never ends...

[sdxrunner619]

So as some of you may know, I, for the most part appose the rear brake conversion, as I screws up the front to rear brake distribution. I finnaly installed a proporting valve. It is adjustable from 0-57% maximum line pressure reduction. With it maxed out, full 57% reduction my rear brakes STILL lock up before the fronts. I bled front and rear brakes, so that's Not the issue. I will say this, its Like 80% better then before. Its takes a significant amount of braking to get lock up. It made a huge improvement, over with out it, but its still not enough...

All of this testing, was done with my ABS and ebd fully disabled, with matching tires front and rear. In the days before my bbk and rear disk conversion, I used to race with my ABS disabled(personal preference, not saying im any faster), and when installed the rear disk conversion and bbk, my rear brakes would lock up under moderate braking.....

So my options as they stand now, is to swap out my front pads for something that bites harder. Front pads are whatever rotora includes with the 355 kit... Any one know if all the calipers on the 355 kit are the same? I.e, rotors 6piston caliper is the same from kit to kit?

Probably going to order some EBC yellow stuff, as I know those sobs bite hard as fawk. Rims will never be clean again..:laugh:

Any thoughts on this predicament?

 

[Whitebeauty]

Damn aint that the truth and whats crazy is only my left wheel gets dusty not my right I bled them again on Monday had a lot of air inthem noticed a big difference but still nothing on the dust change..hey keep us posted on your pad selection..

 

[hottacoX]

Sounds ghetto but can you run 2 valves in series......

 

[Gadget]

You seem to be one of the few that get it when it comes to a balanced brake system. Seems most, even those that make brake conversion kits just can't grasp the concept.

Anyway, one thing you could do is order new front calipers with larger pistons in them to get more brake torque out of the front. That might do the trick with your proportioning valve.

G

 

[sdxrunner619]

Sounds ghetto but can you run 2 valves in series......

That would work....in theroy....but they warn That the "brake set up needs to be changed if 57% is no enough"....lol

One thing worth mentioning, the combination of mono leafs, lack of spare tire...so less weight over the ass end, helps to exemplify the weight difference aft/stern. And having OEM struts with 150k miles, my truck does dive a "bit" when braking....I think once I get proper adjustable bump/rebound up front it should help with the nose dive issue. Which will in turn, keep weight over the rear.

This is all just some crack pot theroy...no idea if coil overs even help this issue...:laugh:

 

[NHXRUNNER]

Sounds like steel drop leaves are in someones near future.....:wink:

 

[sdxrunner619]

You seem to be one of the few that get it when it comes to a balanced brake system. Seems most, even those that make brake conversion kits just can't grasp the concept.

Anyway, one thing you could do is order new front calipers with larger pistons in them to get more brake torque out of the front. That might do the trick with your proportioning valve.

G

Thank you sir, means a lot!:top:

Tom @ tundra racing tried to sell my a 2 piston rear disk conversion. I laughed and said, "you have to be crazy!!" "These trucks have no weight out back, we don't need massive brakes out back" he brought up Ferrari and Porsche have big brakes out back, and those are "race cars" and typically weigh less then our trucks, so we need bigger brakes....he didn't seem to grasp the concept of weight distribution. Our trucks are heavy, we need big brakes up front for racing use....out back, nope, not really...honestly, I wish I would have saved the $1000...could have gone towards a ucon.:smile:

Since im getting the coilsovers made regardless, ill try those first and see if they help with balance issue. If not, your idea might be the next step :/

Sounds like steel drop leaves are in someones near future.....:wink:

4" drop leafs, partner with djm drop and coilovers. Talking to local shop out here about fabbing up the drop leafs. :blurock:

 

[Clifford]

might as well 4 link the rear, that's my plan.

 

[sdxrunner619]

might as well 4 link the rear, that's my plan.

Once I get a daily, and I can afford to have my truck on stands for a while, it will be done too. Really want to make a Watts link with the 4 link. :top:

 

[autobodyX]

So as some of you may know, I, for the most part appose the rear brake conversion, as I screws up the front to rear brake distribution. I finnaly installed a proporting valve. It is adjustable from 0-57% maximum line pressure reduction. With it maxed out, full 57% reduction my rear brakes STILL lock up before the fronts. I bled front and rear brakes, so that's Not the issue. I will say this, its Like 80% better then before. Its takes a significant amount of braking to get lock up. It made a huge improvement, over with out it, but its still not enough...

Probably going to order some EBC yellow stuff, as I know those sobs bite hard as fawk. Rims will never be clean again..:laugh:

Any thoughts on this predicament?

I would look at getting a different master cylinder, one set up specificly for disc brakes front and rear.

I like your idea about different pad compound front and rear, you could also try grinding off some of your rear pads making them shorter or even narrower to reduce thier clamping force. I am amazed how small many of the rear pads are on many of the cars that I have worked on.

One trick I have learned from road course raceng my truck ,is not stomping the brake pedal, but squeeze it down, this helps with the back to front with transfer.

 

[sdxrunner619]

I would look at getting a different master cylinder, one set up specificly for disc brakes front and rear.

I like your idea about different pad compound front and rear, you could also try grinding off some of your rear pads making them shorter or even narrower to reduce thier clamping force. I am amazed how small many of the rear pads are on many of the cars that I have worked on.

One trick I have learned from road course raceng my truck ,is not stomping the brake pedal, but squeeze it down, this helps with the back to front with transfer.

That squeeze trick is what i do, but what happens is, as i progressively squeeze the pedal, the rears lock up before i even reached like 50% of my braking potential....What sucks is, weight transfer is the issue right now....all of it goes forward, and none over the back....

so yeah, with the proportioning valve, i can do about 80%. Like, with my stock brakes, i could brake harder...its that bad. :rolleyez: Sucks. I like your idea of grinding the pads down.:top: I will do that once i have installed, broken in, with the new front pads. Assuming its not enough.

 

[Clifford]

try carbotechs for the front

 

[darthyota]

a master cylinder off a tundra might work as well as better biting pads. endless might make a pad that works with your current calliper set up.

 

[Tunedx]

Thank you sir, means a lot!:top:

Tom @ tundra racing tried to sell my a 2 piston rear disk conversion. I laughed and said, "you have to be crazy!!" "These trucks have no weight out back, we don't need massive brakes out back" he brought up Ferrari and Porsche have big brakes out back, and those are "race cars" and typically weigh less then our trucks, so we need bigger brakes....he didn't seem to grasp the concept of weight distribution. Our trucks are heavy, we need big brakes up front for racing use....out back, nope, not really...honestly, I wish I would have saved the $1000...could have gone towards a ucon.:smile:

Since im getting the coilsovers made regardless, ill try those first and see if they help with balance issue. If not, your idea might be the next step :/



4" drop leafs, partner with djm drop and coilovers. Talking to local shop out here about fabbing up the drop leafs. :blurock:

Any idea when these leafs are going to be ready for production. I'm interested in a 3 drop leaf.

 

[sdxrunner619]

Any idea when these leafs are going to be ready for production. I'm interested in a 3 drop leaf.

once they are done, i will post review and shop info. still need to work out some alignment issues with going lower on our truck, how our axle moves forward and what not.

 

[SouthernmostXR]

what kind of rottoras do you have 4 or 6 piston

 

[redarkx]

I like that your pushing the limits sdxrunner. Keep that crap up.

 

[livinginsa]

what kind of rottoras do you have 4 or 6 piston

Yes, wondering what you have. I have the Rotoras, and I don't have that problem. Just wondering if something else could be the problem, worn tires, bad master cylinder, ...

 

[sdxrunner619]

Yes, wondering what you have. I have the Rotoras, and I don't have that problem. Just wondering if something else could be the problem, worn tires, bad master cylinder, ...

Rotora 6 piston. Says that in my damn sig.!!!!! The front big brakes aren't the issue...the rear disk conversion caused all this crap. Drove around with out ABS for about a week, with just the front BBK. Truck felt fine and braked amazing. ...installed the rear disk conversion...broke them in, then went to an Autocross...that I promptly got kicked out of, because every time I would hit the brakes, the ass end came around. And instead of correcting the slide...I'd just start drifting.:crinklehair:

Internally worn master cylinder is unlikely, my truck brake fine, stock. Fronts would lock up, then rears if I applied more pressure. Definitely Not external leaks, as I see no fluid leaking or resivour dropping.

I have 275s front and back, ventus v12's. Both sides have over 60% tread. :top:

I believe someone nailed the issue before hand, our master cylinder is not valved for rear disk brakes....:dontknow:


The way it is now, if I slam on the brakes, the rears lock up, if I apply like and rch worth of pressure more, one of the fronts shortly follow. Need less power out back. More up front. Going to start with pads, then shaving down the rears if still not enough.:top:

 

[Gadget]

StopTech made a few 4 wheel disc brake kits for the XRunner. Two went to TRD and URD ended up with the rest after TRD decided not to market the kit.

One set was supposed to be put on my truck, but it ended up getting sold.

From what I remember, the kit required the 355 front brakes and the rear used very small calipers and very small pads. StopTech did a good job making a proper system that kept everything in balance and it used the stock master cylinder.

I think if you search really hard on this forum you will find pictures of the system. Jonathan bought the one of the brake kits used from someone that I think ended up with one of the TRD kits. You will see how small the rear calipers are in relation to the front.

G