The Stovebolt Site Forums The Parking Lot Big Bolts Cheap Wheel Cylinders

Just picked up some rear wheel cylinders for $3.34 a piece on RockAuto. Dorman wholesale in private packaging it says. I'm not sure what years/models it covers. I just looked for my 54 GMC 350-27

Just thought I'd let everyone know!

Wow, that's cheap! What bore are they?

The ones I got are 1.5"

Well I found the listings you speak of. Dorman part #s W18197 and W18196. They give some rather generic application info:
GMC 3000 1961-1964
GMC 3500 1961-1964
GMC TRUCK 1953-1960

I wonder if they would fit my '55.2 Chevy 6400? Rock Auto doesn't seem to list my model of truck at all, which is a bit strange.

I've had surprisingly good luck with rock auto as long as you enter in your vehicle info before you search for the parts.
I'll let you know if they fit mine, they're supposed to be here Wednesday.

Every thing lined up great, the new cylinders seem very nice.

But now I can't get the brakes to work well. They feel like there is a bunch of air in the lines, but all four wheels and the hydrovac bleed fluid with no bubbles...

Did you follow the hydro-vac bleeding procedure as described in the Shop Manual?

It is different from the non-Hydro-Vac bleeding procedure.

Hi, New to site and am trying to figure how to post. I have tried to search Rockauto and it will not let me search for c50 or c60 parts, how do you do it?
Phil

I just looked at my manual, I skipped a few steps. I'm going to run through it by the book and see if that fixes it.

could bad wheel cylinders/hydrovac make the brakes feel spongy? I don't want to rebuild the hydrovac if i can avoid it.

Bad cylinders couldn't cause sponginess unless they had a very, very bad leak. It's probably just trapped air somewhere.

Do your long runs of brake lines have peaks and valleys?

I'll take a look at the lines. I don't have leaks anywhere that I can see. No puddles or wet lines.

So unless the hydrovac is filling with fluid I must have a bunch of air somewhere.

sorry this is turning in to a tech thread...

I did the full bleeding procedure and now I get a good pedal feel after 4 pumps or so.
Then, after waiting a little.. like 30 seconds or more, the pedal will go back to the floor and firm up after a few pumps again.
I replace all the rear wheel cylinders and the rear brakes work well when the pedal firms up. However, I have no front brakes at all even though they bled fine. Probably bad wheel cylinders up front?

The thing that puzzles me the most is the loss of pressure after such a short ammount of time.

Sound to me like your shoes are not adjusted up tight and you have to pump to get enough fluid to get the shoes to contact the drum.

I adjust mine with the wheel off the ground to having heavy drag when trying to turn the tire with one hand. They should not free spin, that's way to loose.

Hope this helps,

Mike B

what Mike said. After adjustment if you still have the same problem my advice would be bleed, bleed, bleed, bleed....

I've adjusted the brakes out and still have a squishy pedal at first. I'm gonna check the adjustment one more time and bleed it a bunch when i get a chance.
I still don't think my front brakes are engaging at all when I press the pedal though.

I've been bleeding the brakes by pressurizing the master cylinder to 20 psi like the manual says. Is that really the only way to bleed the brakes? It says the traditional pumping the pedal technique won't work, but I can't understand why.

Is there anything else I could be looking at?

Thanks as always for all of the help guys!

How's your residual valve situation?

I haven't seen a residual valve anywhere, I haven't really looked either though.
Do you know where it should be?

**Edit**

After doing some research, it seems like residual valves would not have come factory. My master cylinder sits well above my wheel cylinders so I wouldn't think that would be a problem. I don't have any experience with them though.

I didn't know if they were integral to the MC or hydrovac units. Isn't your MC under your floor? I don't think that's very far above the wheel cylinders. It's not as good as a firewall. I plan on running a residual valve when I get my system put together. Possibly a proportioning valve too.

Made some progress, the manual doesn't say anything about re adjusting the brakes over and over again.
I adjusted them how you guys said then pumped the pedal to center the pads. Went back to check the adjustment and they were loose again.
I did this like 5 times, now the pedal feels good after one pump, and the first pump is much better than before.
I'm gonna bleed the brakes again and adjust them again and i should be in business!

That's great. It seems as though I may have to go through the same process.

How are you bleeding yours? Gravity, Mityvac, a helper wiring the pedal, or some pressurized MC attachment?

I've decided that vacuum bleeding sucks. I seem to draw in air and get false bubbles. And I'm short on helpers too. I need a pressurized MC solution.

I'm pressurizing the master cylinder with a setup I made.
I taped a hole in the top of the old master cylinder cap and put a barbed fitting in it.
I run a hose from there to a reservoir, an old sprayer tank.
Then I have a air line fitting tapped in to the top of the reservoir.
I use the regulated on my compressor to keep it at 20 psi.

It seems to work pretty well. I can put up a picture tonight.

I"m not sure on your particulat truck, which brakes you have in the rear but, the manual for the 55.2-59 chevy 2-ton brakes says to back off the adjustment on the top shoe on both rear wheels before you bleed. Looking at the way the cylinders are situated on the backing plate, of you don't do this, it will trap air in the top of that cylinder. You might look through your manual again and try that.

Also, if the fronts are not engaging at all, the pistons in the wheel cylinders may be frozen. They will bleed fine but not move. You may need to pull them apart and put kits in them or replace them altogether. I'd do that before doing any more bleeding since you will have to re-bleed once you mess with them.

I thought about doing something similar, but haven't been able to get a spare cap. I guess I could just put a plug in my original when it's done, though. The threads on my cap seem to be on their last leg, but if I'm careful, maybe I can pull off something similar.

A pic would be helpful, it's always a time saver to glean inspiration from someone else. Thanks.

this link gets you the idea of the bleeder http://www.ibmwr.org/ktech/pressure-bleeder/bleeder.shtml

then, you need to modify your cap. I drilled mine out and used a bolt with a hole in the middle for a fitting. Fiber washer on top of the cap and under the nut to seal it, and away we go!

http://i1152.photobucket.com/albums/p494/69B-Cuda/brake%20bleeder_3.jpg

http://i1152.photobucket.com/albums/p494/69B-Cuda/brake%20bleeder_2.jpg

No fair, where'd you get the metal cap? My MC cap is plastic, and it looks like it's been cross-threaded several times in the past. I don't know how well I can make it seal up. Thanks for the pics.

Here's the picture of my setup, I got a second cap when I replaced the master cylinder.

http://i1147.photobucket.com/albums/o546/Adam_Jerstad/Mobile%20Uploads/0410172029.jpg

BR0304 would probably fit. http://www.americanclassic.com/asp/...;iyear=1955&ytype=to&exyear=1959

1 1/4" thread diameter, check yours and see what it is.

That's funny, I think that's the exact same weed sprayer I bought last night! I took the nozzle off, tapped the output to 1/8" NPT, and installed a 1/4" push-fit connector. This will allow me to install the small diameter 1/4" OD clear tubing so I can purge the line of air before I hook it up to the MC. I bought a valve to put inline as well.

I also added an air input line so I don't have to pump it, but plan on making a cap for it so I can pump it and use it without compressed air if needed.

I suppose I'm lucky but I have never used a pressurized system to bleed brakes. I have on a few occasions used a bottle with some brake fluid in it, cut a small hole in the top for a line to slip over the bleed screw and into the jar/bottle and then pump slowly until all the air bubbles are gone.
I know many of you/us have done this and you may want to try it. I had an old 47 Plymouth that fought me all the way and it was the above method that finally whipped it......just saying.

I hear what you're saying, and believe me, I have bled countless vehicles in the past. I won't pump the pedal with the bleeder left open anymore, however, because I've had that reverse the flow when releasing the pedal, and I've had it suck air back into the lines from the bleeder. This turns pumping into a 2-man operation, so someone can open/close the bleeder as necessary. While this is usually effective (mostly fool proof), I rarely have help available. Help can be bypassed with the use of "speed bleeders", but then you have to have all the appropriate sizes. Also, sometimes this just doesn't work (as is the case with some ABS modules, or potentially my hydrovac unit).

Vacuum bleeding can sometimes suck air past the threads of the bleeder, and give you false bubbles.

Gravity bleeding rarely works for me--I think some valves just need a little pressure to get things flowing.

All this has led me to using a pressure bleeder. I know it will work better, and it doesn't suffer from on the pitfalls of other methods. And it really didn't take much fooling around to put together. I'm gonna throw a pun out there, and say I'm pumped to be able to use it.

With rock auto I went with the picture and the wheel
cylinder diameter. Perfect match for my 1946 2 ton.
Jeffrey