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Discussion Starter #1
Buon giorno, tutti,
I found unequal brake pad wear at the rear brakes, with more wear on the driver's side pads than the passenger side pads.
  • On each individual side, each set of pads are equally worn.
  • The side with more wear shows evidence of more heat: I see more peeling caliper paint, and more distress on the pads' backing plate.
Are there known issues to check in such a case as this?
  • Would residual pressure keep the pads in contact w the disc, on one side only?
  • The hand brake isn't binding as far as I can tell. Does it have a side-to-side adjustment that could be off?
I have some photos I can post if helpful.

Grazie,
- Art
 

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Hi Art,

As evidenced by the other recent thread about rear brake caliper adjustment, this design can be finicky.

There is no direct "side to side" adjustment, but there are of course the individual caliper piston adjustments, and there is also the handbrake cable adjustment. It would be a good start to double-check these basic adjustments, and make sure that the handbrake levers aren't sticking on---sometimes the handbrake is adjusted a bit too tight in an effort to make the parking brakes hold better and this causes the rear brakes to drag.

If all of those adjustments are good, take the car for a nice drive (if you are able to during this strange time) and then jack up the rear and check if one of the rear calipers is dragging more than the other. If this is occurring and you know that the adjustments were spot-on when cold, then you likely need to rebuild or replace the calipers.
 

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Discussion Starter #3
Hi Art,
.... take the car for a nice drive (if you are able to during this strange time) and then jack up the rear and check if one of the rear calipers is dragging more than the other. If this is occurring and you know that the adjustments were spot-on when cold, then you likely need to rebuild or replace the calipers.
Right - I will try it hot. Thanks, that's a good start. I don't recall it pulling to one side, but that's something I'll be scrutinizing, in case the difference is only when I'm braking, vs a constant drag.

Yeah I read through the other thread about rear brake calipers and adjustments. Jacking mine up and rotating the rear wheels in Neutral, when Cold - it doesn't reveal any difference in drag.

Both of the handbrake cable 'levers' on top of the calipers are 'loose' and move freely - I have the handbrake adjusted to "grab" fairly high up on the hand lever's range-of-motion.

On a drum brake car, I had the same issue, which I traced to a failure of the mechanical brake-shoe-'advance' mechanism on one side. My sense is there is no such mechanism on hydraulic disc brake calipers.

Grazie,
- Art
 

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Could be that individual caliper needs to be rebuilt.

Use a temperature gun to measure all the wheel temperatures after a drive. That will tell you if one brake circuit is dragging. Had this happen with my 91S. Turned out one of the dual brake circuits in the master had a seal leak and caused that circuit to not release pressure properly after the brake system and master warmed up from use and engine bay heat. This problem caused the circuit for the right front brakes (and wheel) and the left rear brakes (and wheel) to be hotter than the brakes (and wheels) in the left front and right rear circuit.

Just a thought.
 

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Discussion Starter #5
UPDATE - Drove the GTV6 this morning, used braking to get things hot.
  • There was no pull to one side vs the other.
  • But when I parked hot and jacked it up, w transmission in neutral... turning that wheel by hand, the 'offending' side wheel was def grabbing more than the other..
So a caliper rebuild/replacement is in order? Does one go ahead and do both sides, because they both have the same mileage?
Grazie,
- Art
 

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Did you do a temperature check all around? You might also have the opposite rear brake hanging up as well if that circuit is acting up. When this happened to my 164S, there was no pull to one side, as both associated brakes were hanging up at the same time. Both those brakes/wheels were hotter than those of the other circuit.

If you do repair/replace one caliper, it is always wise to refresh both sides at the same time if you have the time and money, just to avoid potential future problems.
 

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That's what I did, and flushing the fluid through evidently removed some crud from under a seal. The brakes are fine now, new fluid nice and clean, no particles as in the old fluid in that particular circuit.
 

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Discussion Starter #9
Thank you Del, & vintagemilano
I'll report back on the front brake temperatures and any results after a quick round of bleeding.

Bleeding and brake fluid:
- Thanks, this is easy and I'll bleed some this morning before taking it for a drive. HISTORY: The brake fluid was flushed and replaced with ATE 200 last spring. The pedal's feel has not changed, it is tight and hard, but I'll bleed the calipers all again. Maybe this has been going on since last spring, because something (grit, muck, particles?) could've 'insulted' the pressure release function when I flushed and replaced with ATE.. ?

Temperatures:
  • COLD: There is no difference in drag side to side, when I jack up and spin the rear wheels.
  • HOT: Yes, the temperature's clearly hotter on the 'offending' side of the rears (92'C vs 60'C).. with more "drag" when rotating the 'hot' wheel up in the air, compared to the other side.
  • SOUND: As I drive the car and the brakes heating up.. after coming to a full stop 6-7 times from 55mph, the hot pads get 'grabby' as the car rolls to a stop.. it makes the whole car groan the last 20ft or so. "GroOOOONNGCK" ...As this is happening, I can stop the 'groan' by pumping the brakes pedal once.
  • FRONTS: I did not check to compare temperatures on the fronts, but I will.
Temperature/Drag:
- After sitting about 10 minutes, not long at all, the drag on the 'offending' side disappeared.

Brake MC:
- On our 94LS, I once had the front brakes overheat and nearly lock up on me. Smokin' hot. It went away once cooled off. Following advice in the 164 forum here from RexCars, replacing the brake MC solved that problem. I don't know if the '82 GTV6 MC circuits are split diagonally or front/rear.

Thought:
- I wondered if any of this could really mean the rear passenger side is NOT braking at all, as opposed to the driver's side braking too much? Could all the brake pedal pressure be going to the driver's side and none to the passenger side? But comparing pad wear to the other three calipers, I'm not sure that can be possible: All other pads were equally worn - and I measured each as best I could for my records, about 3/8" material left on all other pads. The 'offending' pads are down to 1/8".

Grazie,
- Art
 

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Checking the temps all around will tell you whether it is just the one caliper piston stuck or a constricted hose , or a system problem such as bad seals in the master.
 

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Discussion Starter #11
Bled both nipples of the one caliper at the rear, got good clear fluid, no bubbles.

Measured temps after a 5 miles drive, good full stops as I approached home - on the rotor:
Front Dr. = 113F
Front Pass. = 116F
Rear Dr. = 222F
Rear Pass. = 175F

I'd have thought the fronts would "work" harder.. any insights?
Grazie,
- Art
 

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When I measured mine after they started working ok again, the fronts were maybe 10F higher than the rears. Normal in my book.
 

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Discussion Starter #14
Thanks gentlemen,
LOL, I think Del is looking at the temperatures backwards... the fronts are braking a significantly less than the rears, Del.

Is a proportioning valve standard on a GTV6? If so, any idea where i'd find it? The MC looks stock, but the car has been tracked for a number of years, and perhaps one was added..

If there isn't a proportioning valve, I'll check if the MC's two circuits are divided Front/Rear and swap the brakes lines between the two circuits - which may have been installed wrong at some point in its life. That could be entirely possible.

I believe I'd still be looking at rebuilding or replacing the rear caliper(s), but one thing at a time..
Grazie,
- Art
 

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Three reasons why the rears may be hotter than the fronts:

The fronts are vented, the rears are solid.
The rears are mounted next to the transaxle and it's heat gain.
The rears are mounted out of the flow of cooling air.

YMMV
 

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"the fronts are braking a significantly less than the rears"

Really? You do not want the rears to brake more that the fronts, lest you run the risk of locking up the rears, potentially promoting a skid. That's why cars have proportioning valves, and rear brakes of less capability. Napa on line, for instance, says, "Because the front brakes generate up to 75 percent of the vehicle’s stopping force, they generate much more heat, over 500°F in heavy braking".

Are they wrong?

Every Alfa of mine I've checked with the temperature gun out of curiosity has shown the same heat distribution. About 10-15F higher in the front than the rear after repeated moderate braking. Is that wrong?

To me, it means that they balanced the sizes and capabilities of the front and rear braking systems pretty close. Obviously they could have made the rear brakes so large that they would way overheat, doing most of the braking, a real no no for stability, or they could have made the front brakes so large in comparison that they would be much hotter than the rear, but I think that 10-15F difference in real life as I have measured is pretty close to right, the front discs being vented to better handle the higher temperatures.
 

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Discussion Starter #17 (Edited)
Every Alfa of mine I've checked with the temperature gun out of curiosity has shown the same heat distribution. About 10-15F higher in the front than the rear after repeated moderate braking. Is that wrong?
No, everything in your reply #16 is what I would think is right. I apologize for my "LOL" reply, but your choice of words in your reply #12 confused me. I was not doubting your experience. Your reply #12 didn't include any opinion that my temperatures were wrong and included the phase "Normal in my book." I didn't understand the implication of your reference to 'normal' being your temperature pattern of 10F higher in front than in rear. I thought you got my temperatures backwards and were referring to my temperatures, and describing them as 'Normal in my book'.

I have a simple mind that needs a lot of things spelled out.

To summarize where I left off - based on the temperatures listed in my reply #11, I conclude my rears are braking significantly more than my fronts. I think we all agree this is not right. Maybe the relentless high temperatures ruined the one rear caliper.

Del's measurements of 10F hotter in front ... they seem consistent with the cooling advantages of the fronts that horsewidower lists.

I will research my MC circuits to establish:
1.) Whether they are split front/rear or diagonally. If the MC has front/rear circuits, the brake lines at the MC ports may have gotten switched - (unless Alfa did what Chrysler does and threaded them differently) - this car was owned and modified by at least two prior track-racing owners.
2.) Or whether an proportioning valve is present, as OEM, or retrofitted...

...and go from there.

Thanks for your input and tolerance for my misunderstanding.
- Art
 

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No problem, as they say. I just figured the tracks just got switched somehow. It was my mistake in understanding what you were referring to. In these days of virus trouble, we are all understanding, except for the yoyos who protest and want to party on, regardless. Idiots, making it bad for those people who lost their jobs and are really suffering. We are trying our best to support those people.

Good luck finding the problem.
 

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Milano brakes are split front to rear. If the proportioning valve isn't working, symptoms would likely be the rear brakes locking up first under hard braking. I don't see how it could cause side-side variation as the rears share a line.
 

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I don't remember what some of the various Alfa models have for separate circuits. I do know that the 164 is split rf/lr and lf/rr. At least that's how the elevated brake temperatures ran in my car when some of them started to overheat as the one circuit acted up, and what the eper shows.

Re: Milano, "the rears share a line"

If the GTV6 and Milano don't have these diagonal safety circuits, then that suggests either a bad caliper or constricted line.

Usually, the car manufacturers split (required?) the safety circuits in the newer cars in a diagonal manner, for more stable emergency braking if one circuit fails.
 
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