Does anyone know what the difference is between the Ford, Dodge and Chevy 3/4 ton rotors? I am talking about thickness, diameter, hat offset, lug size, etc.


Why am I asking???? Most disk brake conversions have the rotors really close to the axle housing flange. When I put a Chevy 3/4 ton rotor on my D60HD rear axle, I have about 2.75" between the 4 bolt flange and the back of the rotor. I was wondering if different rotors would have more offset and bring that dimension closer to the axle housing flange. I really don't want to weld onto the spindle. I wanted to make some spacers so I could bolt on the caliper brackets. Does anyone have any pictures of a rear D60HD or D70 with disks?

How far away from the back of the rotor should the caliper bracket mount? (I know I can check the distance on my front axle, but I am at work now.)

Ford one ton rotors has the largest hat area...however, the studs for my 14 bolt would not fit into the recess on the rotor. I opted for the 3/4 Chevy one instead (from a 75). I was able to install my rear disk with the large GM calipers and I only has to barely grind the 1/2 ton caliper bracket that I welded to the housing. If you used the AA-Mfg brackets, this area wouldn't exist.

Oh yeah, this is with 3.5" bs allied wheels

Here's is Rockslut's D70 with the ford rotors

Edit: Sorry, don't have one with the calipers installed.

Here's my 14 bolt set up.

Wow, that is quite a difference between the Ford and Chevy rotors for the offset. My 60 has 5/8" lug studs so do you think there will be a problem with using the Ford rotors? I will have to drill out the stud holes on the Chevy and the Ford rotors since they use smaller studs. Can you explain your problem more with the Ford rotors and the studs not fitting?

Do you have any other pics of the D70 or know where I can search for them?

on the backside of the rotor where the studs press in, there is a slight recess for the head of the stud to drop down into. The 14 bolts studs were huge and the 79 Ford 1 ton rotors had a smaller recess. I didn't feel like trying to grind the stud down so i just bought differetn rotors that I knew worked...cause ol' H8Monday used the same ones already..although he had to grind a lot more than me for some reason..probably due to different beadlocks and that fact that everything he builds requires a grinder:D

The 79 Ford rotors are set up for 9/16 studs so you will have to drill them out.

I don't have anymore pics of the 70..but I can get them next week when I get back from Calrocs


Make sense?

On a related brake note (sorry to steal the thread!!) What year chevy caliper is the most common/preferred for disc swapps? I bought mine yesterday and there were 3 or 4 different part numbers... I got the ones for like 74 to 78. I didn't actually compare calipers but they had all different part numbers for the bigger two bolt style for different years.

Originally posted by Aggro
On a related brake note (sorry to steal the thread!!) What year chevy caliper is the most common/preferred for disc swapps? I bought mine yesterday and there were 3 or 4 different part numbers... I got the ones for like 74 to 78. I didn't actually compare calipers but they had all different part numbers for the bigger two bolt style for different years.

I think that the main difference is the banjo bolt size.

Mine are from a 74 waggoneer...cause I had the brake lines already.

I used 79 F350 front rotors on my 70 (pictured above). The hat area was about 1/2" more than the chevy rotors. I needed this because the flange area on the 70 bearing hub is thinner than the 14 bolt. So both setups came out to be around the same.

Hey Rockslut......Where did you mount your caliper bracket and did you weld or bolt it on? My 60 has a huge gap between the housing and the hub (about 5") so I have to weld onto the spindle......I wish I had my camera with me so I could upload the pics of what I am talking about. :rolleyes:
I have some old Chevy 3/4 ton caliper brackets that I am thinking of using.

Well my 70 was out of a 75 E350 and i welded my caliper bracket to the tube/flange area where the backing plate used to bolt on. My setup ended up perfectly lined up with that. Scout dude welded his to the tube and it came out great.

I don't think I can weld to the backing plate because my spindle and hub look like this...

||---------|---

Where the "||" is the flange and the "|" is the hub surface. The distance between them is about 5" or more.

Other axles that I see are like this....

||---|---

so it is easier to weld onto the flange or the housing.



Today at lunch I will compare a Chevy and a Ford rotor at the parts store.

By the way, which MC are you guys running and is it boosted? I am thinking of trying out a 68 Vette MC with my stock booster. My stock TLC MC just isn't cutting it anymore.

Originally posted by Eric
I don't think I can weld to the backing plate because my spindle and hub look like this...

||---------|---

Where the "||" is the flange and the "|" is the hub surface. The distance between them is about 5" or more.

Other axles that I see are like this....

||---|---

so it is easier to weld onto the flange or the housing.



Today at lunch I will compare a Chevy and a Ford rotor at the parts store.

By the way, which MC are you guys running and is it boosted? I am thinking of trying out a 68 Vette MC with my stock booster. My stock TLC MC just isn't cutting it anymore.

I think that RS welded his to his backing plate mount...mine is nowhere near the mount. It was easy to weld it up..More pics are in my www link below..go to the 2002 build up. I run a Camero master cylinder with a Wilwood adj prop valve..but I haven't driven on the rear disk yet. Matt has a (Edit-->) Bronco one with some slight mods done to it and he says it stops great.

I had swapped my stock YJ MC for a 79 Bronco one. I was trying to get a better pedal with my 44/9" (drum) setup. It didnt work. I pulled the o-ring out of the proportioning valve and hold on :eek:

Now with stock GM 60 front calipers and 1/2 ton calipers on the rear I can lock up the brakes no problem.

Thanks for all of the info guys. I really appreciate it since my axle is not like a normal one. :D I have been searching for a few days and I have tons of info now.

hey- this pic:http://community.webshots.com/rz/r1/3/61/34/29836134iyKCkqEgOP_ph.jpg

what springs? what bushings? Where to get the bushings? I bought very similar springs yesterday and need to get some bushings. they are like 2.5" lift springs.

Yours is a dually rear right? Thats why the flange for the backing plate is so far inboard. Cut it off! OR leave it for that matter. I cut mine off.

Make a new one that a.) slips over the spindle and b.) matches the bolt pattern of the chebby 3/4 caliper stands. Assemble the whole works and weld the new "backing plate" flange on. Once you go to discs you're never going back to drums.

Use what ever rotor is cheaper and more available. My pricing shows the chebby to be cheaper. The only "problem" you may run into here is caliper clearance to the rim, if 15" rims are in the mix. That would be the advantage of the pherd rotors. They would position the calipers farther inboard. But I'm running 16.5's and that doesn't matter to me.

MC = '76 Caddy Eldorado. This is the shiznitz!

Sorry no pics of my D70, got it done while home on leave (barely) then off again on the road. IN the pic above that one needs some grinder work. Then it will think its a 60 :D

Originally posted by Aggro
hey- this pic:http://community.webshots.com/rz/r1/3/61/34/29836134iyKCkqEgOP_ph.jpg

what springs? what bushings? Where to get the bushings? I bought very similar springs yesterday and need to get some bushings. they are like 2.5" lift springs.

Those are Rancho 44044 waggy front 2.5" spring
Comes with bushings

some help you are!!!!!!!!

Originally posted by Aggro
some help you are!!!!!!!!

You're just jealous because I have all the answers :rolleyes: :D

Originally posted by The Rockslut


You're just jealous because I have all the answers :rolleyes: :D

yep...or something...

I measured the Ford and Chevy rotors.

F350
12.563" OD, 5.135" ID, 3.210" tall
1.25" thick (1.18 min)
Stud hole: 0.640 dia, 0.335 deep, 1.10"-ish counter bore dia


Chevy K20
12.500" OD, 5.120" ID, 2.780" tall
1.285" thick (1.215 min)
Stud hole: 0.650 dia, 0.405 deep, 1.13" counter bore dia



The D60 HD stud heads (1.15" dia) that I have are slightly larger than the counter bore diameter in the Ford rotors, but they do fit in the Chevy rotors. Both of them will have to be drilled out to fit the 5/8" studs. Ford rotors are 0.43" thicker overall than the Chevy rotors.

I just checked another brand of Ford rotors and the stud counter bore is smaller so I am going to use the Chevy rotors. Here is a pic of my axle with a rusted out Chevy rotor for initial measurement purposes. I would have to make one large spacer for this to be a bolt on caliper bracket.

http://www.off-road.com/~estegall/tech/d60hd-disks/d60hd-disks08.jpg