Brake Temperature / Warning System in Progress

[BellaBo]

After reading about all the brake issues and seeing damage caused by overheated brake systems on this forum, I decided there needs to be a way to monitor the temperature and/or warn the driver of possible problems.

Additionally, I thought it would be a good device for safety when traveling hill country and warn the driver of over-heated brake conditions so they might either pull off to cool their brakes or use lower gears to slow descent.

I now am in process of developing a warning device to provide both visual and audible warning to the driver when any one of the four brake calipers exceeds pre-set temperature settings.

I have the electronic circuit completed using thermocouple type devices that provide a signal to my controller and will set off both a warning light and audible alarm when the temperature thresh hold has been exceeded.

This project is very much a work in progress and I'm hoping to have it completed for testing on an upcoming 2400 mile trip to Al,Ar,Mo,Tex,La,Ms, and home to Florida.

There are still a couple of challenges to over come.
1. connecting the thermocouple to the caliper to collect the temperature correctly?
2. What temperature to set the warning to alarm at?
Any suggestions would be appreciated.

So far I have about $50 invested in this project and is designed for anyone with some electronics DIY skills. I think in the end, total cost could be under $100. A cheap price for some early warning of expensive repairs.

I will update this with progress and pictures if I can figure out how to load pictures.

There is no monetary motivation in this project, if it works, then it will be shareware with my other W/H buds!

[oemtech]

Attaching the thermo coupling to the caliper is either mechanical (bolt on clamp) or chemical (high temp epoxy or some such thing).

As for the temp... I think you would need so testing to record various temps under varied conditions. What's considered normal - 350 degrees?

Send me the photos and I will post them for you.

[TandW]

Oemy, he should embed the sensors in a drilled "well" with epoxy, as you mentioned. But set points will have to be well below fluid boiling point because the heat soak phenomenon will tend to be latent or slow to occur.

[BellaBo]

Oemy.. I was leaning toward the clamp on style of mount.

I may be way off on temperature but was starting my settings a about 700F. Maybe that's too hot though.

I'll click up some pictures of what I have so far. Mostly just bench testing, but 4 individual circuits in an enclosure seem to work with about 15mv input from a themocouple heated by a flame.
Lights a light and sounds an alarm.

[RottenRalph]

My last temp reading using a MicroTemp digital Infrared thermometer averaged 110 degrees on all 4 calipers within 5 minutes of stopping.

[max49]

I can see where this may be helpful if the overheating was caused from riding the brakes down a mountain or something similar but WH's brake problems are caused by bad calipers not completely releasing. So stopping to let them cool won't fix the problem. If it's warranty work, I doubt WH would do much just because you told them the temperatur gauge you installed said they were getting hot, would they?
I'm not trying to be a fuddy duddy, it seems like a good idea: but better for a brake system without all the inherant problems the W seems to have already built in.
I'm not on the 'blame the customer, owner, driver' wagon.

[oemtech]

I picked 350 because most brake fluid boils around that temp.

[Fred and Bonnie]

You could use this NTHSA Brake Investigationfor brake tempertature references.

Fred

[Davel]

Steamerman,

Great idea. Being able to monitor brake temps would take a great load of my mind. I used an infra-red thermometer on the way home from Florida and got readings of the calipers in the 110 degree range. My coach is out of warranty so I'm only interested in protecting my investment, that is until there is a resolution on the federal investigation. Then maybe something will be done to correct this growing problem. I agree with Max49 that the brakes should be w/o problems, but evidently that's not the case for many WH owners.
Another thought on the mounting would be a thermocouple on the brake hose near the caliper. If the brake is dragging the fluid tempurature should rise quickly. Some kind of foam tape would insulate the connection and give accurate readings.

Thanks again,
Dave

[BellaBo]

Thanks for the helpful input. I realize this is not a fix for the brake issues but at least a warning that something is wrong and requires some type of attention and hopefully prevent $$$$$ of repairs.

As stated this is still in bench work phase but will update as it progresses. I will review the recommended brake site too.

Dale... I'm sending some pics over to you if you can load, thanks!

[oemtech]

Thermo Couple


Circuit Board


Control Box - Connections


Control Box - Controls

[Duner]

This is a great idea Steamerman! Sure hope it works as intended. To get some idea of the temps to expect, go to this link for a NHTSA trip report where Bosch & Workhorse were gathering data. Seems like 300 to 450 degF can be expected with hard braking. We need to thank IRV2 member RottenRaplh for uncovering this report see this topic.

To attach the probes : you could use this 2-part putty that will allow you to put the sensor right on the top of the caliper. It make a very strong mechanical bond and should conduct the heat well.
You can buy it here.

[BellaBo]

Thanks for the info Duner. I'm rethinking the temperature setting now based on that article. I thought 700F was a good target, but it looks more like 375F is a good setting to start with. I just need to change the resistors in the circuits to lower my comparator voltage.

I sure would like to see the specs of those ABS sensors for temperature ratings.

[oemtech]

A couple of thoughts..

What if you have to replace a caliper... epoxy, Quick Steel, JB Weld might not be the best solution.

For the proto type how about some small pots to vary the the resistance to control the starting temp?