new cylynders...brake pedal to the floor after bleeding...WTH? (real time) (1 Viewer)

[Fargenamps]

"The CCOT cylinders are definitely 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."


Hmmm, yeah, what he said. Did you take the OEM parts out of the OEM wheel cylinders and install into the new CCOT cylinders?

I did, it worked just like I was using the OEM ones. No bleeding issues. That was in 2006 and they are still working fine...

no....but this obviously sounds like a good idea......

 

[mydogpea]

I don't know how to post the link but I started a thread on this issue titled "Still no brakes" and I took pictures of what I did and how I fixed the issue.
By the way, my truck is a '72 also.

 

[Fargenamps]

I don't know how to post the link but I started a thread on this issue titled "Still no brakes" and I took pictures of what I did and how I fixed the issue.
By the way, my truck is a '72 also.

You sir...are a gentleman and scholar

Here is the link....for the masses:

https://forum.ih8mud.com/40-55-series-tech/599432-still-no-brakes.html

72 vintage...good year...

Thanks again...you rock my friend!

 

[Fargenamps]

To even better understand the difference between old and new POS!!! I took apart both...laid them out so all can see what's up with this problem...

 

[lostmarbles]

To even better understand the difference between old and new POS!!! I took apart both...laid them out so all can see what's up with this problem...

View attachment 651089

Yikes!

Vastly different bore size.

The new one on the left will require probably at least TWICE as much fluid as the old one on the right to get the same shoe movement.


This is probably the cause of your "pedal-to-the-floor & still no brakes" issue (rather than air contamination).


Which size is this cruiser supposed to run?



Edit: Just done some searching and found threads like this one:

https://forum.ih8mud.com/40-55-series-tech/357300-rear-wheel-cylinders-bore-size.html

I think you need to stay with 7/8" bore.

 

[mydogpea]

To even better understand the difference between old and new POS!!! I took apart both...laid them out so all can see what's up with this problem...

View attachment 651089

Is the one on the left an aftermarket wheel cylinder? The bigger bore cylinder is for the front wheels since most of the weight is in the front=more stopping power needed. My aftermarket cylinders are all the same size(7/8) The other cap that goes on the bottom of the spring for the one on the left may be in the bottom of the cylinder.

 

[mydogpea]

You sir...are a gentleman and scholar

Here is the link....for the masses:

https://forum.ih8mud.com/40-55-series-tech/599432-still-no-brakes.html

72 vintage...good year...

Thanks again...you rock my friend!

What comes around goes around. Others have helped me so now I can help others. Just paying it forward. You'll do the same.
Took my truck on the highway for the first time today...stopped when I needed it to

 

[Pin_Head]

In 5 years of turning wrenches and rebuilding thousands of wheel cylinders, I never ran into one that needed to be "burped" or could not be bled with the normal technique. I think that this is just improper bleeding technique that does not develop enough pressure and turbulence to sweep the bubbles out.

The two keys to proper brake drums:
1) adjust each shoe until the drum is locked and then back off 3 clicks.
2) Use the two man bleeding technique and push down hard on the pedal to make the fluid really squirt out of there.

Speed bleeders or suction type bleeders just do not cut it all the time.

 

[Fargenamps]

In 5 years of turning wrenches and rebuilding thousands of wheel cylinders, I never ran into one that needed to be "burped" or could not be bled with the normal technique. I think that this is just improper bleeding technique that does not develop enough pressure and turbulence to sweep the bubbles out.

The two keys to proper brake drums:
1) adjust each shoe until the drum is locked and then back off 3 clicks.
2) Use the two man bleeding technique and push down hard on the pedal to make the fluid really squirt out of there.

Speed bleeders or suction type bleeders just do not cut it all the time.

I think I'm dealing with a weak MC as well....still getting bubbles escaping through the the "rear" reservoir when self bleeding the MC....this is possibly making the bleeding process a no win situation....not doing anything more till I get a proper working MC back in there.....

 

[Pighead]

Hey, those cylinders look close enough. s***.
Shouldn't there be a "Bad CCOT brake cylinder" stickie? This is not the first thread. Somebody could die.

 

[Pin_Head]

Three wheels had the stock OEM 7/8 as shown..... and the passenger front had been replaced with these aftermarket ones at some point....

It is not just an after market cylinder; it is the wrong aftermarket cylinder. Mixing up bore sizes is dangerous.

 

[Fargenamps]

Yikes!

Vastly different bore size.

The new one on the left will require probably at least TWICE as much fluid as the old one on the right to get the same shoe movement.


This is probably the cause of your "pedal-to-the-floor & still no brakes" issue (rather than air contamination).


Which size is this cruiser supposed to run?



Edit: Just done some searching and found threads like this one:

https://forum.ih8mud.com/40-55-series-tech/357300-rear-wheel-cylinders-bore-size.html

I think you need to stay with 7/8" bore.

Yes.....Three wheels had the stock OEM 7/8 as shown..... and the passenger front had been replaced with these aftermarket ones at some point....need to check the units in there now again...fronts are from cruiser corps and the back are CCOT...all were checked for the correct config before install....but if going off memory all seemed to be a bigger bore size than the stock ones....

 

[duffontap]

Took my truck on the highway for the first time today...stopped when I needed it to

Sweeeet! I've been watching for you.



Fargenamps, Pin_Head's suggestions on bleeding technique couldn't cost more than a few cents in fluid. Should be worth a quick try before you refocus on the MC.

 

[Fargenamps]

It is not just an after market cylinder; it is the wrong aftermarket cylinder. Mixing up bore sizes is dangerous.

Yep...good old PO work....+ all the cylinder positions were backwards and the springs installed wrong...hope he never paid to have any of this work done...

 

[Fargenamps]

Sweeeet! I've been watching for you.



Fargenamps, Pin_Head's suggestions on bleeding technique couldn't cost more than a few cents in fluid. Should be worth a quick try before you refocus on the MC.

Good call...it's worth a try first...I'll know right away

 

[Pin_Head]

Fargenamps, Pin_Head's suggestions on bleeding technique couldn't cost more than a few cents in fluid. Should be worth a quick try before you refocus on the MC.

There is more to it than I stated.

Yell "down" and the guy in the cab pushes hard on the pedal and yells "down".
You open the bleeder 1/3 turn and wait until the fluid spurt starts to drop off and then close the bleeder and yell "Up". The guy in the cab lets up on the pedal and yells "Up". Make sure you close the bleeder while fluid is still running out so that air is not sucked back.

 

[mydogpea]

There is more to it than I stated.

Yell "down" and the guy in the cab pushes hard on the pedal and yells "down".
You open the bleeder 1/3 turn and wait until the fluid spurt starts to drop off and then close the bleeder and yell "Up". The guy in the cab lets up on the pedal and yells "Up". Make sure you close the bleeder while fluid is still running out so that air is not sucked back.

Or....you can pick up a bleeder hose that has a check valve in it that only allows fluid and air to travel one way...it worked for me. My truck stops like it should now, no pumping of the pedal.

 

[mydogpea]

Yes.....Three wheels had the stock OEM 7/8 as shown..... and the passenger front had been replaced with these aftermarket ones at some point....need to check the units in there now again...fronts are from cruiser corps and the back are CCOT...all were checked for the correct config before install....but if going off memory all seemed to be a bigger bore size than the stock ones....

The 7/8's are for the rear wheels, the 1 1/4's are for the fronts. The CCOT cylinders are all 7/8's, front and rear.

 

[Pin_Head]

Or....you can pick up a bleeder hose that has a check valve in it that only allows fluid and air to travel one way...it worked for me. .

Maybe you got lucky, but when you are having problems it is best to stick with the 2 man method where you can build up the pressure and give it a good squirt and be sure that you are not sucking air back.

Unless you have some kind of thread sealer on the check valve dealybob, it will let air in on the upstroke.

 

[lostmarbles]

The 7/8's are for the rear wheels, the 1 1/4's are for the fronts. The CCOT cylinders are all 7/8's, front and rear.

Hi again Ben

I'm so confused here!

My cruisers not in this age group (because it's 1979 and not 1972) and I'm not familiar with your vehicle's history (so perhaps I should just butt out?)

Changing cylinder bore sizes (master and/or wheel cylinders) can:

• make your master run out of pedal-travel before your brakes are applied
• cause your vehicle to pull violently to one side (if the bore-size on one side of an axle doesn't match the other)
• make the pedal feel far too stiff
• make it impossible to get pedal-travel within spec
• weaken your overall braking effect
• transfer the braking effort incorrectly from one axle to the other (making it much more likely for you to lose control under heavy braking)
• etc

So surely your first step should first be to check which sizes Mr Toyota used on your cruiser for your master, front cylinders, and rear cylinders? (And I imagine this is easy enough to find out from your production year and month.)

I would never advise relying on what any parts-supplier says (no matter what their reputation may be). And I certainly would never fit what they supply, when it differs markedly from I had before, without questioning/researching it.

I have drums all round and my cruiser has bigger-bore cylinders on the front than the rear because that's where most of the stopping power is required. (But for all I know, Mr Toyota may have used different methods on your 1972 )

In other words, in your shoes I'd want to know what Mr Toyota chose for my master and wheel cylinder bore sizes. Then I'd look at what I have and see what does and doesn't match before trying to get what I've got to work together.

What am I missing here?