We have an old '84 F600 we use on the ranch from time to time and last week I noticed it had brake "issues". I've been searching for an explanation of how the hydro boost system works and have come up with nothing. Can someone explain this to me? What the heck is that electric motor at the booster? I hear it spin when I press the brake pedal. I see the hydraulic pressure from the pump goes to the steering box then to the brake booster and returns to the reservoir. Simple enough... but then there's that motor. I'm loosing fluid from what appears to be a rear wheel cylinder. I've yet to tear into it 'till I understand what I'm working on. Thanks. Dan
Anyone???
The electric motor is an emergency backup system if the pump were to fail or you broke a belt or hose while going down the road. If that were to happen, the booster wouldn't have pressure from the pump and you'd have fun stopping the truck! The motor is controlled by a pressure switch. When the engine is running and all is well, the booster system has oil pressure and the pressure switch prevents elec motor from working. If you were to lose that pressure, the switch would sense it an allow motor to work to apply brakes. You can test motor by turning on ignition switch and depressing brake pedal, elec motor should work until you release pedal. Once you start the engine, the elec motor should no longer work. As for the rear brakes, does it have the Lucas dual wheel cylinder brake system? You can tell if it has a "supply" brake line coming from axle to a wheel cylinder on the brake backing plate, then another "jumper" brake line going from that wheel cylinder to another wheel cylinder on opposite side of backing plate. If that's the system you have, it's not a job for someone not experienced with it. It's a tricky system to work on. Good luck.
Now that I think about it, I believe the electric motor works anytime the engine is not running, even with ignition off. That would allow you to have brakes if truck started rolling. Can't remember for sure, it's been a while since I've worked on one of those.
Makes sense... Half the time i don't use the key when I'm moving it. I hear the booster motor run even though there's no key in the ignition. I'm assuming the motor is running due to a loss in fluid pressure. Stomping on the pedal on grass i get the left front wheel to lock. Nothing else. I see evidence of fluid from one of the rears. Also, there does appear to be a top and bottom wheel cylinder from what I see on the backing plate. This old gal has been sittin for years, has few miles on it and I'd like to get it road ready. Other than the brakes she's pretty tight.
That would make sense, ATCOEQUIP... :thumbsup And, if you have time, and want to... explain a bit more about the system. What makes it... "a tricky system to work on"? OCR...
It's been a while since I've worked on one, so details are sketchy among all the junk in my brain. The Lucas dual cylinder brakes were good brakes, just a PITA to service. If the brakes have been there a while, it's not unusal for at least one of the two adjusters to get stuck making it fun to release the brakes and get the drum off. At least one of the star wheel adjusting slots seems to always be near an obstruction to get to it, like, the rear leaf spring! And I don't remember the pre-adjust procedure for the proper drag on the drum, I just remember if you don't have it right, you'll have brake drag problems. The easiest way to repair/service Lucas dual cylinder brakes is to buy loaded backing plates that have all the goodies, including shoes, pre-installed. You just unhook your brake lines, remove the old backing plates complete, slap on the new ones, put her all back together, pre-adust, and go. As for danielm, if your going to get her road ready, I'd suggest you go through all the brakes and wheel bearings. Got to have a safe truck going down the road.
Well, that makes sense too, ATCOEQUIP... :thumbsup Thank you, OCR...
Thought about something I forgot while working today. You can tell you have Lucas Girling hyd brakes on the rear axle of your old Ford by the parking brake control. You'll have a yellow "Parking Brake" knob on the dash to the right of the steering column, it looks very much like a brake release knob on an air brake truck. The Lucas brakes use a spring applied wedge that expands the brake shoes for parking brake. On the rear of the brake backing plates will be something that looks like an air brake chamber. Thats the spring chamber that applies P brake. To release the brake, you push in the yellow knob on the dash which applies fluid pressure to overcome spring and release wedge on brake shoes.
I will warn you now, brake parts for this stystem are HORRIBLY EXPENSIVE!!! i have receipts for a brake job on my F-800 boom truck with this system for over $4,000. Thankfully this was just before i purchased the truck and didnt have to pay for this repair myself.
I have worked on this brake system to.Ford took something simple and made it complicated.The power steering provides pressure for the brake booster and releases the spring brake chamber.Allot of places for possible oil leaks.ATCOEQUIP described the system well.And Dualie is rite ,Parts are expensive.If its just a wheel cylinder leaking I would try rebuilding it.It depends how often the truck is used weather to spend allot of cash on it.
Finally I may get around to tearing this down this next week. I could have used it to haul hay a few weeks back so, there's no putting it off any longer. The park brake control on this truck is a lever located to the left of the steering column. It pulls a cable and is adjusted by turning the handle. I've located four new rear tires to go with the new brakes. Might as well do it right. Dan
Hyro Boost Problem I have to agree there is'nt much info on these H.Boost.I have a 1985 F-700 w/8.2 diesel.The brake pedal is hard & can't depress at all.Does this mean the H.Boost is bad?Local mech here don't know anything about this system.Need some idea of what to check to fix brakes.
Do you really mean "can't depress at all"? Or is it you can depress only very little and it's very firm/hard pedal?
Hard pedal would be due to no boost. I believe the hydraulic fluid boost circuit is common with the power steering. I have no idea how the, or if, the flow is regulated to each circuit. Does your power steering work? I've yet to dig into my brake issues due to bad weather here. It rarely gets any use but I hate to see it just sit at the ranch. When/if I do get to it I'll try to document the process with pictures. Might help others with hydo-boost problems. I imagine most of 'em have been scrapped or seeing farm use at this point. BTW, this truck also has the 8.2dd. A leaking front seal is next on the 'to-do' list. She marks her spot on the ground when idling.
Does she just kinda' sit there starin' at 'cha? Yeah I'm still waiting to hear your progress Danielm. You described earlier that your parking brake is a lever with an adjust knob which doesn't sound like Lucas brakes, but rather the standard drum brakes that ain't a big deal to work with. If you get a chance, take a pic of your rear brake plate for us to look at. I didn't want to sidetrack your thread by responding to cherrycrk, but asked him a question just for initial info, then was going to suggest he get in a couple more posts so he can start his own thread with his problem. Keep us up to date with your repairs on the old girl.
Yea, she begs to be taken out... as most do. No progress yet. Delays here include weird health issues, rain... It seems to be the story of my life not having a "common problem". First the 'mysterious Hydro-boost' then unexplained chest pains... At least I think I can sort out the brake system. May have to find a better mechanic for the health issue. Feel free to post anything here related to hydroboost. More info here might help a few out when searching for problems with that system.
Honestly what your describing doesn't sound like the Lucas girling brakes. If you could take a picture of the master cylinder on the firewall and maybe the backing plate on the rear that would help.
Hydro Boost Thank you for responding ATCO!Yes it's better defined as a firm -hard pedal.The electric pump works when you first start the motor.The brakes are all good & no leaks in brake cyls.
Hmm, I think we need to clarify something here. The electric motor serves as an emergency backup in case of booster/pump failure or to have brakes when engine not running (as in truck started rolling with engine not running). It should only come on in one of three cases. 1) Engine not running, step on pedal, and electric pump should come on. 2) Turn on ignition switch, pressure switch senses no pressure on booster hyd circuit, electric pump runs until engine starts and develops pressure. Pressure switch senses pressure and turns of elec pump. 3) Engine running and have booster/pump failure. Again, sensing no pressure on system. How does your truck act with these situations?
Hydro Boost The elect pump comes on when key is turned on to start the motor.When motor starts the pump stops.With the motor running I have firm-hard pedal w/some brakes.Thanks again ATCO
OK, sounds like the system is at least working the way it's supposed to, you are getting pressure on the system if the elec pump stops when engine starts. But your saying you have an excessivly firm brake pedal once the engine is running. This get's beyond my knowledge of the workings of the system. We know you have pressure because it turns off the elec pump. But is it enough pressure to operate booster? Is it a problem with the booster, or the pump? :beatsme One thing that would help; does the pump operate anything other than brake booster, like steering?
Hydro Boost I'm trying to figure out if the hydro boost needs replaced .How do you find out if it's bad?Don't want to buy one if I don't have to....
I hear ya bro! If the pump works nothing other than brake booster, we don't have much to work with here. And I don't know how to determine..."yep, the booster is bad." I'm inclined to lean toward bad booster. We know the pump develops pressure as it applies pressure to elec pump pressure switch to turn off elec pump. How much pressure it develops, don't know. We know pumps don't make pressure, they only deliver oil, resistance to flow makes pressure. This has to be done by some kind of "pressure regulator" within the booster. We know the pump is able to "meet" this pressure regulation of the booster because it cuts out the pressure switch for the elec pump. I can't say for sure, but it sounds like you have a hydro booster problem.
Im still not sure this is the lucas setup. as i have never seen one with a handbrake.
I'm still working on it... Can't get the wheels off the brake drum so, I pulled the drum. Any idea as to how to break 'em loose? I have the wheel laying down and tried beating on the lugs/drum... no luck. Soaking in PB Blaster for weeks now.
I haven't reviewed the thread, do you have Budd wheels?
Not sure... They have a split ring. I can't figure out where they are stuck. It looks like it may be rusted around the lugs. Only thing I can think to do is to remount them and "nudge" the truck sideways with the lugs loose a few turns. If I can get 'em off I'll look for some other wheels.
Split ring on wheels, you have Dayton rims. They have those "clips" under the nuts. Take a torch and cut the lug nut off the studs, then you can remove the wheels from the drum. Once you have wheels removed, you should be able to heat the drum with a torch and remove the damaged studs. Replace with new studs and your good to go.
I have the nuts off and didn't find any clips. Outer wheel came off easy, inner wheel is stuck. So, I pulled the bearing and removed the wheel with the drum attached. I tried a 3 jaw puller with no luck. Maybe lots of heat might do it.
Your describing Budd rims with the nuts that hold the outer wheel, and a stud type nut that holds the inner wheel. If you have the outer wheel off, you should be able to apply a little heat to the stud nuts, give 'em a whack on the square end with a sledge, and spin 'em right off. You are turning the stud nuts the same way you turned the lug nuts, right? Budd nuts and studs come in right hand threads as well as left hand threads.
Yea, The studs have a square end. It never occured to me they unscrew. They should spin right off now given all the "attention" they have had. Thanks, I'll give that a try as soon as I recover from this flu bug. Also, Can you tell me what tubeless wheels will bolt up? I'm having a tough time finding tires. Someone suggested 22.5" off UPS trucks. I have located some of them without tires for a reasonable amount.
There ya go! The only advice I can give you on replacement rims is that they have to be Budd rims. You can't use rims made for torque washer lug nuts.
You are the man! A little... make that a lot of heat, a few taps and the studs unsrewed. Wheels are six lug "Accuride".
LoL...yeah, those lugs were "probably" put on with a BIG 1" impact tool.
You probably have 10.00-20 or 9.00-20 size tires on your truck. They are tube type Bud wheels. That means they don't have the spokes in the middle, they look more like a conventional wheel. You can go with a tubless wheels and put radial tires on them. The equivilant size wheel in a tubeless wheel is as follows. a 10.00-20 tube type (split ring). equals an 11R22.5 tubeless radial. a 9.00-20 tube type (split ring) equals a 10R22.5 Tubeless radial. If you can find some used wheels with that bolt pattern, you can have them powdered coated and they will look new, and the cost is pretty reasonable. The width of a normal bud wheel with an 11R22.5 is 8.25in and with the 10R22.5, it is 7.5 in I think. I am not real sure on that one. you should notice a real difference if you got from tube type bias to tubless radials. It should perform better. I took off 10.00-20 Bias dayton wheels and put on tubeless daytons with Michelin tires that I found used from a school bus, and the difference is unbelievable. I couldn't believe that tires could make that much difference, but it did.
Could you tlel me where I can get replacement p brake spring chambers. and some service information for this lucas girling system. 1985 f800 ramp truck. Thanks.
1985 f800 with the lucas girling brake system. The service brakes work the p- brakes do not. any info about the parking brakes would would be appreciated. Thanks
I have a 1985 f800 with the lucas girling brake system. the service brakes work but the p-brakes do not. any info about the parking brakes would be appreciated. where can I get replacement parts and any service information? Thanks.
I think Truck Pro parts stores can get parts for the Lucas Girling Ford brakes. Not sure how much service info they can offer. You might try these folks, they rebuild the Lucas brakes and probably can give you some tech info. http://www.precisionrebuilders.com/about_us.html I'm trying to figure out how the parking brake is not working, but service portion of brakes are. The parking brake is applied by a spring inside the parking brake chamber pot. It takes fluid pressure to overcome the spring and release parking brake. Someone could have manually released the parking brake with the spring retracting nut/bolt in the center of the brake pot. Or, the rear wheel cylinder is so far out of adjustment that parking brake wedge isn't applying parking brake, haven't seen that before though. Servicing these brakes are not an easy task, hard to get to the adjuster star wheels without the OTC service tool, and I've had plenty of stuck star wheels making a real PITA!
ATCOEQUIP thanks for the info. I agree with what your saying. This truck belongs to a friend he just picked it up and explained what the brake system looked like and what the problem. I have not seen it yet. I was able to identify the system from one of your previous post. The link you gave me for precision rebuilders is very helpful. Thanks again for the information.
Your very welcome. Are you going to be working on the brakes of the truck? If you do, keep us informed and take some pics. It's been a few years since I've worked on these things, memory is a little rusty.
Hi. I know this is an older post but figured Id post cause Im having Problems wit hthe same system. I'm working on a 1990 F700 370ci Chip Truck. I have a problem with the brake motor running all the time. I have it currently unplugged but need it fixed to pass inspection. I made sure the master and the power Steering pump were both full and in the case of the P.S. pump working. I read some were that Ford liked to use seperate pumps for the P.S. and the Hydro BoostSystems. Is it true?? I have had Zero Luck finding anything to do with this truck. Its almost as if no one has ever heard of it. I was thinking of replacing the Booster Pressure Sensor but wouldn't know were to get a new one. Is there a way to test the sensor?? Thanks in advance. Bob
Welcome to the forum BIGBOBT. :usa Sounds like you can disconnect the pressure switch and the emergency pump will stop working, as it should. Once the motor starts running, the pressure switch should shut off the emergency pump. If it keeps running, probably a bad pressure switch. If you have good brakes when engine is running, then you don't have a fluid or a pressure problem. A good Ford dealer should be able to obtain a new pressure switch. They may tell you to go to a Sterling dealer. If you don't have one anywhere near you, you could try calling these folks, I've purchased Ford truck parts from them before and they are knowledgeable folks. http://www.longlewistrucks.com/
Thanks ATCOEQUIP!!! I was hoping you would see this cause I read threw all 3 pages and you seem to know this system pretty well. I think your right on the switch becasue I do have really good brakes when it runs. I never thought of it that way. I will take it out and see if Ican get it locally if not I will call the people in the Link you provided. My neighbor has 3 F700's all three with the same sytem all with seperate problems. The parking brake chambers are Spewing brake fluid on one. And the electric motor doesnt work on the other. I'm sure you will bee hearing more of me and my problems in the near future Haha.. Thanks. I will let you know if the switch fixed it.
I used to work on these types of trucks frequently years ago. I would think the parts would still be available, may be a bit spendy though, there's still a lot of these trucks out there. Worst thing about them is servicing the rear Lucas Girling brakes. It's a PITA to loosen the brakes to remove the drums because there's usually somthing in the way of the adjuster hole...like the leaf spring. :Banghead :tong
Ohh ok.. I Know what you mean on the rear end. New loaded backing plates arnt cheap. Halidex still offers them along with the adjusters and cyinders. I have yet to find the dang spring chambers and have a call into a rebuilder to see if they can do it. They are pissin fluid out were the cage nut is so I don't think its something I can fix on my own. Worst case senerio if I remove the two chambers and plug the lines will the truck still be able to operate minus the parking brake?? I thought these were supposed to be a split system just incase this happened but the master keeps going dry. Starting to wish this had air brakes. Spring chambers are a dime a dozen. Thanks for all the help..
Rut roh! Like I said, been a few years since I've worked on these, but I'm near certain the brake fluid in the master cylinder is seperated from the oil that's in the hydro booster circuit. Oil from steering pump, or seperate pump on some systems, goes to the hydro booster to give brake boost pressure against master cylinder to give easy pedal brakes. This same oil circuit supplies oil to the parking brake valve on dash. This valve sends oil pressure to the spring brake pots to release the parking brake wedge. If the seal in the master cylinder goes bad, it will put brake fluid into the oil circuit for the booster, the contamination from brake fluid will travel throughout the oil circuit into all components, and the brake fluid will destroy every rubber seal it encounters. That's probably what has happened to the seals in you spring brake pots. I believe you just might have a mess on your hands bro. :Banghead
Ok Well I have been doing some more work on this and discovered its not as bad as I thought. It leaks out of both Systems but there is no signs of cross contamination. We replaced the metal line going to the two Spring chamers but I think its still leaking out of the chambers. The brake fluid is leaking out of one of the Brake cylinders inside the drum so unfortionally its all going to need to be replaced. It still sucks but its better then replacing everything. I have to pull the drum to remove those spring chambers right? Thanks.
Oh wow...it's been several years since I've been into Lucas-Girling brakes, I can't remember if you have to remove the drum to pull the parking brake spring chamber pot. Sounds like your going to have to remove the drum anyway if you have a leaky wheel cylinder. Go ahead and cage the pot spring with the caging bolt and see if drum will come off. If the adjusters haven't been working, the drum might slip right off. If they have been working, you'll probably have to back off the starwheels on each wheel cylinder, that's usually the job that is a PITA! I do recall the spring pot just threaded into the brake backing plates and was locked in place with a locking nut. Loosen the locking nut with spring caged and see it the pot will screw out of backing plate. I wish I could remember more about those things.
I all so have a hydro boost system New here so had trouble >And the park brake side will not set regular brakes are working fine the boost motor does run if the truck is not on and you step on the brake.We have taken the HR1 vaule off and cleaned it and all so the park brake switch vaule to.It seams to have pressure at the cans at the wheels but will not releave that presure.I,m told the HR1 vaule needs replaced and then some one else is saying that the cans are bad brock springs.What is your thought Thanx Dan
I think there are bleeders on the tops of the cans. If you took the valve apart you might have got air in the system. I'd try bleeding them first and making sure that resevior is full. Its seperate then the Power Steering. If you find new spring chambers let me know were cause I am in need of two myself.
I have read that O'rileys has them but have not checked two ford dealer up here are saying they can get them I should have a price and confirmation if they can today. And as for bleeding them I will check that this truck is new to us and it came not working so we have been checking things and we did check for fluid but did not bleed them
I did find them at Horizon Ford in Seattle 1-800-622-2749 and at Northside Ford in Portland oregon 1-800-622-6670 priced about the same 250.00 to 270.00 each
Ok Great thanks. I ave also heard about O'reilys having them but I need to find one around me. Good to know they can still be had from the dealer. I have tried a heavy truck rebuilder to see if they could do it too. On your truck its very possible its out of adjustment. On the bleeding it just occured to me that your saying they wont release?? If so then the fluid isnt getting back to the Res. These are spring applied Hydro release. It sounds as if there is a blockage or something. If you needed to move it you could always Manually release them by cageing the brakes. Just know in that state you have no Parking brake untill you un cage them.
Welcome to the forum mbccable. :usa Not real sure what your describing, not real clear. Are you saying your parking brake will not set and hold? And you said you believe you have fluid pressure at the spring pots, but will not relieve that pressure? Relieve it how? As BIGBOBT stated, it takes fluid pressure to overcome the spring in spring pot and release parking brake by pushing in the p brake control valve on the dash. When you pull the p brake valve, this releases the pressure going to the spring pots and allows the spring to engage parking brake. If the brake valve does in fact release pressure, and p brake still doesn't hold, either have broken spring in pot, or brakes are so far out of adjustment that it can't hold.
The park brake will not set truck will role right know. the shoes are adjusted out to were they just are scraping.As for caging the brake pot should there be some tension when you move the bolt in or out? things are pointing to broken springs in the pot
Yes when you cage the braks there should be some serious tension there. You are manually contracting the spring. I know on air systems you must cage the brakes anythime you remove the drum. Not sure on this system. I would deffinatly cage them before I removed them.
ya There is some thing broke in the cans there is no tension you can move the cage bolt by hand in till the nut hits the can and out about 3in. I have a few rigs with air system and have had to cage them to do work just not that familure with this system
Yup sounds like you found the culprit. ATCO turns out the pressure switch works just fine. I had to do a little rewiring on the drivers side and then Bled the rear brakes. One of the two fixed it. Maybe there was an air bubble or something but it works now. This has been a heck of a trouble shootin experience thats for sure. One of the other trucks seems to be acting up as well with the motor so I will be posting some more questions this summer when its back in the yard. Thanks Again..
Been a while... Finally, I am back at this extended project. Had some health issues I have been dealing with which kinda had me layed up for a few months. I was able to obtain some wheel cylider rebuild kits for the rears. No luck finding the entire cylinder. Now I am in search of a shoe return spring. Hopefully I can get the brakes done this weekend if the weather holds out. Still looking for wheel/tire options to replace the Budd six hole tube types. But, 'till then I'll just use her at the ranch to move some dirt and brush around. Amazing how much junk an unused truck bed collects when sitting for a few months.
Ha, I finally found that PDF of the Maintenance manual for Lucas-Girling brakes on this $^*& computer. I'll send it to the email address you have on your profile unless you want it to go to a different address. These parts are now made by Arvin Meritor, you should be able to order the parts through Truck Pro.
I did receive the manual, Thanks. However, this one has standard hydraulic brakes with top and bottom 1 1/2" wheel cylinders. I spent a little time this afternoon trying to remove them and finally gave up as there's quite a bit of rusted hrdwr. Ended up using a torch and cut the bolts loose from the backing plate/axle to get the complete ass'y off and on the bench. So far, one cylinder bore has honed up nice. Hopefully the others will too. Thanks again for all your help.
Both rear backing plates completely rebuilt, new seals in hand and bearings look perfect. Maybe I'll get this thing back together this weekend. This has to be the record for the longest brake job.
f600 rear brake booster i have a 86 f600 dump truck.there is something leaking on the rear brake system.it looks like it would be a brake slack adjuster but uses hyd or brake fluid. what is it called and where can i find one.
Welcome to the forum Robman1962. :usa Is it a round canister looking thing on the rear of the brake backing plate that has an oil line going to it?
yes.
From what little has been described here, that sounds like the parking brake chamber on a Lucas-Girling brake system, it needs to be replaced. Truck Pro should be able to provide one.
thanks alot. i thank your rite about it being a parking brake. it only has one line on the unit,3/8 or 1/2" that looks like it runs to a pump. i'll check with pro truck on monday. thanks again.
Hey atco AKA Willie do you think you could shoot me over a copy of that manual?
Sure, it's a PDF file from Arvin Meritor, I don't think it's too large to send via email, will give it a try. It doesn't cover the parking brake chamber, but has the info to service the Lucas-Girling dual wheel cylinder brakes.
Willy... I would appreciate a copy of PDF also. I just got a 1990 f-700 with this type brake system and I'm losing the powersteering fuild somewhere. I replaced a worn hose that may have been leaking. (Low pressure) Now, the fluid fluxuates between, just touching the stick to over full. The break pedals start out nice and tight and after a while of running, they go to the floor. I'd like there's air in there somewhere. Just can't find any info on these brakes. Thank you in advance for any help, RP
Willie59: New to forum and needing help. I have young customer that bought a retired county '89 F700 dump and it has the Lucas Girling hydraulic brake. Could I trouble you for any service info or docs you are willing to share? I have read through the many posts for LG hydraulic brakes and found some great info, but hoping to find an actual document for preservation and owner. A fluid diagram and alarm circuits would be big help in troubleshooting this problem. I have found several parts catalogs from Meritor, Euclid, Haldex and others for most parts on LG brakes. (Not sure if parts are still available, but there are PNs) I am trying to patch this poor thing together so this young man can get a start with his new landscape business. Brakes were working OK until a hyd hose leak occurred at pressure manifold on firewall. I corrected leak, refilled reservoir and bam no hydro pressure. Disconnected pressure line from pump to manifold and no fluid, not a drop. Pump died or burned up from owner's ignorant continued use of truck while in alarm. He indicated he had to stake rear p-brakes to get home. Replaced Hydro Pump from Ford NOS for $250 and hydraulic pressure restored. Pedal has good pressure and truck stops well. Engaging parking brake causes momentary buzz, then silences and red dash lamp "PARKING BRAKE" illuminates. Release P-brake, dash lamp extinguishes and truck rolls easily. I believe hydraulics to p-brake cans is good and it seems hydro boost is functional as pedal feels ok. Now the darn yellow dash Brake Switch light & alarm are on and emg motor is stuck on, key on or off. You have to pull batt +/- to silence buzzer & motor. My guess is one of the two pressure switches fried from the long term slathering of ATF on the wires and sensor. But not sure. Wire insulation is turning to jello and I still have to shrink wrap or spice in, but actual copper cores seemed ok. Multimeter will tell me more at next visit. My thoughts were to try the following in effort to troubleshoot: 1) Disconnect emg motor power and evaluate pedal operation and feel with engine running. Should remain same as new hydro pump is activating p-brake so pressure is restored there. 2) Test and inspect emg motor relay for stuck contact. 3) Pull the pressure transducer switches to see which one may be culprit. I suppose the actual hydro-booster pump could be issue, but pedal seems ok and normal. And with most hydro boost fails I've encountered the pedal goes hard and it is pure two feet to pedal and push like a mad man hydraulics. But I did have a TopKick that fooled me. Pedal felt ok, not great & with truck empty at slow normal speeds brakes worked fine. When you tried to stop under load or at rapid hard stop, the alarm would set. Hydro boost was in early stages of internal failure. Kelsy Hayes elect brake system and it sets alarm that only a scanner can disable. Drove the owner nuts having to drive home with alarm chiming. And I learned the owner did just pay another shop for new emg booster motor installation, but I have no info as to why. Any thoughts, insights or advice is appreciated as I'm doing this as a almost for free charity to help a young man get started in a horrible economy. Thank you, Jim
Welcome to HEF CMC_FLEET. :drinkup The Ford trucks of that vintage used various components for the brakes. Of course the rear brakes are the old Lucas-Girling which is now supported by Meritor as you've discovered, and is know as Merritor DuraPark. The Maintenance Manual for the DuraPark brakes is Meritor MM-99101. The front disk brakes on those trucks were typically the Meritor Quadaulic 4 piston disk brakes. The Maintenance Manual would be Meritor MM-2075. The hydro boost/master cylinder was the Bosch Hyro-Max system. Here's a link to some info on that unit. > http://www.alpinecoachassociation.com/chassis/Bosch HydroMax Booster Manual.pdf
Willie59, Thank you sir. :notworthy Any and all help is appreciated. I'm searching for the Ford Service manual as well so the owner has a better source than my cell phone. :beatsme Many thanks & best wishes.
I did one of these last year...what I PITA. They do make a tool for the adjustments (because yeah theres s*&t in the way) and they also make a special tool for getting the springs on and off the shoes, if you dont go the loaded backing plate route. I strongly recommend the loaded backing plates btw. I also recommend putting new drums on @ the same time. Even if they mic out with in spec save yourself the hassle of blown wheel cylinders. The easiest way I can put it is this system is basically an air brake system that uses hydraulics instead of air for the parking brakes and then a regular hydraulic drum brakes for the service.
I have an '86 F-600/700 that ha s a brae problem. It is the Lucas-Girling system. With the key off, you step on the brake and the elec. motor starts. When you turn on the ignition, the elec. motor starts and the yellow light on the dash comes on "brake syst elec mtr" When you start the engine the light and the motor stays on. You can wiggle the knob on the dash and it will go out temporarily and then comes back on. The right, rear brake is also sticking when this happens. Can someone please give me an idea of a direction to go? Bad sensor, bad motor, loose/broken issue in the release mechanism on dash? I'm at a loss for where is best place to start.
Have you checked the fluid in the reservoir that runs the hydro boost? it uses automatic transmission fluid.
I checked the reservoir on the right side of the engine that states " DO NOT USE BRAKE FLUID- USE ONLY POWER STEERING FLUID" It is below the add mark. I will get the fluid and check this first thing in the a.m. just hope it hasn't burnt up the pump. It has only been driven about 8 miles and is just barely marking on the dipstick.
Looks like I completely forgot to use the K.I.S.S. method of troubleshooting!!!
I know this is an older thread, but I just wanted to say that I have a 1979 F600 with this brake system, and I found this thread highly informative. I even have the Ford Maintenance manual for this model year, and to my way of thinking, it is poorly written and difficult to extract useful information from the book. I am not getting any braking and even though I have replentished the ATF in the pump reservoir, and added brake fluid, I am still not getting pedal. I was not able to detect any leaks last night, but I will also check again to make certain I have tried the test to check the operation of the electric backup pump. and the pump does not appear to be working. I am just going out to do some more troubleshooting on the system to see if I can find out where to start the repair process. Bob. 79 Ford F600 Hiab
Would it be possible for you to send the pdf ** the maintenance manual for the Lucas/Girling brakes to me. I would really appreciate it. Bob 79 Ford F600
I have been doing a lot of searching, and found this link showing a representation of my system. I have cleaned the pump reservoir, replentished the ATF. Then, I checked and replentished the fluid in the master cylinder on the firewall. I went through the complete system, and tightened all the hose clamps. I fired the truck up, a propane powered 351, and checked the system. I have good power steering, but the brake pedal went to the floor. I pumped it up, and got pedal, so I am now going to bleed the brakes. I did a check of all the wheels, and can not find any evidence of leaking secondary cylinders. I have looked everywhere for the electrical pump, and I need a hint as to where it could be located. It is not anywhere around the booster that is attached to the frame under the driver's side of the cab. My system seems a little different from what was being descrribed by others. My emergency brake is on the outpout shaft of the transmission. The parking brake lever is a two piece unit with an unlock bar on the seat side of the lever. The back brakes are the two cylinder type. but I have not had the time to pull them apart to look at the insides. I am not going to do this right now, bexause it is my intention to use the truck in the yard, it has a hiab, and will have plenty of time to get the truck into roadworthy condition. The information I got here was instrumental in helping me solve the problems with my system. . . http://precisionrebuilders.com/images/trbl_images/hydtfmhi.gif