- Thread starter
- #141
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Builds Splurge Overkill - FJ60 build
- Thread starter isbj60
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- Thread starter
- #142
Some frame of reference shots
Front of cruiser
NP205
Dana 70
Front of cruiser
NP205
Dana 70
JEEBUS those things are huge! 
Wow. Makes 'large' Tundra brakes seem puny 
I guess those will do in a pinch.
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- #146
I am definately not interested in endangering a bus-load of nuns and children with this 9000# beast. Go power is cool, stopping ability is dead sexy. This truck will have ABS, since lockup should be easy to obtain. I am going for very light pedal effort and fade free performance. I believe the cans are 20's or 24's (number of square inches of diaphragm). If they are too touchy, I can drop to 16's and change out proportioning springs in the treadle valve. It's going to need some tuning for sure, just like air shocks.
Interestingly enough these are all off of front axles, but the cans have parking chambers as well as service chambers. Usually this is a no-no on fronts, since a loss of air pressure can result in the parking brake spring setting and locking up the fronts, causing directional instability. The good news is the parking chambers can be manually caged out. I will run the fronts like this, but retain the ability to actuate the chambers with the e-brake levers. That way for off road use I can un-override them and use the parking chambers as cutting brakes if needs be.
I wish the rotors were vented, but I can't be choosy at that price! I like the fact they don't have a hat. That will make it easier to make adapters. I don't know yet if the spiders will be of any use to me or not, but they are nice to have to pattern off of if nothing else.
Interestingly enough these are all off of front axles, but the cans have parking chambers as well as service chambers. Usually this is a no-no on fronts, since a loss of air pressure can result in the parking brake spring setting and locking up the fronts, causing directional instability. The good news is the parking chambers can be manually caged out. I will run the fronts like this, but retain the ability to actuate the chambers with the e-brake levers. That way for off road use I can un-override them and use the parking chambers as cutting brakes if needs be.
I wish the rotors were vented, but I can't be choosy at that price! I like the fact they don't have a hat. That will make it easier to make adapters. I don't know yet if the spiders will be of any use to me or not, but they are nice to have to pattern off of if nothing else.
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- #148
Something is definately up with those cans. I am going to do a bit of playing around with them to try and determine function. They just aren't reinforced like regular parking cans are... I may need to swap out the rears to get parking brakes. Not a huge deal. More to come.
Any idea how much one of those solid rotors weighs?
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- #150
Best guess? Probably 80-90#. I was carrying them close in to my body!
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- #151
Did some investigating. It was really late last night when I got home, so I really didn't look at the brakes that closely. The cans are standard type 24 (24 sq. in.) service chambers. What tripped me up is the end port for the service air, which I mistook for a caging screw, and an air vent line coming off of the caliper side of the diaphragm, which I thought was the service line. Normally that side is just vented with a small hole, but in typical military fashion they put an extended breather line on it for fording. So I have two spare front cans, and I need two rear parking cans. That is actually preferable to running with front spring brakes caged out. No cutting brakes, but oh well.
So, with 100 psi of air, the front chambers will push with on the calipers with 2400#. The lever arm in the caliper is 15.8:1, so the pads will see 38,000# of force. Assuming .4 coefficient of friction between brake material and cast iron (dry) and a 6.8" effective radius, that means the brakes are capable of 17,200 ft-lb each corner...
The calipers can handle 2700# of input force from the can...
Do not let out the clutch on locked brakes!
So, with 100 psi of air, the front chambers will push with on the calipers with 2400#. The lever arm in the caliper is 15.8:1, so the pads will see 38,000# of force. Assuming .4 coefficient of friction between brake material and cast iron (dry) and a 6.8" effective radius, that means the brakes are capable of 17,200 ft-lb each corner...
The calipers can handle 2700# of input force from the can...
Do not let out the clutch on locked brakes!
That's exactly what I was thnking...Not!
I have no idea what you are saying most of the time, but it sounds good. Lol!
Me too. I'm just thinking, "Man, what is that thing??"
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- #154
That makes two of us!
This web page does a pretty good job of breaking down how air brake chambers (cans, as they are colloquially known) work. Air brakes are truly incredible in their tolerance for leakage and ability to supply massive amounts of force to the pads. Big downsides are the amount of support valving required, the fact that the compressor needs to be extremely reliable and usually large, and that there is a slight delay in brake application as the air has to move throughout the system (although relay valves help reduce this greatly, but see big downside #1 above).
One thing is for sure: I am really going to enjoy putting it all together.
I'm going to enjoy watching you put or together.
He's essentially building a tractor trailer drivetrain around a 60 series body.
It'll have some sweet towing capacity, that's for damn sure
It'll have some sweet towing capacity, that's for damn sure
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- #158
And that assembly is going to take some work. Big surprise, huh? I got out my spare 5-ton hub (every one has one, right?) and stacked it all up. I have about 1/2" radial clearance to the rim, so the valve stem will need to be shaved just a bit. Shouldn't be an issue. I need to come up with some serious mods to the hub, though, to mount the rotor, suck the caliper into the rim, and mount the rim. I am also concerned about clearing the knuckle with the caliper. Tomorrow I will scope out the front of the 5-ton for ideas.
Pics
Pics
- Thread starter
- #160
There is only 450# or so in the above pic, don't know what is leading you to that conclusion... Lol.
Ya, you are probably right. I think the brakes will handle it, though.
