Fastener Tech for Suspension Bits

[Bulletpruf]

Fellas -

I'm starting to put the rearend together on my 71 Javelin road race car and I'm realizing that I'm lacking in fastener know-how. I know the difference between a grade 5 and a grade 8 bolt, realize that not all grade 8 stuff is created equal, and know that a nylock is not infinitely re-useable. However, now that I'm bolting stuff together that could kill me if it fails, I figure it's time to dig a little deeper. Guess what I'm looking for is generic info on fasteners (good website would be great; a book is my 2d choice) and some help with my questions below.

Tonight, for example, I'm trying to attach the Wilwood rotors to my Speedway rotor adapters, which are attached to my full-floating Speedway hubs for my 9". Based on Speedway's guidance, I'm using 5/16" Grade 8 fine thread bolts and stover nuts (too hot for nylock). I do realize that the stover nuts are a one use only deal. I will use red Loctite on the nuts, even though it's probably overkill. So far, so good?

I don't see the need for a lock washer with a stover nut, but figured a flat washer would be fine under the bolt (where it meets the steel rotor). However, there's not much room at all for a washer here, so do I really need one?

However, where the nut meets the aluminum rotor adapter, I am pretty sure I need one here. Speedway gave me some star washers to go between the bolts that attach the rotor plate to the hubs; this is to protect against galvanic corrosion, right? So I should be using star washers there as well?

Bought the hardware at Fastenal; pretty good selection, but you have to purchase in bulk. Ended up with 100 bolts, 100 washers, etc. Guess I'll have enough 5/16" x 1 1/2" fine thread Grade 8 bolts to last me for a few decades...

Thanks

Scott

https://static1.pt-content.com/images/pt/2011/11/100_2159-1.jpg

[shep]

Aren't the rotor bolts typically safety wired in place also?

[funcars]

There are lots of ways to go - here is my recipe. I prefer using AN bolts with the correct grip length and jet nuts for the brake rotors with a tight ID hardened flat washer between the aluminum and bolt head and under the nut on the inside. I think AN bolts are much more reliable in quality than grade 8 if you get them from a reliable supplier (I use Aircraft Spruce for AN bolts and others for NAS bolts). I've also used some of the ARP brake rotor bolts too and think those are safe from a quality standpoint too, but they cost a lot. Best to avoid ever having the threads of a bolt between the rotor interface and the mounting plate or brake hat - creates a stress riser.

edit - forgot about the safety wire - I do that as well and link them in pairs instead of all together. AN and ARP brake rotor bolts are both available with drilled heads. Drilling heads on bolts can be done using one of those little fixtures but I can't tell you how many cobalt drills I've gone through. Way easier to buy them done.

[Twentyover]

Best reference is probably Screw to Win, Carol Smith's tome on fasteners.Real title is Nuts, bolts,and fastener handbook or some such, bur known by first title after his Prepare to Win, Tune to Win, and Engineer to Win books.

+1 on Using AN for critical functions, and always use a hardened washer under the bolt head and nut. FAA has some publications, available through EAA, about using threaded fasteners.

[UMI Tech]

The answers above are awesome. Fastener knowledge is one thing that separates the fast, reliable guys from the also-rans.

Does the rotor adapter to hub go into a blind hole? The rotor to adapter is the one which you're going to nut and Loctite?

Arp-bolts.com has a pdf catalog with some good reading in the front.

http://www.aaa-aircraft.com/

Pre-drilled socket head cap screws safety wired in place is great for the adapter to hub if the hole is blind.

Your stover nut and red loctite seems good. Torque on stover nuts is a bit weird though. What do you think, Greg and funcars?

I love using proper fasteners!

ramey

[exwestracer]

The AN bolts are definitely the preferred solution. As mentioned above, they have a longer grip length and much less thread than those grade 8 bolts. As you are assembling it now, pretty much all the shear surfaces are going to be riding on threads, not the shank of the bolt. Not an ultimate strength issue, but over time as that aluminum plate heats and cools, the rotor will wander around a little and beat up the holes in the aluminum. Having said that, I've worked on 100s of different race car rotor assemblies, and most of them used socket head (Allen) bolts for clearance purposes. They are threaded all the way to the head and would show some wear on the rotor hat, but we used them anyway.

Regarding the Loctite, don't bother. If the Stover nuts are clamping on the full diameter of the threads (usually the 3rd visible thread), you are fine. No point in safety wiring if it's a nut and bolt type assembly, unless you're going to do both ends.

Be sure to check for caliper interference with the rotor bolts/nuts. I don't know what calipers you are running, but it can be an issue.

[Bulletpruf]

There are lots of ways to go - here is my recipe. I prefer using AN bolts with the correct grip length and jet nuts for the brake rotors with a tight ID hardened flat washer between the aluminum and bolt head and under the nut on the inside. I think AN bolts are much more reliable in quality than grade 8 if you get them from a reliable supplier (I use Aircraft Spruce for AN bolts and others for NAS bolts). I've also used some of the ARP brake rotor bolts too and think those are safe from a quality standpoint too, but they cost a lot. Best to avoid ever having the threads of a bolt between the rotor interface and the mounting plate or brake hat - creates a stress riser.

edit - forgot about the safety wire - I do that as well and link them in pairs instead of all together. AN and ARP brake rotor bolts are both available with drilled heads. Drilling heads on bolts can be done using one of those little fixtures but I can't tell you how many cobalt drills I've gone through. Way easier to buy them done.

Ok, learning a few new terms here - spelling out for the other fastener tech virgins in the audience:

AN is "Army-Navy" (same as AN stainless braided hose) and refers to aircraft spec pieces.

Jet nuts (aka K or Kay nuts): "A good combination of high strength (160,000 psi tensile), light weight and temperature resistance (to 450°). They have a ring base for positive seating, a reduced hex for better wrench access, are self locking and are made of corrosion resistant steel." Pictured here: http://www.truechoice.com/prodinfo.asp?number=MS 21042-06. I assume these are self-locking in the same way that a stover nut is; if so, they should be very similar to a flanged stover nut but with a reduced hex.

Grip length - this is the length of the bolt shank that does not have threads. Grip length is important because "Only the unthreaded portion of the shank – the grip – should carry shear loads." Looks like it is ok if you have 1-2 threads inside the shear area, and you need at least one thread from the end of the bolt protruding out of the nut.

I'll see what I can find from ARP or Aircraft Spruce...

Thanks for the details.

Scott

[Bulletpruf]

Best reference is probably Screw to Win, Carol Smith's tome on fasteners.Real title is Nuts, bolts,and fastener handbook or some such, bur known by first title after his Prepare to Win, Tune to Win, and Engineer to Win books.

+1 on Using AN for critical functions, and always use a hardened washer under the bolt head and nut. FAA has some publications, available through EAA, about using threaded fasteners.

I've heard of Carroll Smith's book; will have to put it on my shopping list.

Thanks for the tip on hardened washers.

Scott

[Bulletpruf]

The answers above are awesome. Fastener knowledge is one thing that separates the fast, reliable guys from the also-rans.

Does the rotor adapter to hub go into a blind hole? The rotor to adapter is the one which you're going to nut and Loctite?

Arp-bolts.com has a pdf catalog with some good reading in the front.

http://www.aaa-aircraft.com/

Pre-drilled socket head cap screws safety wired in place is great for the adapter to hub if the hole is blind.

Your stover nut and red loctite seems good. Torque on stover nuts is a bit weird though. What do you think, Greg and funcars?

I love using proper fasteners!

ramey

The rotor adapter to hub does indeed go into a blind hole. This is already assembled with hardware provided by Speedway Engineering. They were installed with red Loctite and torqued to spec. I see your point on safety wiring. This would be more secure than Loctite, if done correctly.

The rotor to rotor adapter is the one that I am going to nut and Loctite.

I'll check out ARP's catalog for more fastener tech.

I'll also see what I can find out on torque for stover nuts.

Thanks

Scott

[Bulletpruf]

The AN bolts are definitely the preferred solution. As mentioned above, they have a longer grip length and much less thread than those grade 8 bolts. As you are assembling it now, pretty much all the shear surfaces are going to be riding on threads, not the shank of the bolt. Not an ultimate strength issue, but over time as that aluminum plate heats and cools, the rotor will wander around a little and beat up the holes in the aluminum. Having said that, I've worked on 100s of different race car rotor assemblies, and most of them used socket head (Allen) bolts for clearance purposes. They are threaded all the way to the head and would show some wear on the rotor hat, but we used them anyway.

Regarding the Loctite, don't bother. If the Stover nuts are clamping on the full diameter of the threads (usually the 3rd visible thread), you are fine. No point in safety wiring if it's a nut and bolt type assembly, unless you're going to do both ends.

Be sure to check for caliper interference with the rotor bolts/nuts. I don't know what calipers you are running, but it can be an issue.

Appreciate the tech on the bolts, stover nuts, and caliper interference. I'm running Wilwood FSL calipers; will have to mock it up to see where I am.

Thanks

Scott

[UMI Tech]

Hey Scott. Take comfort in knowing you're way ahead of many with what you're doing already. I've seen some pretty scary stuff on race cars and your current setup wouldn't be one of them. What we're talking about here will simply finish off what you're already doing right.

I got my safety wire pliers from JC Whitney of all places. They were made-in-USA super nice ones. Not sure if they still have that same one after 20 years though...

You should be able to find 0.032" dia stainless safety wire in most racing catalogs. Make sure it's not cheap mechanics wire.

A quick Google produced this. It appears very similar to the info in Screw to Win. http://www.ultralightnews.com/pilotslounge/safetywire.htm

Your current adapter to hub I'm sure is fine the way it is as long as you check tightness during routine maintenance. The nice thing about safety wired capscrews is the visual aspect of the "nut-n-bolt" checking.

more as it comes...

ramey

[Bulletpruf]

Hey Scott. Take comfort in knowing you're way ahead of many with what you're doing already. I've seen some pretty scary stuff on race cars and your current setup wouldn't be one of them. What we're talking about here will simply finish off what you're already doing right.

I got my safety wire pliers from JC Whitney of all places. They were made-in-USA super nice ones. Not sure if they still have that same one after 20 years though...

You should be able to find 0.032" dia stainless safety wire in most racing catalogs. Make sure it's not cheap mechanics wire.

A quick Google produced this. It appears very similar to the info in Screw to Win. http://www.ultralightnews.com/pilotslounge/safetywire.htm

Your current adapter to hub I'm sure is fine the way it is as long as you check tightness during routine maintenance. The nice thing about safety wired capscrews is the visual aspect of the "nut-n-bolt" checking.

more as it comes...

ramey

Thanks, Ramey. I'll add safety wire and safety wire pliers to my shopping list.

Scott

[LeighP]

as has been mentioned...not much point in safety wiring a bolt if it has a free mounted nut on the other end.....safety wiring bolts (on aircraft) are done where there is a captive nut that can't rotate.
If you want to mechanically retain a free mounted nut on a bolt, you use a nut and bolt combo designed for a split pin (we use stainless split pins on aircraft).

[TheJDMan]

Scott,
I can't tell from the picture, are your rotor adaptors threaded or no? I have basicaly the same floater setup you have only from Moser. My rotors should be here in the next few days and I will be mounting them like you so this is a timely thread.

Ray,
I have a couple of questions for you based on your experience. First issue is regarding locating the rotor on the adaptor. It looks to me like in my situation I need to mount the rotor more outboard so I can to keep the caliper deeper inside the wheel to avoid interference with chassis parts. So my question is, is it safe to mount the rotor on either side of the adaptor in order to adjust the positioning of the rotor inboard or outboard? Second question, once I have the rotor positioned and the caliper location determined, do you know of anyone who can fabricate a pair of weld on caliper mount brackets?

[exwestracer]

Scott,
I can't tell from the picture, are your rotor adaptors threaded or no? I have basicaly the same floater setup you have only from Moser. My rotors should be here in the next few days and I will be mounting them like you so this is a timely thread.

Ray,
I have a couple of questions for you based on your experience. First issue is regarding locating the rotor on the adaptor. It looks to me like in my situation I need to mount the rotor more outboard so I can to keep the caliper deeper inside the wheel to avoid interference with chassis parts. So my question is, is it safe to mount the rotor on either side of the adaptor in order to adjust the positioning of the rotor inboard or outboard? Second question, once I have the rotor positioned and the caliper location determined, do you know of anyone who can fabricate a pair of weld on caliper mount brackets?

Steve, to answer your question about mounting the rotor on the opposite side of the adaptor...it depends.
We do it on occasion, but the rotor should have a fully machined face on both sides of the mounting lugs.

Many rotors only have a small spot-face machined on the mounting lug, just large enough for an AN washer under the bolt head. I don't like to reverse mount this type of rotor. It would probably be fine, but I just can't get comfortable with that small a contact surface... I'm not sure about your particular combination, but you will typically run into caliper versus wheel center clearance issues when you shift the rotor to the outside of the adaptor. Keep in mind you are moving the rotor the thickness of the adaptor PLUS the thickness of the mounting lugs. If you have the room, fine. FYI, whenver possible I like to machine a slight lip on the adaptor or hat to index the rotor on the ID of the mounting lugs. Letting it hang on the bolts is just asking for some imbalance.

There are weld on caliper brackets available for just about every combination of rotor diameter and caliper type. Hell, I can make you some out of 4130 plate if you can't find any...

What rotor diameter and type of caliper are you running (sorry if I missed that info somewhere...)?

(Forgot to add that you may also lose some rotor cooling potential depending on how thick the adaptor plate is. If you move the rotor to the outside of the plate, the plate will be blocking the inlet area for the vanes to some degree...)

[Bulletpruf]

Scott,
I can't tell from the picture, are your rotor adaptors threaded or no? I have basicaly the same floater setup you have only from Moser. My rotors should be here in the next few days and I will be mounting them like you so this is a timely thread.

Steve -

My rotor adapters are not threaded; that's why I need a locking nut on the other side.

I just placed my order with Aircraft Spruce - ordered AN bolts - AN5-11A to be exact - these are 1 1/8", 11/16" grip length, fine thread 5/16". Using jet nuts/stover nuts to secure them. Will have hardened washers under bolt and nut.

ARP had some nice looking stuff, but they were threaded all the way up. I like the idea of the unthreaded grip length on the AN bolts.

Thanks,

Scott

[UMI Tech]

Steve -

My rotor adapters are not threaded; that's why I need a locking nut on the other side.

I just placed my order with Aircraft Spruce - ordered AN bolts - AN5-11A to be exact - these are 1 1/8", 11/16" grip length, fine thread 5/16". Using jet nuts/stover nuts to secure them. Will have hardened washers under bolt and nut.

ARP had some nice looking stuff, but they were threaded all the way up. I like the idea of the unthreaded grip length on the AN bolts.

Thanks,

Scott

This is how fast, safe, reliable cars come to be!