8 3/4 REAR - WHAT size brakes? 9" or 10-11"

[BIG-B-Barracuda]

i have a 8 3/4 rear end on my 1968 Barracuda one of my drum brake cylinders is leaking i went in to the parts store to buy a new cylinder but they told me that they had two in stock one for 9 in. brakes and another for 10-11 in. which one do i need? :burnout::burnout::burnout::burnout::burnout:

 

[pishta]

I would bet 9 but if it were an S they be 10". Was the barracuda a 273/318 or a slant?

 

[BIG-B-Barracuda]

i cant confirm if this is original to the car.

the car is originally a 318.

when i bought my rear wheels i bought big bolt pattern if that helps. 5xdarn i forget. the size.

ill just end up removing and taking it in to match up at the parts store i guess?

 

[Dave1967]

Measure your drum

 

[AJ/FormS]

I've never heard of 9 inchers on an 8.75

BigB are you in trouble yet again?
Tell you what tho, it would be best to go check out that W/C on account of there could be any of 3 sizes on there. And trying to take it off usually results in a torn hard line.You need a special flare-nut wrench, a good penetrating oil,and probably some heat.
So what I would do is block the brake pedal down some to close the compensating port, so you don't drain the fluid all out. Do that right away. As in right now.Then get into it. Get everything out of there right down to the wc. Pop the rubbers off and push the pistons out. Be prepared for a mess.Clean it all up, and check the wc. bore. Pitting on the inboard side is no biggie. If it's pitted out where the seals go, well, it's had a long life, but it's all over now. Kits are cheap. I would try to kit it if at all possible. You may need to clean the bore out with a small hone. You might as well do both sides.
All the best.

 

[66fs]

I've never heard of 9 inchers on an 8.75 ...

Should be 10 x 1 3/4 brakes on an 8 3/4.

 

[sireland67]

Measure the drum diameter and width of the brake shoes.
Take the cylinder to the parts store with you.

There are a few different wheel cylinders, for the same size diameter of the drum, depending on the year and backing plate used on the rear end.
Found this out on 10 x 2.5" brakes.

 

[MIKERP76]

look on the edge of the drum it should say max dia. then the size. if it starts with 9 then it is a 9" drum and so on.

 

[BIG-B-Barracuda]

i was loosing pressure on my brakes. this morning i noticed my driver side REAR wheel was leaving a nice three inch oil stain on the pavement in the shape of the tire! haha so i figured the cylinder is bad & leaking inside drum. thanks for the input guys.

i have yet to take it apart.

 

[AJ/FormS]

Well you better top up your M/C. I guess you didn't block your brake pedal down last night.....k

 

[KosmicKuda]

i was loosing pressure on my brakes. this morning i noticed my driver side REAR wheel was leaving a nice three inch oil stain on the pavement in the shape of the tire! haha so i figured the cylinder is bad & leaking inside drum. thanks for the input guys.

i have yet to take it apart.

I have yet to hear of 9" brakes on a 67-69 Barracuda. They were all produced with 10" X 1-3/4" brakes on the rear AFAIK.

Having said that, I'll borrow from Forrest Gump and say, "Old cars are like a box of chocolates. You never know what you're gonna get." A 47 year old car can have anything by now.

To be sure, measure the bore of the wheel cylinder and match it up. If you have a puddle of fluid on the ground that means your brake linings are soaked and need to be replaced. Probably not the case but if it turns out to be a leaking axle seal, you'll need to replace that.

 

[AJ/FormS]

6 bangers had 9 inchers. I had 2 of them; a 68 and a 69. Wait I stripped out a 67;also with 9s
340 cars came standard with 10" drums all round.Except with certain option codes. Teeners IDK, never had one.

 

[BIG-B-Barracuda]

so most likely a 10" then.

but to be sure i will removed and match it up at the parts store.

how can i tell if this rear end is original to my car.?

 

[AJ/FormS]

Well, since the car was built over 47 years ago, that would be hard to prove. However, if you ask is it the same type as originally installed, well a peek at the build sheet would reveal that. What? you say, you got no stinking build sheet? After 47plus years, that's no surprise. lol. Well then, a look at the Fender tag will tell you.Oops, hold on, I thought it was in there. Lemme go check. Yup it's on the fender tag, but it will need to be decoded.
It's on the 2nd last line,under the "A",9th from the left.Grab the digit from there and report back. I'll see if my decoder will tell you what the car was born with. But it's then up to you to prove whether or not it's still under there. And if the wheel cylinders are the same size as original?who can say. I got no code for wheelcylinders.
So that more or less takes you back to square one. Sorry.....

 

[66fs]

There are ways to tell if it is correct. The emergency brake hardware and location of the vent threads / brake tee. There are differences from early 67-? and ? till 72.

 

[72bluNblu]

when i bought my rear wheels i bought big bolt pattern if that helps. 5xdarn i forget. the size.

5x4.5"? If you've got big bolt pattern wheels, then what you've got isn't stock. You could have re-drilled small bolt pattern brakes, which would be 10x1.75". That would be easy to see because you'd have an extra bolt pattern drilled into your drums. You could also just have 10x2.5" big bolt pattern brakes, but if that's the case you have aftermarket axles. And of course, since we already know what you have isn't stock, you could also have any of the 11" drum set ups, either 11x2, 11x2.5, or 11x3. Yeah.

Best bet is to measure everything, figure out what brakes you have, and then take the offending wheel cylinder with you anyway. Because there are several different bore diameters available for mopar wheel cylinders, and who knows if you have the "right" ones on your car now. So, you'll want to get one the matches the other side. As was already mentioned, removing the wheel cylinders often results in needing a new over axle brake line, so you might as well know if you need one when you head to the parts store.

 

[cosgig]

You will not find 9" brakes on an original A body 8 3/4" rear, they only came with 10x1 3/4" drums! You will also not find an A body 8 3/4" rear under a slant 6 car unless it was added, or ordered as an option. If it was ordered as an option, it would still have 10" brakes, not sure if the car would be automatically upgraded to all 10", but I believe that's what would happen!

 

[66fs]

You will not find 9" brakes on an original A body 8 3/4" rear, they only came with 10x1 3/4" drums! You will also not find an A body 8 3/4" rear under a slant 6 car unless it was added, or ordered as an option. If it was ordered as an option, it would still have 10" brakes, not sure if the car would be automatically upgraded to all 10", but I believe that's what would happen!

An A body 8 3/4" rear under a slant 6 car it would still have 10" brakes, and the car would be automatically upgraded to all 10". If the car was ordered with disc brakes the rear would also come with 10" rear brakes.

 

[BIG-B-Barracuda]

It was 10" brakes not the smaller 9"

i switched it out and brakes feel "like new"

Oriley's
Driver side drum cylinder - 9.53
brake fluid - 5.43

thanks guys. easy fix & not so expensive thank God

 

[sireland67]

Glad you got it fixed.
Now go out and buy a good Bendix wheel cylinder for $35.00, why?
I bet that china pos you put on it will not last a year, I found out the hard way.
When you need brakes, you need them now.

 

[BIG-B-Barracuda]

Glad you got it fixed.
Now go out and buy a good Bendix wheel cylinder for $35.00, why?
I bet that china pos you put on it will not last a year, I found out the hard way.
When you need brakes, you need them now.

haha, i bet!

well i didn't buy the second one to replace both because i couldn't afford it -
so at this moment in time i cannot afford a Bendix so we will cross that bridge when we come to it. Hopefully we stop in time to do so...... -_-

 

[BIG-B-Barracuda]

But now that I know the proper size and how to replace I can do it with a quality part next time thanks guys.

 

[diymirage]

But now that I know the proper size and how to replace I can do it with a quality part next time thanks guys.

when I wrecked the 7 1/4 out of my duster I got in a hurry to bolt in the 8 3/4 I intended to properly look over during the winter
I took the old brake shoes into autozone to match them up to the new ones
after seeing how much more padding I still had on the 47 year old shoes I didn't hesitate to bolt them right back in

 

[BIG-B-Barracuda]

Glad you got it fixed.
Now go out and buy a good Bendix wheel cylinder for $35.00, why?
I bet that china pos you put on it will not last a year, I found out the hard way.
When you need brakes, you need them now.

Upon your request after getting paid this weekend i went out and got myself a proper $$$$ brake cylinder installed and ready to go. only "GOOD" parts on my car upon your request haha..


:coffee2::cheers::burnout:

thanks hope this thing lasts - and is safer than the last ..:blob:

 

[67bluefish]

Thanks for doing some preliminary work for me, Big B! I'm getting myself psyched up to redo all my brakes in another few weeks, so seeing what hoops you had to jump through is good homework.

Can't wait for some fresh pedal feel of my own...