Author Topic: Front/Rear disc Brakes and Axles.  (Read 2101 times)

Offline Krazed

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Front/Rear disc Brakes and Axles.
« on: March 06, 2006 - 07:10:14 PM »
I've been making some progress over the last few weeks reguarding my Barracuda. I have taken apart the interior to fix a few rust spots, and replace the oogly carpet that was in there before. (Worn out black turned green and ripped!  :o ) Also, I took off the wheels, put it up on jacks and started taking things off, cleaning, etc. Doing so I found the numbers on my 340, and Transmission. Unfortunately this little endeavor got me to finding out that my motor is Not numbers matching like I was lead to believe. That's just the price you pay for not knowing much when buying your first muscle car. Woops!  :banghead:

Anyway, enough of the sob story. What I came here to do was ask a few questions and hope someone could help me out with decisions and answers.

Question #1: I have decided to upgrade the brakes.  I currently have front disc 4 piston's (An option on the car in 68) and was curious if there was just an Upgrade I could purchase for the front discs. Also, I would like to upgrade the Rear drums to discs. Now, the issue with this seems to be that I would need a larger master cylinder as well as the booster if I were to do rear discs, as the original rear drums were manual. Or were they? I could be wrong! Clerification on this would be awsome if anyone has done the conversion. I'm just trying to avoid spending $1200 on the front disc conversion kit if i don't have to, seeing as how I have half the hardware already.

 Since I want to go with the rear discs, It seems I need new axles. I have the small bolt pattern (5x4") and I can't seem to find any rear disc conversion kits for that size, Only for 5x4.5". If anyone knows of any kits please let me know. However, assuming there are none my question is this.

Question #2: Which Axles should I purchase? I won't be going over 500 rear wheel horsepower. That's guarantee'd. If I do I know to upgrade. I have seen alot of posts reguarding Moser, Yukon, and Mark Williams. But, seeing as how my rear wheel power will not be astronomical I doubt i'll need something as strong as MW's.

So basically, I'm just looking for some guidance, and someone to shed some light on the subject.

Any and ALL help is welcome, and very appreciated. Your wisdom will help me save money, and go into the right direction. Especially considering all of this won't be less then $2,000.  :faint:

Thanks in advance for the help!
'68 Plymouth Barracuda 340 Formula S




Offline Krazed

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Re: Front/Rear disc Brakes and Axles.
« Reply #1 on: March 06, 2006 - 07:13:21 PM »
After reading over it quick I realise I made a mistak. The front disc conversion kit that's 'cheaper' is such because it doesn't come with spindles and all the like. As it's just an upgrade to the exsisting 5x4" bolt pattern.  At least, that's what I see on www.summitracing.com and SSBC's website.

If you know of one that's cheaper With spindles for converting to 5x4.5" please, feel free to grace me with your knowledge!
'68 Plymouth Barracuda 340 Formula S

Offline Hopalong

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Re: Front/Rear disc Brakes and Axles.
« Reply #2 on: March 06, 2006 - 09:51:08 PM »
I converted my '68 Dart from drum to disc using all mopar parts.  I followed a setup outlined by Mopar Action.  You use '74-up A body disc spindles and upper control arms.  I also went for the big rotors "12" inch (Measures 11 3/4").  This required caliper adapters from a '78-79 cordoba (or same body vehicle).  I got new rotors, calipers adn hoses from a local parts store.  The whole setup ended up costing about $350 when it was done.  I already had a MP master cylinder, and I kept it all manual.  I bought new axles from moser for the 5 x 4.5 bolt pattern.  I ended up useing 11 x 2.5 drums from a new yorker that I traded for form a friend.  Car stoped on a dime.  For rear discs fairly cheap, you might look at a kit from Speedway Motors (http://www.speedwaymotors.com/xq/aspx/paging.yes/dept_id.351/display_id.1999/qx/Product.htm).  If that link doesn't work, go to www.speedwaymotors.com, click on street rod product, then on brakes.  Go to disc brake kits, then to page two.  It is the kit with the emergency brake caliper.  Just some ideas.
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Offline Hopalong

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Re: Front/Rear disc Brakes and Axles.
« Reply #3 on: March 06, 2006 - 09:58:31 PM »
Oh yeah, f body (diptincrap...diplomat) front stuff will work too.
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Offline Chryco Psycho

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Re: Front/Rear disc Brakes and Axles.
« Reply #4 on: March 07, 2006 - 02:17:55 AM »
the Kelsey hays 4 piston discs are among the best brakes available assuming they are in good condition
 rear discs bring a lot of headaches in this case the factory drums are limited in brake power already by the proportioning valve so they are adequate , if you still wan to continue with rear discs  , I would not change axles , but get Hats for the 4 " bolt circle instead . or have 4.5" hats redrilled , you will need a double disc master with the residual pressure valves removed in both side of the master , , I would use an adjustable proprtioning valve to dial in the balance between the front & rear brakes

Challenger - You`ll wish You Hadn`t

Offline Krazed

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Re: Front/Rear disc Brakes and Axles.
« Reply #5 on: March 07, 2006 - 05:45:48 PM »
Alright, that's kinda what I wanted to know. Thanks for the info Hop , CP. Appreciate your time!

Though I do have a question, as to where to get Hats (Assuming you mean rotors) For my bolt pattern, as well as Calipers to fit. Or perhaps there's some after market 4" kit I can make work? Also, recommendations on where to purchase a double disc master.

Sorry to be asking so many questions, I just want this done right, seeing as how it's the only thing that will slow me down short of a tree.
'68 Plymouth Barracuda 340 Formula S

Offline Hopalong

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Re: Front/Rear disc Brakes and Axles.
« Reply #6 on: March 07, 2006 - 09:42:18 PM »
If you look closly at the picture in the speedway link, you'll see that the rotors have a seperate "hats", which is how the rotor attaches to the axle.  I think the one in the kit comes predrilled for 4 1/2" and 4 3/4".  I don't know if there is room to add another set of holes.  I'm not a salesman for them but Speedway is a local shop for me, and I have solved many problems thanks to their help.
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Offline Chryco Psycho

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Re: Front/Rear disc Brakes and Axles.
« Reply #7 on: March 07, 2006 - 11:13:46 PM »
the Hats are available from many suppliers , then the rotor is bolted to the hat , you should be able to get a hat with 1 set of bolt holes & have the 4" pattern drilled into them

Challenger - You`ll wish You Hadn`t

Offline keithcuda

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Re: Front/Rear disc Brakes and Axles.
« Reply #8 on: April 20, 2006 - 06:51:47 PM »
I got willwood kits front and back.
The fronts have seperate hat and rotor(disc), disc is bolted to the hat.
The hat has holes drilled and taped to take bolts(from rear)for both 4.5in and 4in bolt pattern.
You can download the fitting instructions from the willwood website.
I bought my kits from Magnumforce.
Keith Renouard
1972 Plymouth Ćuda
440 w/ M1 manifold, Holly 770 Steet Avenger
TTI exhaust
best 1/4 ET 13.4 (2005, Santa Pod, UK)
best 1/4 MPH 101.36 (ET 13.984) (31st July 2004, Santa Pod, UK)
G-Tech 0-60MPH = 5.0sec (Santapod 05)
Now i have a 1968 charger too, the collection grows