Kelsey Hayes longer wheel studs

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rmchrgr

rmchrgr

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OK, I have researched this subject enough to know that there are no available options for longer wheel studs for the small bolt disc brakes.

Reading through an older thread on this very subject, Oklacollecto posted an image of longer studs available in Australia through Pentastar Parts.

These seemed pretty cool and looked like they might work so I was going to be the guinea pig for these things. They are really expensive though so before I finalized the purchase I sent an email to them asking to confirm the specs.

They sent me the dimensions from their manufacturer. Here's what they said:

... "hi greg, from our supplier catologue, the following specs
knurl diameter 14.3 mm length 73mm , shoulder 22mm .
sounds a bit short to me"

The knurl works out to be basically the same as the .565" @ 14.3mm. The thing that I am unsure of is the shoulder length. The shoulder on the OE studs is 1.062" or approx. 27mm, the Aussie ones is .866" or 22mm. This would be around a 1/8" shorter shoulder length.

AFAIK, when the OE studs are installed in the hub/rotor, the shoulder sticks out a little bit. How much, I don't know. Probably not a lot.

Think it would be OK to run these with the shorter 22mm shoulder?

Obviously I don't want to run into a safety issue and waste an exorbitant amount of money getting these things here only to find out they won't work.

Any input is appreciated!

Thanks,

- Greg
 
Greg, this something I have always wondered about since these surfaced. I have never found the answer to your question but I have looked at the Aussie Kelsey Hayes disc brake set up and it "looks" identical to ours. I am subscribing to this thread to see what information shows up and if they work should you invest in them.
 
The end of the knurling on the OE studs is almost exactly 20mm, the rest is shoulder. I'm thinking it would be OK since there is nothing grabbing beyond the end of the knurling anyway.

My only concern is that the end of the shoulder somehow positively locates the rotor surface. So theoretically if the shoulder was shorter there may be a slight void (less surface contact area) where the rotor bore makes contact with the stud. But if that is the case, why does the knurl end before the end of the shoulder?

Hoping someone can give a definitive answer on this. Seems crazy to spend so much time and thought on this but it is a legitimate issue for those running small bolt brakes.
 
Just for my own edification, I went out and pressed a stud into a hub/rotor. There is not much of the shoulder sticking up from the rotor surface, it's almost negligible, like under .032".

Here is a pic.
 

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Dont forget a wheel is goin over them and unless you are runnin universal wheels there will be no problems that I could think of
 
got a set of KH with long wheel studs....have had them for years....so there must have been a source at one time....
 
74DartSwinger360 said:
Dont forget a wheel is goin over them and unless you are runnin universal wheels there will be no problems that I could think of
Click to expand...

Of course but if the shoulder is shorter it no longer goes all the way through both the hub and rotor surface. Clearly the lug nuts get torqued down and provide a lot of clamping force but there is a small margin where there is no contact. Splitting hairs? I dunno, that's why I'm asking here.

Lug nuts may also pose a problem with the longer studs, have yet to find a long shank, open-end style with a metric thread. I have 7/16-20 closed end right now which I would not be able to use with the longer Aussie studs. Probably is something out there, likely just haven't looked in the right places yet. I imagine that will be less of a problem than getting the stud itself.
 
Here's what i did, years back, for a customer of mine, that wanted, or needed, longer wheel studs for his 4 piston, Kelsey Hayes, disc brake set up.
Guess when i did this, longer 7/16 diameter studs were, unobtanium, dinosaur eggs, hens teeth, in locating too.
I got the brainy idea of using longer 1/2 diameter studs that would be used, and work on the 70-72 B & E body cars with disc brakes.
I brought over to my machinist friend of mine, an old disc brake rotor, and hub, from one of those B & E body cars.
He used those to get hole dimensions to to drill out the A body rotor and hub to use the 1/2 inch diameter wheel studs.
Worked great. Longer 1/2 studs were easily findable for disc brakes when i did it.
But i haven't a clue anymore what manufacturer would still have them, now a days.
So, if you don't mind using 1/2 inch studs, and lug nuts, that would be an option for you, to go that route.
A lot stronger that what the factory ever had with the wimpy 7/16 inch studs.
Just my two cents on the subject.
Jim V.
 
I guess I got lucky the summer before last, as I went to my local parts store and got 3 replacement studs for my small bolt kelsey hays rotors. The guy had them in a large drawer full of different wheel studs, so it seems there must be someone making them?
 
fanofpetty said:
I guess I got lucky the summer before last, as I went to my local parts store and got 3 replacement studs for my small bolt kelsey hays rotors. The guy had them in a large drawer full of different wheel studs, so it seems there must be someone making them?
Click to expand...

Getting standard 7/16 right hand thread studs for the 4 piston Kelsey Hayes disc brake system is no problem.
Those have not gone out of production by the manufacturers.
 
oh ok, I mis-understood...so he wants studs even longer than stock studs, for after market wheels I assume?
 
hemi71x said:
Here's what i did, years back, for a customer of mine, that wanted, or needed, longer wheel studs for his 4 piston, Kelsey Hayes, disc brake set up.
Guess when i did this, longer 7/16 diameter studs were, unobtanium, dinosaur eggs, hens teeth, in locating too.
I got the brainy idea of using longer 1/2 diameter studs that would be used, and work on the 70-72 B & E body cars with disc brakes.
I brought over to my machinist friend of mine, an old disc brake rotor, and hub, from one of those B & E body cars.
He used those to get hole dimensions to to drill out the A body rotor and hub to use the 1/2 inch diameter wheel studs.
Worked great. Longer 1/2 studs were easily findable for disc brakes when i did it.
But i haven't a clue anymore what manufacturer would still have them, now a days.
So, if you don't mind using 1/2 inch studs, and lug nuts, that would be an option for you, to go that route.
A lot stronger that what the factory ever had with the wimpy 7/16 inch studs.
Just my two cents on the subject.
Jim V.
Click to expand...

Jim, is the shoulder length the same on the 1/2 studs? I think that's the main issue with these is the oddball shoulder set up.

Regardless of knurl size, under head length or any other dimension, no one makes any kind of stud with a 1.062" length shoulder. IMO the shoulder is what locates the pieces together after the knurl is swedged.

BTW, the studs are 7/16 thread so lug nuts should be no sweat.
 
BTW, if anyone cares, the NHRA has a rule on wheel studs. I think a lot of guys will say that you are required to run longer studs but I do not believe that's how the rule is interpreted.
..."Thread engagement on the lug must be equivalent to or greater than the diameter of the stud or bolt. Length of the stud/bolt doesn't determine permissibility (example: a 7/16 inch stud must be thoroughly engaged through the threads in the hex portion of the lug a minimum of 7/16 inch."...
​
So a little math - threads on the OE studs are .9xx". On the Centerline lug nuts I have, the shank is 1.3". Studs are 7/16 (Thread pitch) =.437" so using those specs, it would appear that there is more than double the thread engagement necessary as per the NHRA rule but unfortunately they specify through the hex portion of the lug. If that's the case, it's way short, the threads don't even make it to the hex portion with these lug nuts. The wheel is indeed 1.3" thick so I need to use the 1.3" shank. There's no mention of shank style lug nuts which are threaded all the way up. It's a little unclear.

According to the P.O. of my car, it went 11.97 and it had the OE 10" drums with closed end lug nuts. Guess it must have been OK? I think if the tech guy sees you have closed lug nuts, they make you remove them to check for proper engagement. That's why people say that you need the longer ones - there is nothing to question because the tech guy can see them clearly and they move on, no hassle.
 
So, I took a shot and bought the long studs from Pentastar. Nothing ventured, nothing gained is my rationalization. :mrgreen:

Basically the area of concern with these will be towards the face of the hub, the shoulder ends lower than where it normally would. Theoretically, the longer stud will provide a greater mechanical advantage thus (perhaps) negating any marginal contact area. And like someone said above, the wheels will be cranked down.

Now only if there was 1.3" shank, open-end lug nut with a 4mm conical end it could take up the space of the shorter shoulder but there ain't anything like that out there.

Wish me luck, will post here when they arrive.
 
Greg
Thanks for looking into this. I never needed to meet that rule but do find the standard studs are a pain when swapping on wheels with shouldered lug nuts (like old style cast slots). Since I do this every autocross, long studs would be a time saver. For the rear on my car, I had some long GM style 7/16 studs ground down and reknurled.

In post #7 you mention possibility of metric thread but the link you posted is to a 7/16 threaded strud. I think it will be the same as US when you get it. Even in the 1980s we found Ford Australia had slipped in a standard size bolt - drove us nuts for a while because it was called out as an M something on the drawing.

The example in the NHRA rule follows your logic the important factor for a good thread engagment is to be 7/16 deep on a 7/16" diameter. But the question remains how your local track inspector will interpret it.

Matt
 
rmchrgr said:
BTW, if anyone cares, the NHRA has a rule on wheel studs. I think a lot of guys will say that you are required to run longer studs but I do not believe that's how the rule is interpreted.
..."Thread engagement on the lug must be equivalent to or greater than the diameter of the stud or bolt. Length of the stud/bolt doesn't determine permissibility (example: a 7/16 inch stud must be thoroughly engaged through the threads in the hex portion of the lug a minimum of 7/16 inch."...
​
So a little math - threads on the OE studs are .9xx". On the Centerline lug nuts I have, the shank is 1.3". Studs are 7/16 (Thread pitch) =.437" so using those specs, it would appear that there is more than double the thread engagement necessary as per the NHRA rule but unfortunately they specify through the hex portion of the lug. If that's the case, it's way short, the threads don't even make it to the hex portion with these lug nuts. The wheel is indeed 1.3" thick so I need to use the 1.3" shank. There's no mention of shank style lug nuts which are threaded all the way up. It's a little unclear.

According to the P.O. of my car, it went 11.97 and it had the OE 10" drums with closed end lug nuts. Guess it must have been OK? I think if the tech guy sees you have closed lug nuts, they make you remove them to check for proper engagement. That's why people say that you need the longer ones - there is nothing to question because the tech guy can see them clearly and they move on, no hassle.
Click to expand...

I am very anxious to see how this turns out too.
 
So the studs arrived yesterday, took about 10 days to get here from Australia. Cheers to Pentastar parts.

So I put one in and it looks like it should work. Like I suspected, the shoulder of the stud does indeed end up lower than the flat surface of the hub. There is a slight chamfer on the hub surface where the would be no clamping surface with either stud in place. The shoulder of the longer stud is slightly below that but not a significant amount, maybe a mm or two.

The stud pressed in with some resistance so its in there solidly, no wobbling or anything. The knurl is the same diameter as the OE stud. There is a slightly larger step right under the head but they are essentially the same. It sticks up about an inch and a half +/- above the hub surface.

My hope to use open end long shank lug nuts may not be a possibility because the studs aren't long enough to stick through the open end. They do thread in to the hex portion of the nut though and the shank is threaded all the way up so there is plenty of clamping surface and the increased mechanical advantage will be the largest benefit. I will have to check the specs on the Centerline lug nuts to see if they're worth getting.

Anyway, here are some pics. Hope this helps anyone thinking about doing this.
 

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As much meat as there is on the hubs I would say I would run them. Would you post a side shot of the hub where the stud goes through with a stud besides it? I realize that the rotor would also be there but the other picture will tell us a lot.
 
Oklacarcollecto said:
As much meat as there is on the hubs I would say I would run them. Would you post a side shot of the hub where the stud goes through with a stud besides it? I realize that the rotor would also be there but the other picture will tell us a lot.
Click to expand...

Thanks for the reply! Was hoping more would chime in - I am the Aussie wheel stud pioneer! I will try to get that pic later.

I believe they're good. Again, the shoulder is just below the chamfer on the hub surface so it's just a hair below where the OE stud sits. I'm confident the extra length and increased clamping surface will more than compensate for that little area where there is no contact.

One thing I thought of would be to have a little contersunk area on the back of the rotor surface where the stud head sits. That could make up the slight difference on the other side. The rotor hat is fairly thin though so only a minimal amount of material could be safely removed. Probably not worth the effort.
 
I would be far more concerned about taking off any material of the rotor hat. That hub is thick so I don't think it will be an issue.

The Aussie's are running those studs and they are apparently working without issues over there. I have looked at pictures of the Aussie Kelsey Hayes disc brake set up on several cars and I see nothing different than on ours.
 
rmchrgr said:
Thanks for the reply! Was hoping more would chime in - I am the Aussie wheel stud pioneer! I will try to get that pic later.

I believe they're good. Again, the shoulder is just below the chamfer on the hub surface so it's just a hair below where the OE stud sits. I'm confident the extra length and increased clamping surface will more than compensate for that little area where there is no contact.

One thing I thought of would be to have a little contersunk area on the back of the rotor surface where the stud head sits. That could make up the slight difference on the other side. The rotor hat is fairly thin though so only a minimal amount of material could be safely removed. Probably not worth the effort.
Click to expand...

You could also have the stud heads turned down about a 1/16" or so on the under side rather than counter bore the hub.
 
Russ H said:
You could also have the stud heads turned down about a 1/16" or so on the under side rather than counter bore the hub.
Click to expand...

Modification of the hub wouldn't be an option. The rotor doesn't go over the hub, it mounts to the back. Any modification to the back of the hub would change the rotor location. The only modification I could see possible would be the inside of the rotor but I wouldn't do that either.
 
Russ H said:
You could also have the stud heads turned down about a 1/16" or so on the under side rather than counter bore the hub.
Click to expand...

They're good, not going to mess with them or the rotor. Was just thinking out loud.

Going to get those open lug nuts but that's it.
 
rmchrgr said:
So the studs arrived yesterday, took about 10 days to get here from Australia. Cheers to Pentastar parts.

So I put one in and it looks like it should work. Like I suspected, the shoulder of the stud does indeed end up lower than the flat surface of the hub. There is a slight chamfer on the hub surface where the would be no clamping surface with either stud in place. The shoulder of the longer stud is slightly below that but not a significant amount, maybe a mm or two.

The stud pressed in with some resistance so its in there solidly, no wobbling or anything. The knurl is the same diameter as the OE stud. There is a slightly larger step right under the head but they are essentially the same. It sticks up about an inch and a half +/- above the hub surface.

My hope to use open end long shank lug nuts may not be a possibility because the studs aren't long enough to stick through the open end. They do thread in to the hex portion of the nut though and the shank is threaded all the way up so there is plenty of clamping surface and the increased mechanical advantage will be the largest benefit. I will have to check the specs on the Centerline lug nuts to see if they're worth getting.

Anyway, here are some pics. Hope this helps anyone thinking about doing this.
Click to expand...

For added safety I tack weld the back of the stud. I've never had a problem with the studs backing off.
 
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