Weak brakes (1 Viewer)

[tech_dog]

I've had slowly deteriorating brake performance for quite a while. I'm hoping for some guidance before I start replacing parts.

The vehicle is a 94 LC with a 2" lift and 33" tires. The points that matter, I believe:

1) The brakes are not spongy. They're firm.
2) You have to use a lot of force to get decent braking.
3) The symptom is worst shortly after first starting the engine. I've learned to pump the brakes before actually starting off on a drive. It helps a bit.
4) There's no slow pedal fade when holding force on the pedal.
5) The symptoms have spanned pad changes and rotor changes.
6) I've had this vehicle since it was new and the brakes were very good back in the day.
7) The symptom started before I lifted and went to bigger tires. It seems to just keep getting very slowly worse.

Any ideas or similar threads? I looked, but all I found were bleeding issues. I don't think that's my problem.

T.

 

[BILT4ME]

I've had slowly deteriorating brake performance for quite a while. I'm hoping for some guidance before I start replacing parts.

The vehicle is a 94 LC with a 2" lift and 33" tires. The points that matter, I believe:

1) The brakes are not spongy. They're firm.
2) You have to use a lot of force to get decent braking.
3) The symptom is worst shortly after first starting the engine. I've learned to pump the brakes before actually starting off on a drive. It helps a bit.
4) There's no slow pedal fade when holding force on the pedal.
5) The symptoms have spanned pad changes and rotor changes.
6) I've had this vehicle since it was new and the brakes were very good back in the day.
7) The symptom started before I lifted and went to bigger tires. It seems to just keep getting very slowly worse.

Any ideas or similar threads? I looked, but all I found were bleeding issues. I don't think that's my problem.

T.

Sounds like the booster is going bad. Especially with a hard pedal.

Look into a new Seiken booster.

 

[tech_dog]

Sounds like the booster is going bad. Especially with a hard pedal.

Look into a new Seiken booster.

I've done the brake booster test, and the pedal does fall slightly when the engine is started. That's supposed to indicate a successful test, but I agree it's a likely root cause. Any other suggestions for proving it out?

T.

 

[greentruck]

If you're still on your original calipers, they're worth a close look. Same thing withe the soft lines that connect them to the hardlines.

 

[JeepinPete]

Cheap pads don't grab that well. A frozen caliper piston will cut the force applied to the pad by 50%. Bad brake booster is self explanatory. Other causes (air in system, bad master cylinder) don't fit with your description.

 

[cvenom96]

Cheap pads don't grab that well. A frozen caliper piston will cut the force applied to the pad by 50%. Bad brake booster is self explanatory. Other causes (air in system, bad master cylinder) don't fit with your description.

The pads and calipers are absolutely correct. I put some cheap organic pads on front one time and I may as well have been putting my foot out the door to stop it.

 

[tech_dog]

Cheap pads don't grab that well. A frozen caliper piston will cut the force applied to the pad by 50%. Bad brake booster is self explanatory. Other causes (air in system, bad master cylinder) don't fit with your description.

I think I'll start with the calipers, as your 50% argument is indisputable, they are indeed the original calipers, the symptoms span OEM pads and "upgrade" pads, and the brake boost test indicates the booster "should" be working.

 

[KTP]

I just got done rebuilding all 4 Calipers and switched to EBC Green pads. Actually locked up 37"s.
Of course i bled the system too. I'm happier but i too am still getting that spongee feeling.
But once its pumped " oh boy they work great"
My Calipers were rusted and oil was almost black and burnt.

 

[mattg141]

I have a very similar issue. The brakes work, but something is just not right. PO had a new caliper put on the rear, which indicates the calipers may be going bad. The front pads were worn very unevenly, indicating sticking calipers. When working on my Birf rebuild I noticed the brake hoses are cracked. In short, it is time for new calipers and hoses. I can post if this helps my symptoms. Hopefully getting it done this weekend or next week.

 

[davidp14]

for me, and a few others here, my booster failure was intermittent. It passed the "test" several times until it totally failed. I tried the check valve first because thats cheap and easy. I ended up getting a new siekens and they've worked great for that last 18 months since.