Exhaust Header Split Lock Bolts

Chris Martino · 11-20-04, 02:07 PM

Hi all,

Just found these guys in an article, haven't tried the product but it looks like a fantastic fastener for applications that are affected by vibration, heat or both.

www.go-breslin.com or 1-800-695-3690

Tim Kay · 11-20-04, 03:24 PM

Gee, I don't know. Maybe great for situations without excessive heat.

How often\easily have you seen allen heads strip so the tool no longer works. Especially if the set screw were to be locked in position due to the heat, then need excessive torque to loosen, thereby the allen head strips.

Then what headache. That's my first impression [img]/ubbthreads/images/graemlins/crazy.gif[/img]

Gary Gibbs · 11-20-04, 03:28 PM

I might suggest Stage 8 fasteners for applications requiring locking.

Malcolm · 11-20-04, 03:41 PM

Just drill a small hole in each bolt head between a pair of flat faces and then link them all up with lock wire. Can't move then and heat proof.

Chris Martino · 11-20-04, 05:10 PM

If anyone would like more info on Military Spec (MS) bolts, castle nuts, wire lock etc.. let me know. I work as a Technical Illustrator for an aerospace company so I'm always looking up specs. I have numerous suppliers web addresses and links to PDF documents that contain detailed information on size, threads, torque values etc...

Let me know, and I'll pass on the info.

Lynn · 11-20-04, 07:20 PM

Chris,

I am going to take the high road on these and say that I think they are pretty cool! I have often wondered about the bolts when I was replacing the split ring locks (used during mock up and initial fitment) with locking nuts. Here I was not trusting split rings with nuts, but when using bolts I had no alternative.

Initially, I thought, "the shear strength will be reduced a lot since they have a hole down the center, but the locking screw/bolt will add its shear strength as well so the only loss of material is the tolerance of the threads. Since they are made of either chrome-moly or stainless (which will negate a lot of the concerns over oxidation and thread lockup in high heat areas) they sound like they will be very strong to begin with. I also noticed on the website that they are rated at Grade 8 or higher, so shear strength should not be an issue. I have to think there would be some loss of tensile strength though as compared to the same size solid bolt. The locking screw, while providing some tensile strength, cannot compensate to the same extent it would in shear. Now all they need is locking studs like this for use with heads and main caps as long as they can provide adequate tensile strength and clamping forces.

Regards,
Lynn

Chris Martino · 11-20-04, 07:51 PM

Hi Lynn,

Yup, I agree. I suggested looking into it based on what I know in the MS world of fasteners and these looked to be a well designed, strong and simple alternative. I also hear where Tim is coming from with respect to the hex head striping. Two problems exist with allan headed fasteners - one of them is that most are made of soft, low-grade steel that, no matter what tool you use, strip. Also, I find this happens when using the basic allan key. They are the WORST tool ever designed IMHO - poor seating to the hex slot & control when applying torque causes the the key to "float" due to the minimal area of contact and lack of stability when trying to put a lot of force and hench, the rounding of the slot. Using a 1/4 inch drive and appropriate hex socket will seat and torque way better and give you more stability when really cranking on it. It's very difficult to tell what your fasteners are made from, which is why I tend to be a little bias and use MS, which have to meet FAA spec.

I'm going to order a set as an experiment for another hotrod I have in the garage that needs new header bolts and see how well they work. I know time usually will tell in the end but... I'll see if they are worthy and let you guys know. [img]/ubbthreads/images/graemlins/wink.gif[/img]

Lynn · 11-20-04, 09:46 PM

Chris,

Totally agree re: allan keys. I have a couple of sets of T handle hex wrenches (sae and metic) for the in and out, but all torque is applied with two 3/8 drive allen sockets. The standard fastener on my 40 is a no. 6 counter sink stainless allen screw with stainless finish washers, with some no. 8s and 10s when called for, that I get from a local fastener specialty store. (Buffed out, they look like polished rivets, sort of.) I quickly learned that cheap allen wrenches are only for easy turn part. I also got a quality set of hex bits to go with my hex drive, adjustable clutch electric screw driver and since then have had very few strip outs and that was usually a screw with a poorly formed socket which happens occasionally.

Regards,
Lynn

Howard Jones · 11-20-04, 11:33 PM

Lynn, I was going to use them but I decided to crossdrill a set of socket head cap screws and safety wire them. I did this because I am cheap and I already had the cap screws. It took a couple of hours but I don't pay myself labor.

I think they are a good idea. Any failure would be one of loosening. I don't think they would shear, not anywhere near enough loading. The only way they would get any shear load would be from the cars up and down movement over bumps and the weight of the exaust system. Very little of both on these cars. Maybe dirt track or offroad types might have a problem with breaking header bolts. What I did think might be a problem is the little allen screw in the middle seizeing if left alone for a long time. If I did put them on my alum heads I would try to loosen them, the allen lock screw, up and re tighten every once in a while.

I think good g8 cap screws will be more than strong enough.
Those things look pretty well made. If they stay tight and don't seize they should be a good deal.

Lynn · 11-21-04, 12:58 AM

Howard,

As header bolts, I would only use the stainless models for sure! The chrome-moly would be fine in other locations, but with the rapid oxidation of exhaust parts, you'd be asking for the locker to seize up if you used that material as header bolts.

Lynn

Howard Jones · 11-21-04, 12:41 PM

Damn! now I have to re drill 16 more bolts. Thanks buddy!

TimB · 11-22-04, 01:44 PM

[ QUOTE ]
I might suggest Stage 8 fasteners for applications requiring locking.

[/ QUOTE ]

I would echo Gary's recomendation.

Very easy to install and have held up so far for me.

**J What?** · 11-22-04, 02:42 PM

I use the stage 8 stuff and they work great. Very hard to get on GT40 headers. They are not friendly to frequent take downs.These fasteners look much easier. They work pretty much the same as the bearing retainers I use on the stub axles. If they are the same, the torque is very low in order to set the internal screw, about 15 ft/lb.Not enough to strip even a crappy allen head bolt.

DaveWharran · 11-22-04, 11:53 PM

All the locks talked about are neat...but I'm using plain old 12 point ARP stainless bolts in the headers. No loose bolts in 12K miles.
Tighten. Heat cycle a few times. Check again.

Racing presents very different circumstances, but for me..for street use, the ARP's are doing well.