Excessive brake pedal effort required

[rmcb]

Like others, I do all my own stuff, devoting considerable effort to research and preparations for technically challenging tasks. This forum makes that a lot easier. The free interchange of ideas and suggestions are thought provoking and sharpen thinking. I hope we can keep this thread open and technically oriented.

I am now thinking I should investigate the difference in brake authority between my current coach and my previous one, vs assuming it is merely due to a difference in coach weight. Perhaps it is related to what Van is describing in his coach.

Hmmmmm.... could this be the beginning of the third classic Monaco chassis thread?

[Vanwill]

Originally Posted by rmcb

Like others, I do all my own stuff, devoting considerable effort to research and preparations for technically challenging tasks. This forum makes that a lot easier. The free interchange of ideas and suggestions are thought provoking and sharpen thinking. I hope we can keep this thread open and technically oriented.

I am now thinking I should investigate the difference in brake authority between my current coach and my previous one, vs assuming it is merely due to a difference in coach weight. Perhaps it is related to what Van is describing in his coach.

Hmmmmm.... could this be the beginning of the third classic Monaco chassis thread?

Roy, I have only taken a cursory look at how the treadle valve is designed, but assuming all else in the braking system is operating as it should, the actuator spring and pressure-balancing would be the key to total pedal pressure. Someone here mentioned that large trucks have gauges to indicate the amount of air pressure actually entering the plumbing that connects all the air chambers. Probably the place for me to start is to attach a pressure gauge to the line leaving the treadle valve, and see what pressure results from an extremely heavy pedal application with the coach not moving. Although my coach has ABS that adds a lot of plumbing, there does not seem to be any kind of front-to-rear proportioning valve like on some vehicles that have front disks and rear drums.

I once thought that perhaps the S-cams need lubrication, but a mechanic I think is competent told me only the S-cam SHAFT is greased, and I've already done that.

Come to think of it, the easiest place to read that braking system pressure would be at the connection I added for the Roadmaster air braking system for the toad. Maybe I can get around to that this weekend. I'm knee-deep in adding an addition on my motor home shed.

[nodine]

Originally Posted by twinboat

You all done dazzling US, with your knowledge .

If you know, don't ask.

I know Van and have spent some time with him both working on my coach and just having fun camping. He is not trying to dazzle you with his knowledge. I think he is responding to those who are telling him he should not work on his brakes. He has a degree in mechanical engieering and owns a machine tool business. He is not going to do something stupid with his brakes.

Bob

[rmcb]

Just thinking out loud here, but given the experience we have had with the Sheppard vs TRW steering gear, I suppose it is quite possible that Monaco put differently calibrated treadle valves in some coaches for some reason (perhaps availability?). It seems reasonable to me that different weight class vehicles could have different valve calibration.

Are you adding rental parking to your MH shed?

Getting mine put up turned into a big PITA but I am sure glad I have it now with our scorching 105 degree heat. Now I am making up some roll-up shades to keep the sun off the ends and sides during parts of the day.

[Vanwill]

Originally Posted by rmcb

Just thinking out loud here, but given the experience we have had with the Sheppard vs TRW steering gear, I suppose it is quite possible that Monaco put differently calibrated treadle valves in some coaches for some reason (perhaps availability?). It seems reasonable to me that different weight class vehicles could have different valve calibration.

Are you adding rental parking to your MH shed?

Getting mine put up turned into a big PITA but I am sure glad I have it now with our scorching 105 degree heat. Now I am making up some roll-up shades to keep the sun off the ends and sides during parts of the day.

Roy, the different treadle valves is a very real possibility. Sounds like I've got a lot of research to do.

Nope, the addition is not for rental But that "Watts Link Party" we all had at my house is still one of the most enjoyable times I've ever had. Craig F (alias "Pit Boss") scurried around arranging work schedules on all the coaches, and I was furiously machining all the necessary parts.

[YC1]

Just to throw this out again. My 2008 HR Endeavor with toad, (toad braking disabled today), stops great. This is a heavy setup close to 40K lbs. Yes I like the toad braking when it works but I have some issues to sort out now that we are stopped for several days again.

The brake pedal effort is not as soft as my Ford Edge which is really too light but anyone could use this brake pedal. Yes it will panic stop extremely well.

[rmcb]

I think I could feel the excitement all the way out here on the left coast. I really wanted to make a speed run back there to join in the party.

[Vanwill]

Originally Posted by YC1

Just to throw this out again. My 2008 HR Endeavor with toad, (toad braking disabled today), stops great. This is a heavy setup close to 40K lbs. Yes I like the toad braking when it works but I have some issues to sort out now that we are stopped for several days again.

The brake pedal effort is not as soft as my Ford Edge which is really too light but anyone could use this brake pedal. Yes it will panic stop extremely well.

Thanks, Myron. Your brakes are drums front and rear, right?

I think there are enough folks responding with totally different amounts of required brake pedal effort that Roy may very well be right--that there have just been different components used in varying combinations. And some of the combinations may just be better than others. Who knows?--the way things turn up on this forum, we may run across someone who has actually changed from one treadle valve to another. I'll try to take a look a bit deeper into this as soon as my schedule permits. Thanks again.

[Vanwill]

Originally Posted by rmcb

I think I could feel the excitement all the way out here on the left coast. I really wanted to make a speed run back there to join in the party.

Having you there would have made the "Party" complete, Roy! You and Deb are welcome any time!

[YC1]

Van, yes mine are drum brakes. Time to check the part numbers and build a list.

I would have run this thing over a cliff if the brakes were anything near as bad as the handling was. It would not have been an accident either.

On my last rv the chassis was a workhorse. It had hydroboost brakes and it took two feet to stop it. Some improvement was made at the service center but it was never anything I would let my wife drive. It was horrible.

To throw an observation into the mix, I noticed the rear brake line tubes went from one line of about 1/4 inch and then to smaller ones to each rear wheel. I always thought this was a bit strange. Seems that would lead to a decrease in pressure at the wheels. Had I kept it I was going to change the size of those lines.

[Stretch]

Years ago I bought and old 40ft Continental Trailways bus that had over a million miles on it. I spent several years converting it to a motor home. My first time out I noticed that it took excessive pressure to stop the coach. When I took it to a brake shop they said that only one wheel brake was stopping the coach. All of the slacks were way out of adjustment. My point here is that the amount of foot pressure did not translate into good braking. When the slacks were adjusted I applied the same amount of foot pressure and stopped much better. So if I were you I would check the slack adjuster first

[deSanford]

Took the motor home to my favorite tire shop for some nitrogen to get ready for the up coming trip. Before I moved the rig I pushed down on the brake and released about 10 times to adjust the slack adjusters. My new procedure before I move the rig. I will call Monaco and see what I can find out about the "treadle" valve etc. Sanford

[NVMike]

Originally Posted by deSanford

Took the motor home to my favorite tire shop for some nitrogen to get ready for the up coming trip. Before I moved the rig I pushed down on the brake and released about 10 times to adjust the slack adjusters. My new procedure before I move the rig. I will call Monaco and see what I can find out about the "treadle" valve etc. Sanford

[rmcb]

Interesting, a quick Google search yielded lots of posts about treadle valve failures and an apparently growing problem with internal corrosion. Now I gotta find out what kind I have, what its failure modes are and how to functionally test it.