72V TXT or bust....

720Deere · 07-29-2013, 12:27 PM

Quote:

Originally Posted by mjhoward

I just read this and lots of good info here.
FWIW, my experience with brakes in cars is that drums in good condition will stop better than disc...until they get hot.

If that is the case, why has every manufacturer of heavy duty pickups gone to rear disc brakes and effectively increased their braking power by more than 50% in the process?

mjhoward · 07-29-2013, 01:59 PM

Quote:

Originally Posted by 720Deere

If that is the case, why has every manufacturer of heavy duty pickups gone to rear disc brakes and effectively increased their braking power by more than 50% in the process?

There's always exceptions. How come every manufacturer of 18 wheelers still uses drum brakes?
Once drum brakes get worn out, fluid on them or hot they suck. They are good for one hard stop and they are done...the reason they have run-away ramps at the bottom of mountains for big trucks. If your not over stressing them they are better (generally). They are less reliable for daily driving than disc.

mjhoward · 07-29-2013, 02:07 PM

On the topic of motor temps with 72v as dicussed on pg 2 of this thread, using a thermal protector on the motor in line with the main solenoid is something i'm going to look into.

http://www.bi-metal-thermostat.com/c...ed-407408.html

yurtle · 07-29-2013, 02:19 PM

Has anyone ever asked for RTDs (or any of a number of devices) to be embedded in the windings of custom built motors? That would be the best way to monitor the internal temperature, since winding insulation is what you're trying to protect.

gornoman · 07-29-2013, 02:38 PM

Quote:

Originally Posted by mjhoward

They are good for one hard stop and they are done...

They are less reliable for daily driving than disc.

So, in your experience, they actually suck AND are quite dangerous. This logic is faulty at best.

mjhoward · 07-29-2013, 02:55 PM

Quote:

Originally Posted by gornoman

So, in your experience, they actually suck AND are quite dangerous. This logic is faulty at best.

I gave same of the pros and cons.
As in my original statement:
FWIW, my experience with brakes in cars is that drums in good condition will stop better than disc...until they get hot.
I was trying to give some experienced info on the fact his actually stopped better with drum brakes. It happens in some cases.
You have done nothing but pollute the man's thread and belittle my intelligence.

gornoman · 07-29-2013, 04:14 PM

If "in your experience" is to be your definition, I suggest you keep it to yourself. The swept area of modern disc brakes far exceeds the swept area of drum brakes on any given wheel size. This is the primary reason they are so effective. Also, their ability to self-clean either water, mud, or snow keeps them in the safe zone.

As for your intelligence level, it is up to you to educate yourself. My intent was simply to challenge a faulty statement.

mjhoward · 07-29-2013, 05:17 PM

Drum brakes have more friction surface area thus generate more heat faster causing brake fade to come in quicker than disc. Disc have 7/8 ths of the surface cooling while only 1/8 is being heated. Drums are almost exactly the opposite. Disc cannot lock the tires up on an 80k pound machine In a panic stop. If one would educate themselves they would find they both have their own superiorities and weaknesses. A cart with 750lbs of batteries would likely, and proven so, stop better with drums than discs...for one stop of course.
Educating one's self is important. As well as removing blinders.

gornoman · 07-29-2013, 08:22 PM

Just yesterday morning I experienced the scare of a loose dog running in front of my cart at the campground. I hit the hooks full-on, locked the tires on the asphalt, and felt my substantial body lift from the seat and head for the steering wheel. The disc brakes in my cart saved that dog a trip to the hospital. I stopped so fast the dog's owners weren't even upset with me. They were upset at the dog.

Any blinders in use are being worn by yourself. I'm certainly old enough to remember drum brakes on my cars, especially on the front axle. They were shlt. They still are. Drum brakes are a relic of the past, and only a slight improvement over the stick we pushed against the rolling wheel of our first go cart. If you want to drive on drum brakes, just don't follow me closely.

mjhoward · 07-29-2013, 09:17 PM

Discs are superior to drums in most cases. That is why they have been phasing out since the 60's. This all started with me having similar experiences as the man's thread and you disagreed. He has proof, I have "experience" as you say. I had a nova drag car with drums all around and it performed great because I had to stop once. I have a 74 cj5 and it does great. I steer around every mud hole I can and I have never driven a car in salt. I can imagine how salt would wreak havoc in quick order on the mechanics of drums. I feel our discrepencies and life experiences is a matter of demographics.
Wait wait... now if detroit was in the south, we may all be driving around on superior drum brakes with 100 years of engineering!

Actually it almost was in the south. Politics stepped in. Read the 5th paragraph.
http://www.cityofmuscleshoals.com/?ID=11

07-29-2013, 02:07 PM	#253
mjhoward Not Yet Wild Join Date: Jun 2013 Location: Decatur, AL Posts: 64	Re: 72V TXT or bust.... On the topic of motor temps with 72v as dicussed on pg 2 of this thread, using a thermal protector on the motor in line with the main solenoid is something i'm going to look into. http://www.bi-metal-thermostat.com/c...ed-407408.html

07-29-2013, 02:19 PM	#254
yurtle Gone Mad Join Date: Oct 2009 Location: Buford, GA Posts: 8,988	Re: 72V TXT or bust.... Has anyone ever asked for RTDs (or any of a number of devices) to be embedded in the windings of custom built motors? That would be the best way to monitor the internal temperature, since winding insulation is what you're trying to protect.

07-29-2013, 04:14 PM	#257
gornoman Stay thirsty my friends! Join Date: Jan 2007 Location: Suburban Chicago Posts: 24,292	Re: 72V TXT or bust.... If "in your experience" is to be your definition, I suggest you keep it to yourself. The swept area of modern disc brakes far exceeds the swept area of drum brakes on any given wheel size. This is the primary reason they are so effective. Also, their ability to self-clean either water, mud, or snow keeps them in the safe zone. As for your intelligence level, it is up to you to educate yourself. My intent was simply to challenge a faulty statement.

07-29-2013, 05:17 PM	#258
mjhoward Not Yet Wild Join Date: Jun 2013 Location: Decatur, AL Posts: 64	Re: 72V TXT or bust.... Drum brakes have more friction surface area thus generate more heat faster causing brake fade to come in quicker than disc. Disc have 7/8 ths of the surface cooling while only 1/8 is being heated. Drums are almost exactly the opposite. Disc cannot lock the tires up on an 80k pound machine In a panic stop. If one would educate themselves they would find they both have their own superiorities and weaknesses. A cart with 750lbs of batteries would likely, and proven so, stop better with drums than discs...for one stop of course. Educating one's self is important. As well as removing blinders.

07-29-2013, 08:22 PM	#259
gornoman Stay thirsty my friends! Join Date: Jan 2007 Location: Suburban Chicago Posts: 24,292	Re: 72V TXT or bust.... Just yesterday morning I experienced the scare of a loose dog running in front of my cart at the campground. I hit the hooks full-on, locked the tires on the asphalt, and felt my substantial body lift from the seat and head for the steering wheel. The disc brakes in my cart saved that dog a trip to the hospital. I stopped so fast the dog's owners weren't even upset with me. They were upset at the dog. Any blinders in use are being worn by yourself. I'm certainly old enough to remember drum brakes on my cars, especially on the front axle. They were shlt. They still are. Drum brakes are a relic of the past, and only a slight improvement over the stick we pushed against the rolling wheel of our first go cart. If you want to drive on drum brakes, just don't follow me closely.

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07-29-2013, 09:17 PM	#260
mjhoward Not Yet Wild Join Date: Jun 2013 Location: Decatur, AL Posts: 64	Re: 72V TXT or bust.... Discs are superior to drums in most cases. That is why they have been phasing out since the 60's. This all started with me having similar experiences as the man's thread and you disagreed. He has proof, I have "experience" as you say. I had a nova drag car with drums all around and it performed great because I had to stop once. I have a 74 cj5 and it does great. I steer around every mud hole I can and I have never driven a car in salt. I can imagine how salt would wreak havoc in quick order on the mechanics of drums. I feel our discrepencies and life experiences is a matter of demographics. Wait wait... now if detroit was in the south, we may all be driving around on superior drum brakes with 100 years of engineering! Actually it almost was in the south. Politics stepped in. Read the 5th paragraph. http://www.cityofmuscleshoals.com/?ID=11