1

I had a brake issue in my car as I mentioned in this question 7 months ago. After that, I did a complete repair to the brake system.

I found out that the one of the caliper bracket is not functioning correctly. So I replaced both front caliper brackets with new ones. Then I had some master cylinder issue so I replaced it with a new one as well. I also checked all the brake lines. Now everything is in perfect condition and brake works smoothly.

However the problem is again, it is generating more heat. To confirm this I bought a temperature gun and measured the temperature of all 4 wheels.

NOTE: The measurements were taken by pointing the temp gun to the lug nuts and center of the wheel.

Car is front wheel drive car with front disk brakes and rear drum brakes

First test

Drive 5km with no passengers that has few downhills. Both front wheels recorded 90C heat. Both rear wheels showed 40C.

Then I drive back that 5km again. This time, front wheels recorded 75C heat and 35C rear wheels.

Second test

Drive about 40km (20km back and forth) with no passengers in a hill country road. This time no different it was around 80C in both front wheels and 40C in both rear wheels.

Third test

Drive down one of the steep downhill in my country with max passengers(5) in 3rd and 4th gears with the speed of 40 - 55kmph. ( I didn't used the clutch when braking so no it always drove in the gear. Usually vehicles go down 60 - 80kmph in this downhill)

This time I had to stop my vehicle after I drove down about 5kms as I started to smell the brakes burning and my brake paddle started to feel loose. When I check the heat, both front wheels shows, 280C and both rear wheels shows 40C.

I just stopped for about 5min and then started to drive down the hill in 2nd gear. After the downhill ended, I drove about 3 - 5km on flat road around 50kmph. Then checked the heat again. This time it came back to 90C. Then I drove about 200kms on flat roads without any issues.

On each of these tests, the rear wheels heat never reached above 45C.

Every time I asked this from my mechanics they say it is normal to front disks to get much hotter than the rear wheels, however I drives that road 1 - 2 times a month with full passengers but I never experienced any brake issues even with my faulty caliper brackets that tends to get sticky when get hotter.

I can confirm that calipers are working 100% fine now. Also my mechanics told me that there's no need to adjust the rear brakes ( drum brakes ) as they get adjusted automatically.

What could possible go wrong here ?

Improve this question

1 Answer 1

Reset to default
1

From your description, there is nothing wrong here. As your mechanic stated, the front brakes get hotter than the back brakes. This is because the front brakes do about 70% of the braking for the vehicle. You have to expect the heat on the front brakes are going to be pretty warm when you are applying them for a long downhill (the 5km you stated). I've never tested the heat of the brakes after something like this, but it does not seem out of place considering what they just went through. Considering they cooled back down to 90C a few KMs after that leads me to believe they are functioning exactly as expected. Depending on how long the brakes had been on the car at that point, the brake pads may not have been fully cured which might have caused what you were smelling. The friction material has a binder in it which fully cures when heated. If they hadn't been hot enough at that point, they could easily have exhibited what you're talking about. Seriously, I think this was a non-event and not much to worry about. As long as braking didn't go away or faded very badly, I wouldn't think anything is awry.

Improve this answer
5
  • Hi again :) Braking did go away. I mean not entirely but it started to not responding to the brake paddle. Honestly I had to use the handbrake to completely stop the vehicle. Usually I can smell the brake burning of other heavy vehicles ( like buses ) on that road. They just drive fine even with that smell. I would do the same but the problem is brake started to not responding to the paddle. That's what I'm more worried now.
    – Dilshan
    Jun 28 at 13:40
  • btw, I had an issue with the handbrake is not being completely released. So found out that the two springs of the handbrake near the rear wheels didn't had enough tension to release the cable completely. So one of my friend which is a mechanical student replaced these two springs with two new springs that has much higher tension. Now I only have to pull one click to apply handbrake. It is enough to stop the vehicle even on a slope. Also when I release the handbrake it completely release the handbrake. Could this be affecting with auto adjusting of the rear brakes ?
    – Dilshan
    Jun 28 at 13:54
  • Some brake fade under extreme conditions is not unexpected. Again, I still suggest there's nothing here to worry about. You just have to control the amount you are using your brakes at any one time. Any vehicle is going to go through the same thing. Engine braking is a good alternative to constant use of the brakes on long down hill travel. As far as the rear brakes now, the two mechanisms which control the handbrake and auto-adjust the rear shoes are usually two separate things, so shouldn't have an affect on one another.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 28 at 14:08
  • Also, when driving down hill as you are suggesting, use the brakes intermittently instead of continually. Use them to slow down to your desired speed, then let off. You will be in a continual bit of speeding up and slowing down, but you'll be giving your brakes a rest in between, which should alleviate fade and increase overall performance and longevity during the long downhill portion of your journey. This is coming from the experience of a person who grew up and learned to drive in the mountains of Montana (in the US) where there are a LOT of downhills to deal with.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 28 at 14:12
  • 1
    Thanks for the advise. I guess that was my driving habit on top of the heavy load causes the trouble. Next time I'll use the technique you mentioned :) Thanks again.
    – Dilshan
    Jun 28 at 14:50

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .