LC100 Weak Brake (1 Viewer)

[Rebin Rajan]

I have a LC100 2006 non abs variant. Purchased the car recently, the braking is very weak.

Already did the below
1. Checked Brake pads, still more to go
2. Bleeding of the brake oil, and changed full oil
3. Rotor Skimming
4. Brake booster replaced (A black round device)

Still once i apply the brake the car doesnt come to a stop, the brake distance is high

Note: Its not because of non abs variant, abs help in car not skidding. In my case the wheels are still rotating on applying full brake. The brake pedal resistance is normal to me

 

[Hokie LX]

To reiterate above, worn seals or caliper pistons can cause this as well as old brake lines expanding under pressure. I just put new OEM Toyota calipers and Slee stainless lines on the front of my LX and the brake feel is drastically improved even though it felt fine before.

 

[SteveH]

Are you running OEM (Toyota) brand pads? Also - stock size tires/wheels? Much larger tires will impact braking performance.

 

[Rebin Rajan]

Your troubleshooting efforts are really commendable. While the lack of ABS shouldn't cause weak brakes, there are still some potential culprits to explore.

Worn pistons or damaged seals can restrict clamping force despite a firm pedal. Also a failing master cylinder might not generate enough hydraulic pressure. Look for leaks around the cylinder.

Deteriorated hoses can impede fluid flow. Inspect them for cracks, bulges, or restrictions.

Hopefully these helps out

Thanks for the inputs, i will get those checked. My car is in the service center, will let you know the outcome

 

[Rebin Rajan]

Are you running OEM (Toyota) brand pads? Also - stock size tires/wheels? Much larger tires will impact braking performance.

My car is in full stock condition, no modifications

 

[Rebin Rajan]

Is brake booster push rod adjustment the issue ?

 

[4matic1]

Ive recently replaced almost the entire brake system, all hoses, booster, master cylinder, caliper kit comes with seals. skimmed rotors. Braking has improved to near stock when I bought it. Mine is lifted and 285/75 tires. Also a lot more weight than stock.

 

[2001LC]

Is brake booster push rod adjustment the issue ?

Weak brakes with good pads and rotors. Indicates low (assist) pressure.

1. Is master working properly to build pressure.
2. Any leaks.
3. Condition of the 6 flexible lines. Check for bubbles or expanding while braking hard.

You did not say, why your "black round device" replaced?
I assume this was booster "motor". But if you don't have ABS. You may have a vacuum assist master, which doesn't have a motor.
Pictures of your master will help?

The threaded rod is used to adjust pedal free play. I've never adjusting with excessive pedal free play, so not sure of outcome. But not likely your issue! Just check free play. Which is how far pedal travels, before resistance (move rod/plunger) felt: 1mm to 6mm is standard.

Note:
In USA 100 series 98-99 have only 5 flexible lines, 00-07 have 6.

 

[Rebin Rajan]

Weak brakes with good pads and rotors. Indicates low (assist) pressure.

1. Is master working properly to build pressure.
2. Any leaks.
3. Condition of the 6 flexible lines. Check for bubbles or expanding while braking hard.

You did not say, why your "black round device" replaced?
I assume this was booster "motor". But if you don't have ABS. You may have a vacuum assist master, which doesn't have a motor.
Pictures of your master will help?

The threaded rod is used to adjust pedal free play. I've never adjusting with excessive pedal free play, so not sure of outcome. But not likely your issue! Just check free play. Which is how far pedal travels, before resistance (move rod/plunger) felt: 1mm to 6mm is standard.

Note:
In USA 100 series 98-99 have only 5 flexible lines, 00-07 have 6.

Thanks for the inputs, i replaced the brake booster thinking that might be causing this issue. There is a rod adjustment in this

 

[2001LC]

So you've a vacuum assist system. I work with electric booster assist only. Sorry I can't be of help.

 

[Fairgame]

How to bleed your brakes -

 

[Rebin Rajan]

The update that i received from the service center is that they can see issue in the master cylinder and in the calipers. They are going to service the calipers and replace the master cylinder.

 

[2001LC]

Shotgun approach.

 

[Jack90210]

Weak brakes with good pads and rotors. Indicates low (assist) pressure.

1. Is master working properly to build pressure.
2. Any leaks.
3. Condition of the 6 flexible lines. Check for bubbles or expanding while braking hard.

You did not say, why your "black round device" replaced?
I assume this was booster "motor". But if you don't have ABS. You may have a vacuum assist master, which doesn't have a motor.
Pictures of your master will help?

The threaded rod is used to adjust pedal free play. I've never adjusting with excessive pedal free play, so not sure of outcome. But not likely your issue! Just check free play. Which is how far pedal travels, before resistance (move rod/plunger) felt: 1mm to 6mm is standard.

Note:
In USA 100 series 98-99 have only 5 flexible lines, 00-07 have 6.

I actually didn't realize that adjustment to free play was possible. The free play in my pedal feels like "slop" and I was wondering if there was a bushing that had worn, but now I'll try adjusting the free play. Thanks for that.

 

[Jack90210]

OP, I would keep bleeding brakes until you are *sure* there is no air in the system. Are you using a vacuum/pressure tool to do so, or are you doing pump/squirt? These vehicles have a stout braking system that is responsive and capable when in good working order.

 

[hoser]

I would check for vacuum coming into the booster. And then do a booster test. The LSPV is also prone to internal rust on older vehicles that haven't been maintained.

 

[Rebin Rajan]

I would check for vacuum coming into the booster. And then do a booster test. The LSPV is also prone to internal rust on older vehicles that haven't been maintained.

Does 100 series have LSPV, i was under the assumption its only for 80, 90 series

 

[hoser]

Yes, for the 100.... pretty much any LC with a vacuum booster.... but I have not checked every single one.

 

[Rebin Rajan]

Replaced the brake master cylinder, still tje brakes are weak, now not sure what to check more

 

[hoser]

I know you said you installed a new booster but…. Once again, check the brake booster and especially the one way valve going into the booster. If aftermarket, many are bad. With a gauge, check how much vacuum the hose is pulling, should be 20hg at least.

If you or your mechanic have a handheld vacuum pump, hook it into the booster.