Brake Pull--Need Diagnostic Help?

[mikepvg]

I have a moderate brake pull (jumps over a couple of feet) to the LEFT under light to moderate pedal pressure. Under FULL #ad
pressure she'll stop straight enuff. Disassmembled caliper & cleaned up top/bottom slide areas & mounting bolts/slides. Worked piston in/out w/ no observable leaks etc. Upon reassembly/test drive; only slightly better #ad


1) How do I know if piston is functioning properly w/ it off the rotor?

2)Should I proceed to removing piston & clean it up & reassemble w/ new seal kit?

3) What else should I look it since its ABS?

I vaguely remember reading somewhere that there might be a common problem w/ these services brakes?

Thanks in advance!!! #ad


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94 2500HD 5sp 4. 10LSD 4X4 ABS w/GearVendor OD, K&N Oval w/ Pre-Filter, F. F. Exhaust, Geno's Fumotovalve, AW-Direct HI Idle Cable, 123K miles. NRA Member. V1.

 

[illflem]

Mine used to pull to the left as you describe. I finally fixed it when I discovered the rear brake self adjusters don't work,and adjusted the rears. It will still start pulling to the left after about 5k when it's time to change oil and adjust them again. Sort of a built in time to service indicator. Try adjusting the rears before you do anything else.

 

[sam peterson]

The problem with the pull to the left as you describe it could be a bad brake hose on the right side. The hose could have a cracked inner liner that will act like a check valve. As you apply your brakes the left side starts to brake first and with more pressure the right side overcomes the restriction and starts to stop straight. If the brake pads are worn evenly you can swap them side to side to see if the pull moves over to the right. If so the problem can be with the pads. Like was mentioned earlier the pull can be caused by the rear but ususlly it will drift the vehicle left as opposed to turning the steering wheel. Sam

 

[mikepvg]

Removed rear wheels, examined adjusters & pads. A little uneven but not dramtic. Readjusted & installed. Tested to find no difference in brake pull to left.

Everything on the brake system checks out so I repulled the front wheels & swapped the pads. I now have the same dramatic pull to the RIGHT #ad
I have never experienced a problem with brake pads, but it sure seems to be the case here.

Is this just some kinda of s$#^ brake pads problem or a symptom of some other brake system problem?
Before I swapped the pads they measured as follows:
Left piston side: 10/32 Outboard 11/32
Right piston side: 12/32 Outboard 8/32

Any recommendations on good brake pads?
Thanks Guys!!! #ad
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[sam peterson]

the outer pad difference in thickness indicates that the caliper sliders were sticking or not releasing properly. change the pads to start with even wear and lube all metal to metal contacts with sinthetic {if possible} brake lube & dow 111 or paste lube on the rubber slider bushings. the best pad to use is carbon metalic, costs a little more but well worth it. if you can get a set of caliper slider bushings--4 pieces---, replace them when you do the pads. this type of front brake maintanance is a must on these type calipers. ----sam

 

[mikepvg]

Sam
I agree that the caliper sliders had to be sticking or not releasing properly. I guess its hard to really test full braking line pressure w/ the ABS. Under full pedal pressure the ABS system made the truck go straight by adj'ing/releasing pressure.

The part I don't understand is how I moved the pull to the opposite side by swapping pads from left to right.
1)Yes, they are now a different thickness but w/o ABS influence isn't the hydraulic presssure equal to both fronts as long as the piston can still work within its design limits? (i. e. the pads aren't too thin)

2)The bushings I should replace, are these the 4 little bushings per caliper--2 per mounting bolt?

3)Since I can move the pull by moving pads does this mean the calipers are functioning properly now?

4)Are carbon metallic pads easy on rotors?

Thanks for your advice! #ad

Mike

 

[sam peterson]

Mike--I will try & answer your questions. fist off the calipers themselves are probably ok. I think your truck has rear abs brakes only--correct me if you have 4WAL--thus the abs function has no bearing on the front pull. by swapping left to right shows something wrong with the pads--uneven wear caused by binding in the caliper bracket, maybe pads are tapered a little also. the bushings are a 1 piece bushing that pulls through the hole, uses 1 per bolt. carbon met pads have all the advantages--long wear, work better the hotter they get, don't wear the rotors. the rotor surface needs to be smooth and it will become dark black and shiny--this is good--if your truck has never had the calipers rebuilt--do it. they build up a rust ring between the o-ring seal & outer dust boot and on the piston. when you push the pistons in to accept the new pads you can be causing the piston to stick. the only thing that returns the piston on release is the square cut o-ring. it has 2 purposes that of keeping in the fluid and returning the piston a few thou. good luck and let me know if you need more help. ---sam

 

[Big John]

Mike, I experienced this problem on the '94 my son drives. I fixed it in my case by taking a flat file to the inside brake pads and the caliper where the pads metal base sticks up throu the caliper housing. This area had been roughed up by previous pads and the inside pad only would stick and all the brake wear was transfered to the outer pads. I now check this area every time and lube with synthetic lube. No problems over the last few pad changes.

John

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'94 2500 Diesel Reg. Cab
Auto 3. 54 4X4 TST 230hp
"If you can't Dodge it, Ram it!
'96 2500 diesel clubcab 4x4 5speed

 

[mikepvg]

Big John
Thanks for the advice. I'll be looking @ that next.

Sam
I do have the optional 4wheel ABS.
I think I'm gonna put on some inexpensive dust producing pads next & monitor their wear rate. I'll be good to go straight for a while anyways. Then I'll plan on a caliper rebuild this spring w/ the good carbon pads per your recommendation.
I'll by then know if I corrected the problem by cleaning/lubing or if I need the caliper rebuild.
More importantly the weather will be warm & I can get my alternative transportation out (ZG1000) & take my time w/ this task.
Thanks #ad

Mike



[This message has been edited by mikepvg (edited 02-21-2001). ]

 

[mikepvg]

As a follow up:
Had a large payload over the w/e getting the trucks total wt to almost 12,000 lbs. Gave the brakes a good workout in the mtns. Kept the pads swapped from left to right. My pull to the right decreased & started to stop straight again #ad
These calipers might be working again. If this is the case it would seem that it doesn't take much to get them to hang up & not much to clean & lube them to get them work again. I think I'll clean & lube them as part of reg maintenance when the change oil interval comes up.
Mike

 

[sam peterson]

Mike---Ever feel like tearing your hear out? Some of these brake problems are a real mystery. Lubing the caliper slides is real important but may not be necessary to do it at every oil change but it sounds like you are making progress----sam

 

[mikepvg]

Yep... Loosing a lot of hair these days!
Ya gotta love these trucks for there quirkyness! A LOT of character, for sure.
And after driving a Toyota for most of my life & never having to fix anything on it, its gets boring...
Ya know how some people complain that the DC doesn't have that Toy quality etc. . , So what? What can you do in a Toy p/u compared to a DC? VERY LITTLE by comparison. .
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Mike

 

[mikepvg]

Hey Hey Hey I've great brakes today!
Following my last post, my brake left pull returned! Definately something SNAFU'ed. Popped for new sliders & bushings instead of sanding.
Closer examination revealed previous stress to piston (1/4" gouge marks). Popped for a pair of reman piston caliper kits (great price @ Carquest).
Close examination of brake line revealed chaffing--took no chances here. (Carquest had good price on exact replacements--wanted to go to SS braided but too many odd connections).
Put new PFCM pads in from AutoZone. (Interesting note on PF website; says CarboMet=cheap imitation. Don't know, don't care, cuz I can't find 'em anyway... )
Flushed entire system w/ Mighty Vac (worked pretty well).

Initial road test; PFCM pads works WAY better compared to what I had (?). Sorry for poor comparison-bought truck used.
Big test will be coming down the Divide w/ a full load.
Hope this helps anyone working on a brake problem.
Later
Mikey
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[HEMI®Dart]

Good Fix Mike #ad


Sam,

Do you know whats available in the way of a good aftermarket slotted & drilled front rotor for our Rams?

Thanks for the good brake tech. #ad




[This message has been edited by HEMI®Dart (edited 03-16-2001). ]

 

[sam peterson]

Mike--glad to hear you got your brakes fixed. Sometimes its beter to do a complete job when you get a lot of miles on the truck than trying to cut corners. As far as perf friction comment about carbomet, I wouldn't expect anything else. Afterall carbomet is their competition. Perf Frict is a very good product and I have sold both for years but I perfer carbomet for all round use. What does Auto Zone charge for the pfc for your truck?
Hemi---I don't know of any high perf rotors for the rams but I question weather they would be worth the price or if they would improve the brakes----Sam

 

[mikepvg]

Sam
AutoZone charged me $38. 99 . I was going to go w/ Carbomet per your advice but couldn't find 'em locally. Was a little nervous when I saw the heavy leading edge camber on the pads, but WTF they seem to work great. Wonder how they would work w/ full contact area?
I can get the truck to stop... . Now I have to get it to GO!
Necessary test equipement is on its way.
Thanks for all the advice. It may not be a "performance power" mod but it feels great to get it done & correctly! Especially since I was approaching my limit concerning the "rule of three". That happens a lot when you buy a used truck!!!
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[sam peterson]

Mike---don't worry about the pad chamfer, they do that to help the pads seat to the rotors and help with noise. You will get good life & performance from them----Good luck--Sam