8 3/4 Rear Disc Brake Conversion

[5.7 hemi]

Just an idea for the rear drums....drilled and slot those bad boys then the heat will dissapate, lol!!!

 

[old tired rebel]

Just an idea for the rear drums....drilled and slot those bad boys then the heat will dissapate, lol!!!

I seen where someone has done that to drums,but I wonder if it will cause stress fractures?

 

[Meep-Meep]

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

I'm pretty sure it's a 74 and that's a one year only. Very hard to find. When I get around to actually doing the conversion I'll start a thread.

 

[kb67mopar]

Wow you guys have been a bit busy since the last time i read this lol.

No I doubt I'll sell these seeing as how I really have no good way to test them and I sure as hell aint taking the liability of you guys trying to break em

I am sure I will test the hell out of them once I get the car up and running but I am really not concerned that they would fail. I have looked at several other designs some of which use just caliper bolts to take the total force and their overall surface are for shear and moment is very small compared to even my welds. I would have had to put a liability waiver of some sort in with the kit since I cannot test to the level of a OEM or aftermarket guy.

i have also noticed a few other kits out there lately after doing some more research so there are some options just nobody using cheaper off the shelf stuff.

Like I said though, if anybody wants to make a set for themselves I will help support them...this wasn't about getting rich or making a quick buck as much as making it possible for some of us to make the conversion without spending a ton of money.

 

[Budnicks]

thanks for the information

Wow you guys have been a bit busy since the last time i read this lol.
i have also noticed a few other kits out there lately after doing some more research so there are some options just nobody using cheaper off the shelf stuff.

Like I said though, if anybody wants to make a set for themselves I will help support them...this wasn't about getting rich or making a quick buck as much as making it possible for some of us to make the conversion without spending a ton of money.

:iamwithstupid: thanks for the information... it's great to see ideas/options, others have come up with... that's what the hobby is all about...

 

[kb67mopar]

I finished up with my brackets and re-assembled the rear end. It went together great and I welded more on the tabs for strength. I was going to add a gusset but there wasn't a good place to put one that would actually add strength. I got really god penetration on the welds so I have confidence that they will hold. These should work well. Thank you all for your input and I am sure I will update this when I get the car on the road this spring/summer.View attachment 101237

 

[440amf]

I would trust your design, especially since if it failed, I'd still have approximately 70-80% of the total braking power in reserve on the front anyway. I've driven cars with rear drum brakes and thought they stopped pretty well, only to find that the automatic adjusters had been frozen and caused the drums to have little or even no effectiveness. The worst thing I can imagine is that the caliper somehow breaks free, jamming and stopping the wheel, but I can't imagine that ever happening. You've made a heck of a nice stab at it for sure.

 

[kb67mopar]

Just wanted to update this and with the car slightly drivable (up and down my street only) everything seems to work well. The brake setup feels phenominal, pretty sure i could lock up all 4 in a hurry with the grab these have. And with the brake booster the pedal is super easy...feels just like a late model car...no more scary moments heading to a stoplight here.

I highly recommend to anybody at the very least, upgrade to a power system with front discs. Its worth the effort!

 

[plazomat]

kb67 - how are your disks now?

Just wanted to update this and with the car slightly drivable (up and down my street only) everything seems to work well. The brake setup feels phenominal, pretty sure i could lock up all 4 in a hurry with the grab these have. And with the brake booster the pedal is super easy...feels just like a late model car...no more scary moments heading to a stoplight here.

I highly recommend to anybody at the very least, upgrade to a power system with front discs. Its worth the effort!

Is everything holding up? are you gonna sell the brackets or kits, did I miss something here...my 8 3/4 wants an upgrade....

Oh yeah will this fit under a 14" wheel?

Plazomat

 

[mopwrd340]

I was doing the parking brake shoes on a 94 gc with a dana 35 and thought about putting them on my rr it looked like it would all swap over . i had a 74 imperial with the rear discs i sold it because i couldnt find rotors for it ,

 

[kb67mopar]

Is everything holding up? are you gonna sell the brackets or kits, did I miss something here...my 8 3/4 wants an upgrade....

Oh yeah will this fit under a 14" wheel?

Plazomat

Sorry, its been a long time and I never saw this post. I haven't had a chance to think about putting this back into a kit. I have moved and changed jobs since the last post and am still kind of getting situated and the other house sold. It will be a while before I can really work on it if I decide to. I need to find another 8 3/4 to use as a guinea pig and then come up with a nice design using a caliper with a P-brake. If I take the time to do all of this I would get a supplier to price out making/stamping/bending etc my brackets. But right now its not on the radar.

To answer your other part of the question so far these brakes are phenominal. I have only been able to drive them at lower speeds as teh car is not completely assembled. But the braking I have done, its very crisp and quick stopping. I'd venture to say this thing stops better than quite a few newer cars I have driven.

My complete package are A-body front disks , 98 Jeep Grand Cherokee Rear Disks, 98 GC brake booster and master cylinder and a summit racing generic proportioning valve. I think I have less than $500 total in the whole brake system.

 

[kb67mopar]

I wanted to give this an update. I took the car for the first REAL drive yesterday and have some notes. It stops great...way way way better than it ever has. I also ended up having to do a bit of a panic stop. And ended up locking up the rear brakes at 55 mph. So I learned two things. One I need to adjust my proportioning valve. And Two that my brake brackets definitely are strong enough.

So anybody in the midst of doing this sort of thing....its worth doing.

 

[72Fourspeed]

Any update on price & when you'll get to making them ? I have the pieces for an A body front conversion waiting.

 

[kb67mopar]

Any update on price & when you'll get to making them ? I have the pieces for an A body front conversion waiting.

Unfortunately I don't see me producing them. I moved locations and lost my connection with the shop to have these cut out and really just don't have the time to try to produce them. I will be glad to help you if you'd like to make a set yourself.

 

[Budnicks]

thanks for the update

 

[kb67mopar]

Another quick note on this setup. I tested last night swapping wheels and tires so I can paint my cop wheels. Turns out 14's will not clear this setup. so with these rotors and calipers (regardless of bracketry) you will end up needing 15" wheels+.

I think if I had to do this all over again I would keep these rotors and select a caliper from a more modern car with the parking brake built in. I would build the brackets in a similar way but hopefully with a caliper that uses a pad retainer almost like a cage. those would then just bolt to my lower bracket and be a simpler bracket.

Anyway I think this will be my last brake update. Best of luck to any and all that attempt a custom brake package. I thought it was a cool process and like I said. I am willing to help out anybody who'd like to attempt it.