DurasII

I have a 68 Cutlass S convt which when I bought some years ago came new with four wheel drum brakes and was converted to front disc before I bought.
My question for y'all is as follows;
1) Being that the car when new came with four wheel drum brakes would the rear wheel cylinders be of the larger bore...1"
2) If not then I would like to know which bore it might be.
3) Does any one know where I can find both left and right rear wheel cylinders.


Thanks y'all in advance for all thoughts and ideas!

joe_padavano

Your 1968 Chassis Service Manual spells this out on page 5-41.

Rear wheel cylinders are 7/8" with four wheel drum and 13/16" with front disc brakes.

Of course, this sizing ASSUMES the stock brake configuration with the separate metering valve. If the disc brake conversion used a later combo valve, all bets are off on the correct rear wheel cylinder bore.

RockAuto lists the correct rear wheel cylinder for front disc brakes in both the Centric line and Raybestos. The Chinesium Centric parts actually state that they are 13/16" bore. The Raybestos doesn't state what the bore is, but they do list front drum and front disc as separate listings and different part numbers.

jaunty75

The Raybestos parts are likely to be made in China as well. At least, all of the Raybestos parts I bought when I redid the brakes on my '78 Toro were made in China.

The "Made in China" label was separate and on the other side of the box from the label with the brand and part name and number.

joe_padavano

I've had mixed luck with Raybestos/Wagner parts from RA. Drums and rotor are definitely all Chinesium these days. Other parts, maybe not.

This is an image of the Raybestos wheel cylinder from the RA website. Yeah, I know, take that with a grain of salt...

jaunty75

Not sure what to make of that. If I go to the rockauto site and get the raybestos part number for a wheel cylinder for my '78 Toro (WC37048) and then go to the Amazon website and type in that part number in the search box, it, of course, pulls up this wheel cylinder. Scroll down the page to "Technical Details," and it will show you more specs, including country of origin. In the case of this part, it's China.

I ended up buying ACDelco brand wheel cylinders, and it says right on the box "Made in China."

I think you will be hard pressed to find any brake parts not made in China. Every single part I bought, mostly ACDelco, but also Centric, Wagner, and Raybestos, was made in China. As I bought other parts for the car (water pump, thermostat housing, alternator, stabilizer link pins, and more), I was pleasantly surprised to see that some were made in the U.S. As the world will tell you now, manufacturing plants are now global. These companies get there parts from all over the planet. Some are made domestically, most are not. Unless you are able to find nothing but NOS, I think it's impossible to keep your old car completely free of non-U.S. made parts if you want to be able to drive it.

joe_padavano

I tried that with this part no (WC37117) and COO was not listed at Amazon. I went directly to the Raybestos website, and COO was not listed there either, however the same photos that show "USA" are used by Raybestos. Note that when I checked your P/N at Raybestos, here is the photo that comes up:

jaunty75

It doesn't show much of anything.

joe_padavano

My point. Specifically, it does not say "USA" the way the other one does.

jaunty75

If you google this casting number (29452S), this site

http://www.kakapart.com/parts/casting-29452s.html

cross-references it to Raybestos WC37024. Put that number into the Amazon search box, scroll down to the Technical Details section once the page comes up, and it says Origin is China. You just can't get away from it.

joe_padavano

Look, I can't vouch for what aftermarket catalogs (or even manufacturer's catalogs) list. I do know that I do NOT rely on RA, Amazon, etc. for correct info. I also know that WC37117 has a 13/16" bore and WC37024 has a 7/8" bore, so despite the casting number, the parts are physically different.

jaunty75

No one is expecting you to. I was merely pointing out that even a part that says "USA" on it is not necessarily made in the USA. Or perhaps that photo is old and from a time when that part was domestically made? Just speculating.

joe_padavano

Which is why I said "take this with a grain of salt" waaaay back when I first posted that photo...

DurasII

LOL
Thanks all for the response. So if I am getting this correctly even if I take the ones out of the car that are presently in there, there is no saying that they are the correct ones? The only chance that I have is to;
1) Just buy two of the same and it is what it is??
2) Redo the entire brake system (booster, proportioning valve, all the way through to the disc and calipers.


Am I kind of getting this?


I have to do something as my pedal is getting soft the first half and when I took the rear drums off it was easy to see that the wheel cylinders are leaking and probably letting air back onto the system.


So I should just to get the car back on the road until winter when I can redo the entire system with matched parts, just grab what I can and put it together to get me through the summer????

Fun71

New wheel cylinders, even if they do not have the correct bore diameter, are better than what you currently have.

I doubt the 1/16" difference in bore diameter will cause your car to explode into flames.

oldcutlass

If your brakes worked well before the parts became worn, then replacing the worn parts with the same sizes will return the system back to that state of serviceability.

joe_padavano

Understand that Olds selected the wheel cylinder diameters to achieve the proper front/rear brake balance. The 1967-1970 factory disc brake cars do not use a proportioning valve, only a metering valve on the rear wheels. Contrary to popular belief, a prop valve is NOT required in a disc brake system if the brake parts are sized correctly. This is why these cars have different diameter rear wheel cylinders for drum/drum (7/8") and disc/drum (13/16") applications. By the way, the disc brake cylinders have 14% less area than the drum cylinders.

Interestingly, the 1971-72 cars that DID use a prop valve (as built into the combo valve) used 7/8" rear wheel cylinders with factory disc brakes.

Assuming this car was converted with a combo valve, I'd use the 7/8" cylinders. Keep in mind, however, that something as simple as tire diameter can affect front/rear brake proportioning requirements and cause premature lockup.

Allan R

Dan, a point of interest for you in the interpretation of "Made in USA". If you already know this ditty, disregard.
Here it is FWIW: If the component parts of an assembly are manufactured offshore, but the final product is assembled in USA, the company has the right to claim it is an American made product. Tomato, tomahto. Would the quality be better if all was manufactured in USA? Likely, but also likely more expensive. However it would promote jobs in America and lend more authenticity to the claim "Made in USA". I know that even some of the 'genuine' parts that I buy through RA are not made in the USA or Canada even though they claim that status. Thoughts?

DurasII

Again Joe you are full of wisdom and I am greatly appreciative of your expertise.
Thanks for all of your input. I am fully aware now that all pieces have to be matched for each other in order to have correct performance characteristics. I am going to do my best to get the system to work the best that it can to get me through the summer safely and then next winter when the car is stored in the toy box will reanalyze what is needed to make it better.