8 3/4 Rear Disc Brake Conversion

[kb67mopar]

Guys,
I am working on a rear disc brake conversion package for the 8 3/4 axle. Its an off the shelf rotor, caliper, pads, and seals, plus 2 brackets which I am making and are bolt on. You lose the parking brake since I am not using a stock setup here.

The jist of my question here is, are you guys interested in buying these from me? I should be able to get you complete disk brakes on the rear, keeping your stock or green bearings for around $250-$275 max.
Basically I would sell you the brackets and a set of instructions with part numbers/year vehicle for the parts store to get your off the shelf parts (eliminates the need for shipping cost and mark-up on those parts).

I am still finishing up the brackets but it will be spring/summer before I can give them a road test.

Leave a reply and let me know if you are interested!!

 

[old tired rebel]

I would be interested but I would have to have a parking brake set up. And I think scarebird does the same as you.I could not find a parts list or instructions on how to do this with the exception of the front disc swap

http://www.scarebird.com/index.php?id=1
rear brake conversion

1964-79 Dodge, Plymouth 8-1/4", 8-3/4", Dana 60 $130

 

[kb67mopar]

I would be interested but I would have to have a parking brake set up. And I think scarebird does the same as you.I could not find a parts list or instructions on how to do this with the exception of the front disc swap

I do not know much about his conversions. I won't be doing it with a parking brake provision at least not yet. Basically I would sell you the brackets required for $100 (maybe less if quantity goes up) and you would buy 1998 Jeep Grand Cherokee rear disks, calipers (with bolts), pads,and hoses. Those parts come out to be about $150-160. So $250-300 all said and done for most people and bolt on with no welding or axle modifications.

For a parking brake most people would need to run a mechanical line lock/roll control device.

 

[RustyRatRod]

I just see no reason for rear discs when drums are working like they are supposed to. Pretty much just more bench racing fodder.

 

[rolling_Thunder]

If I were you I would make the brackets to accept a Viper parking brake - they are a small lever actuated parking brake - those who want them can buy them - those who dont care won't need to --- if you are designing the bracket anyway it might be a good idea to incorporate that,

 

[old tired rebel]

I do not know much about his conversions. I won't be doing it with a parking brake provision at least not yet. Basically I would sell you the brackets required for $100 (maybe less if quantity goes up) and you would buy 1998 Jeep Grand Cherokee rear disks, calipers (with bolts), pads,and hoses. Those parts come out to be about $150-160. So $250-300 all said and done for most people and bolt on with no welding or axle modifications.

For a parking brake most people would need to run a mechanical line lock/roll control device.

That being the case why wouldn't I pull everything including the brackets and swap them over?

 

[kb67mopar]

That being the case why wouldn't I pull everything including the brackets and swap them over?

Each caliper requires a different bracket be designed for it. So to use viper calipers I would have to design another caliper bracket specifically for that caliper. I am doing this mostly for myself and want to know if people want them. Parking brakes mean more expensive parts beyond my original scope.

As far as replacing drums...I don't like drum brakes. Never have. Disks are way easier to work on and in most cases cheaper if you need drums and shoes and every other part with a car that's been sitting.

As for pulling the stock brackets and swapping over...they don't fit without extensive modification.

 

[Budnicks]

Sounds interesting, a new parts entrepreneur...Hmmmmmmm.... any photos of you rear disc brake set up or prototype ??, if your driving really hard or on allot of curvy roads allot of hard braking, then the disc's don't heat up as bad & don't fade as bad as the original drums will/do, but 90% of the time, it's just overkill on a regular driver, especially if your not pushing it hard or drive it, like you stole it... I still like the idea your suggesting, thinking outside the box.... GOOD FOR YOU, GO FOR IT !!

 

[kb67mopar]

Sounds interesting, a new parts entrepreneur...Hmmmmmmm.... any photos of you rear disc brake set up or prototype ??, if your driving really hard or on allot of curvy roads allot of hard braking, then the disc's don't heat up as bad & don't fade as bad as the original drums will/do, but 90% of the time, it's just overkill on a regular driver, especially if your not pushing it hard or drive it, like you stole it... I still like the idea your suggesting, thinking outside the box.... GOOD FOR YOU, GO FOR IT !!

Thanks. It made sense to me because I needed to completely rebuild the rear brakes anyway including cables lines etc. So by the time I made it all the way back up to the parking brake lever with cables and lines etc I was going to be exceeding this cost anyway and I hate the look of drum brakes behind open wheels (which I will eventually have). So its mostly an image thing for me not to mention better performance and no springs.

 

[YY1]

I like that it's all Mopar parts.

Is it really a 98 only parts swap, or is there a year range?

I se LOTS of cherokee/grand cherokees at the u-pulls.

Is ther any rotor index hole machining required?

It sounds like that Viper parking brake might be a seperate part than the caliper.....

If this works, I wonder why so much time and effort has been spent on mustang/explorer adaptions to the 8 3/4?

 

[kb67mopar]

I like that it's all Mopar parts.

Is it really a 98 only parts swap, or is there a year range?

I se LOTS of cherokee/grand cherokees at the u-pulls.

Is ther any rotor index hole machining required?

It sounds like that Viper parking brake might be a seperate part than the caliper.....

If this works, I wonder why so much time and effort has been spent on mustang/explorer adaptions to the 8 3/4?

I forget the exact years but I think its 96-98 is the same back there. The rotors are straight out of the box, no machining required. Not sure about the viper stuff, i looked last night at a viper caliper and was like $288 with core. (for one).

I don't know much about the exploder stuff. It really isn't that difficult for me to put a different caliper up there but would take some extra R&D...It doesn't take too much to do this stuff but you just have to be patient and take your time. I also have access to a couple tools as an engineer that some others may not.

Either way, this is an inexpensive way to get rear disc's if you want them. Only real negative is the lack of the parking brake. (this should also work on the DANA 60)

 

[old tired rebel]

I forget the exact years but I think its 96-98 is the same back there. The rotors are straight out of the box, no machining required. Not sure about the viper stuff, i looked last night at a viper caliper and was like $288 with core. (for one).

I don't know much about the exploder stuff. It really isn't that difficult for me to put a different caliper up there but would take some extra R&D...It doesn't take too much to do this stuff but you just have to be patient and take your time. I also have access to a couple tools as an engineer that some others may not.

Either way, this is an inexpensive way to get rear disc's if you want them. Only real negative is the lack of the parking brake. (this should also work on the DANA 60)

I would like to see you get this worked out with a parking brake. Once My Charger is done I will be driving it a lot and don't want to worry about it rolling away from it's parking spot

 

[Meep-Meep]

I have a set of Imperial rear discs I'm putting on my 69 RR only because years ago they fell into my lap, and like Rusty said, for bench racing fodder only. You just don't see the Imperial brakes, so if I can get them on without much fuss that would be cool. Your method using easily available factory parts sounds like a pretty good approach.

One note on your bracket. Have you considered folding the caliper slides over instead of welding? I'm thinking taking a potential weld failure out of that equation might me a good thing. Maybe play around on a 20 ton press and some press brake dies.

 

[YY1]

I gave up on two rear disk conversions- the scarebird one that wanted you to find 2 year only eldorado calipers, and then machine the center of 300M rotors, and the one that used mustang/explorer parts, but wanted you to press/weld in a new bearing spacer and/or race.

I don't like working on drums either, although I've gotten awfully dang good at it.
It's real messy, and there's always that slim chance you might lose a fingertip.

Is there a m/c residual valve issue?

 

[old tired rebel]

I have a set of Imperial rear discs I'm putting on my 69 RR only because years ago they fell into my lap, and like Rusty said, for bench racing fodder only. You just don't see the Imperial brakes, so if I can get them on without much fuss that would be cool. Your method using easily available factory parts sounds like a pretty good approach.

One note on your bracket. Have you considered folding the caliper slides over instead of welding? I'm thinking taking a potential weld failure out of that equation might me a good thing. Maybe play around on a 20 ton press and some press brake dies.

What year Imperial,also will you be doing a thread on this? The same question for KB67Mopar

 

[YY1]

I almost bought one of those Imp axles off ebay.

Calipers are offset, one in front, one in rear?

 

[kb67mopar]

Lets see if I can answer all of your questions.

I may consider a parking brake option but at present not really an option until I would head to the salvage yard and find a cherokee to pull the parts from to figure out how to retro-fit. This probably won't work so I may have to come up with another option if I even decide to do it...remember guys I started this as a one off for my car in my garage.

On the bracket I don't think i could get that folded over in the exact right place too easy aside from the fact I do not have access to a press break, press or anything of the sort. ( I paid a shop to cut out my designs that I drew up in CAD) So the welds are about the best I can do. I do plan to add a couple of gussets but ran out of time last night.

My build thread is under members projects and restorations "67 Coronet Deluxe" and its just my personal thread for the car. Nothing dedicated solely to brakes.

What is special about these imperial brakes? not sure I know what the point is.

And for the residual valve issue I do not know the answer to that question. Personally I will be running a 97 Grand Cherokee booster and M/C so I doubt I will be able to answer that.

 

[Budnicks]

Your method using easily available factory parts sounds like a pretty good approach.

One note on your bracket. Have you considered folding the caliper slides over instead of welding? I'm thinking taking a potential weld failure out of that equation might me a good thing. Maybe play around on a 20 ton press and some press brake dies.

KB67mopar I have to agree with Meeps, that bending of the Caliper Bracket/part could, be a better approach for a finished product, than welding tabs on like the prototype, less chance for failure, especially if you want to sell these at some time later... but I like the simple, inexpensive, no frills, idea & concept you've done so far... maybe have them stamped & pressed ultimately... or find someone with a water-jet & someone with capability of bending 1/4" or what ever material your using... lots of options, good luck, looks good

 

[kb67mopar]

KB67mopar I have to agree with Meeps, that bending of the Caliper Bracket/part could, be a better approach for a finished product, than welding tabs on like the prototype, less chance for failure, especially if you want to sell these at some time later... but I like the simple, inexpensive, no frills, idea & concept you've done so far... maybe have them stamped & pressed ultimately... or find someone with a water-jet & someone with capability of bending 1/4" or what ever material your using... lots of options, good luck, looks good

I don't disagree one bit, my only issue is I have to have enough interested parties to make it worth any additional investment here. Just doing it the way I did it in one off form just the laser cutting is around $100 for one set. So quantity starts to reduce price and finding somebody with the ability to bend 3/8" plate the way I want might be a bit more expensive then its worth. Also adding in a parking brake would be another expense which would have to be justified. I can't go out and spend 1k making a package only to have 3 guys buy it because the rest like their drums... I suppose this is why nobody really makes kits for less than $500.

 

[dickdale]

View attachment 99206

Is this strong enough? Not having enough "meat" around the holes?