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Author Topic: !!CAUTION!!1800 Stud Installation
Karl Verified Driver Made Donation to Website
2001 ARRC Winner


Region: SW
Car #: 50
Year : 1600
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The knurl on the 1800 (or superceded 1600) rear hubs is larger than the 12 mm thread. As a result there must be a transition from one size to the next. Our newest studs taper down from the larger knurl to the 12 mm threads which can cause a clearance problem to some rotors. This is also a problem with some other after market studs. If you design the stud to make full contact with the hub then the taper extends into the rotor's "space." If you design the taper to end before getting into the rotor's "space," then you compromise the contact between the stud and the hub. Clear?

Some rotors must be chamfered so that the rotors seat on the hubs rather than on the taper of the studs.

Please top this Mike.

Jim Boemler Verified Driver
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I assumed these were an off-the-shelf part -- did you have them specially made, Karl? I bought a set last year, and didn't realize this in advance. I ended up drilling (9/16") about a sixteenth of an inch deep, since I didn't have a large-diameter countersink. Worked fine, but a pain in the butt.

Is there any evidence that a shorter knurl would either slip out or turn loose? If not, as a customer I think I'd rather see the knurl shorter, so I didn't have to worry about things like borrowing a rotor at the track. For those of us who can't carry much for spares, using vanilla parts is a consideration.

Besides, where does the GCR say you can countersink or drill your rotor holes? [Big Grin]

jim

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Just a clown

Jerry Cabe Verified Driver Made Donation to Website
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"Besides, where does the GCR say you can countersink or drill your rotor holes?"

You beat me to it Jim.

Jerry

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Just driving SM until the F-1 car is ready.

Bad Al Bell Verified Driver Made Donation to Website Series Champ
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In the rulebook J and J-
Stock replacement parts may be obtained from sources other than the manufacturer provided they are the exact equivalent of the original parts. The intent of this rule is to allow the competitor to obtain replacement parts from standard industry outlets, e.g., auto-parts distributors, rather than from the manufacturer. It is not intended to allow parts that do not meet all dimensional and material specifications of new parts from the manufacturer.


If the original rotors are countersunk and your replacement ones are not, they need to be countersunk to meet all the dimensions of OEM parts.

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"Bad"Al Bell
SM/SSM #3 "JD"
SM #09 "Nadine"
2006 MARRS SM Champion
DC Region SM Driver's Co-Rep
SM cars for sale and rent, and rent-to-own
www.MEATHEADRacing.com

Jim Boemler Verified Driver
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quote:
Originally posted by Bad Al Bell:
If the original rotors are countersunk and your replacement ones are not, they need to be countersunk to meet all the dimensions of OEM parts.

I won't even disagree, but I don't think the OEM parts are countersunk.

jim

--------------------
Just a clown

Jim Daniels
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It is a gray area, parts that are sold as direct OEM replacements to the IG community and parts that look exactly like OEM parts for our rules.

It has been my experience that it better look exact regardless how it is marketed and sold to the street car guys.

Bad Al Bell Verified Driver Made Donation to Website Series Champ
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Karl knows more about this than I do, but from his post I conclude:

On a 1.8 car or replacement 1.6 hub
1-No matter what stud you have-ART, XYZ, OEM, the knurl is larger than the threaded diameter.
2-There has to be a transition from large to small. This can't be 90 degrees for strength reasons.
3-If all studs are this way, then there must be a countersunk area in the rotor to prevent catastrophic failure.
4-Original 1.6 rotors would not be this way, due to smaller knurl and no need to chamfer
5-Replacement 1.6 rotors need to be countersunk due to superseeded parts (hub and studs).

And since the aftermarket studs are specifically permitted, the measures needed to install them properly are allowable.
The rules say you can install hood pins. I don't see where it says you can drill the hood.

Thanks Karl.
(Is your car still painted Cub Scout colors)

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"Bad"Al Bell
SM/SSM #3 "JD"
SM #09 "Nadine"
2006 MARRS SM Champion
DC Region SM Driver's Co-Rep
SM cars for sale and rent, and rent-to-own
www.MEATHEADRacing.com

Steven Burkett Verified Driver
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What Al said, and my favorite underused quote:

"If it doesn't say you can, you can't, but if it says you can, you bloody well CAN."

Steven

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www.tuxedoparkracing.com

Karl Verified Driver Made Donation to Website
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Thanks Al. You put it better than I.


Jim,

If you look at an 1800 rotor you will see that it is chamfered (though some not enough) to accept the transition in all studs. If a 1600 owner moves to the updated rear hubs (1800 hubs) they need to make sure their rotors have the chamfer BECAUSE not all rotor manufacturers know about the superceded hub and stud.

Yes, we designed them and had them made. It made more sense for us to have the knurl contact the hub through its entire thickness. Rotors are relatively soft. It may be a PITA, but the next time you are at the hardware store pick up a countersink. I know you will find someone at the track with a drill. What do you have to do between sessions anyway? [Smile]

Kent Carter Verified Driver Made Donation to Website
Future Never Has Been

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Al,

Karl's car got redecorated when a rookie spun in front of me in this weekend's Double Regional Crash Fest at MSRH. I hit him... hard.

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Do I turn my 99 Hard S into a killerfast SM or seek a donor?

Sean Allen Verified Driver Made Donation to Website
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I'm having a little trouble understanding what exactly you guys are referring to. Anyone care to go in to a little more detail, or even attempt to draw a diagram?

jensen Verified Driver Made Donation to Website
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I encountered this problem with my first race of the year in the '99. I never knew the difference between 1.6 and 1.8 rear hubs, now I do. The taper of the 1.8 protrudes past the hub and does not allow the rotor to seat on face of the hub. When you torque the wheel you push the studs inboard and the wheels will not stay torqued and studs will spin in the hub. I have brembos, needed to counter sink. I looked at my spares, oem Mazda's, and they are countersunk. Small item to fix vs. big problems...

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Matt Jensen
SCCA SM Cen-Div
MC NASA 68

inflatable Series Champ
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quote:
Originally posted by Karl:
Thanks Al. You put it better than I.


Jim,

If you look at an 1800 rotor you will see that it is chamfered (though some not enough) to accept the transition in all studs.

Are you referring to the stud holes, also known as a countersink? The two terms are sometimes used interchangeably, but clarification in this case would be nice. In my mind chamfer=outside edge, countersink=inside a hole.

Sean Allen Verified Driver Made Donation to Website
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So basically you just need to counter sink the inboard side of the brake rotor? Is this only for 1.8's?

I am about to buy new rear 1.6 hubs because mine are 200k+ers and it's probably a good idea. I notice people are saying all new rear hubs are 1.8's. Does this mean I will have to run 1.8 brake rotors now?

jensen Verified Driver Made Donation to Website
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You guys need to countersink the inside of the rotor'holes for the wheel studs. Sean, you do not need to worry about this issue because you have 1.6 brakes/rotors/hubs/studs...

--------------------
Matt Jensen
SCCA SM Cen-Div
MC NASA 68

Sean Allen Verified Driver Made Donation to Website
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Jenson, only reason why I ask is that on the ART site, it was wheel studs for 1.6 and 1.8/new hub 1.6. So I'm wonder if this problem also exist with the new hub 1.6.

Karl Verified Driver Made Donation to Website
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Year : 1600
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Understand that ALL front hubs are the same. They take the smaller OD knurl (1600) studs. All new rear hubs have the larger knurl (1800) studs regardless of which car you have when you place the order. Clear? The 1600 rear hub part number supercedes to the 1800 rear hub part number.

cham·fer (chmfr)
tr.v. cham·fered, cham·fer·ing, cham·fers
1. To cut off the edge or corner of; bevel.
2. To cut a groove in; flute.
n.
1. A flat surface made by cutting off the edge or corner of a block of wood or other material.
2. A furrow or groove, as in a column.

The tool required is called a countersink. Do you Hoover your carpets or vacuum them? [Smile]

Karl Verified Driver Made Donation to Website
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Boredom at the track and silliness aside, call it whatever is more understandable so that you make sure it's done. As I said before and will say again..."he said it better than I."

inflatable Series Champ
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Does anyone know whether the same installation problem with the ART studs has been found with the ARP studs?

DW Verified Driver Made Donation to Website
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It's not an issue with the studs. The issue is with many non-OEM rotors.
If you have original 1.8 rear hubs or any new hub, most, including OEM, studs will have the knurl protrude out toward the rotor.
OEM rotors, and many others, have the stud holes chamfered to accept this. Some do NOT.

Bottom line: when installing new rear rotors, make sure the rotors seat properly over the studs. It is relatively common for them not to, which is why Karl posted this alert. If they don't, look for the chamfer. If the back of the rotor stud holes are flat, you need to fix them. Things get ugly if you don't.

A "step" drill bit makes easy work of it.

--------------------
Darrell Wheeler
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WBR Graphics
King RAT Motorsports
PBC Automotive
Meathead Racing

   

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