74 Duster front drum question

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Pumpkinduster

Pumpkinduster

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My 74 Duster looks to have had the front brakes converted to the 10" drums, portioning valve installed and the split style master. I am looking to overhaul the brakes since the pass side is not engaging when the driver side is. I'm struggling to find replacement parts since mine comes up with 9" drums in all my searches. Anyone have recommendations on where to look and best options to search that had the 10" front drums?
 
You need to take a guess what the drums came off of and put that application in the parts catalog. B body or whatever...............

Didn't some 340 cars come with 10" drum?
 
A '74 Duster would have had 10" drums from the factory if it was a /6 car (v8's were all disks '73+). '73+ front drums were different than '67-72 front drums, they used a different spindle that uses the larger upper ball joint like the '73+ disk spindles. They also use a different size wheel bearing than the earlier 9" and 10" drums. No 9" front drums in '74 either, '73+ front drums were 10".

From the original TSB, full size at hamtramk-historical
https://www.hamtramck-historical.com/images/TSBs/1973/05-03-73C page1.jpg
05-03-73C page1.jpg

05-03-73C page2 copy.jpg


What parts are you looking for?
 
Early '73 slant 6 cars could have 9" brakes. They were unique for early '73, but, used the same spindle as the '73-6 10" drum brake cars. They also use the same inner and outer wheel bearings as the '73-6 10" drum brakes, and the same outer bearing as the earlier 10" drum and KH disc brakes (A2) The inner bearing on the '73-6 cars is an A17, drum and disc. Also, the '73-6 drum brake cars had the 4" bolt circle for the wheels. The disc brakes went to the 4 1/2" bolt circle.
 
67Dart273 said:
You need to take a guess what the drums came off of and put that application in the parts catalog. B body or whatever...............

Didn't some 340 cars come with 10" drum?
Click to expand...
Not in '74. Near as I've been able to determine, all '73-up V8 A-bodies came with disc brakes. Slant 6 car could have drum or disc.
 
cudamark said:
Early '73 slant 6 cars could have 9" brakes. They were unique for early '73, but, used the same spindle as the '73-6 10" drum brake cars. They also use the same inner and outer wheel bearings as the '73-6 10" drum brakes, and the same outer bearing as the earlier 10" drum and KH disc brakes (A2) The inner bearing on the '73-6 cars is an A17, drum and disc. Also, the '73-6 drum brake cars had the 4" bolt circle for the wheels. The disc brakes went to the 4 1/2" bolt circle.
Click to expand...
You still trying to pass along that BS in regards to 9 inch brakes on a 73 using a 10 inch drum spindle.
That's nothing but an urban myth.
 
Since I used to have some of those cars, I know it to be true. Different backing plate, sure, but, the spindle was the same as the 10" drums that year. There was only one drum brake spindle from '73-6, part# 3402739. They had both 9" and 10" brakes that year. The 9" ones were only used early in the production year....Aug thru Oct '72 or so. After that, they did away with the 9" stuff. Why is that BS? Just because you never saw one? I've only seen a few myself....maybe 3 or 4. Being I was in the used auto parts business for over 32 years, and having parted thousands of Mopars in that span, I would say it was a rare setup. I only saw them on plain jane slant 6 Swingers and Scamps with an auto transmission. They may have been used on Dusters and Sports, but, none of the ones I had were those models. Mine were all manual brake, manual steering, no A/C, bench seat cars.
 
So, you mean to tell me there is a nine inch brake drum out there, with a large inner wheel bearing, used on a ten inch spindle.
Then show me a part number for something that doesn't exist.
You will never find a part number in any 73 Chrysler parts book, or any after market parts book.
Something like that never existed at the factory level, from the beginning.
Then prove to me, some documentation to back up your claim.
I will call you out, any day of the week, until you can no longer pass along fake news, as fact.
If a 9 inch drum ever existed with a big inner wheel bearing it's one sure mystery part.
 
So, you're saying there was never a 9" brake in a '73 A-body?
 
Probably a very few, but with 72 and earlier drum brake parts, and components.
A big bearing, 9 inch drum.
No way, no how.
No such thing exists.
 
So you think they had a unique spindle to match the unique hub and drum assembly? and they continued using the A1 and A4 bearings from previous years?
 
cudamark said:
So you think they had a unique spindle to match the unique hub and drum assembly? and they continued using the A1 and A4 bearings from previous years?
Click to expand...
Show me proof of a 9 inch front drum on an A body car with a large inner wheel bearing on a 10 inch drum spindle, then i will shut up, and go away.
Until then, it's nothing but fake news, until proven otherwise.
I don't know anything about wheel bearing size letters and numbers.
That is meaningless to me, between the years.

You personally parted, took apart. THOUSANDS of cars in your 32 years?
You previously own a junk yard?
So you took apart every old Mopar that you got your hands on.
I would say that's an impossibility.
You must have paid employees to take cars apart at the level that your talking.
Then in 32 years of me wrenching on cars for a living, in my past life, did i work on every Mopar car that came into the repair shops?
 
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cudamark said:
So you think they had a unique spindle to match the unique hub and drum assembly? and they continued using the A1 and A4 bearings from previous years?
Click to expand...

They didn't have a unique spindle, they had the old spindle. And since they had the old spindle, they had the old hubs and bearings.

It's right in the TSB I posted above, the dates and everything, straight from the factory. The conversion to the new 10" drums happened around November 1, 1972. We all know that Ma Mopar used up remaining stock from the previous model year if it was at all possible before starting in with new parts. That would mean that August to October the small upper ball joint spindle would still have been used on the 4 wheel drum cars, with the small ball joint UCA's. Which, in theory, could mean that some of those cars had 9" front drums. Either way, 9" or 10", they'd have been the 67-72 style. After "approximately" November 1st 1972 they all would have had the new 10x2.5" front drums, the larger wheel bearings, and the large upper ball joint spindles.

Again, the TSB tells you everything you need to know. The 10" drum, hub, and backing plate, although primarily B-body, all still had to be re-designed. Which would have also meant re-tooling. Not cheap.

So let's consider the options:

Ma Mopar designed a new drum spindle with a larger bearing and upper ball joint, a new 10" drum, a new 10" drum hub, and a new 10" drum backing plate. And then decided, for some reason, to not roll out the new 10" drum, hub and backing plate until November 1. But, in the meantime, they decided to ALSO design a new 9" drum, hub, and backing plate just to use for 3 months. Oh, and of course the new 9" drum and hub was ready immediately in August, while the 10" stuff that was planned wasn't ready until around November. And, there's no TSB on the new 9" drum stuff they designed, but there is for the new 10" drums.

Or, more likely-

Ma Mopar decided there was roughly 3 months worth of 67-72 style drum spindles, drums, and upper control arms and started production of the '73 model year with the old stuff. And used the old stuff until it was used up, and then switched to the new '73+ design drums and spindles. Also explains why the date is approximate. If the new parts had been rolled out all at once, they'd have the date. But if the new parts were on the assembly line already, just waiting to go into use when the old parts ran out, well, that date would be different at every plant. November 1 was just the catch all date, all the old stuff was completely gone by then.
 
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hemi71x said:
Show me proof of a 9 inch front drum on an A body car with a large inner wheel bearing on a 10 inch drum spindle, then i will shut up, and go away.
Until then, it's nothing but fake news, until proven otherwise.
I don't know anything about wheel bearing size letters and numbers.
That is meaningless to me, between the years.

You personally parted, took apart. THOUSANDS of cars in your 32 years?
You previously own a junk yard?
So you took apart every old Mopar that you got your hands on.
I would say that's an impossibility.
You must have paid employees to take cars apart at the level that your talking.
Then in 32 years of me wrenching on cars for a living, in my past life, did i work on every Mopar car that came into the repair shops?
Click to expand...
Yes, I owned an all Mopar auto recycling business, and yes, I had help. Of course I wasn't the one who removed every nut and bolt, but, I was the one who made almost every sale. I also had to know what fit what to make sure my customers got the correct part. I'm retired now, so, I can't produce the actual part anymore. Since neither one of us is likely to run across one of these cars, it's pretty pointless to argue about it. Most of those cars are dead and buried. I can get you part numbers if you like. Maybe you can come up with the special 9" spindle part number you insist exists. I only see the one in the parts book.
 
cudamark said:
Yes, I owned an all Mopar auto recycling business, and yes, I had help. Of course I wasn't the one who removed every nut and bolt, but, I was the one who made almost every sale. I also had to know what fit what to make sure my customers got the correct part. I'm retired now, so, I can't produce the actual part anymore. Since neither one of us is likely to run across one of these cars, it's pretty pointless to argue about it. Most of those cars are dead and buried. I can get you part numbers if you like. Maybe you can come up with the special 9" spindle part number you insist exists. I only see the one in the parts book.
Click to expand...

There's literally no way Ma Mopar didn't just use 67-72 spindles and drums until they ran out and then phased in the new 10" stuff. Just like the TSB says.
 
So you figured they used some '72 and earlier upper control arms in '73 too? Not on the ones I had. The upper arms were one of the first things I sold off those cars for disc brake changeovers.
 
cudamark said:
After that, they did away with the 9" stuff.
Click to expand...
In 1999, I had a low optioned 1976 2 door Dart with 4 wheel non power 9 inch drums brakes. The only options that car had were carpet and an automatic transmission.
 
cudamark said:
Yes, I owned an all Mopar auto recycling business, and yes, I had help. Of course I wasn't the one who removed every nut and bolt, but, I was the one who made almost every sale. I also had to know what fit what to make sure my customers got the correct part. I'm retired now, so, I can't produce the actual part anymore. Since neither one of us is likely to run across one of these cars, it's pretty pointless to argue about it. Most of those cars are dead and buried. I can get you part numbers if you like. Maybe you can come up with the special 9" spindle part number you insist exists. I only see the one in the parts book.
Click to expand...
I NEVER said anything about a unique, special disc brake spindle for a supposedly nine inch Drum with a larger inner wheel bearing.
Your putting words in my mouth.
I mentioned 72, and earlier parts, and components.
Chrylser, Ma Mopar, didn't tool up for something that was going to be used for only maybe two months worth of production.
Just doesn't make any sense.

Then a 9 inch drum with a large inner bearing, is a dinosaur, umnobtanium, obsolete, like a rotor used on Rear disc brakes on the 74-75 Imperials.
 
cudamark said:
Yes, I owned an all Mopar auto recycling business, and yes, I had help. Of course I wasn't the one who removed every nut and bolt, but, I was the one who made almost every sale. I also had to know what fit what to make sure my customers got the correct part. I'm retired now, so, I can't produce the actual part anymore. Since neither one of us is likely to run across one of these cars, it's pretty pointless to argue about it. Most of those cars are dead and buried. I can get you part numbers if you like. Maybe you can come up with the special 9" spindle part number you insist exists. I only see the one in the parts book.
Click to expand...
Your right about the "argument" part of the topic between you and me.
The way to just shut me up, is to just not to post your inaccuracies in regards to the topic.
Then i won't have anything to challenge you on, or call you out, in regards to passing on fake news.
 
Kern Dog said:
In 1999, I had a low optioned 1976 2 door Dart with 4 wheel non power 9 inch drums brakes. The only options that car had were carpet and an automatic transmission.
Click to expand...
Sure you could have had a 76, with Drums on it, as it was a Slant 6 car.
 
cudamark said:
So you figured they used some '72 and earlier upper control arms in '73 too? Not on the ones I had. The upper arms were one of the first things I sold off those cars for disc brake changeovers.
Click to expand...
Yes, the small ball joint upper control arm would still have to been used on a 73 car with the leftover, 72 and earlier 9 inch drum brakes.
I really think you are confused with parting out cars with early 9 inch parts, and between 10 inch parts.
 
The early '73 only 9" hub and drum part number is 3699574. Google it. You'll see several available for sale. It's not like the '72 and older hub and drum. I already gave you the part number for the spindle, which is the only one listed for the '73 and newer drum brake cars. Both Mitchell collision guides and interchange manuals along with Hollander interchange manuals show that same information, which they got direct from Mother Mopar. If you look in any bearing manual from Timken, Bower/BCA, SKF, Etc, they only list one bearing set for '73. I don't know what other evidence you need short of handing you one in person. As for your claim that Mopar wouldn't tool up to make a part that would only be used for a few months, how about the grille emblem on the early '66 Barracudas. They tooled up to make the V emblem (like my avatar), then changed their mind and started making the fish emblems. The V emblem was only used on the first 2-3 months of '66 models. Early '70 models had unique gas caps. Early '66 B-bodies had unique front sway bars. '76 A-bodies had foot operated e-brake ratchets that year only. That year was also the only year you could get a factory rear sway bar. There's all kinds of examples of Mopar making short run parts.
 
Where did you come up with that part number?
If that's the number your information is something that i couldn't come up with.
Then Mopar came up with a brake drum that was only used for a hand full of weeks of assembly line production.
Unbelievable.
Talk about saving a buck or two, in the assembly of a car, but then they lost their *** on that one between the engineers, designers, then going 10 inch, 6 cylinder car, from then on out.
 
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Probably penny wise and pound foolish. They listened to the accountants on how to shave pennies off the cost of a cheap car, and people wouldn't buy them because they wanted better brakes. The history of how I found these brakes is that I bought one of those cars for parts. In parting it out, I discovered the 9" brakes, and since I hadn't seen them before, I did some research at the time. I was hoping they were an upgrade and interchangeable with the earlier models, but, they weren't. This was in the early 80's. I found that even though they were fairly rare, I had no problem selling the drums since Mopar stopped stocking them and there were still some of those cars running around, and the upper arms were what I needed for early disc changeovers, so, win-win for me. I just didn't run across many of them. Most of those '73's had either the 10" drums or disc.
 
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