Brake PRoblem

[pbglas]

Sorry for posting here. I tried 'How to' section but couldn't post there.

Yesterday, I pressed the brakes and the car wouldn't stop initially and then did stop but taking three to four times the distance I would have expected. Fortunately, I hit no one. After that it was OK but felt a bit mushy. Then it happened again. Does anyone have any idea why this might have happened. I will take it to a mechanic but any past experince I can take with will help. This is scary.

[Ldub]

Did the pedal go to the floor?

Have you checked the fluid level?

[MSHardeman]

Ditto. Sounds like air in the lines. If your fluid is low then the brake light should have come on. Maybe the light is out?

Good luck and be careful until you get it to your mechanic.

[pbglas]

Thanks, everyone. This really is terrific group. Fluid was ok. He bled the lines. brake pads were effectively gone. We ended up replacing pads. Seems to be better. Let's see. Thanks everyone.

[Ldub]

If the pads were "effectively gone", the rotors may have been damaged also.

If that's the case, braking power will be decreased & pad wear will be increased, niether is good.

[VX crazy]

could be brake booster too.....

[IRONVIKING]

Seems weird that the pads would cause it to fail like that. No noise from the worn pads?
And you said it happened twice? Just be careful. To me it seems like it would be something other than the pads.

[Marlin]

Mine has similar mushy feeling, almost scary. Installed SS brake lines today. Only got 3/4 done, the drivers front was rusted together, gotta buy 6 feet of hard line to run from the ABS module to the caliper. Boo!! Doesn't seem to have made a difference, need to replace the booster next. Hopefully yours is something simple as well.

[Ldub]

Mine has similar mushy feeling, almost scary. Installed SS brake lines today. Only got 3/4 done, the drivers front was rusted together, gotta buy 6 feet of hard line to run from the ABS module to the caliper. Boo!! Doesn't seem to have made a difference, need to replace the booster next. Hopefully yours is something simple as well.

In pics you've posted of your new lines, I only see four lines...:_confused

Without the fifth line, you're not going to see as much improvment.

[RamAirZ]

The 5th line is for the line running to the rear axle right? You should still see improvement as most of your stopping is done with the front brakes so if those are upgraded you SHOULD feel a difference if everything else is working correctly. I'd say master cylinder before booster myself. Your brakes won't feel mushy with a bad booster, it will get stiff and have weak braking. It sounds like air in the lines which can also be a leaky booster, sometimes the "piston" seal inside the booster (where the pedal slides in and pushes the fluid out) gets a tear or gets worn out and will allow leakage inside the cylinder, instead of pushing all the pressure out, it leaks some by. That would be my guesses on it. It's very rare that a booster fails before a master cylinder does. Here's a good read if you want to know how a booster works

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake1.htm

A good test for your booster, turn the engine off, pump the brakes several times until they get hard to push (if you can even push them at all), then while still holding the brake, start the truck and you'll feel the pedal get softer and move down, voila, your booster works. If you do this and it stays stiff, your booster is either bad or it's not getting vacuum.

[Ldub]

Without the fifth line, you're not going to see as much improvment.


The 5th line is for the line running to the rear axle right? You should still see improvement as most of your stopping is done with the front brakes so if those are upgraded you SHOULD feel a difference if everything else is working correctly.

On most vehicles I'd say you're right, but I've never seen or heard of a VX wearing out it's front pads before the rears.
I have replaced my rears twice before the fronts needed it.
Unless they're using a softer compound for the rear pads...:_confused

[RamAirZ]

The compound and the "pre-load" could be factors, shoot my wife's 07' Camry has a TSB for the rear pads wearing out too fast. Your always going to have more than 50% (usually like 85/15 or so but sometimes more rear bias) because all the weight is on the front end with the engine etc. Now on a rear/mid engine car, the bias is probably different but you want most of the stopping power up front where all the weight it. And sorry, didn't see the "as much" for some reason lol

[Ldub]

The compound and the "pre-load" could be factors,

By "preload" do you mean proportioning? :confused:

[Marlin]

In pics you've posted of your new lines, I only see four lines...:_confused

Without the fifth line, you're not going to see as much improvment.

That is true, I did not do the rear T-line or feeder or whatever it is called. I'm gettin there.

[Gussie2000]

On most vehicles I'd say you're right, but I've never seen or heard of a VX wearing out it's front pads before the rears.
I have replaced my rears twice before the fronts needed it.
Unless they're using a softer compound for the rear pads...:_confused

X 2
Had my rear pads replaced a month ago,my front pads still remains relativately new after two years.

Both front and rear were replace the same day back in 2008.

[RamAirZ]

Anyone have pics of the front/rear pads next to each other? I know on my previous cars and my wife's Camry, the rear pads are usually thinner too. There'd be no logical reason for having more brake bias at the rear unless more of the weight is at the rear. In a perfect world (more so for racing purposes) you'd want the front/rear bias to be "equal", and by this I mean the ratio of brakes-to-weight, so if you have a perfect 50/50 split as far as weight front-to-rear, then you'd want the same braking force front-to-rear. But say a 60/40 split, you'd want 50% more brake torque on the front tires. With our trucks having a larger rear rotor though that tends to effect brake bias a bit so that could be why also, higher center of gravity effects it, less weight on rear axle, there are a ton of factors involved in brakes that it's not even funny lol. A rear-biased vehicle will be squirrely and not that much fun to drive. I'll quote a great brake article that I've had for years:

"As braking force is continuously increased, one end of the car must eventually break traction. If the front wheels lock up and turn into little piles of molten rubber first we say that the car is “front biased”, as the front tires are the limiting factor for deceleration. In the not-so-desirable situation where the rear tires are the first to lock we say that the car is “rear biased”, but the driver would probably have a few more choice adjectives to add. In either case, however, one end of the car has given up before the other, limiting the ultimate deceleration capability of the car.

Just like the car that pushes its way through corners all day long, a car which is heavily front biased will be slow and frustrating, but relatively easy and benign to drive. On the other hand, like the oversteer monster that people are afraid to even drive around the paddock, a car which is severely rear biased will be a scary, twitchy ride resulting in a bad case of the white-knuckle syndrome. Envision an imaginary co-pilot yanking up on the park brake handle in the middle of every corner, and you begin to get the idea. While a rush to drive at speed, it will be horribly slow on the stopwatch."

[Marlin]

So I did the little booster trick, pedal gets hard as a rock, as soon as I start the car, swoosh, down the pedal goes. I know there is no air in the lines (feels the same after bleeding as it did before we changed the brake lines). Whats next?
I have upgraded the lines, cross drilled rotors, I was thinking of finding the softest brake pads I can find and trying that.

[RamAirZ]

That's worth a shot, does your pedal ever change during braking? You'll have to test mine out in October and see if it feels the same to you. Only other thing I can think of is the master cylinder has a small leak or something inside

[MSHardeman]

Marlin, I had the same issue when I replaced my rotors, brake pads, and brake lines. I figure with all that work the pedal should be solid as a rock, but I could step on the pedal and the VX would stop, but if I kept pushing on the pedal it would eventually go to the floor. The VX never moved during this little exercise, even on a decline. After repeated bleedings, and replacement of a hardline or two that I thought was leaking, I finally decided that it was the master cylinder. I made the mistake of letting the entire system run dry, and sit open, for a day during the rotor/pad replacement process so that may have caused my master cylinder seals to crap out, or maybe they where on their way out anyway.:_confused

Anyway, I replaced the master cylinder before Moab this year, and it seems to have solved the problem. In truth the pedal still feels softer than I would have expected, but it doesn't hit the floor any more.:thumbup:

[circmand]

but the symptoms remind me of when a masterylinder goes out. I am not even sure if cars still have those but that happened to me (you remember stuff like that) and it was the master cyklinder

[RamAirZ]

a master cyklinder or masterylinder? Never heard of those :smilewink Just messing with you and yes all cars still have master cylinders lol

[Marlin]

Those match my symptoms, pedal all the way to the floor, car stops, but it is impossible to make the tires skid. It has been this way since I bought it, I can get the master and booster used for 100 bucks for both. I will try that and cross my fingers.

[MSHardeman]

Marlin, be careful of the used master cylinder's. There are seals in the master that go bad and allow fluid to slowly flow past them which is why the VX will stop initially (seal isn't bad enough to let the fluid just blow by it) and when additional pressure is applied the pedal goes to the floor (fluid gets slowly forced past bad seals). I have no idea where these mythical seals are, and if they can just be replaced, but a master cylinder that has been sitting around with little to no fluid in it may have busted seals already and could REALLY put you and your VX in danger when you try to stop.

I was told by Merlin that the booster rarely goes out, and that it's usually the master. I just replaced my master cylinder and left the old booster in place and so far all is well.

[RamAirZ]

Ya the internal parts of the booster itself really don't "wear" and SHOULDNT go bad for a LONG time unless an outside force messes with it. I'd just buy a new master cylinder as well. Would suck to get the used one, put it on and have the same problem. I don't have this issue in mine luckily

[Marlin]

New OEM master cylinder is 283 bucks from Isuzuparts. I can try and give Merlin a call, Ebay has em for >$300. On a side note and completely unrelated, I am watching Cop Out with Bruce Willis and Tracy Morgan, ROFL!!!!!!!!!! This movie is frickin hilarious. Also watched Eclipse and Toy Story 3, gotta love Flea Market movies:)


Screw the OEM part, autozone has it for 140 including a $35 core charge. I know which one I am getting....even if it is lower quality, the OEM one only made it 100K miles, so if this one lasts half as long, that is still longer than the VX will probably last me anyway (3-4k miles a year)

Wait, deal just got sweeter,autozone is doing 15 bucks off every 100 bucks spent online...that means this thing only costs me 91 bucks!!!!

Free shipping too!!!!!

[RamAirZ]

heck ya, Cop Out was freaking awesome!

[etlsport]

couple of photos i took at work of VX pads to compare front to rear. these arent OEM, they are wagner thermo quiets

http://www.vehicross.info/gallery/data/500/medium/SNC00251.jpg (http://www.vehicross.info/gallery/showphoto.php/photo/18625)

http://www.vehicross.info/gallery/data/500/medium/SNC00250.jpg (http://www.vehicross.info/gallery/showphoto.php/photo/18624)
.
http://www.vehicross.info/gallery/data/500/medium/SNC00247.jpg (http://www.vehicross.info/gallery/showphoto.php/photo/18623)

[Marlin]

WOOHHHHOOOOO!!!!! I have brakes again!!! I ordered a new master cylinder and put SS kevlar brake lines in. We couldn't get the drivers front hardline to come out of the hose so I went and bought 6 feet of pipe to replace it with. I also decided to get one of those vacuum bleeders while I was at it. Before getting started, we decided to bleed the lines again. The vacuum pump worked wonders. The brake fluid we got out looked like motor oil, there was so much gunk in the lines!!! We did all four, pumped 2 quarts of brake fluid through the lines when all said and done. Ended up getting the front line apart without replacing the hard line. Didn't need to replace the master cylinder, took it back, got to keep my 15 dollar gift card as well. I made money on the deal!
The brake pedal no longer goes to the floor, its been that way for almost 2 years, even had em flushed at Pepboys and no difference. I would guess that the hoses were where all the gunk was jammed up, once I swapped to the new lines, I was able to get good flow. Still not very good brakes, but I can make the tires chirp a bit if I lock em up. Still need to replace the rear t-line hose. That may solve the final problem. Look out world, you don't have to look out for me and my ridiculous stopping distance anymore.

[RamAirZ]

lol glad to see you got it worked out Chris!