Disc/Drum Double Pump Pedal Finally Solved (1 Viewer)

[FJROSS]

Once again I'd like to thank the memebers for all there help. I just got done going thru a few weeks of brake repair that started out with the front discs locking up. This lead into flushing of the lines and replacement of the master, booster and wheel cyclinders and brake lines. I believe that the brake lock up was do to crude in the brake fluid and the residual valve not relieving the pressure. After replacing all the components mentioned, I tried for a couple weeks to get a hard pedal with no luck. After isolating one item at a time it ended up being the rear wheel cylinders. The wheel cyclinders I purchased were the economy models from CCOT since I plan on restoring the truck in the future. After weeks of bleeding and adjusting brake shoes, the culprit was air that was trapped in the rear cylinders. This air trapped in the rear cylinder gave you a pedal that would pump up. I myself thought that air would make the pedal soft all the time and not pump up, but not so. Awhile back Mud member hamm made me aware of a problem with CCOT cylinders and bleeding the air out of them. The method that we used was to remove the caps off the rear cyclinders and push down the piston with a large c clamp vise grip to bleed the air out the tapped holes that are located below the high point of the wheel cylinder. This was done while pressure bleeding and bleeding thru the bleeder screws. This method did not work. It wasn't till member 65swb45 offered the method of disassembling the cylinder, removing the rubber seal and inserting it into the cylinder in the vertical position and then rotating it horizontal while being submerged in the fluid. While performing this you must have the drum on the opposite side of the truck and a clamp on the other wheel cylinder that you are trying to bleed. This is for you don't push the piston out of the other wheel cylinder as your working on the current one. While assembling the cap you want to be bleeding thru the bleeder screw to displace the fluid while inserting the cap into the cylinder. The CCOT cylinders are definetly different from the stock ones that were removed off the truck , The stock ones have a metal cap that has the seal on top of it as the ccot basically has a spring with just a rubber seal that causes a larger area to catch air. The absence of this cap may be the reason why the CCOT cylinders were such a pita to bleed. If it wasn't for 65swb45 and my mechanic's thrive to not let the drum brakes get the better of him, I don't think this problem would have been solved. Some may say that normal bleeding should have taken care of this problem, but not so. This system was pump blead, vacuum blead and pressure blead several times. I hope this may help others with the same ongoing problem.


Thanks again Dave

 

[lostmarbles]

.......This air trapped in the rear cylinder gave you a pedal that would pump up. I myself thought that air would make the pedal soft all the time and not pump up, but not so. ......

Yes. I've also found it possible to get a "hard pedal" with air still trapped. (With the air simply causing extra pedal travel.)

...The CCOT cylinders are definetly different from the stock ones that were removed off the truck , The stock ones have a metal cap that has the seal on top of it as the ccot basically has a spring with just a rubber seal that causes a larger area to catch air. The absence of this cap may be the reason why the CCOT cylinders were such a pita to bleed........

Pity you weren't able to show photos Dave because that's very interesting.

Anyway - At least you (and your mechanic) never let it is beat you. And both of you have gained heaps from the experience so it wasn't at all wasted.

(Not to mention the fact that you shared it with us so we all gained knowledge as observers.)

 

[Cruiserdrew]

Good post.

Other than adjustments, I've never had a single issue with Toyota wheel cylinders. They bleed on the first try and last for close to 20 years!

CCoT. You get what you pay for.

 

[igotta40]

Interesting....I had problems with those guys a few years ago. I got into a debate with them when they sent me rear wheel cylinders for all four wheels. They didn't want to refund the four incorect ones or listen to me when I tried to explain that they aren't all the same. They finally refunded my $$$ after arguing that I must have the wrong axle on my truck because they sell hundreds of these cylinders with no complaints. Since putting the truck all back together ('74 all drums w/ booster) my pedal goes all the way to the stop but I have only partial stopping force. I had been thinking I need to adjust the booster rod but your post has me speculating about air in my cylinders.

Great post, this is the reason IH8MUD is such a good forum!

 

[FJROSS]

Good post.

Other than adjustments, I've never had a single issue with Toyota wheel cylinders. They bleed on the first try and last for close to 20 years!

CCoT. You get what you pay for.

This is true, the $109.00 wheel cylinders were to get by until I did my restoration were I would switch over to silicon fluid and rear discs.

 

[FJROSS]

Interesting....I had problems with those guys a few years ago. I got into a debate with them when they sent me rear wheel cylinders for all four wheels. They didn't want to refund the four incorect ones or listen to me when I tried to explain that they aren't all the same. They finally refunded my $$$ after arguing that I must have the wrong axle on my truck because they sell hundreds of these cylinders with no complaints. Since putting the truck all back together ('74 all drums w/ booster) my pedal goes all the way to the stop but I have only partial stopping force. I had been thinking I need to adjust the booster rod but your post has me speculating about air in my cylinders.

Great post, this is the reason IH8MUD is such a good forum!

While refurbishing my brakes, I also converted to the mini booster. In doing so I had to adjust both rods. After adjusting the rod to master cylinder, I would find it hard to believe that this rod could go out of adjustment on its own unless modifications were done on the vehicle. That rod was a fighter to hold back on and adjust.

 

[igotta40]

I got a mini truck booster too, to save money.

The rod was too long to be adjusted per the measurement in the FSM so I cut it. Now I'm thinking it's too short. You mention two rods- is the other the one from the pedal into the booster?

 

[FJROSS]

I got a mini truck booster too, to save money.

The rod was too long to be adjusted per the measurement in the FSM so I cut it. Now I'm thinking it's too short. You mention two rods- is the other the one from the pedal into the booster?

After looking around for a week or so, I came to the conclusion that nobody had the parts to rebuild the stock dual diaphram booster besides $pecter or CCOT. I ended up cutting about 1/4 to 3/8" off the pedal to booster rod and still had clevis adjustment.

 

[igotta40]

Yeah, The mini booster was half the cost of an FJ booster rebuild.

I'll have to look into the rod lengths. Thanks, you're a big help!!

 

[Fast Eddy]

This is true, the $109.00 wheel cylinders were to get by until I did my restoration were I would switch over to silicon fluid and rear discs.

Toyota OEM are only about $140 from Cruiser Dan...

 

[dgangle]

...I got into a debate with them when they sent me rear wheel cylinders for all four wheels. They didn't want to refund the four incorect ones or listen to me when I tried to explain that they aren't all the same. They finally refunded my $$$ after arguing that I must have the wrong axle on my truck because they sell hundreds of these cylinders with no complaints...

Oh man, don't get me fired up about these boobs again. Same deal here 8 years ago except I threw mine in the trash. Seems as though they haven't learned a thing. All from the "Nation's Foremost Restorer of Toyota Land Cruisers". Yikes!

Rear disks made all this just go away.

 

[lostmarbles]

Oh man, don't get me fired up about these boobs again. Same deal here 8 years ago except I threw mine in the trash. Seems as though they haven't learned a thing. All from the "Nation's Foremost Restorer of Toyota Land Cruisers". Yikes!

Rear disks made all this just go away.

On the other hand - I'm quite happy with the quality of the gear I bought from CCOT. (Stainless hood hooks, seat belts, door pins etc).

And I reckon it is companies like them that make it possible for us to "restore" our cruisers well into the future because the supply of OEM parts is rapidly running out. (I seldom even bother checking with Toyota themselves for parts now.)

And you can't suspect me as having any connection with them - Cos I live the other side of the world.

And they support MUD by advertising on it.


(Just added this to create some "balance" here.)

 

[peesalot]

yup, we've had to burp them rear wheel cyl. with an air hammer while bleeding to get the air bubble out.

 

[homebuiltcruiser]

How do i tell what cylinders i have?

I have a similar issue with my '78, but don't know what wheel cylinders I have in the rear.

Since I put my truck back on the road since rebuilding I've had a soft pedal. It stops the truck fine and haven't had any problems but pedal is near the floor and tough to lock up. 2-3 full pumps and the pedal will be hard and near the top. Even then it seems to sink a little bit.

Here is what I have. I replaced the front calipers brand new from NAPA. All lines are new. I took the wheel cylinders off my parts truck because they had been recently replaiced, but I don't know who they came from. I replaced the master cylinder with one from CCOT. I've heard some questionable things about CCOT brake parts.

Everything has been bled multiple times, lines, master cylinder, everything! I'm trying to figure out if I possibly have this problem with air in the rear wheel cylinders or could the master from CCOT just be a bum master??? How do i tell the CCOT wheel cylinders apart by looking at them?

I do have the original master, but its a little rough. Is there a rebuild kit that would make it putting that one back on rather than the CCOT?

 

[iokepa]

I wish I had read FJROSS’ post years ago. I have always struggled to get the brakes on my FJ40 adjusted and bleed correctly. I think up until now I have just been getting lucky after dumping loads of brake fluid through the system. Lucky, up until now…

Several days ago I pulled off two of my rear wheel cylinders to rebuild them because they were leaking. When I was done I expected the adjusting and bleeding process to be the normal PITA, well it wasn’t. It turned out to be a MAJOR PITA! I spent the majority of three days trying various things to get a better pedal, most of what FJROSS has described going through. I tried gravity bleeding first because that has worked for me in the past. I then tried pedal pump method, no luck… I figured I needed to tighten the adjusters more so I did. That gave me a slight improvement but still not even close to drivable. I had my adjusters so tight that I couldn’t spin the wheels by hand, even with a lot of force! At this point I knew there must still be air in the system but I had already put literally a gallon of fluid through it. What next?

I decided to build a pressure bleeder out of a garden sprayer like I saw on YouTube. The bleeder worked great and I even got some more air out of the system. I thought for sure this was the answer. Sadly I was disappointed when I went for a test drive. Still too unsafe to drive on the street, let alone off road!

By now three days of frustration had gone by and my time off for hunting season was diminishing. I had already been looking at mud for answers but didn’t see any thing I hadn’t heard to try before. I decided to give it one last look. That’s when I stumbled across a thread that referenced this one. I immediately thought the burping idea was great and couldn’t wait to try it the next day.

So I got up early the next day and pulled the rear wheels off for the umpteenth time. Hooked up my pressure bleeder so that I wouldn’t have to worry about the reservoir running out of fluid and started burping the cylinders on one side. After burping two cylinders on the passenger’s side and putting the drum back on I decided to give the pedal a feel. It was already 100% better! I knew then that this was going to work. After following through with the driver’s side the pedal feel was better than I think it ever has been in the 13 years I have owned my FJ40! Thank you FJROSS for sharing this.

I highly recommend having a pressure bleeder when performing this technique so that you don’t have to have someone stand at the reservoir with a bottle of break fluid keeping it full while you burp the cylinders. Be sure to pressurize the bleeder after you hook it up and then release the pressure so that it removes air above the master cylinder reservoir. Additionally make sure that you put the bleeder tank at a height above the master cylinder so that it will siphon feed it. I have included some images of the bleeder and how it adapts to the master cylinder reservoir. Also included is a parts list with Ace Hardware part numbers. The gauge and its fittings aren’t included in the list they were just spare parts I had in the garage (Summit sticker optional). The key parts here are the flex couplers that allow you to use it on the LC master cylinder.