With the bigger brakes on my truck since I went to the 3/4 ton swap, I can stop on a dime and give you a nickels change.... and thats with 37s. No comparison to when I had the 10 bolts and 35s.
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
The Great Smaug
- Thread starter campfire
- Start date
Won't be able to do that until after my next road trip (this coming week). I have time for small projects, but the next 2 days won't be long enough to receive special-order parts.
But I was trying to figure out what difference the caliper piston size makes. I understand they're different. I'm just trying to figure out what the difference is before I rip the system apart. I'd rather rip it apart once than chase my tail throwing random parts at it. I've wasted a lot of time doing that already.
I have the same question about the extra 3/8" or so of radius that the 3/4-ton discs have. Was it really worth stocking another set of parts just for that last fraction of an inch?
Did you change out your 10-bolt front? Or just the rear?
With my setup, I have no problem locking up the rear brakes. But the fronts are more reluctant.
This never bothered me when the P/S pump was broken. But now that the brakes are much more sensitive (touchy?), I find the rear end locking up more often.
I don't think your wheel cylinder in the rear axle changed much by going up to the bigger drum brakes so its just the surface area that is causing the rear lock up.
Going to a bigger piston caliper in the front would help if you also went up to the bigger master cylinder as well. Its' been a while but I believe the 3/4 ton master cylinder with the larger rear brakes has a larger master cylinder as well, but more so for the front larger piston calipers.
For your scenario, you'd probably be best off with the proportioning valve. Albeit, makin' your jump to the larger rear brakes a little bit less of a bonus since the proportioning valve is going to ultimately undo that to some extent.
EDIT: when working with your brakes you need to consider the whole system rather than any one component on its own. As is true with any hydraulic system.
Going to a bigger piston caliper in the front would help if you also went up to the bigger master cylinder as well. Its' been a while but I believe the 3/4 ton master cylinder with the larger rear brakes has a larger master cylinder as well, but more so for the front larger piston calipers.
For your scenario, you'd probably be best off with the proportioning valve. Albeit, makin' your jump to the larger rear brakes a little bit less of a bonus since the proportioning valve is going to ultimately undo that to some extent.
EDIT: when working with your brakes you need to consider the whole system rather than any one component on its own. As is true with any hydraulic system.
If I ran the larger MC, more fluid should be displaced (right?), so I would presumably be pushing more on the slaves. But would the proportion be any different? I would think that both circuits would be scaled up equally. So it would just be locking up the axles with less pedal travel.
I'm not concerned with the amount of braking force that I have (it's already enough to fairly easily scoot the rear tires), I just want it more evenly distributed.
My first step is going to be dialing down the adjusters in the rear end. I know that's not really a solution, as they will tighten back up to their equilibrium point, but it will help me out for now.
I'm thinking that the calipers take more fluid for movement than wheel cylinders do, so proportionally they are different (why there are different reservoirs as well)
going to a larger caliper in front would seemingly REQUIRE a larger M/C to feed those larger bore calipers.
going to a larger caliper in front would seemingly REQUIRE a larger M/C to feed those larger bore calipers.
But...if If I have a small MC, a small SC in the front, and a large SC in the rear, wouldn't I have soft rear brakes and normal front ones?
This is what has been bugging me for the last couple of weeks.
But...if If I have a small MC, a small SC in the front, and a large SC in the rear, wouldn't I have soft rear brakes and normal front ones?
This is what has been bugging me for the last couple of weeks.
What I had said was the wheel cylinder in the rear probably changed very little. Without looking at the two side by side, I can't say that with absolute certainty. If my memory serves me correctly there isn't much difference if any. So, the reason your rears now lock up early is because of the increased braking surface. Your hydraulic system is the same, you simply made the friction surface larger. Now the rears lock up earlier than the fronts.
Master cylinders can change flow to the front or rear independently of one another.
But in addition to increasing the area in the rear, I also increased the diameter of the disc in the front. I have been assuming that they would match up. I guess not.
But I still can't understand how changing the calipers is supposed to change this.
But in addition to increasing the area in the rear, I also increased the diameter of the disc in the front. I have been assuming that they would match up. I guess not.
But I still can't understand how changing the calipers is supposed to change this.
What did you do to the fronts? Apparently I missed that.
The front brake calipers (still 1/2-ton) have been replaced, and the rear 11" drums have been swapped for the 13" drums on the 14bff. That caused no issues last summer when it was loaded down. But now that it's unloaded the rear end is locking up too early. Today I was driving through a torrential downpour and it was quite noticeable on the slick streets. I hardly ever drive it in inclement weather (this is probably the first time), but the issue is at least on the radar screen now. Might just be a matter of loosening the adjustment screw in the rear, but I'm guessing that the larger shoe area is throwing off the proportion some.
Anybody have any insight?
You didn't say anything here about changes to the front.
Switched from 1/2-ton to 3/4-ton rotors & discs. Not much difference. Just enough to be annoying. I assumed there had to be some technical gain to having the slightly larger rotor, or they wouldn't have bothered stocking 2 parts of such similar dimension with different backing plates.
Hoses and calipers were replaced with new 1/2-ton hardware.
rotors and discs are the same thing.
Nothing you have changed in the front has made any difference in the front. If the rotors are a different diameter, I don't think they are, it doesn't matter. Your pads are the same. Therefore the available friction surface is still the same.
So, what you have is 1/2 ton front brakes (JB6 caliper) and a 3/4 ton rear brake drum with the larger drum.
Your rear brakes generate more friction than the fronts do causing rear lockup early.
Three possible solutions.
1. Go to the 3/4 ton front caliper (JB7 caliper). I'd change out the master cylinder as well if you want to go this route. Now you'll have a balanced system again.
2. Install an inline proportioning valve for the rear brakes to limit the amount of fluid fed to the wheel cylinders.
3. Learn to drive it as is. It can be beneficial to have a little bit heavier brake in the rear off road.
Ugh. Wrong word choice (I meant hubs). Apologies.The disc is larger then the 1/2-ton disc, which is why the slightly larger backing plate is needed. If I put the 3/4-ton rotor on with the 1/2-ton backing plate, the caliper contacts the disc and the pins cannot be installed. It's not a huge difference, and it may have no noticeable effect in this case.
But increasing the disc radius does increase the braking ability for a given system at a given hydraulic pressure. It's not just a function of area. Been reading through this writeup tonight, and he seems to make good sense of it. I'm definitely learning a bunch.
http://www.pirate4x4.com/tech/billavista/Brakes/
Question:
Are the 2 pistons in the MC rigidly connected (so they move the same amount and push equal volumes of fluid)? Or are they maintaining equal pressures? This picture makes it look like they're not rigidly connected. If so, that would be what I've been tripping over all week.
Are the 2 pistons in the MC rigidly connected (so they move the same amount and push equal volumes of fluid)? Or are they maintaining equal pressures? This picture makes it look like they're not rigidly connected. If so, that would be what I've been tripping over all week.
But if they're rigidly connected, doesn't a given amount of pedal movement equal a fixed amount of fluid volume going to each output? The amounts may or may not be equal, but they would be fixed amounts, right? With a rigid relationship between the two, how could we adjust the proportion?
It made sense when I thought about it the other way (lightbulb moment), but now it's back to being confusing.
Thanks a bunch for talking this out with me.
I'll get it figured out eventually.
