength so that the bolt breaks when overtightened. That way, the cheap part (bolt) fails before the expensive part (head). I'm pretty sure they probably got it right.

I would use the "STOCK" bolts. I would not upgrade to a stronger bolt or stud. Problem here is the stock bolts have no markings so we have no way of knowing what material they are made from. Are they grade 8.8? Are they made from something stronger? Are they made from something weaker? Only da shadow knows.

Use the stock bolts. Apply good quality never seize intended for high temperature applications. Be very careful not to cross-thread during installation. Tighten to the specified torque.

Title: Re: Studs versus Bolts - Exhaust Header
Post by NucleaRR on 07/03/18 at 14:07:40

Thanks to everyone for the responses. You all have reassured me that stock is the way to go with the proper anti-seize. I have Loctite Silver Anti-Seize Stick that states it is rated for 1600° and is rated for cylinder head and exhaust bolts.