[Dagwood_73]

I now have a F650 with Hyd. Disc brakes. They seam to work great. I got 185000 miles before needing any work at all.

But now I'm upgrading to a F750 or It 4300 and I can get either the air brakes (what most people buy and run) or the hyd disc.

What are the diff in braking power and maintance???

If I go with the hyd disc I won't have to upgrade my CDL, as it has a no-air-brakes endorcement. So they would be the eaisest, paperwise...but there must be a reason everyone gets the air-brakes.

 

[Mr_Roboto]

Go with the air brakes. They are superior in any way I can think of.

You can get a leak in an air brake system and it will still stop as long as the compressor can pump faster than the leak. And if you DO lose air pressure, the spring brakes will stop the truck automatically (hold on tight).

Hopefully you can upgrade the CDL by taking a written test. At least here in Ohio, the pre-trip and driving tests are a bear. I never want to take them again!!

 

[meat4u69]

to up grade your cdl to airbrake you have to take a ritten test and driving test.

 

[DonRobbie]

[ QUOTE ]
I now have a F650 with Hyd. Disc brakes. They seam to work great. I got 185000 miles before needing any work at all.

But now I'm upgrading to a F750 or It 4300 and I can get either the air brakes (what most people buy and run) or the hyd disc.

What are the diff in braking power and maintance???

If I go with the hyd disc I won't have to upgrade my CDL, as it has a no-air-brakes endorcement. So they would be the eaisest, paperwise...but there must be a reason everyone gets the air-brakes.

[/ QUOTE ]

If you are just adding an endorsement you shouldn't need to take a driving test. It should just require a written test and a fee.

Hydraulic brakes have the advantage of being basically an automobile system. They are a larger version of what is installed on your car. You can take the truck to the mechanic on the corner and he can fix them. You are already used to using them. Air Brakes are a different animal. Do you feel comfortable adjusting brakes? Do you know when you should adjust them? Do you have access to someone certified to inspect* and work on air brakes? Are you ready to adapt your driving style to air brakes?

Concise Version:
http://www.ntsb.gov/Events/journalist/lessons/LL_truck_air_brake.txt
Full Story:
http://www.ntsb.gov/publictn/2006/HAR0601.pdf (PDF)

*Title 49 CFR 396.25, “Qualification of Brake
Inspectors,” requires that each brake inspector successfully complete an apprenticeship or training program or have a certificate of experience totaling at least 1 year.

 

[Mr_Roboto]

[ QUOTE ]
to up grade your cdl to airbrake you have to take a ritten test and driving test.

[/ QUOTE ]

It's probably different state to state. While a CDL is a national license, the testing requirements are *very* non-standardized. I went through school in Wisconsin, many students were tested on-site and had their CDL's. I had to go back to Ohio for 2 weeks of additional training to pass Ohio's test.

 

[Jrod13]

when I took my CDL test back in MN, air brakes weren't a endorsement persay, but more of a restriction(much like the intrastate restriction because I was 18 at the time)
In order to not have the restriction on your license, there was a additional 15 question test, and a little bit more on the pretrip portion of the driving test. I think the extra cost was $2.50
The test it's self was stupid simple, like all the others other than the hazmat and school bus test.

IIRC, all you had to do was open the hood to point out the air compressor, yank on a slack adjuster, and then pump the brakes till the low air warning light came on.

 

[DieselFan]

[ QUOTE ]
You can get a leak in an air brake system and it will still stop as long as the compressor can pump faster than the leak. And if you DO lose air pressure, the spring brakes will stop the truck automatically (hold on tight).

[/ QUOTE ]

I noticed your comment about a leak in the air system. Just to clarify, if the air leaks down from normal to 0 psi, then the brakes will lock up and the only way to move the truck is to build air pressure back up in the system.

Is this the way the F650/F750 air brakes are set up? Does the F650/F750 have glad-hand connectors to use with trailers equipped with air brakes? How is the air compressor powered with the engine choices on this truck? I suspect the Cat has an on-board compressor. Just curious. I'm not familar with the truck.

It's so important to know the in's and out's of air brakes. They are technically superior to hydraulic brakes but they require frequent inspection and maintenance because so much is being asked of them.

You learn the value of a well maintained brake system (and a Jake brake!!) the first time you go down Black Mountain or Monteagle with 45,000 lb of whatever, in my case powdered iron, on a 53 ft. trailer. It definitely wakes you up. /ubbthreads/images/graemlins/eek.gif /ubbthreads/images/graemlins/shocked.gif

 

[Birken Vogt]

All air brakes are the same, Ford or whoever doesn't do them any different than anybody else. They always use the same Cummins/Bendix/Midland compressor, the same Bendix/Midland valves, the same MGM/whoever brake cans, the same Meritor/whoever brakes (this part is becoming more OEM specific though) but they are all extremely similar and you can usually even interchange one manufactrer's part for another. It makes it very easy on the mechanic.

That being said I now have one vehicle with the hydraulic discs and am soon getting another. These brakes are simple, long lasting, and effective. In fact I think I might even prefer them on an MDT over air brakes they are so good these days. Depends on the GVW I think. Under 20k probably hydraulic, over 20k air might be a good cut off point.

Birken

 

[BurnedBronco]

[ QUOTE ]


I noticed your comment about a leak in the air system. Just to clarify, if the air leaks down from normal to 0 psi, then the brakes will lock up and the only way to move the truck is to build air pressure back up in the system.

Is this the way the F650/F750 air brakes are set up? Does the F650/F750 have glad-hand connectors to use with trailers equipped with air brakes?

[/ QUOTE ]
yes, if your pressure falls below about 20lbs the E brake know on the dash will pop out, and the rear axle spring brakes will apply. they will only work if the brakes are PROPERLY adjusted....
front axles do not have spring brakes
you can spec your truck out to have glad hands installed on the back no problem, most have the knob on the dash, but some are not plumbed, usually involes mounting the glad hands and running air lines.

 

[DieselFan]

Birken, Burned, thanks....

I take it that on all engine options with the F650/F750 that the compressor is belt driven, correct?

Birken, how do the hydraulic brakes differ from what's available on F450-F550?

I'd also add that if you are hooking to a trailer, nothing I've seen yet beats air. But then I've only dealt with class 8 tractor-trailers and trailerless straight trucks. I've often wondered what kind of braking systems are available on the kinds of trailers you'd pull behind a F650/F750.

 

[trucky]

Essentially larger thicker pads and larger dispacment rotors, other than that same operating principle.
The magic number for air or hydraulic brakes seems to be 26,001#s.
Below that, hydraulic, above that air.
A word of caution, antilock disk brake rotors are appx $400.00 each, pads are appx $80.00 per set and a LOT more labor to change than drums. However it is easier to do just a pad swap on hydraulic pads.
Air brakes on a factory speced truck will most likely be a mechanical driven air compressor. They are all self adjusting slack adjusters, but you have the ablility to tighten them up if you want to. As for cost comparison if you need brakes replacment on an air system you should do the shoes and drums together along with hardware kits. A two axle brake job with shoes,drums,hardware,and rear 30/30 maxi cans
costs me appx $800.00 parts cost, and about 4 hrs time.
Good luck on your decision.

 

[Birken Vogt]

I've never seen a VT365 (International 6.0) in an air braked truck (or air suspension/hydraulic brakes which seems to be more common these days) but I seem to recall that the 7.3 in the International trucks had an engine mounted air compressor available, not sure though. All the Cummins and Cat motors however have engine mounted compressors I know.

You are right that air is the only thing for a trailer. The only other option is electric, however I know a guy that tows skidders, dozers, etc. behind his log truck with a large beaver tail trailer that has electric brakes. Not as big as a 53' trailer but bigger than a travel trailer anyway.

The 450/550 have Ford's own proprietary braking system, much like a regular truck beefed up. I suspect the 650+ have a commercially available system made by Meritor/Bendix but I don't know that.

For hvytruckmech, I replaced rotors on an ambulance that has the Bendix 2.6" dual piston discs, after 60,000 miles the pads were finally wore out (unheard of for Ford van ambulance brakes to go that long as I'm sure you know). The rotors would have been fine but....

I must confess that I am having an issue with one of these brakes right now. There seems to be too much friction on one of the caliper slides causing the back side not to release away from the rotor which causes that pad to wear out quickly and burn the rotor. The previous one actually ground into the rotor because I didn't catch it in time. I am trying to figure it out with Bendix right now. But they are so simple that it can't be that hard to fix even if I just wind up replacing the spider which is the only original part left when doing a brake job.

Anyway the rotors only cost around $80 as I recall and they have the ABS ring. I think there may be proprietary systems out there that cost more though.

Birken

 

[BurnedBronco]

most of the f550 and IH hydro systems have detachabel tone rigns, some of the GM's have the cast in tone rings which are the $ high dollar rotors.


biggest problem we have with the disc systems is that the slide and wedge spring get loose and the wedge then falls out under driving conditions. then backs out and usually brakes off the wheel valve stem on the front.
this happens from the caliper bracket and the caliper wearing away, and can only be fixed by replacing with a NEW caliper(not reman) and a new caliper bracket.
i have, but this is probaly not good, but i have welded beads on where the caliper slides and then ground it flat to build up what had worn off when guys needed there trucks immediatly.

 

[trucky]

Birken, what year/make/model amb. is it? Slide pins or wedge spring assembly? You are right, 60k on ambulance brakes is unheard of.
Secondly,I can not say about Ford F550's but I can say with the utmost of certainty that I/H Does not have a serviceable abs ring.
They are all cast into the rotors and I assure you they are all of around $400.00 clams per rotor, give or take a few. Non abs is less than half the cost per rotor. As far as wedge spring assemblies, I/H does offer an oversize replacement kit to take up a small amount of wear that occurs on the knuckle assembly, but as stated above excessive wear can only be cured by replacing the knuckle assm. and calipers with new.
Also has that bus ever shot out the inside pad before? If so you could have a bent knuckle causing the accelerated pad wear?
Keep us posted on your results and best of luck
Stay safe, Tim

 

[Birken Vogt]

It was the original set of brakes that wore out the outside pad first...I replaced with Genuine Bendix reman calipers and rotors...now it is doing exactly the same thing. They are the Bendix 2.6" dual piston brakes, I guess I have nothing left but to replace the spider or whatever you call it on a disc assembly. I will have to dig up that invoice on the brake parts to tell you exactly how much it cost, it was a rotor with a cast in tone ring. Although it is not part of the hub, it bolts to the hub.

Birken

 

[trucky]

Birken, don't worry about diggin up slips, I know you can get 1 ton rotors for about 80 bucks, no problem there. I am missunderstanding
what you mean by "spider" assy. I guess I'm just having a brain cramp.
I have had outer pad wear on a couple of my trucks, a new slide pin kit seemed to be the fix. I made that standard replacement when i Change out rotors yearly on all my hyd. brake I/H's.

Tim

 

[Birken Vogt]

We haven't got any IH's yet, this is a FL with a 19,500 GVW. There aren't really any slide pins on this setup. The lower end of the caliper has a groove that the lower end of the spider/bracket/whatever fits in and then you slide the upper end into place and you drive in a pin along with a spring and they fit in there pretty darn tight, really have to be hammered in. It's a wonder to me that it even releases at all.

Birken

 

[FMTRVT]

Birken,

We did a fair amount of testing with that assembly a few years back. Yes, there can be too little clearance preventing the caliper to slide back away from the rotor and causing drag wear. Also check the outer pad for taper wear. On many different manufacturer applications, I have seen occasional non-parallel mating surfaces between the spider and knuckle, and the resulting taper prevents the pad / caliper from fully pulling away.

For the last 1 1/2 years we've been working on the air disc brakes which are coming over from europe. These are really expensive right now. Like $1500 per caliper.

 

[BurnedBronco]

[ QUOTE ]
We haven't got any IH's yet, this is a FL with a 19,500 GVW. There aren't really any slide pins on this setup. The lower end of the caliper has a groove that the lower end of the spider/bracket/whatever fits in and then you slide the upper end into place and you drive in a pin along with a spring and they fit in there pretty darn tight, really have to be hammered in. It's a wonder to me that it even releases at all.

Birken

[/ QUOTE ]
thats the style i see wwear out and fall out.........
you are cleanign all the rust, and other junk off the bracket , caliper, and wedge correct? you can buy new wedges and springs for cheap, so might be worth buying.

 

[Birken Vogt]

After the initial failure I made it a policy to hammer out the wedge and lube the sliding surfaces annually...this issue with discovering that the accelerated wear was happening again happened only on the first annual inspection though. It was pretty dry though, but I did lube it when it was initially installed.

Birken