Home » Public Forums » GMCnet » Trouble adjusting parking brake
| Trouble adjusting parking brake [message #63696] |
Tue, 10 November 2009 11:42  |
LarryInSanDiego
Messages: 336
Registered: September 2006
Karma: 0
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Senior Member |
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I'm having trouble getting sufficient "hold" with the parking brake in the up position AND having minimum/no drag in the released position. I've tried balancing cable tension side to side and between middle and rear wheels.
All cables have been lubed and work smoothly, including in the cable housings. All brake parts are there. The cockpit adjuster turns smoothly and nothing is at either end of it's travel. I've muscled the U-turn brake cable adjuster dealy to better even out the cable tension, both the front one and both rear side ones.
I either get a wheel to lock up too quickly or drag or I get nothing if I adjust so they don't drag. I thought I had the star wheels lubed, adjusted, and correctly oriented (Jim K, are you listening?), when I was recently in there.
Any suggestions?
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
[Updated on: Tue, 10 November 2009 11:45] Report message to a moderator |
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| Re: Trouble adjusting parking brake [message #63710 is a reply to message #63696] |
Tue, 10 November 2009 13:52  |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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Senior Member |
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Larry,
This is just my opinion, but you will never have a good parking brake using the factory setup. I went through the same issues a couple of years ago and no matter how clean and smoothly operating all the components were there was no way to have the parking brake BOTH hold the coach properly and release completely, like a proper parking brake system should. There is a kit that some GMC vendors sell that replaces the factory linkage parts with pulleys and rods and other stuff, but since my last name isn't Trump I had to find a more affordable solution.
There are two issues, one is that the cable return springs in each wheel are not quite strong enough given the amount of cable and associated bits on the rest of the system (easy issue to fix), and the other is not enough travel in the lever assembly in the coach so you can apply enough force to the brake shoes (harder to fix).
The cable return springs can be assisted by external springs at the u-shaped adjuster things on either side. It doesn't take much additional spring tension to reliably retract the brake shoes fully. I can't remember whether the springs I used came from an auto parts store or from Lowes or Depot. That took care of the dragging-shoes problem.
I looked at replacing the handle assembly with a foot pedal or a t-handle type actuator. I hadn't found anything workable when I won a 4" diameter 8" throw air cylinder on Ebay for something like $27. Long story short, I used that air cylinder which is bolted to the right frame to push the cable. It is way overkill for the application but the price was right. Total parts were the air cylinder, a dashboard air switch (something like $15), a Harbor Freight air pressure regulator ($6), some air tubing, and several other small parts. Something like $60 total. The parking brake now holds great and releases completely and sounds neat when you flip the air switch to release the brakes.
I found that about 35psi holds the coach just fine. With that big of an air cylinder I would probably bend parts if I used the full 120+ psi from the air system. I don't think a 4" cylinder is needed and something smaller may work out better but that was what I had to work with. Maybe even using 2 small cylinders, 1 on each side and eliminating the big u-cable would work.
Again, just my opinion and JWID. All I know is that I move the switch one way and the brakes come on and actually WORK, and I move the switch the other way and the brakes turn off and there is no drag whatsoever on the rear wheels. And the price was right.
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: Trouble adjusting parking brake [message #63805 is a reply to message #63800] |
Wed, 11 November 2009 08:26 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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To get enough pull on the barking brake cable, I had to go to the Ragusa handle extension. The air cylinder idea sounds neat. And the additional springs are also a good idea. Jim, registar as a Virginia Antique (GMC, not you) and no more inspections.
Tom Phipps
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Trouble adjusting parking brake [message #63827 is a reply to message #63710] |
Wed, 11 November 2009 10:08 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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I found that about 35psi holds the coach just fine. With that big of an air cylinder I would probably bend parts if I used the full 120+ psi from the air system. I don't think a 4" cylinder is needed and something smaller may work out better but that was what I had to work with. Maybe even using 2 small cylinders, 1 on each side and eliminating the big u-cable would work.
___________________________________________________________
The Parking Brake (PB) has been one of my issues also.
Do you use the spring action to set the brake when the air pressure is off? That, if I am not mistaken, is how the truck trailers do it.
Air on, the PB is off and you travel. Air off, the spring sets the brake and you go now where, hopefully.
did you make your own cables?? Mine are shot.
Can I make my own ends? such as in the brakes?
You have given me ideas I just don't know how well this can be constructed.
If you would like to discuss more, I hope you might, you can contact me off site, or on site. Thanks
SLawrence111(at)Yahoo(dot)com
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
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| Re: Trouble adjusting parking brake [message #63852 is a reply to message #63696] |
Wed, 11 November 2009 12:12 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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Senior Member |
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Let me see if I can answer all the questions.
The original handle assembly is still there and fully functional, I just keep the adjusting knob fully counterclockwise to loosen the main cable. If I want to use the handle I just turn the adjusting knob in about 10 turns or so and then lift the handle and it works just like it always did. The only problem with the original setup is if you adjust the tension tight enough to really clamp the wheels then it doesn't release all the way and the rear brakes drag, not to mention you have to be a bodybuilder to set the handle tightly. I have a Ragusa handle extension but if you use it's lock screw then you cannot easily get to the adjustment knob. If you don't use the Ragusa lock screw then you run the risk of the extension handle flying off just as you're putting lots of force on it and then you then mash your knuckles into the dashboard. Fun. If they had made the handle assembly have maybe another half inch of cable travel it would probably work fine. There is a lot of cable in the original system and cable stretches, slightly, but it still stretches when tensioned. The air cylinder just has lots of travel relative to the original actuator setup.
I added the external springs because I want the springs in the wheels to pull back the rear cables and let the external springs pull back the rest of the cabling. On my coach one side cable was replaced and the other one is an original in good shape. When I was re-doing the rear brakes a couple of years ago I removed both side cables and cleaned and lubed them. They slide smoothly and don't drag any more than you would normally expect. The factory springs aren't quite strong enough to reliably retract all the brakes fully. Notice I said 'reliably'. I don't want ANY drag from my rear brakes so I used just enough external spring tension to make darn sure all the brakes retracted fully each and every time.
The air cylinder applies the brake. If you lose air pressure the brake will release. The compressor runs for about 30 seconds every 90 minutes or so and always has since the day I bought the GMC. The parking brake setup hasn't changed a thing. Some day I will find the air leaks, but it's not on the top of my things-to-do list. My compressor runs off the house battery so there's plenty of electricity. I have a switch on the dash and usually turn off the air system when I'm not using the GMC. I don't need a parking brake where it's stored so there's no reason to leave it on for an extended period. Really, the only time I need a parking brake is if I stop somewhere and have to park on an incline. I obviously won't be camping with the coach off-level by much so when I actually use the parking brake it's not for days-at-a-time. If it were, I would just use the original handle actuator with the adjustment knob cranked down.
I bolted the air cylinder to the inside of the right-side frame, just behind where the main pb cable goes through the frame on the right side. The only modifications to the GMC were to make the slot the cable runs through a bit longer and to remove the cable guide rod that goes from the cable to the right front crossmember. I adjusted the main cable at each side to take up the slack. That's it. If I want to go back to 'stock' I just unbolt the air cylinder, reattach the cable guide rod, and adjust the main cable at each side. The only 'custom' part is a kind of hook-shaped thing I made to bolt onto the plunger of the air cylinder so it grabs the cable and pushes it towards the front.
I've only tried up to about 40 psi of air pressure and it holds the GMC fine. I don't want to break cables or other parts so I'm not going to try and see what happens if I crank up the pressure. Someone else can do that experiment!
The kit that Al Branscombe makes looks great. I would love to have one, but it just comes down to money. I guess I picked the wrong family to be born into! I had to make do with what I could find and within a certain price range. If I hadn't found that air cylinder on Ebay for the price I did then I'd still be trying to figure out how to get a pedal-operated mechanism to work.
Dan, I did that once. I thought the GMC was a bit lacking for power one day and since my 'brake' dash light doesn't work all the time I forgot to release the parking brake. Thankfully I only went about a half mile at low speeds before I looked down and saw the brake handle up. That won't happen now, it's really obvious when the parking brake is on!
Hope that answers everything!
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: Trouble adjusting parking brake [message #63923 is a reply to message #63805] |
Wed, 11 November 2009 18:56 |
78 Barbi
Messages: 80
Registered: August 2004
Location: Tiverton, Ontario , Canad...
Karma: -1
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Hi All from the " Northland"
It seems there are those who believe our stainless park brake assemblies are out of line price wise. Just a note to explain the whys and wherefores as to why they have to be the price they are. A couple of nights ago " The Donald" (NOT!) and one of his meandering buddies appear to have implied that the kits are the ultimate in overkill and expensive.
This observation could hold some merit if we only sold parkbrake kits in Texas, Oklahoma or Arizona but unfortunately this is not the case. We would happy if we did not have to take into account corrosion issues and as such could cut the kit price by at least 33% perhaps more, BUT of course you can go down to your local auto parts store and buy that kind of park brake components. In fact that's what was done for 30 or so years until our stainless kits became available in 2005. If you are near the sea , in the northern states , Canada or England , then corrosion protection is a must.
Believe me , anodized aluminum and stainless steel are expensive and as such the kits are on the pricey side. However take a few minutes and check the prices of park brake components of a major GMC supplier in Florida ( not Jim or Jeff) and you'll be shocked at the price for 4 conduit assemblies and an intermediate cable. Nearly $500.00 and no stainless , no teflon, no anodized pulleys , etc. , A builder in Michigan is better but not vastly.
We have approx. 106 kits out there and 106 happy customers and hopefully the remaining 94 will be as happy, we bought equipment to do 200 kits so we're half way there . If one is going to give a 10 year warranty on material and workmanship , then you must have a superior product, the standard warranties on park brake components are typically 90 days to 6 months, hmmmm, why do you suppose this is ? Our paper work states a 10 year warranty but in actual fact as long as I exist the kits are warranty covered to the original owner . The only damage not covered is items that have been destroyed in an accident.
The same philosophy applies to the air assist actuator and a new 65 mm hydraulic/ mechanical caliper that we are prototyping. The installation has to be DOT approved and a legal entity anywhere its used. This type of engineering and manufacturing and component testing does not come cheap , and as such the costs are passed on to the customer. We are proud of our product and pleased that we can provide components at a fair price for those that require them. Cheers all and hope to see you down the road.
Albert Branscombe
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| Re: [GMCnet] Trouble adjusting parking brake [message #63938 is a reply to message #63923] |
Wed, 11 November 2009 20:08 |
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Kerry Tandy
Messages: 33
Registered: January 2004
Location: Merkel, Texas; Gold Canyo...
Karma: 0
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Very Good, Albert. I am sincerely extremely Happy with My/Your
Brakes. Let me know when you come up with something else.
Kerry Tandy
Bewartz Farms
Gold Canyon, AZ
Efax-253-563-2514
To see where we are now, click on
http://map.datastormusers.com/user1.cfm?user=38
http://www.satellitefriendly.com/user/info.php?id=bewartz
Blog:http://bewartz1.blogspot.com/
Pray Incessantly!!!
On Wed, Nov 11, 2009 at 5:56 PM, Albert&Sheila Branscombe
<branscoa@bmts.com> wrote:
>
>
> Hi All from the " Northland"
> It seems there are those who believe our stainless park brake assemblies are out of line price wise. Just a note to explain the whys and wherefores as to why they have to be the price they are. A couple of nights ago " The Donald" (NOT!) and one of his meandering buddies appear to have implied that the kits are the ultimate in overkill and expensive.
> This observation could hold some merit if we only sold parkbrake kits in Texas, Oklahoma or Arizona but unfortunately this is not the case. We would happy if we did not have to take into account corrosion issues and as such could cut the kit price by at least 33% perhaps more, BUT of course you can go down to your local auto parts store and buy that kind of park brake components. In fact that's what was done for 30 or so years until our stainless kits became available in 2005. If you are near the sea , in the northern states , Canada or England , then corrosion protection is a must.
> Believe me , anodized aluminum and stainless steel are expensive and as such the kits are on the pricey side. However take a few minutes and check the prices of park brake components of a major GMC supplier in Florida ( not Jim or Jeff) and you'll be shocked at the price for 4 conduit assemblies and an intermediate cable. Nearly $500.00 and no stainless , no teflon, no anodized pulleys , etc. , A builder in Michigan is better but not vastly.
> We have approx. 106 kits out there and 106 happy customers and hopefully the remaining 94 will be as happy, we bought equipment to do 200 kits so we're half way there . If one is going to give a 10 year warranty on material and workmanship , then you must have a superior product, the standard warranties on park brake components are typically 90 days to 6 months, hmmmm, why do you suppose this is ? Our paper work states a 10 year warranty but in actual fact as long as I exist the kits are warranty covered to the original owner . The only damage not covered is items that have been destroyed in an accident.
> The same philosophy applies to the air assist actuator and a new 65 mm hydraulic/ mechanical caliper that we are prototyping. The installation has to be DOT approved and a legal entity anywhere its used. This type of engineering and manufacturing and component testing does not come cheap , and as such the costs are passed on to the customer. We are proud of our product and pleased that we can provide components at a fair price for those that require them. Cheers all and hope to see you down the road.
> Albert Branscombe
>
> _______________________________________________
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Where are we now?
<a href=http://map.datastormusers.com/user1.cfm?user=38>http://map.datastormusers.com/user1.cfm?user=38</a>
Pray Incessantly!!!
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| Re: Trouble adjusting parking brake [message #64168 is a reply to message #63923] |
Fri, 13 November 2009 15:47 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Senior Member |
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| 78 Barbi wrote on Wed, 11 November 2009 18:56 |
Hi All from the " Northland"
It seems there are those who believe our stainless park brake assemblies are out of line price wise. ...
snip
... Albert Branscombe
|
I am in the process of rebuilding my brakes, including the parking brake. Included with my GMC were several parking brake cables. I ordered what else I needed to complete the job. Most all my parts will now be new. Looking at the work involved and the $$ I have in it, I believe I would have been able to sell what parts I have and gotten Branscombe's kit and been way ahead in time, not too far behind in $ and way ahead in quality. Bottom line, if I knew then what I know now I would have bought the kit. Don't forget, the kit has several improvements over the original design.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: Trouble adjusting parking brake [message #64242 is a reply to message #63923] |
Sat, 14 November 2009 12:46 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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The same philosophy applies to the air assist actuator and a new 65 mm hydraulic/ mechanical caliper that we are prototyping. The installation has to be DOT approved and a legal entity anywhere its used.
_____________________________________________________________
Would you happen to have a site for the DOT document?
I have an idea I have played with but we have to stay legal, hadn't we?
Gatsbys' CRUISER 08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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| Re: Trouble adjusting parking brake [message #64294 is a reply to message #64242] |
Sat, 14 November 2009 21:04 |
78 Barbi
Messages: 80
Registered: August 2004
Location: Tiverton, Ontario , Canad...
Karma: -1
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Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
Hi Larry C.,
There are as many DOT documents as Carters has pills, the’re everywhere, if you were to use a brake rotor for instance from Brembo, TRW or PBR then you would get the appropriate approval number for that piece of equipment from them, notwithstanding it has to be used for the purpose intended and within the guidelines of its particular design capabilities. In our case where we had to manufacture our brackets, we had them tensile strength tested , doucumentated and PE stamped.
The replacement part must meet or exceed OEM equipment specs, a lot of these terms tend to be blanket statements and as such help poor lawyers to provide and feed themselves. With regards to an engineering structural analysis of the GMC Motorhome park brake setup, it didn’t take a lot of imagination to conclude that the weak point was the “ thru frame S - hooks” , they in fact had a negative safety factor number. I consistently use 3.5 as an acceptable safety factor.
In the case of our actuator , it is a power assist apparatus and complements the OEM handle setup, if it should fail for some reason, the full OEM capability is still there, therefore making it a legal entity. It still went thru all the testing the park brake kits were put to because of “due diligence” but it is not part of the mechanism that keeps your coach stationery on a hill. The cylinder depressurizes about 2 seconds after you toggle in the handle and let your foot off the service brake.
With regards to the ( possible ??? ) prototype hydraulic /mechanical caliper , it will have a DOT number from the manufacturer due to the fact that it was used on some of the Beaver Monaco coaches that weighed substantially more than ours . Our coaches at 12000 pounds or so are in the range of vehicles today that primarily use air brakes. We may never find a mechanical caliper that fully qualifies as a park / emergency brake . Reasonably decent park brakes can be achieved with drums due to the duo-servo action but discs are a completely different story. The Eldorado calipers were barely suitable for the Caddy, Riveria and Toranado except under ideal circumstances, why should we think for one minute that they should work for us ?
Excuse my rambling, hope this helps a bit, but with that said; Goodness help us if we ever “ T-Bone” a bus load of kids with our modified GMC’s , myself being just a guilty as the next one.
Cheers................Albert
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| Re: Trouble adjusting parking brake [message #64302 is a reply to message #64296] |
Sun, 15 November 2009 00:37 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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Just look at the bottom of the page, there is a button that says [ EDIT ]
Click that, then hilight all that you want to get rid of then hit [DELETE]
Thats it.
btw
Do you know how much psi ( in lbs ) and what the cable travel is required to set the Parking Brake???
I don't think the handle by the dash is real reliable in that matter.
thanks
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74 GLACIER X, 260/455-APC-4 Bagg'r
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[Updated on: Sun, 15 November 2009 00:40] Report message to a moderator |
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