Brakes, soft pedal, looking for more stopping power

Joined
Oct 22, 2002
Messages
4,758
Location
Durango, Colorado
Website
www.durangomagazine.com
OK, I’ve been looking for more stoping power but can’t seem to find any.

Current system mostly all new parts
DBA Rotors
EBC yellow stuff pads
New booster, push rod set per spec with tool
New master cylinder
New soft lines
No sticking calipers, no leaks
Bleed system, no signs of air bubbles

Pedal still feels soft and I feel like there should be more power to the brakes. I can my the 37’s howl but no lock up. No ABS input on dry pavement.

Thoughts?
 

lumbee1

Native American
Joined
Sep 21, 2011
Messages
4,057
Location
Holly Springs, NC
I just did something similar.
Brake booster failed while we were on vacation. I limped the Cruiser home and ordered a new booster and MC rebuild kit.
  • Rebuilt MC
  • Installed new Seiken Booster
  • Adjusted booster rod with the Corvette tool
  • Replaced brake lines with SS lines from Manafre
  • Bled system with power bleeder.
  • EBC green pads and OEM rotors were already installed.

The first startup with new hardware and the pedal was soft with loads of travel. I drove it 50 feet and didn't feel comfortable taking it for a drive. I bled the system again with the power bleeder but this time I had my wife also pumping the brakes. Loads of bubbles came from the rear lines. Some tiny bubbles from the front lines. My brake pedal now provides more feedback and stopping power but I don't feel like I have the same aggressive stopping performance that I've had previously. Both the LSPV or ABS were removed a few years ago.

Next step for me is pull the pads (about 50% material left on front, 20% left on the rear), deglaze the pad surface and clean rotors with rotary scotchbrite and brakeclean.


Many years ago when I first removed the LSPV, I tested the braking and had massive braking power. I couldn't understand why everyone was complaining about the brakes.
 
Joined
Oct 2, 2007
Messages
204
Location
Colorado Springs, CO
Like others, I found the most significant difference with mine was after I deleted the ABS and LSPV, and a thorough vacuum bleed/fluid exchange. You can always install a brake bias valve for the rear if there's a concern about deleting the LSPV. I just returned from a 1,000-mile trip in N. CO. with plenty of wet, steep downhill rocky descents, and it was a noticeable difference. I think with your rotor and pad combo you will notice it even more as I'm on stock rotors and pads. Otherwise, there's the bolt-on big brake upgrade kit @synapse is working on.
 
Joined
Apr 8, 2018
Messages
223
Location
Squamish, BC
Post on the BBK I'm working on here: Stopping a 6k lb 80 on 38's better than our bone stock LX450 with refreshed brakes. F+R "motorsport grade" brake upgrade. - https://forum.ih8mud.com/threads/stopping-a-6k-lb-80-on-38s-better-than-our-bone-stock-lx450-with-refreshed-brakes-f-r-motorsport-grade-brake-upgrade.1290784/

Are you running the DBA T2 rotors or T3? T3 rotors are high carbon and better in my opinion, but won't really address your current concerns.

Did you go through bedding in procedure on your new rotors and pads? Whenever installing new pads and rotors you should go through proper bedding in procedures. Yellow stuff pads are a bit higher friction/higher heat range so its more important on these types of pads. During this time friction levels won't be very high and typically require much more pedal input so it will feel like you have a mushy pedal. EBC has bedding in procedures on their website. Also with yellow stuff pads(I'm running blue stuff on the rear to match the friction levels up front with the BBK) they do require a bit of heat to operate optimally. Nothing extreme, I've found after 3-5 stop around town warm them up enough. Once they're up to temp pedal pressure will be noticeably firmer and brakes stop better.

Reason for developing a rear BBK is to avoid running a high heat/high friction pad in the rear in pursuit of well balanced F+R brakes. Rear BBK will allow me to run cooler pads and have more consistent braking even when cold.
 
Joined
Oct 22, 2002
Messages
4,758
Location
Durango, Colorado
Website
www.durangomagazine.com
Pads bedded when installed last summer. Could be glazed from spirited MTN driving since then.

I believe T3 rotors but would have to check receipts.(edit, confirmed T3)

LSPV valve, I made my own extension like the one Slee offers. No scientific method, just an educated guess for my 4” lift. Winter driving has yielded predictable braking results so I’ve always felt good about the results.

I have no interest in deleting g my ABS unless the pump failed, then maybe but I drive in snow often.

I don’t have much interest in deleting the LSPV
 
Last edited:

lumbee1

Native American
Joined
Sep 21, 2011
Messages
4,057
Location
Holly Springs, NC
I was almost in an accident because of my LSPV and that convinced me to remove it. Once removed, I found that the LSPV was way out of adjustment and rotten with rust and old brake fluid. A union from Advanced Auto was cheap and easy to install and fixed my brakes.
 
Joined
Nov 11, 2019
Messages
73
Location
Hawaii
Joined
Feb 10, 2006
Messages
131
Location
S.E. QLD Australia
Website
www.flickr.com
When you bleed the brakes are you at least disconnecting the LSPV and bleeding with it fully up, and again with it fully down? I always found I couldn't get a full bleed without these extra steps.
 
Joined
Sep 25, 2014
Messages
1,852
Location
Gilbert, AZ
When you bleed the brakes how much did you bleed them? I try to get out as much of the old fluid from the system as I can.

When bleeding how are you bleeding, 2 person method or a vacuum pump? I use the vacuum pump as my wife doesn't care to help and sit in the heat of AZ while I do it. If you are doing the vacuum method make sure that the fitting over the bleeder screw is tight and not letting air in.

When I had my Civic I used the Motive power bleeder and it worked miracles and was crazy easy to use.

There are different adapters for different manufactures master cylinders so it can be used across multiple cares.

1661950684537.png
 
Joined
Oct 22, 2002
Messages
4,758
Location
Durango, Colorado
Website
www.durangomagazine.com
Wheel bearings all fine. No visible alignment issues.

Two person bleed technique. Starting at the LSPV, then working caliper furthest from master. Bleeding each until new clear bubble free fluid passes. Then did the same all over again. Did see some bubbles on 2nd bleed.

I did not adjust the LSPV in any manor during bleed.
 
Joined
Oct 2, 2007
Messages
204
Location
Colorado Springs, CO
I was almost in an accident because of my LSPV and that convinced me to remove it. Once removed, I found that the LSPV was way out of adjustment and rotten with rust and old brake fluid. A union from Advanced Auto was cheap and easy to install and fixed my brakes.
Same! I have also found the ABS is a joke on these anyway, especially with a modded truck. It either engages when it shouldn't or not at all. Seemed more dangerous or pointless to have it than not to have it. Maybe I'm just less patient than others and could have made it work, but meh... Same with the LSPV. My truck stays loaded all the time.
 
Joined
Apr 14, 2016
Messages
2,257
Location
Oregon
IMO it's important to cycle the ABS when flushing after opening the system. That said, I don't know if the stock brakes are capable of locking up 37" tires on dry pavement.

I had a friend with a then-newish ~1990 Honda Civic Si. He was really proud of the anti-lock brakes. He'd regularly demonstrate by standing with both feet on the brake pedal. It stopped really quickly. I asked him if he felt the ABS pulsing. "Huh?" Turns out ABS was never even an option at the time. His brakes, while good for their day, just couldn't lock up the wider, stickier tires he'd put on. Of course, we proceeded to make many jokes at his expense.
 

inkpot

SILVER Star
Joined
Jan 30, 2003
Messages
13,793
Location
All over Arizona
I try to cycle my ABS every month or so. I run over the paved speed bumps when there is no other traffic at about 40 mph. With a bit of practice you can chirp/cycle the fronts by stabbing the brakes just when you nthe fron tires hit the bump. They will lock up very briefly the they will release.
 

landtank

Supporting Vendor
SILVER Star
Joined
Mar 27, 2003
Messages
20,583
Location
Groveland MA
Website
landtankproducts.com
LSPV valve, I made my own extension like the one Slee offers. No scientific method, just an educated guess for my 4” lift. Winter driving has yielded predictable braking results so I’ve always felt good about the results.
on a 4" lift that has a slight stink bug I'm recommending a 5" change in the sensing arm position. That wasn't possible with an extension alone at the axle as the rod would contact the UCA.

Have your wife or son help you with this test.

Have them at the wheel with the engine running and depress the brake pedal as if in a panic stop. While to doing watch the sensing rod for the LSPV and look for it to deflect when under pressure. If it does than that is your soft pedal. You can test this by switching positions and have them hold onto the sensing rod preventing it from deflecting, you'll feel the difference.

And I recommend a final bleed with the engine running and max pedal pressure. This will compress any air in the system and help purge the ABS actuator.
 
Joined
Sep 22, 2021
Messages
35
Location
Saint Charles, MO
I have not messed with the brakes on my 80 yet, but I will tell you that the brakes on my 4th gen 4Runner vastly improved when I replaced all of the rubber lines with Stainless Steel braided lines (including the ones running from body to rear axle). You will notice big difference in heavy braking. Old rubber lines will flex (balloon) slightly under hard braking. I used to track my Mazadaspeed3 and my DSMs. One of the most noticeable changes in brake feel when I changed both cars to braided stainless lines.

That said, you MUST get all air out of lines or none of this matters. ABS and LSPV complicates that process. My 80 has no ABS, which I am happy about, but I don't like the LSPV either. I would ditch the LSPV and buy an adjustable rear bias valve, and dial it in to your needs/suspension setup. just my .02
 

Users who are viewing this thread

Top Bottom