Meritor Braking Improvement

[EngineerMike]

OT- the answers you were given would not have satisfied me. The pedal-to-the-floor response is not indicative of an electrical failure, but rather a brake fluid failure (overheated fluid which has lost its incompressibility, air in the lines, or leak). With system returning to normal, the only one of those that makes sense to me is overheating.
ABS should be agnostic as to braking power unless it overreacts w/some kind of brain fart & overengages. ABS systems are supposed to fail to a safe condition, i.e. normal braking as tho no ABS existed in the system.
Ordinary brake boost is hydraulic not electrical, you only get electrical interjected w/engine off and the electrical pump making brake assist, which it sounds like you have working correctly. As to the pedal going to the floor w/little resistance, question is w/parking brake off can you stop coach from rolling easily? If you are trying it w/coach park brake ON, then you are not testing the brakes, just the pump. I would have to say it is easier to push the brake pedal down on mine w/engine off & electrical pump making brake assist than it is w/engine running, so that sounds like your and my rigs feel somewhat comparable.

I think the pre-adjustable pedal rigs like yours have more mechanical advantage to operate the brakes than the 04+ rigs, but I haven't done any measurements on that to prove it; just looking at owner responses who had older rigs they traded for the new design.

[EngineerMike]

Quick update- we stopped at Redlands Truck & RV on the way home from Quartzsite, and had them swap the 2" m.c. out for the 1.75"
Results- Priceless.
Braking improved by about the theoretical 31% referenced above, plus the pedal feel is smoother and braking power more linear through the length of pedal stroke. I drove around town in Redlands w/the Jake off and no problem braking in traffic. Driving on freeway out of town (rush hour was just starting, so no real stop & go, but getting thicker) was a breeze, and again I only put the Jake on when on-ramp traffic was thick merging in w/us in the slow lane. My pedal feels just like Al Goodman's per my earlier test drive of his coach at Tahoe in early Sept. Have couple hundred miles on the new brakes, and W-O-W!! EngineerAnnie is going to love this. I think a lot of spouses will improve their confidence behind the wheel on 04+ rigs w/this mod. Jim Archer, who had Redlands take a shot at this per prior posts, pulled in for other service as we were hooking up, and will probably have them complete this mod on his 04.

I don't think you can reliably swap out master cylinders w/out bleeding the whole brake system, and highly unrecommend it. In discussing it w/Keith, they will likely modify their kit price to only include a full bleed process; doesn't make sense to attempt only a swap of the m.c. as you will introduce air. I had Redlands remove all wheels; I did caliper inspection at all 4 corners (allz well) while they bench bled the new m.c., & took the opportunity to have them finally fully seal the bulkhead in front of rear wheels and install Henderson's MCU's on rear air lines (we also discussed double-shocking the front for fun (will report on further dual shock developments if such transpire). I worked w/their tech on bleed process (which we promptly screwed up by power bleeding a full tank plus some air into the first caliper). We made up a custom power bleeding cap out of one of my 2" tank caps, used a regulator & valve to hold bleed pressure down below ~15 psi, mostly below 10. Once we had the process down the other 4 corners went straight forward. Takes a gallon of Dot3.
We'll be on the road all day tomorrow, and will post more when we are home.

And yes, the wrist is healing nicely. Stitches came out Friday, and we left Havasu Sat a.m. I drove a bit yesterday, and a bit more today including test drive and Escape from L.A.

[Jim A]

I drove Mike's coach yesterday, and he is right. The feel of the brakes is very good, and plenty of pedal.

[EngineerMike]

Got home to Auburn, CA and the whole trip was a pleasure. EngineerAnnie did much of the driving, and felt very confident in being able to handle the coach now w/its improved service brakes. I can't lock the wheels up on dry pavement, but stopping is substantially shorter now. And braking below the Jake threshold of 16mph is comfortable, not a nail biter. Holding rig at a stop light is a breeze as well.
I'll post comments again for follow up. We don't have a trip planned till ~April.

Anyone contemplating this mod should compile a list of other things you've been needing that can be accomplished easily w/the wheels off & gen slide out. 4 Wheel caliper/rotor inspection for sure, wheel end inspection also (I found FR Stemco oil bath cover leaking due to slight overfill, so I wicked out some excess oil w/rags & cleaned that up; other wheel ends all tight & clean), MCU's (I've been carrying rear MCU's for several months, and had Redland's guy put them on), seal any rear bulkhead dust leaks (I've been fighting that, and hope we finally got the last openings tightened up), grease rear end, inspect shocks (and do some more figuring on double shocking project for front axle), check fuel fill circuit(s) for leaks & cracks in neoprene tubing, check wheel well wiring looms for adequate securing to frame.

The whole process of setup (coach on jack stands, 4 wheels off, gen slide out, laydown of fluid catch mats, assemble & arrange tools), bench bleed of new M.C., swap of M.C., 4 corner bleed (outside caliper first then inside, then next wheel), cleanup @ M.C./gen & 4 corners, wheels on, test drive, is going to take ~5 to 5.5 hours in my estimation, assuming you are set up for this type of work (power bleeder assembled). We started right at 08:00, and test drove starting ~14:30, and this included lunch hour, & ~20 minutes making the power bleeding adapter, and some analysis about the order & process (total for my swap ~7hrs). On a 34 or 36' coach, front calipers are farther as line travels from M.C. than rears; on 40 footers front & rear are about the same distance tho on all lengths RR is farther than LR due to axle cross over. So bleed process for uniformity IMO should be FR outside/FR inside, FL out/in, RR out/in, LR out/in. The outside caliper is fed from a cross over line off inside caliper fluid gallery, so bleeding outside first partially bleeds inside as well, and inside should take a bit less time. Total bleed will require a gallon of fresh Dot3 on hand, and a good pumping setup to deliver to the tank. Pigmat (oil absorbant mat) is a good precaution under the M.C. & on top of gen to catch fluid that would otherwise eat up the gen paint. Some attentive cleanup time will be essential.

I am very happy to have this completed.

[Basil Shannon]

Now that several owners have had this mod done, inquiring minds want to know about how much it costs. Do I have to apply for some Obama bucks to pay for it?

[EngineerMike]

For cost reasons, I would only recommend this mod when you are doing your regular brake fluid flush/brake inspection (which should be on a 2 year cycle regardless of mileage, Dot3 fluid gets old & absorbs water, which is a bad thing for brake systems).

Once you are in for fluid flush on the 4-piston brakes, you have already burned the overhead of setup (getting into facility, putting coach on jacks, wheels off/on, fluid flush, clean up, test drive). No reason to duplicate this work out of cycle IMO.

Now the cost of the mod is simply- cost of new M.C., bench bleed, & part swap. Bleeding & reassembly from there is implicit in the brake bleed process we pay for anyway. My M.C. was ~$340 delivered, call it an hour & a half or so of shop time for the parts setup, bench bleed & swap. If that was under $500, I'd say its a good price for what you can get on the street, and a bargain for the braking improvement. If getting ready to order this, I'd call the shop ahead of time & make sure they order in the new M.C. to have it in stock; that makes it a same day job.

I'm not sure what standard pricing is for fluid flush. I'd say anybody doing this w/wheels on has either got to be a genius to get at the outer bleed screws, I can't see how to do it reliably, or is cheating the process. And of course you have to remember any Dot3 spill on caliper parts has to be cleaned up, the stuff is quite corrosive, so w/wheels on if you spill any fluid on the calipers you won't be getting a proper job. I did my fronts some time back for fun, & its way the heck difficult to do the bleeding w/out some spill. Doing a full power bleed to eliminate air from the system is harder due to increased fluid velocity (I was doing gravity on my fronts & still slopped my share of fluid around).

[two sailors]

I was quoted 1295 by Redlands. I am schedule for Tuesday. The brakes on our Alpine has always been a concern of mine. I am very happy that a fix has been found.
Thanks to those who figured it out!

[JohnLori]

How does that relate to post #30? What all are they doing?

[two sailors]

The post on #30 is the price of the master cylinder. There is alot of man hours involved in doing the job properly. My 05 has never had anything done to the brakes.
I feel much better about being in heavy traffic. A BIG difference in stopping ability.

[Old Trucker]

Quote:

Originally Posted by EngineerMike OT- the answers you were given would not have satisfied me. The pedal-to-the-floor response is not indicative of an electrical failure, but rather a brake fluid failure (overheated fluid which has lost its incompressibility, air in the lines, or leak). With system returning to normal, the only one of those that makes sense to me is overheating. ABS should be agnostic as to braking power unless it overreacts w/some kind of brain fart & overengages. ABS systems are supposed to fail to a safe condition, i.e. normal braking as tho no ABS existed in the system. Ordinary brake boost is hydraulic not electrical, you only get electrical interjected w/engine off and the electrical pump making brake assist, which it sounds like you have working correctly. As to the pedal going to the floor w/little resistance, question is w/parking brake off can you stop coach from rolling easily? If you are trying it w/coach park brake ON, then you are not testing the brakes, just the pump. I would have to say it is easier to push the brake pedal down on mine w/engine off & electrical pump making brake assist than it is w/engine running, so that sounds like your and my rigs feel somewhat comparable. I think the pre-adjustable pedal rigs like yours have more mechanical advantage to operate the brakes than the 04+ rigs, but I haven't done any measurements on that to prove it; just looking at owner responses who had older rigs they traded for the new design.

Hi Mike, I have a 99 Alpine. This trhread talks about the brake pedal going straight to th floor with no resistance. You and everybody else say, it must loose fluid in the master cyclinder. I have worked around cars, motorcycles and owned several 18 wheelers. I would certainly agree with that, Until I has TWO experiences with this coach loosing all brakes with a full master cylinder with no fluid lose. The first time there was a loose wire to the electric booster. The second time a sensor on the ABS. My Abs has since been unplugged Brakes were not hot either time.

After reading the Alpine Form and Meritor brake info, it appears that brakes are a common problem. Why is everybody replacing the Master cylinder, What is going wrong?? I am planning to change fluid this week, it is a 99 model with 72,000 miles. I have owned since 12-09. Doubt fluid has been changed. Sure appreciate your help. Best wishes, old trucker

[Dave Fernandez]

Hello Old Trucker; The majority of the replacement Master Cylinders on the Alpine’s has been on the Newer Alpines with the adjustable pedals because of high pedal pressure. The replacement Master Cylinder reduces the amount of pedal pressure needed to stop the coach. On your 99 and my 2001 and all of the through the floor brake pedals have not experienced high pedal pressure to stop the coach.

The older Alpines through the very early 2001’s (Build in late 2000) the brake calipers were floating and have pin sliders which need to be lubed regularly to prevent them from sizing up. The remainder of the 2001’s and newer have fixed calipers and lubrication is not needed on the calipers.

The brake fluid on all hydraulic brake systems (Autos and Motorhomes) should be flushed every two years due to contamination of the brake fluid.

I hope this answers some of your questions.

[gjstacy]

We are taking our coach down to Redlands on Monday for this upgrade, and picking it up again on Thursday. We can't wait to feel the difference on our way back home!! Let you know how it goes....

[kraig]

Al- The Wagner part #F131759 was correct. Brake Systems Inc in Portland had one on the shelf, in a sealed box, so I took mine on off and matched it up it ok.
It is even made in the USA. Cost was $352.99.
Thanks for the part number.

[Paul "Sully" Sullivan]

Just ordered a MC from Amazon, $232.00, shipping included no tax. Will post if there are problems.

Amazon.com: Wagner MC131759 Master Cylinder Assembly: Automotive