ok my a body buddies.. i am not a mechanic.. i have a 1972 lymouth duster 340, it has manual brakes. does not stop well.. and i know if i could brake better i would drive it more...what front brake conversion would you recommend. of course im trying to get the best bang for my buck. i guess i will need some kind of power booster. looking for everything in one kit... need name of vendor you use also. any advice is very appreciated... Arab
front disk brake conversion kit
- Thread starter arab
- Start date
-
72Dart6pack
Harder Better Faster Stronger.
Dr Diff has everything. Problem solved.
Professor Fate
Push the button, Max...
Before you dive into a conversion and opening that can of worms, are you SURE your brakes are up to snuff and performing to their designed potential? Duster 340s had 10" drum brakes, and while they may not be world-beaters by todays standards, they should definitely be better than "not stop well"- they'll lock 'em up and darn near put you through the windshield when operating correctly.
Make sure your brake shoes are in good condition and adjusted properly, and that all brake hardware is present and intact. Make sure the system is bled properly. After 50 years, are you sure the master cylinder hasn't been replaced with one with an incorrect bore size? Brake hoses can also go soft over time, contributing to a "spongy" feel.
I have never had 10" drums feel inadequate in normal driving.
Make sure your brake shoes are in good condition and adjusted properly, and that all brake hardware is present and intact. Make sure the system is bled properly. After 50 years, are you sure the master cylinder hasn't been replaced with one with an incorrect bore size? Brake hoses can also go soft over time, contributing to a "spongy" feel.
I have never had 10" drums feel inadequate in normal driving.
stroked340
Well-Known Member
I had manual drums on my '70 duster switched over to Wilwoods nice and easy install too..car stops way better no power booster needed money well spent
Divenut
Well-Known Member
I had manual drums on my '70 duster switched over to Wilwoods nice and easy install too..car stops way better no power booster needed money well spent
I went the same route with my 72 Duster 340. Very happy with it.
Pat
One thing to consider is that replacement parts like pads, rotors and calipers are widely available for kits based on OEM brake systems. Dr. Diff sells this type of kit.
Kits that use proprietary parts will eventually be worthless should those parts made by one manufacturer become unavailable.
Kits that use proprietary parts will eventually be worthless should those parts made by one manufacturer become unavailable.
Like said above, check to see if what you have is in good shape before going with upgrades. Many of the older cars had 8 3/4 rear ends and the axle seals leaked which soaked the rear brake shoes. There is absolutely nothing wrong with manual brakes that are in good working order. If you want to go with power brakes, then fine, but except for the pedal effort.... there is nothing wrong with manual.
Jarlaxle
Well-Known Member
Rick Ehrenberg's Disc-O-Tech. Still the gold standard 35 years later. Master Power has spindles and caliper brackets, everything else is part store stuff.
DISC-O-TECH: Stop on a dime
If you insist on keeping the small-bolt-pattern wheels, you will need something less effective...Scarebird offers a kit for that.
ultimatejay
Well-Known Member
He doesnt reply to phone calls or texts. He said email only
Just ignore everything he says about the FMJ spindles.
And the small bolt pattern thing isn’t true either, DoctorDiff will sell you the 73+ disk kit with a 5x4” pattern now. PirateJack will too, although their customer service and parts quality isn’t as good.
DoctorDiff
Well-Known Member
My website is actually www.doctordiff.com
In other words, do not abbreviate "doctor" in my Email address or web address.
In other words, do not abbreviate "doctor" in my Email address or web address.
BillGrissom
Well-Known Member
If your 10" drum brakes can't skid the tires, something is wrong. You will have to push the pedal harder than with a booster. You could install an M.C. w/ smaller bore for an easier pedal (with more travel). A 1990's 2-bolt aluminum M.C. can be used with an adapter plate ($30 ebay, or buy set from Dr. Diff). Could also install a vac booster ($170 new ebay, GM type w/ Mopar standoff and pedal adapter). People here don't believe me, but tires stop the car, so if your brakes can stop the tires rotating that is the best any brakes can do. Brake until just before the tires skid for max braking. The problem with drum brakes is that they will overheat and fade from constant braking but if not road-racing or "riding the brakes" down long grades you shouldn't experience that.
If you go with disks, Scarebird's kits are easiest and cheapest. If you use the common 1973+ factory front disks, you will need new front wheels for the different bolt spacing and your spare won't fit both front and back unless you change the rear-end. Plan your battles wisely and consider the big picture of what changes you will make. Scarebird, Wilwood, and a few other kits let you keep your current spindles, balljoints, and wheels.
If you go with disks, Scarebird's kits are easiest and cheapest. If you use the common 1973+ factory front disks, you will need new front wheels for the different bolt spacing and your spare won't fit both front and back unless you change the rear-end. Plan your battles wisely and consider the big picture of what changes you will make. Scarebird, Wilwood, and a few other kits let you keep your current spindles, balljoints, and wheels.
People don’t believe you because that isn’t actually true.
If being able to skid the tires was the only measure of braking, then the 10” drum and the 73+ disk brakes would have the same stopping distance. They do not.
The same could be said about the rear brakes too, they only provide 20-30% of the braking and the later big bolt pattern 10x2.5” drums are more than capable of locking up the rear wheels. And yet a disk conversion still shortens the stopping distance. The article is in the other drum brake thread currently circulating, and that was like to like for tires in the article.
Not true completely true. Wilwood disks will not let you keep factory 5x4” wheels. The center hub diameter on the Wilwood disks is over 3”.
Ok, so we must have some kind of Ehrenberg follower here.
The simple truth is that Ehrenberg was wrong about the F/M/J and 73+ B/R spindles. Which is probably why he has NEVER posted the actual geometry issues or quantified any of the claims he made regarding their use. Fortunately, someone actually DID. And you can look at all of the differences yourself, right here.
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
If you look at suspension geometry plots, you should notice several things. One, the geometry changes are pretty small. Like most people won't even notice the difference small. Yes, there is a slight increase in bump steer with the FMJ spindles. However, there is also an improvement in camber gain. Everything in suspension set up is a trade off. As the Bill Reilly article points out, camber gain can be very important, and for those of us that run wider tires with more modern compounds an improvement in camber gain can be more important than a slight increase in bump steer.
And then there's the "ball joint overangling". Well, that's just BS, plain and simple. I run FMJ spindles on my Duster (and for 70k+ miles on my Challenger too, although E-body geometry is slightly different). Because I also run adjustable strut rods and do my own alignments I have cycled my suspension through its entire range of travel more times than is probably healthy and can therefore say there is no "overangling" that occurs. Certainly not on either of my cars at any rate, and I had no premature ball joint wear on my Challenger over the 70k+ miles I used it as a daily.
The FMJ spindles work great. They work especially great if you've upgraded your wheels to run wider tires with modern compounds and tread designs. And if you haven't upgraded your suspension to improve your handling, well, you probably won't notice the difference. Unfortunately, the days where even F/M/J cars can be readily found in the wrecking yards are pretty much behind us. Who knows how many people could have gotten a cheap disk brake upgrade if they hadn't listened to Ehrenberg's unsubstantiated nonsense.
Beyond that, it is a great article and has lots of good information about ID'ing parts. But yeah, unfortunately almost none of these cars are easily found in a wrecking yard, so, most would be better off buying the stuff from DoctorDiff rather than junk yard diving for parts.
You just gonna keep disagreeing, or do you plan on explaining yourself or supporting your opinion with data?
I’d love to see another analysis of the suspension geometry, data plots, whatever you’ve got. Bill Reilly’s info looks pretty good to me though, and it shows Ehrenberg wasn’t right about a lot of things he said. And while I’m not a fan of coilover conversions either it’s pretty clear Bill Reilly is really knowledgeable when it comes to suspension. But hey, if you’ve got more data I’d love to see it.
I’ve run 73+ A-body and FMJ spindles on the same car. I stand by what I said as far as the geometry changes being small and arguably beneficial for a car set up like mine. And the ball joint thing, well, it’s not a thing on any of my cars running FMJ spindles. I’ve checked. I’m not actually convinced Ehrenberg did check, and his complete lack of data supporting his opinions certainly doesn’t help him. He threw out a lot of speculation and not much else.
After all, the B/R and FMJ spindles were “factory engineered” too. Some of those cars even ran radials from the factory, something the A’s and E’s never did. And that changes a lot with regard to the suspension geometry needs. Why fight so hard to keep geometry that was designed to be run with bias ply tires? What works best with bias ply’s is not best for radials.
Jarlaxle
Well-Known Member
There is nothing you'll accept. You believe your kludge is better, and NOTHING will change your mind.
Maybe it really is time to require any vehicle with altered suspension geometry be tested and signed off on by an engineer before permitting it on public roads.
Maybe it really is time to require any vehicle with altered suspension geometry be tested and signed off on by an engineer before permitting it on public roads.
So no evidence or data to back up your opinions then? Just handwaving and name calling. Just like Ehrenberg. You want to change my mind? Provide suspension plots backing up your position, like Bill Reilly did and Ehrenberg never has.
The mistake all you purist types make is picking one piece of factory engineering and ignoring others. Like, the entire suspension system was designed around bias ply tires. The torsion bar spring rates, the factory alignment settings, heck even the ride height (because of how it changes camber gain).
Slap on a set of radial tires and all the factory suspension settings go out the window. Better traction means the factory torsion bar rates are too low. The factory alignment settings are for bias plys, radials need more positive caster and tolerate negative camber better because of their construction. Oh, and negative camber gain works better for radials. So, lowering the car to improve camber gain results in even better handling. And what do the taller spindles add again?
Even Ehrenberg admits some of that, just look at where the SKOSH chart came from. Even he knows better than to run bias ply factory alignment numbers.
Suspension is a system. Change one component and everything is effected. Unless you run bias ply’s the reality is you’re not running the factory settings. The factory engineers would have changed the factory geometry and settings if these cars had come with radials from the factory. You know, exactly like they did when radials became standard?
Requiring an inspection is a bad idea, but I’d welcome it. My altered suspension geometry works far better with my modern radial tires than the factory geometry would. Just like the factory geometry works better with bias plys than my alterered geometry would. It’s physics.
Last edited:
doogievlg
Well-Known Member
Just wanted to say that I’m running FMJ spindles and will be a witness to this statement. Car drives like it’s brand new.
How about maybe the OP's brake cyls are frozen in rust, or bad M/cyl, rusted plugged brake lines, wet brake shoes, bad distribution block or all of the above. I never had a problem stopping my '69 Dart back then. If he wants disc brakes or wanting to go in another direction, that's one thing, but there was nothing wrong with the drum brakes.
Yeah, there could totally be a problem with his brakes that needs fixing. But the question was about a disk conversion.
And sure, there was nothing wrong with drum brakes in 1969 and they do stop the car. But disks will stop it faster, all the data and all the evidence shows this clearly. In 1969 you shared the road with other drum brake equipped vehicles that all stopped in about the same distance. Now you share the road with 4 wheel disk equipped vehicles with traction control that can stop in 2/3 the distance (or less) than these cars with drum brakes. If you want to drive your classic Mopar frequently, it makes sense to upgrade your braking capabilities. Especially if you’re already running better tires than what was available in the ‘60’s and ‘70’s, which most people do.
pishta
I know I'm right....
I had 9's in my first 65 and they were scary. loaded with 5 people it was tough to stop let alone lock the brakes. when they got wet? Forget about the first 2 seconds of braking. Went to 10's for a month and then jumped on an entire 67 setup I found in a pick-a-part. super rare these days ill admit. Scarebird has (had) fronts for 9" spindles with 5 on 4s drilled out of Toyo Previa rotors. IIRC their adapted rears were Eldorados with integrated parking drum or something. Still stock parts at autozone besides the rotors.
Agreed, but if you reread his first post , and read between the lines, he doesn't like driving his car because of poor braking. Having said that, he is thinking that converting to disk brakes will cure his problem. It might, but he probably needs to go through and replace the better part of his whole braking system.
I read his first post. Even perfectly functioning 9” or even 10” drums don’t provide great braking. Most of the disk set ups out there put the braking capabilities of these cars much closer to modern vehicles.
He will probably have to replace a significant portion of his braking system either way, so why spend almost as much money to replace drum components that won’t provide great braking even when fixed when he could spend a little bit more and actually have brakes that work well?
I went through the trouble of rebuilding the 10” drum brakes on my ‘71 GT. I replaced a bunch of components, adjusted everything properly, etc and was still underwhelmed by their capabilities. I’m putting the later 11.75” disks on it like I did on my Challenger and my Duster for a bit, they work great with 15” wheels and really improve the stopping abilities of these cars. Maybe not quite the same as more modern vehicles, but at least in the same ballpark if you know what you’re doing.
-
