A Body Disc Brake Anomlie with 4.5" bolt pattern??

Have a pair of what seem to be A body 2 piece disc brake rotors. Same dimensions and such, but the bolt pattern is 4.5" with 1/2 studs. Has the smaller A6 inner bearing and the studs cross to a one year 72 Chrysler type by a Dorman catalog.

I have been told some super stock A Bodies had the big bolt pattern disc brakes, but that the 340 A bodies did not get it until 73. I also thought by 73 all rotors where one piece, but no expert on this. Any idea what they came from? Did some late 340 A bodies get the 4.5" bolt pattern with disc brake option?

Well, the 68 Hemi Dart's and Barracuda's did use the 4 1/2" inch bolt pattern, and 1/2" inch wheel studs, so you just might have rotors-hubs, from those cars.
On the back side of the hubs are there the letters K/H cast in the hub?
Where did you get them, anyway?
An old racers stash of parts?

And, no 72 A Body car, ever got a 4 1/2" bolt pattern.

Someone just brought this to my attention.
Possibly, you have Ford Mustang rotors, they are 4 1/2" inch bolt pattern.
But i would need to see an official pair of early Mustang rotors and hubs, to compare.

I doubt a Ford two piece, rotor, hub, is machined to work on a Mopar spindle, (knuckle) or it would have been done long ago.
Even though there is a vendor that re-machines one piece rotors, with 4 1/2" inch bolt pattern to work on a Mopar spindle.

were any of the studs RH thread?

Long Time Mopar Mechanic and Racer who did have super stock cars. I will take picture of back, but no KH markings on rotor or hub. Just some other casting mark. The Studs are marker with KH though.

Both Rotors have RH studs and they cross by dorman as 1972 Chrysler ONLY. The Stud Head is unique as compared to the other 2 piece KH or Bendix rotors. In matched perfect to the picture in a Dorman 1984 catalog. Hub and rotor is a match to the 7/16" 4" pattern A body hubs, and is small bearing which is what drove me to a 1972 type.

Did Mopar make another run of parts in 72 for the early cars or as an upgrade to add 4.5" pattern?

I haven't got a clue if Kelsey Hayes ever produced a rotor-hub assembly, back in 1972, with a 4 1/2" inch bolt pattern, for an A body automobile.
It certainly wouldn't have been for any regular, assembly line, production, automobiles.
Running off a batch of them, as replacement parts, for a 68 Superstocker, who knows.
I doubt if anyone knows.
I used to rebuild these Kelsey Hayes a body disc brake systems for resale purposes, and i kept track of all the ones that i rebuilt during the 12, 13 years that i was doing them.
Rebuilt 32 sets of brakes in that time frame, and never came across anything with 4 1/2" inch bolt pattern, for a Mopar A body automobile.
If you do have a 68 Superstock pair, they certainly would be dinosaur eggs, hens teeth, unobtanium parts, to have in this day and age.
But a very, very, limited market for them if the rotors aren't machined undersize already.
For street A body cars, the enthusiasts are just buying the one piece Mustang rotors for 4 1/2" bolt pattern machined for a Mopar, that a machinist, vendor, advertises on the web sites.

The rotors were used in 66 trans am cars. Actually they were first developed for that or the Rally off road 63-65 A-bodies Scott Harvey and others campaigned.

Mopar in the mid 60’s had an over the counter performance parts listing/catalog. These disks may have been available even then in those list/catalogs.

Humm, good to know. Thank's.

I’m not sure if they were available over the counter. I have a 65 or 66 Performance Parts list from a Super Stock magazine or something. I have to check it tonight.

Not sure if there are scans of those list available online.

I looked up the 65 Performance Parts Catalog on HH (thank you Barry)

It doesn’t have the Disk.

But on a side note, does offer 15x6 small bolt steel rims. There’s some weird parts in there.

http://www.hamtramck-historical.com/_1965Hi-PoParts-01.shtml?load_img=9

Here are the back pictures and there was a number on the rotor. If the Dorman Catalog is correct the studs in these, and they seemed to be original are a 1972 stud. Cross to a 3580598 Chrysler part number. Which some dealer have listed incorrectly as a rear stud.

I also noticed that the casting symbol after the rotor number looks like a casting symbol I have seen on the 90425 KH type Pin Caliper Brackets.

That is not a small bolt 15" rim, that is under the Dodge and Plymouth rims which were 4-1/2".

I do think your confusing some issues here, Those wheels are showing width, not bolt pattern. I would assume the ones listed under Valiant and Dart as small bolt pattern. But the largest wheel there is 14" by 4.5" width.

Nothing to do with this type of rotor and a 4.5" bolt pattern.

The Mustang rotors did not look like that and were one-piece.

Then it's pretty much a given that he has a pair of 68 Hemi Dart, Barracuda rotors & hubs.

Then it's pretty much a given that he has a pair of 68 Hemi Dart, Barracuda rotors & hubs.

All the 4 "inch bolt pattern, 65-72 Kelsey Hayes, 4 piston caliper, disc brake systems, that i have worked on, have the letters K/H cast into the back side of the hub.
I see the letters DSK on the hub in the picture. Meaning Disc?
To me, i feel that is manufacturing ID for those special 4 1/2" bolt pattern hubs.
What are your intentions for those rotors & hubs?
You got yourself a Superstock car?
I'm not a buyer or anything like that, but your posting peaked my interest.
I have heard of those rotors & hubs, but never have seen any in person, or pictures of them before this.
Thank's for sharing.

Your welcome. Rotor has H 50137 and a symbol that looks like a cross between an F and a T. I do not own them and they will probably wind up on ebay. They are not bad, but are below minimum. Hub is good, but that register size is smaller than the b body types.

I am a B body guy with a 69 and 70 Disc Brake car, so I was scavenging for those parts. You where on the post in the B Body Forum helping a guy overseas with a single piece rotor on his car. Not sure if you saw what I added. I have broken down KH and Bendix rotors and compared Hubs.

I forget the company but they used to have a jig for drilling the old KH rotors so you could run a 4 1/2 inch bolt pattern. We looked into it and hit a dead-end and ended up having his done locally. Worked out great for him and he updated his OLD centerline wheels.




23023734_10155737519032777_1329839039_n by John Cadamore, on Flickr

Thank you for sharing the pictures and info. Really neat to see these up close out of a car.

Could you measure the register diameter at the bottom where the wheel sits ?

I’ve never measured, I thought it was probably b-body register. But never had clarification.

Thank you all for sharing the info here.

I've not seen or heard of any definative info on whether large bolt pattern hubs were developed before '68. We see plenty of photos of '66 Trans-Am cars using aftermarket rims in the later races, but they could have been SBP or BBP. I agree it seems possible, and it may or may not have been a special run or a remachined part from another application.

The Part Number for the special 4 1/2" bolt circle hub-rotor was 2836148.
"The same bearings and seal are used and all wheel studs are 1/2-20 right-hand thread."

"The rear axle shafts..[ for 8 3/4"]...may be replaced with special axle shafts with 4 1/2" bolt circle for wheel mounting, P.N. 2513750-M and 2513751-M. All wheel studs are 1/2-20 right-hand thread. The brake drums must also be replaced with P.N. 2534173. The same brake shoes, etc. may be used."

from "Rally Preperation" in Mopar Chassis, Carroll Shelby Speed Secrets: Direct Connection Suspension Modifications... Chrysler Corp. Part No. P4349341 (1984) page 53.

Anyone know when the rally bulletin was first released? It had to be long before 1984. By '84 there's a note that the large bolt pattern 8.75" axles mentioned are no longer available.

Just checked. Not mentioned in the Feb 1966 Prep Notes 1.

What about the FIA papers on the team starfish site?

In a Ehrenberg article on Scott Harvey it said they had them for 66.

Torozzi does not have drawings/notes to make them special. He has stuff on everything else. Torozzi helped a little on the 66 Trans Am after hour employee team.

Sure would have made it simple to have those back then and now. I like the "feel" of those better than the later single piston.
And no overbite!

I pretty sure I have an e-mail or PM with Rick E and he didn't know for sure. Maybe Mike has something, but the FIA papers don't mention the bolt circle; the width, diameter, and material yes.

Is there a way to estimate when a part was released based on the part number? (Not that means a prototype couldn't have been used earlier.)

So for the LBP Rotor I measured the Rotor Hole dia which is about 2.90". The Rotor hat area is about 6" Diameter and tapers larger at the rotor surface.

The hub inner register that goes into the rotor is also 2.90". The Hub Flange diameter is about 6.17". The hub diameter at the wheel hole is 2.70". This hub flange is also about .020" thicker then a SBP A Body rotor. Thickness where studs go through hub.

I took apart an older A Body SBP rotor that was heavily worn, but had 7/16 Left Hand Studs. KH Stamped. You will love the picture as the rotor was so thin on one side it pushed the hat area through the rotor when I pressed it out.

The Original KH SBP Rotor Hat area is very similar in all dimensions as the LBP Rotor. Same hole size for hub.

Also this Hub had the Same symbol as the LBP, a small O inside a box. Not sure if KH had their own foundry or subed out the casting. Did have K/H Letter as you can see.

The SBP Hub has a 5.76" Flange Dia with 2.30" Wheel register. The hub rotor side Dia is the same as the LBP at 2.90" So I can swap hubs between the two rotor, the stud holes just do not match up. Plus the LBP Studs have a .625" Knurl, while the 7/16 studs are the stock .56?" Dia.

Basically the LBP Hub is a beefer hub like B/E body two pieces but with all the other attributes/dimensions of the smaller A body hub other then the changes needed to be a LBP hub.

Pictures are the Original KH SBP hub I took apart this afternoon.