Full Floater Hub Stud Upgrade write up (3 Viewers)

[Mace]

Typically hex cap screws are higher grade than grade 8. Here is an exerpt from Wiki:

Hex cap screws
ASME standard B18.2.1 -1996 specifies Hex Cap Screws that range in size from 0.25–3 in in diameter. These fasteners are very similar to hex bolts. They differ mostly in that they are manufactured to tighter tolerances than the corresponding bolts. The Machinery's Handbook refers parenthetically to these fasteners as "Finished Hex Bolts".[9] Reasonably, these fasteners might be referred to as bolts but based on the US government document, Distinguishing Bolts from Screws, the US government might classify them as screws because of the tighter tolerance.[10] In 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592[11] "Fastener Quality Act" This resulted in the rewriting of specifications by the ASME B18 committee. B18.2.1 [12] was re-written and as a result they eliminated the "Finished Hex Bolts" and renamed them the "Hex Cap Screw".

a) He did not use hex cap screws

b) There is nothing in there about a grade 12 (there is no ASTM standard for a grade 12) or even being stronger than a grade 8. Tighter tolerances does not have anything to do with metallurgy.

c) Hex cap screws can be purchased in just about any grade you want.

Cap Screws & Hex Bolts | Fastenal

 

[Moby]

Metric 10.9 == SAE 8
Metric 8.8 == SAE 5

Bolt Grade Markings and Strength Chart

And more than you would ever want to know about fasteners:

Amazon.com: Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook (Motorbooks Workshop) (9780879384067): Carroll Smith: Books

I've had this book for a couple of years but won't even try to pretend that I've absorbed even half of it. Great reference though. Also covers hoses and fittings, AN and other, and brake and hard lines.

 

[Cammo30]

Im also doing this upgrade to my FF, but have gone with shouldered bolts so there is no chance of movement on the treads.

 

[VETTE60]

Dam Mace, you know your stuff!

isint the Friction of the flange and the hub what creats the strenth in this instance? not the bolts themselfs. (hence the Cone washers)

i would think that if the mating surface is clean and smooth, and the bolts are tourqed properly, you would never have an issue. if you broke the studs (they could have been loose), and they mared the surface when it broke, that could have been why they broke a second time.

Similarly to Hi Steer, I run stock studs, and ensured that the top of the knuckle was nice and flat, i keep them tight, and dont have issues with them

I would not be so quick to assume that mace knows all...

actually if you look at the torque specs for the hub studs, it is not enough to add any significant clamping force (25 ft. lbs.). yout steering studs are torqued way tighter that the hub studs (70ft.lbs.), so in this case i would think that does not apply in the same manner.

 

[VETTE60]

a) He did not use hex cap screws

b) There is nothing in there about a grade 12 (there is no ASTM standard for a grade 12) or even being stronger than a grade 8. Tighter tolerances does not have anything to do with metallurgy.

c) Hex cap screws can be purchased in just about any grade you want.

Cap Screws & Hex Bolts | Fastenal

these are automotive/aircraft grade which are harder than grade 8 and andy is right. the grade 10.9 was my mis-type and is indeed metric. and yes you are right, they are not hex cap screws...they are socket cap screws. BTW Fastenal does not have all manufacturers of bolts and is not the "end all, be all"

fact: the best grade 8 hex cap bolts are composed of Medium Carbon alloy Steel, quenched and tempered and have a tensile strength of 150,000psi
Fact: the best Socket head cap bolts N.A.S. (aircraft standard) are made of High carbon steel, quenched and tempered and have a tensile strength of 160,000psi

the latter being the bolts I used.

there are BTW aircraft standard bolts with a tensile strength of 220,000psi

aside from arguing propeller stuff about bolt grade here's what i know.

I have a much bigger stud/bolt diameter
I have a much highher torque value for the axle/hub mating surface
I have no movement on the axle shaft
toyota AFAIK is the only manufacturer to use cone washers....and the studs break...

seems better to me. as I said, I will keep you updated.

 

[Mace]

these are automotive/aircraft grade which are harder than grade 8 and andy is right. the grade 10.9 was my mis-type and is indeed metric. and yes you are right, they are not hex cap screws...they are socket cap screws. BTW Fastenal does not have all manufacturers of bolts and is not the "end all, be all"

They may indeed be stronger (you need to be careful using the term "harder") than grade 8, but there is no grade 12. The increased "strength" that andy was referring to was a result of a flood of crappy Chinese bolts on the marketplace and a easy solution of dealing with them. What I was trying to do was prevent someone from marching into their local ace hardware and asking for a grade 12 bolt.

fact: the best grade 8 hex cap bolts are composed of Medium Carbon alloy Steel, quenched and tempered and have a tensile strength of 150,000psi
Fact: the best Socket head cap bolts N.A.S. (aircraft standard) are made of High carbon steel, quenched and tempered and have a tensile strength of 160,000psi

the latter being the bolts I used.

there are BTW aircraft standard bolts with a tensile strength of 220,000psi

aside from arguing propeller stuff about bolt grade here's what i know.

Yes, however aircraft bolts use a different set of standards than the SAE Grade scale. 99% of wheelers would not have easy access to them. And, there are other aspects to proper bolt selection than shear strength. Like stainless bolts. Stainless bolts are great at not rusting (mostly) but are certianly NOT the strongest bolt out on the market today.

I have a much bigger stud/bolt diameter
I have a much highher torque value for the axle/hub mating surface
I have no movement on the axle shaft
toyota AFAIK is the only manufacturer to use cone washers....and the studs break...

seems better to me. as I said, I will keep you updated.

Lots of axle builders used cone washers. Not as many used them in the hubs tho.
And, this should be a significant strength upgrade. Thanks for keeping us updated!

On the flange friction. The paper gasket does a good job of negating the compression effect between the hub and the axle itself. The studs take up the Shear force more than anything.

 

[VETTE60]

good points Mace, it is definitely something your usual hardware store would not have.

 

[Dusty]

my dana 70 rear uses 7/16" bolts like you used. so nice not to have cone washers anymore. the cones are such a PITA.

much easier to use bigger and more bolts.

are the lock washers needed? i didn't use em. just used red locktite on mine

 

[VETTE60]

my dana 70 rear uses 7/16" bolts like you used. so nice not to have cone washers anymore. the cones are such a PITA.

much easier to use bigger and more bolts.

are the lock washers needed? i didn't use em. just used red locktite on mine

prolly did not need lock washers, but if you shear a stud at some point, it is more of a PITA to drill and tap the bolt to extract it when it has been locktite-ed. that was my thought process

 

[Volcano cruiser]

Typically hex cap screws are higher grade than grade 8. Here is an exerpt from Wiki:

Hex cap screws
ASME standard B18.2.1 -1996 specifies Hex Cap Screws that range in size from 0.25–3 in in diameter. These fasteners are very similar to hex bolts. They differ mostly in that they are manufactured to tighter tolerances than the corresponding bolts. The Machinery's Handbook refers parenthetically to these fasteners as "Finished Hex Bolts".[9] Reasonably, these fasteners might be referred to as bolts but based on the US government document, Distinguishing Bolts from Screws, the US government might classify them as screws because of the tighter tolerance.[10] In 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592[11] "Fastener Quality Act" This resulted in the rewriting of specifications by the ASME B18 committee. B18.2.1 [12] was re-written and as a result they eliminated the "Finished Hex Bolts" and renamed them the "Hex Cap Screw".

a) He did not use hex cap screws

b) There is nothing in there about a grade 12 (there is no ASTM standard for a grade 12) or even being stronger than a grade 8. Tighter tolerances does not have anything to do with metallurgy.

c) Hex cap screws can be purchased in just about any grade you want.

Cap Screws & Hex Bolts | Fastenal

Metric 10.9 == SAE 8
Metric 8.8 == SAE 5

Bolt Grade Markings and Strength Chart

And more than you would ever want to know about fasteners:

Amazon.com: Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook (Motorbooks Workshop) (9780879384067): Carroll Smith: Books

I've had this book for a couple of years but won't even try to pretend that I've absorbed even half of it. Great reference though. Also covers hoses and fittings, AN and other, and brake and hard lines.

I´m not sure whether it is scary or reassuring that there are three guys on Mud that have this level of knowledge about bolts/ fastners. That being said I´m subscribing as I have rear FF and I am giving it an upgrade. All that being said shouldered bolts seem a good way to go to the completely untrained eye. Now receding to the dark lurkers corner where I will bw watching for the take away lessons from this really interesting debate.

 

[lenross1]

subscribed just in case i go this route...

 

[Gumby]

Good timing. I have to do this next week. I blew all the studs on a FF rear and pop them pretty regularly on the fronts.

 

[BenMara]

your creating stress risers if you dont use some thing with a shank, at a shear point......but what do i know...

 

[VETTE60]

your creating stress risers if you dont use some thing with a shank, at a shear point......but what do i know...

Very good point Ben. one of my other buddies went with 3/8" shouldered bolts. this may be better, but I think either way we will be good. no carnage yet. Barret Lake is next week. we'll see then.

 

[Gumby]

Did one front and one rear today. The rear was a bitch because all the stock studs were sheared and smeared. The front was easy.

 

[GLTHFJ60]

I have yet to shear any studs and since I'm only running 35's I ordered a set of the ARP hub studs. When I upgrade to larger tires I'll do this upgrade for sure.

 

[VETTE60]

I have yet to shear any studs and since I'm only running 35's I ordered a set of the ARP hub studs. When I upgrade to larger tires I'll do this upgrade for sure.

yeah, I would save your money on the ARP's. It is a heck of a lot cheaper to just do the upgrade. I snapped my ARP's and I have a gentle right foot. or better yet I have a set for you that I was going to use for the front.

 

[VETTE60]

Did one front and one rear today. The rear was a bitch because all the stock studs were sheared and smeared. The front was easy.

nice! I also had the same problem. had to drill and easy-out all of the sheared studs. woulda been way quicker if not for that.

 

[Volcano cruiser]

What causes hub stud failure

Guys,
Ever since I first began following this thread I have been nagged by this very basic question, what is causing hub stud failure? There are lot of guys in my clubs who have been wheeling 20+ some 30+ years and no one here has ever seen this phenomenon. Once I can understand how this happens I can better evaluate the risk and the whether this mod is worth doing.
Thanks,
John

 

[VETTE60]

Guys,
Ever since I first began following this thread I have been nagged by this very basic question, what is causing hub stud failure? There are lot of guys in my clubs who have been wheeling 20+ some 30+ years and no one here has ever seen this phenomenon. Once I can understand how this happens I can better evaluate the risk and the whether this mod is worth doing.
Thanks,
John

simple: big tires with stock 8mm studs. there is a lot more torque on the studs with a larger diameter tire. especially when you ad lower gearing to the mix. when you break your studs, you will decide that you either continue to replace hubs and studs or you upgrade and mod. 20 and 30 years ago, 33's or 35's were as big as anyone ever went, at least with Toyota. now it seems that 35's are small and even my 37's don't seem that big anymore....