new tires = brakes go weird = HELP

[CSL]

Need some advice/direction/opinions/etc. in regard to some funky braking issues I have been having, and they seem to have begun once I got slightly larger tires and an alignment (265/75/R16)

Symptoms (possibly related or not...I don't know)

1) When it is really cold in the morning (10 degrees or so) the red brake light is on. It will turn off after about 10 min. of driving

2) At a stop, when I take my foot of the brake, it is very sluggish, and upon pressing the brakes again the truck stops very abruptly. (note gas peddle never pressed, just barely crawling)

3) After performing #2 above about three times, when releasing the brake the truck will not move at all until I touch the gas. (brakes sticking)

4) Generally it is hard to brake smoothly, it's hard to explain but the brakes seem to act very abruptly. However it appears to occur somewhat randomly

5) City gas mileage decreased from an average of 17 mpg to about 12.5 mpg. Seems a bit much for just 1" larger tires.

Things I have already determined that may be related or not.

1) My suspension is toast, thus I don't want to spend the money I have saved for OME's on brake repairs (hope I can fix it myself). The truck bounces around everywhere

2) Brake fluid is not low

3) Powersteering fluid is low, and appears to be leaking (another issue I must handle)

4) Emergency brake is not stuck and is working fine (appears so at least)

5) There are no strange sounds when braking (ie. no screeching, squeeking, grinding, etc.)

I am going to pull my front wheels and brake assembly to look at the pads as soon as I finish posting this

Any comments would be great. Thanks.

 

[blk runner00]

just a thought but sounds like a caliper hanging on.also is there any smoke or smell from brake?

 

[JeremyH]

First, your mileage has likely decreased by a significant amount due to the extra weight of the tire. It is more likely that you need to modify the reading that is given from your odometer/trip meter. Since you have installed larger tires, your vehicle actually travels farther (however, your vehicle is not aware of this fact) per rotation (the linear length of the tire is greater than it was with the smaller tire) and appears to use gas less efficiently. You need to factor this into your mileage calculation. For example, if you went from a 30" diameter tire to a 33" diameter tire, then you have increased your diameter by 10%, which also decreases your speed by 10% and decreases your mileage by 10%. Your speedometer and odometer will both be off by this percentage.

As for your brake problem....is the vehicle pulling to one side or the other during braking? If so, then you might have a stuck caliper. I'm not sure how that would cause the brake light to come on. If you have insufficient brake fluid pressure (air in the system), then it will come on, but I don't think it can sense a stuck caliper. Do you hear any noise when braking?

BTW, 10*?!?!? Holy hell....get out of there!!!

 

[Victor]

I would check and double check your brake fluid.

How does the parking brake feel when you pull it up? If it does not feel right, chances are your parking brake levers may be siezed lever arm (that's mounted to your backing plate with the cable on the other end).

Remove the rear drums and check the shoe condition, leaking gear oil from the axle seals that contaminate the shoes will cause the abrupt braking conditions you are noting. As well, mis adjusted brakes will give you a low pedal feel and can cause the abrupt braking conditions as well.

 

[CSL]

Well, I took apart the front brakes yesterday. Pads are okay, calipers are okay (surface and thickness). I cleaned them both and put them back together.

Test drives seemed to have made some difference, but I will know for sure after driving around today for work.

I will take apart the rear this weekend and do the same.

Jeremy, I had already done the math with the tire size and adjusted my mpg calcs. I used a few methods to compare the calcs., including using a gps unit from my friend (I am a hawk about my mpg's) 10*...yeah but it's a dry cold. I grew up in College Station, TX (not far from Houston) I will take Colorado's dry 20* over your humid 50* (the -11* a couple weeks ago did SUCK however)

No weird noises, and the parking brake is fully functional, but thanks for all the other suggestions. I will recheck the fluid again.

 

[JeremyH]

Ahh....so it is an actual decrease...then something is definitely dragging in the brake system. You might have a rear wheel cylinder (assuming rear drums) that is stuck which is forcing the pads to contact the drum. Something like this would account for your mpg decrease.

BTW, you aren't kidding about the humidity....I've only lived here for about a year and it still gets the best of me. Everyone keeps saying it is good for your skin....but I think that is just a line of BS...

 

[CSL]

UPDATE: During the drive to work (started at 37* ended at 45*) the brakes seem to work better, but now the brake light (the one that goes on with the parking brake) comes on for a few minutes, then off, then on, then off... It does this randomly for a few minutes each time. Wiggling/messing with the parking brake handle did not make a difference.

The weird is still weird

 

[JeremyH]

It sounds like you are getting some air into the system. That will likely trigger the brake light. My guess is still that you have a rear wheel cylinder that is leaking/bad and is letting air into the system.

Just to clarify, you do have rear drums, correct? Also, does the pedal feel squishy?

 

[CSL]

Yes, the rear are drum brakes. No, the pedal is not squishy. When barely rolling and repeatedly depressing the brake (with letting off completely between presses) the pedal gets harder and harder to press. I "think" this is normal, but it did not do this before cleaning the front pads yesterday. ??????

Thanks Jeremy for your repeated replies to my problem!

 

[JeremyH]

No problem....hopefully I can help.

I would check the rear drums before you go any further. If you see any leaking fluid then that would indicate a bad wheel cylinder...

 

[Victor]

Is your brake fluid clean? Check the light indicator float and make sure that's all clean and moves freely. If you haven't done one, do a brake flush.

 

[JeremyH]

CSL,

BTW, if you have never dealt with drum brakes, then I have a bit of advice for you. First, purchase one of these tool kits:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97804

They make changing drum brakes MUCH easier.

Second, only work on one side at a time. Leave the other side in tact so that you have a reference. It gets a bit difficult to remember exactly how all of those springs and levers go back together unless you change them often.

Sorry, I was a bit late with this info, but I was thinking about it this morning...

 

[CSL]

Yup, it was the back brakes. The shoes were less than 1/8 inch in some places. Also have a leaking seal.

I bought the brake spring plyers in the link, jeremyH. Thanks, they did help a lot. The hardest part for me was getting the big spring loose. The job went pretty well. I havent' tested it all yet, but I am sure that was my problem. The new tires were just a coincidence.

 

[JeremyH]

Good deal....I'm glad you got it figured out!

Now...about this leaking seal....which one and where??? Wheel cylinder (inside the drum brakes) or an axle seal??

 

[CSL]

Now...about this leaking seal....which one and where??? Wheel cylinder (inside the drum brakes) or an axle seal??

You tell me...Though I am basking in the glory of my first (and successful) brake shoe replacement job, I have not fixed the leaking seal problem.

There is a thick black grease with little metal shavings all inside the drum on the right rear wheel. The guy at the shop that was turning my drums said it was probably a "seal", but I am not sure which one it is.

I have yet to research this new project, but I am certainly going to see if I can do it myself. Feel free to comment. I cleaned all the crap out, and will probably check it next week when I do the suspension to see just how bad the leak is. Maybe I will get lucky and the problem will just go away...not likely...HA!

 

[JeremyH]

Well, if you can take a picture of the leak, that would be helpful. It sounds like the wheel cylinder (the mechanical device that is fed by the master cylinder that pushes out the shoes to contact the drums). There is one wheel cylinder per drum brake and they look like this:

And mounted:

These can easily be rebuilt with a cheap seal kit and a honing tool (an attachment for your drill), but I usually just toss them and install new ones. They are only ~$35 new.

A wheel cylinder is easy to replace, however, it will require that you bleed the brake system (you will have to remove the line from the back of the cylinder). Remember, when you bleed the brakes, start at the wheel that is furthest from the master cylinder (the passenger rear wheel if your MC is on the drivers side firewall) and work your way toward the wheel that is closest to the MC (this will result in a zig-zag pattern). Since you'll have to bleed the entire system, it wouldnt be a bad idea to just replace both wheel cylinders on the drum brakes.

BTW, good job on the drum brakes!

 

[CSL]

Dude, you rock...thanks for the effort in your replies

I will look next week and see if I can see where the leak is coming from.

:bigok:

 

[JeremyH]

No problem.

I do have another suggestion. When you check to see what is leaking and if it happens to be the wheel cylinder, then you should invest in some speed bleeders. They make bleeding a brake system much easier and are simple to install (just a replacement for the current bleeder valve). Here is a link to what I am referring to:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=RUS-639560&N=700+115&autoview=sku

Any auto parts store should have these in stock. They are a nice, cheap upgrade.