70 Duster--conv. to 73-76 front disc??

-
tom340

tom340

Well-Known Member
Joined
Jul 20, 2007
Messages
364
Reaction score
2
Location
Northwestern Ct
My '70 Duster, pictured top left..I currently have the standard front disc, rear drum brakes, manual steering box. Of course, without saying the 70-72 kelsey hayes front disc setup sucks. Its expensive, and thats available is rebuilt at the parts stores. Nothing aftermarket that works w/sm. bolt pattern and stock factory original setup because it sucked so bad.
The pitman arm is in bad shape, so just ordered one new from Just Suspensions.To avoid additional co$t, Im staying w/stock pitman arm. I asked about my "braking" options and he referred me to Wilwood. He said to keep cost down and stay sm. bolt pattern I can convert to the '73-'76 style front disc and keep my spindles. He said the aftermarket calipers they make for this style work fantastic.
This is a project that needs attention by this autumn, and any feedback I can get from you guys would be great. Im sure someone has upgraded to this setup, and kept the sm. bolt pattern intact. For me, $$$$ is an issue. No way am I investing over 2 grand front and rear just to fit large bolt pattern wheels.
Exactly what is involved with this conversion?
 
If you want the factory big bolt pattern 73-76 discs, you're spindles and upper control arms must be changed. Aftermarket may have conversions using your factory spindles.

The Conversion kits using stock parts are available. The kits run about 200-400 for the core parts. Sometimes you get very nice rotors sometimes not.

I occasionally get them and charge 300-350, depending on completeness, for everything plus shipping
 
crackedback said:
If you want the factory big bolt pattern 73-76 discs, you're spindles and upper control arms must be changed. Aftermarket may have conversions using your factory spindles.

The Conversion kits using stock parts are available. The kits run about 200-400 for the core parts. Sometimes you get very nice rotors sometimes not.

I occasionally get them and charge 300-350, depending on completeness, for everything plus shipping
Click to expand...
Actually I want nuttin' to do w/ the large bolt pattern. The A body 73-76 conversion is to the 4 1/2 pattern??
 
340mopar said:
Yes, it would be large bolt pattern.

If you want small bolt pattern then it is either the stock 4 piston stuff or the Scarebird conversion stuff.

http://www.scarebird.com/

Chuck
Click to expand...

That brings me right back to square one..the guy from where I purchased the pitman arm told me about Wilwood brakes and the conversion kit. He must not have heard the 4 minutes I spent on what I would like to do to avoid the $$ investment in converting to the BB pattern.
Thats nice, for all intents and purposes, the car "really" has no brakes! This F'n sucks.
 
You want the bigger bolt pattern, I want the little, Trade?
I have a 73 valiant 4 dr with manual disc 5x4.5 I want 5x4.
 
For affordable small bolt pattern disc brakes Scarebird is probably the best route.
 
Stainless Steel Brakes also makes kits to convert from the 10" drums to a 4 piston discs and still have 4" bolt pattern. I'm not sure if they have anything for the spindles you already have.

Probably the most knowledgeable person around on the brake swaps Is Andy F with AR Engineering.

http://www.arengineering.com/
 
All 1970 Duster 340s came with the Kelsey Hayes 4 piston disc brakes as standard equipment from the factory. My brother sold these cars new in 1970 and I purchased a new 1970 Duster 340. The 1970 Plymouth Duster sales brochure documents this well.

So just to get this clear, this gentleman already has the factory SBC K-H discs on his 1970 Duster 340, not drums.
Plymouth did resort to 10" drums on the 1971 Duster 340s as standard equipment, with the K-H discs as optional.

As far as having no brakes with the current factory SBC - Kelsey Hayes setup, have you considered having your calipers rebuilt with the stainless sleeves? Also, Firm Feel sells great upgraded disc brake pads for this setup.
Rotors are available from numerous sources, including slotted / drilled SBC rotors from Summit for $79 each. Raybestos, Wagner and Centric all offer factory replacement rotors from $39.99 to $92 each.

I have a 1971 340 Duster with the factory K-H disc setup and it stops great.
Check the adjustment on your rear brake shoes and the condition of your rear drums. New Drums are available in the 10 X 1.75" size from the same manufacturers listed above. Many times if your rear brakes are out of adjustment, the car WILL NOT STOP well.

If your car sits for extended periods of time, many times the pistons in the calipers will not move freely in the piston bore(rust build-up in the bore) or in a worse case, seize up. Brake fluid is hydroscopic, meaning it absorbs moisture and that moisture travels throughout your brake system. A hone cleanup of the piston bores and new seals ccure the rust buildup in the bore. The factory service manual describes all this in great detail with great large drawings of the caliper, and the entire front brakes.

The stainless steel upgrade is a permanent piston bore fix and upgrade.

I'm like you; I do not wish to move to the BBC, and I have found that there are many SBC wheels now available.

With some work, your SBC disc setup can work great, trust me.

Good luck with your brakes and let us know what you decide.
 
Whether the KH brakes will stop it or not he is right about cost and availability of those rotors and pads in long term. The spindles for 9 or 10 inch drums can be found cheap enough and the normal wear parts used in the Scarebird conversion "should" be affordable and available for many years to come.
 
I just took the 10" drum brakes off my '66 Cuda,are these the spindles you need to go the Scarebird route?
If so let me know.
 
RedFish said:
Whether the KH brakes will stop it or not he is right about cost and availability of those rotors and pads in long term. The spindles for 9 or 10 inch drums can be found cheap enough and the normal wear parts used in the Scarebird conversion "should" be affordable and available for many years to come.
Click to expand...

There are many K-H equipped cars still on the road, and the prices are exactly what I quoted in the earlier post, $39.99 for Centric rotors. Summit is selling these rotors in slotted/drilled form for $79.99. Caliper parts are widely available. Stainless sleeves can be installed to solve any rust issues in the piston bore, as a lifetime upgrade. Overall the cost to convert to any brake system is going to be a lot more costly even over time, then sticking with a good, highly effective K-H system with the SBC wheels.

Sticking with the factory K-H setup avoids the expense with swapping rear axles (re-drilling existing rear drum bolt patterns is a potential safety issue), the wheels and picking up either aftermarket pieces or the '73-'76 setup.
When you add up all those expenses, the change to the BBC is not cheap.

Unless the car is a daily driver getting really hard usage, the rotors should last, and can be turned at least once. Given how many use these cars, mostly for weekend events, you can buy a couple pairs of rotors for future usage.

A couple of buddies of mine are running 416 or 408 strokers with the factory K-H setup and the brakes haul the cars down at the end of the 1/4.

All I'm saying is look at the total expenses with any conversion; the costs can mount up quickly.
 
Tom, No matter what you do your going to need to swap out your spindles. There are no kits available to upgrade factory KH disc set ups. All the aftermarket disc kit will use either the 9" or 10" drum spindles.
 
You must log in or register to reply here.
-

Back
Top