I turned a couple of rotors into hubs and now I need longer wheel studs to make up the difference of the rotor thickness. The motormite # 98501/Dorman 610-323 will only work on one of the "hubs"

One of the rotors I used was probably not a factory replacement. Anyone else have this problem or can suggest some different part #'s? thanks, Ben

 

I've had no problems on either GM or aftermarket rotors, sorry. You could always upgrade to ARP -7708 studs and drill a .484" hole to install them and you'd be all set. That's what I'd do.


Ed

 

napa carries a longer length wheel stud for the front rotors.

part number 641-1581

they may or may not work for you. i'll let you know once i get my brake upgrade done.

 

Those are the Motormite studs I use...they work great, I'm very pleased with them.


Ed

 

awesome.

 

Ben,
You didn't mention why the studs won't woork on one hub but I assume the holes in the hub are too big for the knurl diameter of the stud. I am having this problem with the LS1 brakes on my 85 IROC. I made hubs out of aftermarket rotors and the knurl diameter on the wheel studs in those rotors was larger than what some of the other guys are using. I used the NAPA studs which are the same as the Dorman 610-323. I did not drill the holes in the hub and the NAPA studs went in very easy with a few light taps from a hammer. Now after a day at the track they are loosening. Here is the text from a thread I saved a while back on wheel studs. Maybe there is something useful for you here.

Stock wheel stud size?
I need longer wheel studs for my front LS1 brake upgrade. I went to the auto parts store today to find out the stock knurl diameter of the front studs so I can order some ARP’s. But the auto parts store computer said the front and rear studs are the same but they are not. The one’s they listed will only fit in a 10-bolt rear axel. My front studs have a larger knurl diameter. Can someone tell me the knurl diameter on stock front wheel studs?


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07-20-2003 05:09 PM



alloy
Senior Member

Registered: Jun 2002
Location: washington state
Posts: 636
Order ARP 100-7708. They are .509 knurl diameter. The stock ones on my hubs measure around .489. The ARP's are a little larger, but will fit. Jeg's has them in stock, but as usual summit is back ordered on them.



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07-20-2003 06:41 PM



89 Iroc Z
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Registered: Aug 2001
Location: Fairfax, Virginia
Posts: 1201
My concern with them is that they are to long. I have aftermarket lugs that will probably bottom out on those studs. I know I could go with an open back stud but I personally don’t like that look.



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07-21-2003 12:56 AM



91Z28-350
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Registered: Feb 2003
Location:
Posts: 240
From toddlsf's C5 page http://82lt1.cz28.com/brakes/page5.html

Motormite 98501
Dorman 610-323

http://www.motormite.com/

They are 54mm long (about 2-1/8"), .509 knurl with an 8mm shoulder.


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07-21-2003 09:14 AM



slowTA
Senior Member

Registered: Jan 2000
Location: Clifton, NJ
Posts: 372
I asked almost the same question a few weeks ago and only got the ARP numbers.... At least we have another option. I have to say that my front and rear studs are the same, but I have a 9 bolt rear.


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07-21-2003 12:27 PM



slowTA
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Registered: Jan 2000
Location: Clifton, NJ
Posts: 372
This is what the Doorman/Motormite studs look like when they are installed. I just happend to find a local NAPA that had them in stock. You can tell that they are MUCH longer than stock, but the plastic caps still fit.

slowTA has attached this image:



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07-28-2003 12:21 PM



ebmiller88
Senior Member

Registered: Mar 2001
Location: Fort Mill, SC, USA
Posts: 2302
Slow TA, did you redrill the stud holes at all when you installed the Dormans? I did on a kit I did and now we are having trouble with the studs turning. I just drilled the hole too big (.500"), but I'm curious if you drilled or not.

The Dormans you listed (610-323), which I used and will use again, have a 12.80 knurl diameter which equates to .5039" => .504" knurl diameter and the ARP studs I installed on my kit have a .509 which is where my problem lies...not enough meat in the hole to hold them still on the other hubs.


Ed


Last edited by ebmiller88 on 08-25-2003 at 04:00 PM

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08-25-2003 03:48 PM



slowTA
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Registered: Jan 2000
Location: Clifton, NJ
Posts: 372
Nope, no drilling at all! I just used a vice and a long socket to remove and install them. They actually went in pretty easy without drilling. I just assumed that they were the correct size based on the info that 91Z28-350 gave, both at .509. FYI, those are the rears that I did.

I have to say that I have removed the front studs with a hammer, they didn't seem to be as tight as the rears were. I haven't installed the fronts yet, I'll do that when I get to the C4 conversion.



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08-25-2003 04:26 PM



91Z28-350
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Sorry, it's .504 like ebmiller88 calculated. I copied off the .509 from somewhere, I should have done the conversion.


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08-25-2003 04:44 PM



alloy
Senior Member

Registered: Jun 2002
Location: washington state
Posts: 636

quote:
--------------------------------------------------------------------------------
Originally posted by slowTA
Nope, no drilling at all! I just used a vice and a long socket to remove and install them.
--------------------------------------------------------------------------------



Well I just made a set of hubs for a C4 upgrade for a local guy, and he pressed in the .509 ARP #100-7708 studs without drilling and cracked one of the hubs. I told him to drill them, but he didn't listen. I've got the hub here if you want a pic of it. Cost him $50 for a new hub from me.

So my advise if you are using the ARP studs is to drill the hubs out to at least .484 (31/64ths). And unless you are using a milling machine or drill press with the parts clamped securely, you will end up with a hole around .495 or so. This is perfect for the ARP .509 knurl studs. I've done several sets of hubs like this and haven't cracked a hub yet.

If you are not using a machined down hub for a big brake upgrade and pressing these into a stock rotor or axle, you might get away with it. But a modified rotor will crack when pressing in the .509 stud.

Anyway, just my $.02 worth.


Last edited by alloy on 08-25-2003 at 05:03 PM

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08-25-2003 05:00 PM



slowTA
Senior Member

Registered: Jan 2000
Location: Clifton, NJ
Posts: 372
Hmm... I just measured a stock stud and it came up .496" to .499". The hole in the rotor is just about .486". So that's about .010" interference.

So if this holds true for most interference holes should I look for a bit around .494” for use with the Doormans?



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08-25-2003 07:51 PM



ebmiller88
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Registered: Mar 2001
Location: Fort Mill, SC, USA
Posts: 2302
That's what I thought..I shouldn't have drilled any larger for those Dorman studs. I think you'd be good with the .494"

Ed



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08-26-2003 07:12 PM



slowTA
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Registered: Jan 2000
Location: Clifton, NJ
Posts: 372
So are you saying that I still have to drill for the doormans, just not as big for the ARPs? I wonder why my rears went in with no trouble, just a bit crooked. They straightened out with a lugnut and a washer.

Ed, think you can throw in a set of ARPs and maybe they wont spin or is extra material worn away already?



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08-26-2003 07:16 PM



ebmiller88
Senior Member

Registered: Mar 2001
Location: Fort Mill, SC, USA
Posts: 2302
Yep, that's what I'm saying. I drilled the hubs my kit to .500" and installed ARPs and they fit great, no problems. I used the Dorman studs on a kit I just made, also drilled to .500" (like an idiot...didn't note the knurl difference), and they were loose. The Dormans should be frilled smaller, IE .494 or so, and like Dan recommended. The ARPs need to be the larger.

Yes. I got 2 sets of ARPs to replace the Dormans and it should be fine.

Long story short, both Jegs and Summit are backordered on ARP studs. I contacted Dan (alloy) and he drove 20 miles to and from his supplier on the west coast to get me 2 sets and send them to me over here in SC.

KUDOS TO ALLOY!!

Ed

 

I searched a couple stores and finally found some studs at the local auto value that worked. They didn't give me a part number and I had to grind some metal off each to get the rotor to slip over them completely and fit flush with the "hub". Thanks for the help, glad to hear i'm not the only one to run into this. I did the C5 swap, it wasn't too bad with only a couple hitches and took about 12 hours start to finish. That included machining hubs, spindles, repacking bearings, assembly, and all the etc.

Is there a difference in the height of some hubs compared to others? I just ask because when I went to put the abutment bracket over the rotor it wouldn't fit. I wanted to test out the new brakes so all i could think of was to throw some washers between the hub and the rotor to space it out far enough. I figured the best way to eliminate the washers would be to just take the bracket someplace and have the same thickness as the washers, milled off the bracket. turning another hub down would be an option 2 I guess, I'd rather not have to go through buying 5 more studs and having to grind them down as well. **edit, I only ran into this problem on one side?!