Bad master cylinder symptoms

[tatkin]

Sent: 6/19/2006 11:39 AM

Here is what is going on.   I just had the back wheel cylinders replaced. They bled the entire system.    The mechanic told me that when driving the rig the brake pedal gets lower and lower with every ? brake pedal push. This is why I originally took it in.     They think it is the master cylinder.   Could that brake booster cause this ?

[Slantsixness]

Sent: 6/19/2006 12:18 PM

Tom,

Here's the scoop.

If the pedal gets lower as he drives, you have to be leaking fluid. If you're not leaking fluid that you can see, it could be the master cylinder.

Common practice os to blame the rear wheel cylinders frist, even if they are not the root cause. The internal piston seals in the master cylinder will break down over time and leak between the front and rear fluid reservoirs, and you will never see a fluid leak per-se. Alternatively, the rear seal can go , and you can fill the whole Brake booster with fluid until it finally starts getting into the intake manifold (this has happened but rarely.)

The Master Cylinder in these Winnies is such a bear to get to to fill or check, that it's just easier to count on replacement if it's suspect, rather than servicing or repair. They're cheap enough, just ask Geoff at   he'll have the part on it's way in no time (and just as cheap as anybody will have it, give or take the minimal Core charge...).

Your symptom can indicate a bad master cylinder. However, it very well could be Just air in the lines. (I suppose they already checked the bleeding 3 or four times already!) So I Hope that's all it is, for your sanity!

Hope this helped. Geoff should actually even have the Master Cylinder in Stock ready to ship....

Tom

[denisondc]

sent: 6/19/2006 12:22 PM

If the fluid is leaking from your master cylinder, and you can not see it dribbling anywhere, the next thing to check is the vacuum hose from the booster to the intake manifold. You want to find it mostly dry inside. If there is a leak into the booster, you will find the inside of that vacuum hose damp with brake fluid.

[tatkin]

Sent: 6/19/2006 4:32 PM

I printed this thread out and took it to the mechanic ...   These guys are allready good mechanics.  I told them sorry, but I am putting my nose in here,  I have an interest in the outcome ...  Finding a good mechanic is like finding a barber you always want to use .

[salplmb]

Sent: 6/19/2006 6:01 PM

hey tatkin,

my rig is the rm350 model also. i had a hard time getting the right master cylinder also. got the wrong one twice. ended up just replaceing the seals in my old one and it works great. i didn't have the resource of geoff and alretta at the time. this master cylinder has a weird size bore piston and rod. everything eslse looks right but the insides will be wrong. makes a big difference. i would go with geoff and order the right one the first time. once i got the brakes back together it it really stops on a dime! it will litterally almost throw you out of the seat if you hit them hard. i wish my dodge daully truck stopped as good.
well, good luck.
sal

[brakeparts]

Sent: 6/20/2006 2:31 PM

Tatkin -

Please call me and I can supply a new master cylinder for your vehicle. There is only one correct part and the local stores do not have it, but they will have one that looks like it and will play havoc with your front brakes, locking them up.

Save the trouble and follow the various members advise!

Call me at 508-788-9409 days, 8am - 6:30pm EDT, exclusive hours for Classic Winnebago members (wink,nudge).

I need to ask a couple of simple questions like front disc brakes, GVWR, twin piston calipers, twin hydrovac units ??

This is not an inexpensive part, but making a mistake will invariably cost even more.

Yours,

Geoff

--------------------------
Alretta Truck Parts, Inc.
Bldg.#5B, 2nd floor
One Watson Place
Framingham, Ma. 01701

Tel# 508-788-9409

http://www.alretta.com

"Where Parts are a Science and Service is an Art!" ?

[tatkin]

 
Sent: 6/25/2006 2:44 PM

Well the master cylinder is off, I think that is a good sign.   I don't know if they called that Geoff though ...

[tatkin]

Sent: 7/1/2006 11:50 AM

I went down today 07/01 to take a look and there is a brand new master cylinder on there .     Hope that ends this fix ... 

[tatkin]

Sent: 7/6/2006 2:28 PM

The saga continues.  Now the front disks, cutting of something.   This baby better/should/will be brand new under there when done ...    They are even replacing the brake lines ...

I think we should have a lottery for the closest guess as to what all this is going to cost me ... 

If they do/better get it right then I am wanting to do all the steering next.   

[denisondc]

Sent: 7/6/2006 3:47 PM

The need to replace brake lines is fairly common on any vehicle as old as ours. Other than advanced rust, it is usually the result of trying to unscrew the flare nut from the brake fitting - (be it at a wheel cylinder, to a brake hose, or to the master cylinder or brake-warning switch). The brake line turns with the flare nut, and is ruined by the twisting.

I was able to get all of the fittings to unscrew on my winnie, but mine was only 19 years old when I did this, and I was able to soak the fittings with penetrating oil, day after day. A commercial repair facility doesnt have the luxury of being that patient. Since then I keep all of those locations from further rust with at least annual doses of oil or grease.

It will be interesting to hear what they did to the front brakes. Often a repair shop will want to machine the brake rotors to make them smooth, and eliminate grooves. Its called 'turning the rotors'. I have replaced rotors for being worn thin or being warped - but not for just having grooves.

I am eager to learn what a thorough brake job would cost in a vintage motohome. I know it takes me plent of hours to do the brake work on mine every few years.

[ClydesdaleKevin]

Sent: 7/6/2006 3:48 PM

poor bastage!!!  Should have done it yourself!!!...lol

Anyhow, nothing you pay could be worth the safety to you and your family that good brakes will afford.

Kev

[tatkin]

Sent: 7/6/2006 7:16 PM

In my mind, whats left of it anyways,  2 or 5 thousand is a heck of a lot better than $70k+ for a new RV.    And it will be a  KoolAssic

[Slantsixness]

Sent: 7/7/2006 4:02 AM

Tom,

I did my brakes myself. All new lines, new Master cylinder, proportioning valve, new rear hardware, new rear shoes, and I converted the front brakes to Discs from drums, which meant new rotors, calipers, pads... in doing this, I also replaced all the wheel bearings (all 8 of them, including the races). I got the disc brake hubs, brackets and other hardware from a '75 RM350, at a very nice price (Thanks Bob!)

Total brake cost (parts only, I didn't pay myself to do the work, of course!) $1150.00 (95% of the new parts came from Alretta). Not bad, and I figure this isn't bad for the same reason you do. A new Winnebago View is $70 K. I have over $10,000.00 in my Winnie. I know I'll never see that money again, but being able to say I did it myself, and enjoying every minute and every awkward stare when people see it (you drive THAT? and THAT still runs??) is priceless!

Now... last night my wife and I came across a '75 Chieftan 27CL on the way home... and It's for sale..... so what?... do I start all over again???!!! If the price is decent..... my WIFE wants it....! WhatthehellamIgonnado with 3 Winnies??? Geez!

Speaking of Winnies for sale.... I know where there is a 72 C20 for sale (northern VA) GM chassis with a 350/Turbo400 and independent front suspension, recent roof, in running, useable condition. I haven't seen it in person for about 3 years, but It's a co-workers neighbor.... he now wants to get rid of it... it should be fairly cheap...maybe under $1K but I dont want another 20 footer.... I may go up and take some photos and put it up here for sale for him.... Winnies are everywhere...!


Tom

[denisondc]

Sent: 7/7/2006 7:03 AM

I agree you cant get the money back you sink into it, but if you check out the cost of renting a motorhome for a week or two, you find that you are still money ahead for the pleasure you get. And my Winnie is still my private space, with lots of memories of family vacations. One of the reasons I enjoy driving my vintage Winny, is knowing that 99% of the other RVers would are just not able to keep an old one going. Either from lack of time/skills or money to pay to have the work done.

I have somewhat under $10,000 sunk into mine, including purchase price, cumulative repair parts and the tires too. Thats over the 15 years of our ownership. I have a stack of spare parts too, which is almost as tall as I am, which cost me about $1000 and many afternoons in junkyards, fighting ticks, wasps, snakes, poison ivy, and rusted bolts.

[tatkin]

Sent: 7/14/2006 1:27 PM

I can't believe it, I'm gonna cry.

So I goes down to the mechanic.  He says everything is done on the brakes, Hooray is in my mind.   Now it won't start he says, he says it started every time before today.   I go out to it and the head lights light, I test the battery and it shows plenty of juice,  but nothing when turning the key...   I pull the captain chair and get under there, the ignition fuse is burnt.   I replaced it but sill no go.  Anyway I told him, now you have another task ...   Sheet ... 

[tatkin]

Sent: 7/15/2006 4:06 AM

Whew, I went down to the mechanics shop at 5 am this morning.  Popped the dog house.   When they put new brake lines on they must have got caught up in the starter relay wires, after putting the two pluggable wires back on the relay she started right up ...  I am back to hooray in my mind ...

Hmmm, creative income it sounds like now that I think about the timing of this...

[tatkin]

Sent: 7/21/2006 2:05 PM

And the grand total is $1541

The labor was the expensive bit $1018

1 Set rear shoes
2 wheel cylinders
2 axle seals
1 maxi pack ? huh
1 30 in brake line
1 rebuilt master cylinder
3 brake fittings
2 brake lines

They cut the front rotors and repacked the front bearings.

I can't read the chicken scratching for the indiviual part costs ...

They forgot to add the cost of the new belts on the engine ...

[Slantsixness]

Sent: 7/21/2006 7:24 PM

Price isnt' too bad.... Glad you're stopping now...

But........

The Air lines for the air bags are running and tied to the Leaf springs!!!

Big No-No!!!! You'll be surprised just how much those leaves move!!!

Did THEY do that? Or you? If they did it... shame on them! If you did it, just undo it and get the lines off the Springs and we won't tell anybody! (oops!)

Tom

[ClydesdaleKevin]

Sent: 7/21/2006 8:31 PM

Tom's right, Tat!!!  Move that air line!!!  Our springs flex a LOT!  It will eventually break that air line.

Kev

[tatkin]

Sent: 7/22/2006 3:29 AM

Them line were done by me , weekend MechanHack ...

[brakeparts]

Sent: 7/22/2006 5:51 AM

Poor Tatkin!

This master cylinder picture shows a Delco-Moraine type cylinder on a Bendix design system. A rebuilt? This gender changing is one of the troubles with rebuilts...

Won't anyone listen to me? Rebuilts ARE the work of the Devil!

A new cylinder costs $30 more for this type of M300 and is an all NEW part. It costs the same amount to install. Why use a 'used' part that has had the minimum amount of work done to make it saleable?

All of you need to know how truly cheap the rebuilt master cyl equation is - this type of part sells to the distributor for around $10 - how much money can the US rebuilder spend on it? $3 ??

I predict this will leak or fail within three years of installation.

It does not pay to use a rebuilt, ever, unless it is the course of last resort.

Tatkin, you did have a choice, which you apparently did not exercise, because you could have put your foot down with the installer. They need to provide you a full and legible list of the part numbers they used, too. You will want to know where the bodies are buried when the government calls to make a deal... when something goes wrong it will help to know exactly what work was done and what parts where used.

Sorry to lay on you, but the learning curve will hopefully benefit others. Based upon the booster design in the picture, you have a 72-73 M300 chassis.

Regards,

Geoff
Alretta Truck Parts Inc.
508-788-9409

purveyor of brake system components for all Dodge chassis ( and others!)

[tatkin]

Sent: 7/22/2006 7:31 AM

You know, I gave them guys this thread,.  the Alretta info and told them the scoop.   If this thing goes south I am going to be a bit p'd ...

I have to ask, are you saying that a mechanic, no matter how skilled they are wouldn't be able to fix the brake system unless they bought the master cylinder from you     I am not digging into you here ...


Thank you Air Heads ...   I rerouted them...   Thanks for the tip, I have yet to see the springs in action ya know ...

[ClydesdaleKevin]

Sent: 7/22/2006 8:01 PM

I think what Geoff is saying is that for about 30 bucks more you could have got a NEW master cylinder from him, and that no matter HOW good a mechanic is, he is only as good as the parts he puts in.  Consider that a rebuilt master cylinder is rebuilt on an assembly line by folks getting paid not too much, and a rebuild consists of just honing it out, cleaning it out, and replacing the O rings and seals.  Because of the volume rebuilders do, they don't look at the small details like cracks, messed up threads, and super high tolerances...they replace the guts and sell it.  A quality NEW master cylinder, like those sold by Geoff, are of the highest quality.  Everything is exactly right, every nuance is tested, etc.  For instance, the master cylinder I bought from Geoff is only available from Geoff...If I bought a rebuild, it would be the wrong rebuild with the wrong chambering...in other words, my MC looks just like one from an international harvester, and that is what you would get if you bought on from AutoZone or Napa...but the porting is wrong, and the pressure sent to front wheels and back wheels is out of balance for our rigs.  Geoff is only saying that these old rigs are finicky, and you are much better off getting the parts from him or one of his equals.  He is a great guy, knows his stuff, has great prices, and is quite helpful in helping us getting our rigs to stop on a dime...well...maybe a king size sheet...lol.

Kev

[brakeparts]

Sent: 7/23/2006 6:33 AM

Tatkin -

No, naturally, s skilled mechanic is a skilled mechanic and should be able to trace his way through a hydraulic brake system repair.

No, if you found a major name brand part made in the USA, like a Raybestos, or Wagner, or Bendix, then that is the criteria that I am espousing. Quality first before price if the price difference does not reach to the stars. These are big rigs, not small cars, and do not stop on command that easily... you need to have the full tool set that Dodge provided!

That said, I think that Kevin has the correct take on what I am saying. Rebuilts are bargin basement parts. They were designed to appeal to a market segment that only saw price and did not see a future operations quotient - that in a short period of time (motorhome speaking) there would be a need to repair again. A rebuild might be fine for a vehicle you are getting rid of, a kid on a budget, inner city joyriding, but not a motorhome, which sits for long stretches and needs to be dependable. Aside from the special unit on Kevin's M400, most times the new is not much more in gross dollars than the rebuilt, especially today with velocity pricing having brought prices for new units lower over the last 8 years.

Yes, it may be twice the cost of a rebuilt here by the numbers, but what is a safety factor worth to you in the long run?? Thirty bucks??

No, the garage did not call me and they wouldn't under most circumstances. They would assume they know their job and how to get the parts needed, and they may be right, ..and they may be wrong, sooner than one would like to know...

In the narrow case of your M300 part, there would be other points of distribution for this nationwide, provided someone knows to vend out the correct part. Kevin's situation involves an obsolete part with a close looking cousin that will fit but then not run correctly.

Honing out cylinders is really for the most part a waste of time when you tally up the time and effort spent to repair a failed hone job. This is why wheel cylinder and master cylinder kits can not be found easily anymore in stores. Frankly, the pricing of rebuilt masters has also infringed on the economy of a m/c kit which costs at least as much. It won't be long before these kits are impossible to buy, I believe.

I hope you are happy with your rig now and all is well.

I am presently on a weekend vacation in Maine and need to answer my wife's dulcet tones to "get MOVING!"

Regards,

Geoff
Alretta TrucK Parts
508-788-9409