Meritor Braking Improvement

[JohnLori]

From Mike's post on another thread on 10/11/2011: "Redlands decided they didn't like the pedal feel on the Alpine they were 1.75-ing, so they put the 2" back on. I have an email in to Keith to figure out what that means (I heard it thru PM from the coach owner). Will report further progress when such exists."

Whatever happened with that, too? What did Keith have to say? (As it is now, I am building up a stonger left arm from using my hand controls on the weak brakes.)

[EngineerMike]

I haven't heard anything new on that from Keith; we'll get a full report when he appears at the DRR gearhead Jan 20th (and when he hosts wine & cheese the evening of the 19th!!!!!).
I noted a different pedal feel on Al Goodman's 08-36MDDS w/the 1.75, it seemed softer, & like it traveled further thru a stroke w/more stopping built in earlier in the stroke, more even additional stopping throughout the length of stroke, and easier stopping overall. Keith did a stroke length test and reported same length of travel, so maybe my foot calibration is misreading the stock pedal travel w/less stopping early in stroke as a shorter stroke (maybe I've got DFS- Dumb Foot Syndrome). I plan to install the new 1.75 cylinder as soon as I can do a 4-wheel bleed and fluid replacement at the same time.

[wa8yxm]

Originally Posted by kraig

I did get a chance to give it a severe test on I-5 in Seattle. I was in the right lane and there was a car stopped on the shoulder. Without signaling or a accelerating pulled out directly in front of me!!!!

You ever wonder what (OR IF) the drivers of those little bumps in the road are thinking when they pull out in front of 25,000 pounds of motor home or worse yet 160,000 pounds of steel hauler?

The one who pulled out in front of me recentlly at least did it far enough ahead that I did not have to flat spot the tires.

[RickGyver]

I have been having trouble finding the correct master cylinder for the hydroboost system with disc brakes. I finally had success an hour ago and the MC is being overnited. I have casting number 2232543, 1.75" bore, sensor plug on inboard side to turn on warning lite and a bolt head on trailing end. On line at FinditParts.com for heavy trucks etc.. The PN is Centric - 130.79025. About $240 from L.A., Ca.. I have the remote reservoir but may leave attached one on.Aluminum plate on top of MC with lines going to res on firewall. I got lots of info from this thread and am looking forward to modifying the pedal linkage. MC should arrive in the morning and I hope I don't have to edit this post because I have been sent two wrong master cylinders this week!! Will let you know how it turns out. These people at FinditParts.com were very helpful finding the correct part. I made the man go pull the MC and describe it to me so I'm fairly confident I'll get the correct MC. WOOHOO!! I would post a picture if I knew how!! (hint,hint)

[takepride]

Originally Posted by RickGyver

....I would post a picture if I knew how!! (hint,hint)

Several people have asked about posting photos recently, so here goes.... From Forums 101 thread:

Click Quick Reply and scroll down to bottom of text box.
Click Go Advanced, add text to message window and then scroll down.
Click Manage Attachments. A separate window will pop up.
Click Browse... then select the file to be uploaded. Be sure that the photo is appropriately sized. 620 x 620 pixels (or smaller) and no more than 100K. Forums software will automatically reduce the size, but smaller size photos will upload much faster. You may select several photos to upload at the same time by repeating the last step.
Click Upload. After pics have loaded, close the pop-up window.
Click Submit Reply to post the text of your message - photos will automatically appear at the bottom of your post.
You can also:
Click Post Reply or, if starting a new thread, click New Thread
Click on the paperclip symbol in the top row of the message box. A separate window will pop up.
Click Browse...then select the file to be uploaded. Be sure that the photo is appropriately sized. 620 x 620 pixels (or smaller) and no more than 100K. Forums software will automatically reduce the size, but smaller size photos will upload much faster. You may select several photos to upload at the same time by repeating the last step.
Click Upload. After pics have loaded, close the pop-up window.
Click Submit Reply (if you are replying) or Submit New Thread (if a new discussion) to post the text of your message - photos will automatically appear at the bottom of your post.

[RickGyver]

I' definitely going to bookmark this page! Thx, Takepride.

[Renipladlo]

All - I don’t want to rain on anyone's parade butttttt!

If you make the change of master cylinders (MC"s), and have an accident, have you?

1. Changed a DOT approved chassis braking system and opened yourself up for a lawsuit?

2. Modified an approved design of a brake system with the changed and done the same as number 1?

I am asking, because although I want easier brakes, so the BH can drive the coach, I am very leery of making a change like this and then some hotshot ambulance chasing lawyer finds out and his client sues me to the moon and back if I’m involved in an accident where my brakes might fail!!! Personally bi-annual brake fluid flush/change makes it work much better for our coach.

I am opening up this discussion because every day there are hundreds of commercials on TV about this lawyer wanting to get your business for every medical condition known to man and god only know what else so they can get you 1 cent on the millions of dollars in a class action suit, etc. This is not a slam on lawyers (well it is actually there should be restrictions on them, or something) but I am for one real tired of seeing their ads, in fact, it's one of the reasons I am planning on cancelling my Direct TV when I get home.

So back to my original thought, are we in violation of some rule by modifying the brake system changing the original design? Now that brings to mind, in Hawaii years ago (when in the Navy there), you could get a permit from DOL, to change a basic mechanical design on vehicle, it was called a “reconstruction permit”, you outlined the changes and they approved it, and it went into the vehicles DMV record. Does anyone know if we can file a paper with DOT for this change? The steering bracket stiffener might also be under the same rule or called the same thing. But in that case, I can tell you, I have at least 50% improvement in my steering after the bracket installation with the additional two bolts being added because of the cracked OEM bracket. The crosswinds don’t push me as bad, and the MH tracks down the road with less input to keep it straight.

[Family Man]

Monty,

You are exactly correct - you should cancel DirecTV. I did several years ago and my family is much better for it!

The Family Man

[Jim A]

Monty,

Buy a DVR and record everything (which is very easy to set up), and scan through those annoying (and repetitive) commercials. Watch what you want when you want, and save about 20% of the time by skipping through commercials. I have two at home and one in the coach, and rarely watch anything "live". Worth every penny.

Back to the thread. I would be willing to risk the suit to obtain better braking power. But it is also why I went to a professional that I trusted to test it out. They weren't happy with the change, so we went back.

Unfortunately in this country anybody can sue for anything, and many abuse this right. Many people in CA view having an accident as winning the lottery and the chance to sue somebody with deep pockets. Fortunately many eventually don't collect that pot of gold. (Only the lawyers do.)

[EngineerMike]

NHTSA doesn't "approve" brake systems per se. They require brake systems to meet certain standards, and they 'accept' various forms of evidence demonstrating accordance w/their standards, up until field evidence shows they don't (in which case they issue a recall notice). E.g.:
~ brake parts must be of materials & design "suitable" for the application (corrosion, vibration, deterioration resistant as needed for the subject part, durability to resist the forces applied...)
~ brake system must have certain redundancies &/or safety features
~ ABS & other add-on features must fail to a failsafe condition
~ system must be capable of certain stopping power levels

Typically a manufacturer will test, or have their stuff tested, to provide a 'certification' that the system meets the min. standards of DOT Spec xxxxx, to demonstrate such compliance. DOT3 brake fluid for example has to meet certain standards out of the bottle, and is tested by the mfgr's or some independent lab to so demonstrate; however over time it absorbs water during actual use. Is the motorhome operator whose brakes fade subject to liability because he never changed his brake fluid and it doesn't meet DOT# spec anymore, and it looks like dirty honey, contains plenty of water, and steams off during hot hard braking, killing his braking capacity and causing an accident? The guy is at fault for that accident, and liable for the damages, but the liability isn't because he didn't change his brake fluid, but rather because his failure caused the accident.

If you do something that improves braking function, so much that you cause a wreck by stopping too fast, you may be liable. If you improve function some, but don't cause an accident nobody has cause to sue. The real question is whether you did something non-standard to your brakes that caused an accident for which you will be liable. I recommend don't. And if you are messing w/your brakes, I recommend you make sure they work at least as well as the OEM setup, and maybe so note in your maintenance records when the mod is complete.

[Al Goodman]

It’s been over a year since I replaced the master cylinder on the Alpine with the smaller bore unit(1.75 inch vs the factory 2.0 inch) and I have no regrets. My wife enjoys driving the coach and there is substantial improvement in coach braking. I note where Redlands Truck was unhappy with pedal feel after installing the replacement master cyl. I had discussed the difficulty I had with getting a good pedal feel with Engineer Mike after my installation, and am not totally surprised at their difficulty as well (however I’m certainly NOT questioning their method or ability). I contributed my problem with getting air pushed into the system from the new master cylinder; I still feel this was the case. I spent almost a full day in getting the system fully bled and a good pedal feel (fyi – although several years expired, I have held a class “A” brake certification/repair license, and do know a bit of what I’m speaking of). I first bled the system with all wheels off first using a venturi suction device (made specifically for bleeding brakes), when that didn’t produce a good pedal I tried with having someone inside vehicle pushing pedal, neither method produced a good pedal. What I finally found did produce a good pedal was to “force bleed” it. I accomplished this by utilizing one of the tops from the old master cylinder and installing a Schrader valve in the cap, then connecting that cap to the new master cylinder. Using nitrogen at 6-10 psi I “forced” (brake) fluid thru the system (be sure to check fluid level often).
Several people have inquired how to purchase the replacement Master Cylinder. In post 25 above is the source where I purchased mine, Redlands Truck and RV (post 30 above) also appears to have found the correct unit, Post 46 above shows a part number and where Rick may have found his, or it should be available from any heavy duty truck parts house. Since purchasing mine I have found what I’m quite sure is the correct part number. I established this by going to a local heavy truck brake parts distributor, showing them my stock unit and what I was looking for. They found the correct replacement pretty easily. Wagner PN 131759 - Wagner is not the manufacturer of the entire product, but was told their name is on the “final” assembly, and of course it is a direct bolt in. Cost is not much different from what I paid ~$300. But hopefully some of you can get a better deal on it.
Last but not least - Brake Fluid - I used almost a full gallon to get the system completely bled. I would use any quality DOT 3, or 4 brake fluid, these are advertised as synthetic (polyglycol and glycol ethers), however do not use a silicone based DOT 5, as it will be detrimental to your pedal feel.
Only really noticeable (outward) difference of the master cylinders is the reservoir size is larger on the original, however that’s not an issue with disk brakes, we need pressure, not volume.
The fine print/liability disclaimer: The information above is simply a statement my findings and of what I’ve done for what I felt was a problem. This modification is not for everyone, if you’re happy with your brakes, I wouldn’t change a thing. I urge you prior to even considering this modification to check with your mechanic / professional of choice get and follow his advice. This is a safety issue and should be treated with due respect. This is simply a statement of what worked for me.
Al Goodman
2008 36MDDS

[Al Goodman]

Monty, I think your right, should any of us that have modified anything be involved in an accident, and that accident was caused by or proven to have been escalated by such modification we would be named as a partly in any lawsuit. That said I don’t think it would be any problem to prove this modification made the coach safer. Honestly I’d be more worried if the coach was over weight limit.
So I’d ask you… If I knew the brakes were (shall we say) less than “perfect” would I have increased liability should I have an accident where I couldn’t stop the coach? I like my legal standing much better being able to more easily stop the coach, and the bonus is my wife can drive it comfortably!
All that said you don’t stop 30,000 lbs on a dime and I agree with wa8yxm I to truly do wonder what (or if) cars are thinking as they dive in front of us?

Al Goodman
2008 - MDDS

[Renipladlo]

This is why I love this forum, so much great information.

FWIW#1 - About a month or maybe only a little less, before I left from home and headed south, I had the local Detroit Diesel/Allison shop flush and bleed my brakes since it has been two years since the last time. The other day we had to move the coach from one park to another, doing much of the trip in traffic. I can report, that the flush improved the brakes a whole lot and I did not feel as apprehensive as before the maintenance was done. It may not have cleared up the whole issue, but made a vast improvement in mine. This note is not intended to invalidate anyone else doing the MC change. I am good on brakes but not an expert by any means so unless I can/could drive my coach and one with the change to see and feel the difference I will live with it this way.

FWIW#2 - The BH is not strong enough to drive the coach anyway, regardless of the pressure needed to push on the pedal. She has a lot of trouble pulling the parking brake knob out, and pushing it in, so to drive it would be more than she is capable of.

But, she is the best navigator and map reader bar none, and I trust her to help me back up more than anyone, so our "team" works for us. Plus on occasion she will bring me a beer when we are parked and taking it easy, so she is a pearl among the sand as far as I’m concerned.

FWIW#3 - I have considered an upgrade DTV unit with the DVR option, but then you must commit to another two year deal. I don't want that either, so I'm going to look through the thrift stores, etc and see if I can run across one, someone turned in as a contribution. Then I will clear its account and put it in the MH in such a way as I can move it to the house when we are home. I will say the digital antenna WRV used on the roof does not have much gain for my signal, as we need to be very close to the transmitter for the TV to receive a good digital local signal. It also might be the Dell Tuner is just not very good, but every other part of it works well. Heck, I should not be in front of the TV anyway, should be out walking or getting some kind of exercise so I can live long enough to pay this thing off.

[Old Trucker]

Originally Posted by EngineerMike

Since we've just been 'Round the Horn on Jake Brake, this is the perfect topic to come next.

Kraig- what shop made up your no-longer-new brake lines, and how did they reuse the banjo (it looks to me like its crimped on the hose end)? Sounds like a worthwhile mod.

I know of two Apliner's who have modified their bell-crank that sets between the brake pedal and the Hydro-Max. One moved the lower pin closer on its original offset plate to the vertical spindle pipe by about 5/8" changing the bell-crank from a 1:1 (top offset from the brake pedal to spindle, lower offset from the spindle driving the HydroMax), to a ~1.3:1 or maybe 1.5:1 leverage. Bada-Bing, improved brake response. He angled the HydroMax to maintain the correct actuator geometry, accomplished by shimming out the forward two bolts holding the hydromax to its bracket w/about 1/4" of stacked washers.
The other bell-crank modifier IIRC ground off the OEM lower offset plate, and welded on a new one w/the actuator pin located about the same shorter offset from the spindle as the first guy (~5/8"), and then ovaled the HydroMax mounting holes to slide the master cylinder forward the 5/8" on its mounts (no shimming required) to maintain actuator geometry.
Both drivers report satisfactory brakes after long frustrations of inadequacy.

Just heard a couple days ago from another Alpine hot-rodder who can't leave OEM stuff alone. His brake frustrations took him to a truck shop in San Diego area w/a sort of Yoda-like brake sage. The sage's advice- "You've got the wrong master cylinder sonny. You've got the 2" bore HMax (you can see the bore diameter cast on the steel cylinder, it says 50.80 which is 25.4mm x 2 or 2" for us dummies which they could have cast on the cylinder so I don't have to do higher math), and you should git yerself the 1.75" cylinder." Preliminary tests and the driver reports about 30% better brake response out of the box (which corresponds directly to the ratio of 2" cylinder area to 1.75" cylinder area). The actual master cylinder portion of the HMax is the right-hand (for under the gen cap HMax rigs, and forward facing for under the drivers floor boards rigs) black painted portion w/4 bolts holding it to the aluminum housing of the boost section of the HMax assembly. On the 04+ M.Y. rigs it has the Dot3 tank on top of it. The driver changed it out himself, then bled all 4 corners inside & outside bleed screws. He reported the bleed process took a long time, but Voila! better brakes.

My theory takes us back. Way back, to maybe 1997-ish. In my collection of trash bequeathed to me from Cummins NorthWest is a stained, partially illegible, hand drawn partial hydraulic schematic. I asked Mike Young what that was all about. CNW participated in a recalibration of the hydraulic system somewhere in those earlier years with WRV personnel, necessitated by early death of some air compressors. Seems too-high strain on the compressor shafts from the hydraulic pump (which is mounted on the forward, for us (rearward for Cummins since the engine in a pusher is mounted backward according to them) making unnecessarily high pressure. Fix was to put the rig in the shop and tune the pump output down by shimming, which relieved strain on the compressor's shaft. Future pumps were supposedly ordered pre-shimmed to make the correct, somewhat lower pressure.
Fast forward to 2007, Cedar41 had a brake problem where when he started the engine & the brake pedal depressed 1/2" partially applying the brakes (and overheating his fronts after not very long down the road, and probably using up a lot more fuel). Turns out his hydraulic pump was over-pressuring the system and auto-applying the brakes; new pump and Voila! back to good again.
Fast-forward some more to 2011, I'm test driving the heck out of some Jake Brake issues, and I notice the hiss coming from my steering gear at idle RPMs, which goes away w/even very slight rise in RPM. So I put 2+2+2+2 together to make 4, and codger up a theory. Hydraulic pumps are not all sent out of the factory the same. As you can see, its a pretty complicated theory, which explains why it took me 4 years to codger it up. My pump is mounted on a PTO off the transmission (I think all ULSD-Only engines received this new setup), so for it to be different in output than the compressor shaft mounts is easy to surmise. But the earliest units (which were likely all the same pump model) needed tuning, so maybe mine does also.

Sooooooooooooo, my bottom line is I think my rig isn't making enough hydraulic pressure to properly boost the 2" cylinder, and maybe that's the trouble w/the various, random Alpines that report hard-to-operate brakes. I have some hydraulic pressure gauges, but I may need a flow gauge also. I have the R.H.Shepperd steering gear spec (2175 psi max, 3-5gph) and the HydroMax spec for input some place (1000psi and some flow er other IIRC). Placing one gauge before the steering and one after should tell me if the HMax is getting correct feed and steering also. Just need to hunt down the equipment and get some hydraulic fluid all over myself to run the test.
Motorhomes are great!

Hi Engineer Mike, I have a 99 alpine 36 ft SDS. I have had total brake failure twice. Each time the master cylinder was full, the pedal would go to the floor and would not pump up,. The first time a Peterbilt shop found a loose wire at the brake booster. The second time the computer showed a faulty sensor in the ABS system. Parts were not available and the system was unplugged. At t
he time of failure, no repairs were made, but the brakes came back to normal?? This is spooky. This is when the system was unplugged.It does not make sense to me is when one wheel sensor appeared to be faulty, but loose brakes completely??
With the engine off ,the electrical brake motor makes the noise with the switch on or off, but the pedal will go to the floor with very little resistance. Is this normal. Pedal has always been just a slight bit spongy, but no problem stoping. Any suggestions?? old trucker