Gramp's Old Guy Build - Agnus the GX

Do tell?

 

truth^ ive been discussing this with quite a few guys at work, they all said the same too... the brake system was designed for drums not discs.... more headache than its worth. which is why i decided to make my drums work. and t hey are working beautifully!

 

That is good info. for sure. It definitely will make me think about the variables quite a more on this.

 

So when I was looking a doing a newer 4runner brake conversion to my older 3rd gen I did check out some stuff. The surface area between the caliper piston and the wheel cylinder is almost the same (each wheel cylinder has 2 pistons). In theory this should net a similar pedal, what gets odd is how that pressure equates to pressure on the brake shoe/pad. I was thinking I would need to see what pressures a vehicle ran with 4 wheel discs (I have access to a brake pressure gauge set). My thoughts is the pressure would be way off due to the difference in surface area of the friction surface. Due to this next concern I never pursued the pressure test, what do you do about the brake residual pressure valve? Without removing it the caliper would drag, would it drag enough to cause problems, I never chanced it.

Why not chance it? I found that the rear brakes were more then adequate. I did a Tundra rotor/caliper swap in the front and found all the braking I needed. Even after the swap, the rear could still lock up 1st.

 

That is odd, what calipers did you use? The smaller calipers used the same piston diameter with a larger pad. I found a stiffer pedal with more touchy brake feel. Really all I was gaining was rotor thickness and pad surface area.

I do remember a lower brake pedal when we would do the TSB to the Tundra, just not that bad to make a customer want to take them off.

 

I'm sorry, you don't know me. If you did, you would know I don't pay anyone to work on my trucks either. I might purchase bumpers and other quality parts like that, I just don't have time/tools for tube bending fab work. I'm not sure if you were taking a shot at me personally with that comment.

Being that you used the larger calipers with larger pistons I could see how you would have those issues. The larger caliper did increase piston size, this was the reason I installed the smaller Tundra calipers.

Eric, the biggest hurdle I see is the brake residual valve. Hence why we should check it with the brake pressure gauges and get an idea. If they check out, it still doesn't take into account for the difference in friction surface area. We can check my 2004 4runner side by side with your truck. Then you can search you mind and see if your very well functioning rear brakes are worth messing with. I just don't think it would be worth the hassle because the gains, if any, would be minimal.

 

You guys are funny. Very good discussion though.

I Brian I say we do some testing just see how different they are in pressure but really I think my focus should stay with the front. I am more curious now knowing you fit 16"wheels over the larger 4runner rotor and all is well. More then anything it might worth getting 4 runner rotors and calipers to get some more stopping power. Worse case scenario it will be time for some EBC stuff soon.

 

No joke, it's getting down in here.

 

I'll check on Tuesday, I think they are the same setup. The specs on TIS show the same starting rotor thickness (1.102"). And the same brake pad thickness (.453"). I think all the vehicles that use the light truck suspension style all have the same brakes (FJ, 4runner, Tacoma, GX470/460).

Jberry and I are pretty much talking about the same thing. Changing/modifying brakes takes a lot or research. Changing things like surface area of hydraulics or friction surface area can make a big change. Do they do anything about the difference in residual pressure between drum and disc brakes? Without accounting for this there could be issues. I'd be curious what they have to say. In the end, is your braking system performing so poor that a change is needed?

With my 96 4runner I needed a change. I had serious issues with brake fade and rotor warping. I knew the solution was larger rotor mass, not a pressure change. I looks at the Tundra calipers and found the pre-TSB caliper matched the piston size I was running, the friction size was a little larger and could have a negative effect. I tired it with cheap junkyard parts and got lucky. The reason we have such a difference in our Tundra caliper/rotor swap comes down to friction and hydraulic surface area differences.

All that being said, 2nd gen Tacoma drums seem to warp less then 4th gen rear rotors, just food for thought. You might ask Jace though, he gets more of the brake cookers off of I70 then I do.

 

Here is what I should say.

A negative experience with brakes can make for a scary ride or a serious accident. Just like Jberry, if I had a similar experience I would have ripped them right off also. I would hope with the parts being sold by some sort of manufacturer that they would have answers and a tested product.

 

my .02.... a PROPERLY set up drum brake system will work great. Brian will agree with me, especially in first gen tacos, how many ebrakes are adjusted correctly that come in the shop? very few... now u add in, wheeling, high speed maneuvers, flexing..... no u really need to focus on setup.


I spent 5 hours the other day, making custom brackets, adjusting , cleaning, lubricating my whole rear setup. wow, what a difference... no with a rear setup that works correctly.... my next step would be like Eric said, probly some ebc love in the form of pads and rotors.

 

I'm going to have to look into this EBC stuff. As much as I stalk your guys build pages It allows me to learn a lot. Thanks to you guys for putting the info out there.

 

he speakseth the truth^ lol. i bet u could get longer life out of the rotors if u turned them jason