drum to disc O.E issue

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KramerSwinger70

KramerSwinger70

70 Dart Swinger360
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so ive been shopping around for a front disc brake conversion kit an im noticing what may be an issue: most say they bolt to O.E 10" drums....my car has, i think, 9" drums all the way around (original 225 /6 car). so how would i get these kits to work? upgrade to 10" drums all the way around and then switch tio discs in front? do i need a new front-end or can i use the stock set up? HELP!
 
The spindles are bigger on the 10" brake cars so you need the spindle to use those disk brake kits. There are kits out there that come with the spindles.
 
I have disc brakes from a 70 challenger that would work for your charger. PM me if you are interested, I have a great price on them I cant believe someone hasnt snapped them up.
 
The only problem with the 9" spindle is the tiny ball joint retaining bolts. they are a bit of a safety issue. Is their a specific reason you don't want to swap to the later model discs? do you want to keep the sbp?
 
bjkadron said:
The only problem with the 9" spindle is the tiny ball joint retaining bolts. they are a bit of a safety issue. Is their a specific reason you don't want to swap to the later model discs? do you want to keep the sbp?
Click to expand...
I have a set of 68 GTS disc brake spindles. They used the smaller ball joint and worked fine.
 
There is a bzillion cars running around with the 9" drums and hasn't been an issue so far. I wouldn't worry about it unless someone was going to do some road racing or something.

Chuck
 
bjkadron said:
The only problem with the 9" spindle is the tiny ball joint retaining bolts. they are a bit of a safety issue. Is their a specific reason you don't want to swap to the later model discs? do you want to keep the sbp?
Click to expand...

i am keeping sbp in this swap, yes. i know that im going to swap to 10" drums in there rear when i do discs up front
 
340mopar said:
There is a bzillion cars running around with the 9" drums and hasn't been an issue so far. I wouldn't worry about it unless someone was going to do some road racing or something.
Click to expand...

I don't think there ever was a "bzillion" cars with 9" brakes, there certainly isn't today. That not with standing, the issue is; back when these cars were new everyone's brakes stunk so if the guy in front of you made a panic stop from 60 mph it took him the same 200 ft as it did you to stop. Today that same guy in front of you will be able to stop in 120 ft or less and it will still take you 200, that my friend is a problem. With all the conjestion on the roads even adding an extra 80 ft of space doesn't work because some one will fill it up as soon as you back off. That's not to mention all the accidents that occured with immoveable objects that would have been completely avoided with today's braking systems.

I speak from experience the 9" drum brakes in A-bodies in a panic stop from 65 mph will slow you to about 45 then heat up and fade to the point that they no longer slow the car and you have to lift your foot to allow them to cool before you get any stopping ability back. Even at 45 mph your heart will be in your mouth if everyone in front of you is grinding to a halt and you are waiting for the brakes to cool. You likely have heard the saying "my life flashed before my eyes".

With all the conjestion on the roads these days it is mandatory (IMHO) that you have a braking system that is on par with the cars around you. If you have 9" brakes I would recommend that you upgrade before even registering the car.

The factory disk brake systems from 40 years ago coupled with the modern brake pad materials available today will put you on par with 90% of the cars on the road.
 
73charger said:
i justed checked out MP brake....thats a big chuck of change for the swap!
Click to expand...

Then you need to look for a set of factory 10" spindles or even better the spindles and upper control arms from a 73+ A-body disk brake car and you can use readily available factory parts.
 
OK,
All you really need to do is find a '73 up a body with Disc Brakes and get the parts from it.
Then you will only be changing Spindles once. This will take you to big bolt patern but new Rims will be cheaper then the alternatives. << My opinion only!
Give this thread a read through:
http://www.forabodiesonly.com/mopar/showthread.php?t=90216

Hope this helps,
Laer,
Bruce B.
 
73charger said:
ok...so i should upgrade to 10" drums at all corners and then do discs upfront?
Click to expand...

Why go to the expense of upgrading to the front to 10" drums only to do a disk brake up grade latter? All you need from the 10" drum set up is the spindles.

Or as I said earlier and 7071DartGTReg just mentioned look for a 73+ A-body with disk brakes and get the upper control arm and spindle. You then have the choice of 10.75" or 11.75" factory rotors that are readily available at the corner parts store for $50 or so and rebuilt factory calipers for $30 or so. Note: the 11.75 brakes will require 15" wheels. This swap has the added benifit of giving you the larger 4.5" bolt pattern opening up a world of wheel choices at a much more reasonable cost than the sbp.

If you have an 8.75" rear it will already have 10" drums but they are narrow at 1.75" and have the small bolt circle. If you are going to build a rear end from pieces I would recomend getting axles with the B/E body offset then you can use the more readily available 2.5" wide 10" drums or 11" drums. If you don't have an axle yet then you may want to consider an 8.25. It is more than strong enough for what it sounds like you are building in your signature line, already has the 10" by 2.5" brakes and will be the larger 4.5" bolt patern.
 
i do NOT want to go to lbp! i need to stick with sbp because im keeping the wheels i already have. the only wheels i want on my car are either the ones i got (dish centerlines) or some mopar rallyes down the road. thats it! changing to lbp is WAY more expensive for me. then id have to buy new wheels, tires, ect. wheels and tires alone would be $2k
 
Quick FYI:
Not all 8-1/4 Rears have 4.5 Bolt Pattern!
So unless you are taking it offa the DISC BRAKE donor car I would check that.

Later,
Bruce B.

Wow! $2K huh?
My (used) Magnum 500's with (new) Firestone Firehawk Indy 500's was only $600.00.
 
well considering the only wheel id move to is a rally....ya i can guesstimate quite a lot. maybe not $2k but more than i want. and whats 8 1/4 about? im trying to get my hands on an 8 3/4 but im doin drums in the back anyway.

so what would i need to look into to find 10" spindles sbp then? 73+ is lbp, if im reading this correctly, so would i want to look for 67-72 spindles? are there repops or 10" spindles?
 
73charger said:
well considering the only wheel id move to is a rally....ya i can guesstimate quite a lot. maybe not $2k but more than i want. and whats 8 1/4 about? im trying to get my hands on an 8 3/4 but im doin drums in the back anyway.

so what would i need to look into to find 10" spindles sbp then? 73+ is lbp, if im reading this correctly, so would i want to look for 67-72 spindles? are there repops or 10" spindles?
Click to expand...

Yes, the 67- 72 ones is what you want... Why not try posting a want add for them? I know their is probably a ton of them floating around this community Because they went to bbp. Mine were the 9" though so they wouldn't help.
 
i would post a want ad, but at the moment i dont have money for em, seein as id have to pay a few hundred (my assumption). i just want to know where i could find this kind of set up. if someone were to have exactly what i need i would want them to hang onto it for me but whats the likelyhood they would trust id get the money?
 
7071DartGTReg said:
Quick FYI:
Not all 8-1/4 Rears have 4.5 Bolt Pattern!
So unless you are taking it offa the DISC BRAKE donor car I would check that.

Later,
Bruce B.

Wow! $2K huh?
My (used) Magnum 500's with (new) Firestone Firehawk Indy 500's was only $600.00.
Click to expand...

All 8.25 rear ends had a 4.5" bolt circle. Starting in 73 the 8.25 replaced the 8.75 as the a-body heavy duty rear end. It could be had with cars with disk front brakes or v8 cars with 10" drums either case the bolt circle was 4.5". Only cars with the 9" drums had the sbp, if the 8.25 was ordered it required a brake upgrade which also came withe the big bolt circle.
 
73charger said:
i do NOT want to go to lbp! i need to stick with sbp because im keeping the wheels i already have. the only wheels i want on my car are either the ones i got (dish centerlines) or some mopar rallyes down the road. thats it! changing to lbp is WAY more expensive for me. then id have to buy new wheels, tires, ect. wheels and tires alone would be $2k
Click to expand...

You can certainly spend $2k on tires and wheels but you don't need to spend even 1/2 that. When I did the disk brake and 8.25 rear swap I had picked a used set of lbp ralleys for $125. I just cleaned up the wheels, gave them a coat of paint and swapped over the tires I had on the sbp wheels, total cost was less than $200.

I now have brand new 15x7 and 15x8 Rallies with brand new BFG Radial T/A tires total cost less than $950.

I would recomend that you not limit yourself to sbp wheels if you still need to get the disk brakes and rear end.
 
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