Classic Winnebagos & Vintage RVs

Topic Boards => Dodge - Chrysler Chassis => Topic started by: ClydesdaleKevin on November 10, 2008, 06:17 PM

Title: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on November 10, 2008, 06:17 PM

Sent: 9/14/2006 8:04 AM

I looked through all the message boards, and while there a lot of related topics, I thought it best to start a new thread so that anyone in the future doing a message search could dial right into this one if they have an M375/400 Chassis, and 5 lug Budd wheels.

Its raining today, and is supposed to rain tomorrow, so after this weekend, I'm going to be up to my elbows doing the rear brakes on the Ark.

I'm replacing all 4 wheel cylinders, the return springs, and the rear brake hoses.  Also, of course, the rear axle seals.

I'm also going to document each step in the process on camera, and post them to the Budd Brake album, Brakes, Budd M375 .  A picture is worth a thousand words, eh?  Sorry the pictures did not transfer in this post.

Additionally, since my shoes are still almost new in pad thickness, I'm just going to clean them up instead of relining them.  This will be accomplished with Easy-Off oven cleaner, and of course brake parts cleaner.

I'll document each step, from cleaning and repacking the bearings, to installing new seals, to replacing the wheel cylinders and springs, the hoses, and then of course bleeding the system.  I'm also going to tackle replacing a couple front brake lines, and the front brake hoses.

To bleed the system, an RV shop turned me on to a sweet little hand-pumped brakeline evacuator, which sucks out the bubbles...one person, Patti, keeps the reservoir in the master cylinder full, while the other, me, simple attaches the hose to the bleeder, opens it, and pumps the handle...there is no pumping of the peddle.  This is how this shop bleeds RV brakes, and I'll let you know how it turns out.  Its 68 bucks for the tool, but it would cost me more to have a shop do it, and then I'll still have the tool if I need to bleed them in the future.  I decided to invest in the tool since I will be breaching the brake lines so much, and last time we bled the brakes manually, without nearly as much air invasion, it took forever to get it even close to right, and even then it wasn't quite right.

Another thing I considered is the Hydrovac Boosters.  If I do all this work, meaning that now my entire braking system is more or less new, and the brakes are still not up to snuff, then the last thing to be replaced, the weak link, is the boosters.  I thought they were crazy-expensive, but Geoff at Alretta has them for just 200 bucks and change a peice, plus a core charge.  Not bad!  If I had known that ahead of time I would have gotten them too, but I spent the rest of my available funds this week on new holding tanks...lol!

And speaking of Geoff and Alretta...WOW was shipping fast!  I ordered the parts late on Tuesday afternoon, and they were delivered by UPS the very next day, by around noon!  I opened the box, and true to form, Geoff sent exactly the right parts the first time around!  Gotta love Alretta!

So, I'm waiting out the rain and will be writing papers all day, but will keep this post active as I work, and post a ton of pictures.

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on December 11, 2012, 06:45 PM

Sent: 9/14/2006 10:36 AM

I have used a vacume bleeder before. The only issue I am aware of with the vacume method is that when the bleeder screw is cracked open, air is sucked in from around threads of the bleeder screw.  The air goes to the vacume pump not the cylinder though.  That can make it difficult to determine if you have all the air out of the system.  From my experience, the best way is to either perform a 2 man bleed or use a 1 man bleeder system.   The vacume pump is still good for doing a lot of other checks on a car though (i.e does the EGR valve work?, etc.).

Dave
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: denisondc on December 11, 2012, 06:46 PM

Sent: 9/14/2006 11:22 AM

Dont tell anyone, but I put a light coating of rust-preventer on the threads of the bleed screws and of the flare nuts. If I have it, I use a product that comes as a spray; a marine sealant that dries to a waxy slime. But to avoid contaminating the brake system with this stuff, I only spray it into a teaspoon, then dab it on the threads with a q-tip. If im out of the marine sealant I use the silicone based anti-sieze that works so well on exhaust manifold nuts/bolts.
If you have any anxiety that you will get these products interior to (and therefore contaminating) your brake system.....dont use 'em.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: brians1969 on December 11, 2012, 06:48 PM

Sent: 9/15/2006 3:05 PM

I saw at a parts store bleeder fittings that had a check valve built into them. Seems like a neat idea. No more opening and closing the bleeder in conjunction with the guy pushing on the brake pedal......anyone have any experience with these?
They had different sizes for various wheel cylinders.
brian
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: moparmotivator on December 11, 2012, 06:50 PM

Sent: 9/17/2006 10:44 AM

http://www.precisionrebuilders.com/new_site/index.html (http://www.precisionrebuilders.com/new_site/index.html)

Precision Rebuilders is also a great source for parts for the old motorhomes.

I got both boosters for less than $170 each.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:51 PM

Sent: 9/17/2006 8:06 PM

Patience, my beloved readers!!!..lol!!!

Tomorrow, once I have my coffee, I will be running out and grabbing brake fluid, the brake vacumm tool, and the new holding tanks.  The holding tank epic will come later in another post.

I stand firm that Geoff is the best place to buy any brake part that he does stock...and I'd rather pay Geoff at Alretta an extra couple of bucks and know the boosters are the RIGHT ones, built to high standards, than anywhere else.

That said...stay tuned for more!  Tomorrow begins the epic saga!

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:52 PM

Sent: 9/20/2006 6:19 AM

I got off to a late start, but finally got around to the rear brakes...yay! 

After removing the wheels and axle and drum, I found that my rebuilt wheel cylinders and makeshift dust seals had failed catastrophically...no wonder they were leaking!  The inner tube rubber must not be resistant enough to brake fluid.  Ah well...they are new now!

I put on new return springs from Alretta as well...the old ones were all stretched out.  I also noticed that the cotter pins on the castle nuts that hold down the brake shoes were rusted away...not a trace of them.  So, I put on new ones.  Anyone know if I should grease the shoes under the hold-down washer?  Seems logical, but I'm not sure.

I cleaned up the shoes again, which were saturated in brake fluid...again.  I soaked them overnight with Easy-Off...so this morning I'll clean THAT off with brake parts cleaner, and hopefully they will again be servicable.

Today I'll finish the driver's side brakes, attack the passenger's side rear brakes, jack up the front and adjust the FRONT brake star wheels, and then bleed the whole system.  By the way, I removed each bleeder from everything, and put teflon tape on the threads...this should minimize any air bubbles when I use my cool new brake bleeding suction/vacumm thingy tool!

I have all new brake hoses to install, but all the fittings look pretty crusty...I might put it off for now...I don't want to get into a situation where I have to order new parts and fittings if the ones on there break!  I soaked them overnight in PB Blaster, so we'll have to see how it works out.

Anyway, I added more pics to the Budd brake album...check them out, along with the description!  I'll add more today as the job progresses.

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:52 PM

Sent: 9/21/2006 7:56 AM

The rear brakes are finally done!  I finished up yesterday.

The passenger side wasn't nearly as bad as the driver's, but its all done now.  New wheel cylinders, both sides, new cotter pins on the castle nuts (shoe holddowns), both sides.  New return springs, both sides.

The star wheels are all freed up.

The bearings are cleaned, and all repacked with grease.

The axles are reinstalled using RTV Blue Ultra as a gasket.

The wheels are back on, both sides.

The star wheels are adjusted, with just the slightest contact to the drums...just a slight hiss.  They will be re-adjusted, along with the fronts, once I finish bleeding the system today.

And DAMN I'm sore today!...lmao!  I give full salute and credit to heavy truck mechanics, I'll tell ya!  I have muscles I forgot I had crying out in agony this morning...ouch!  I'm not used to heavy physical labor anymore...hehehe.

So, today I bleed the brakes, and adjust the star wheels one more time.

Then I start the holding tanks, which HAVE to be finished by tomorrow night.

Pictures are added to the Budd brake album, along with detailed descriptions.

More pictures will be added of the bleeding process.

Kev (The sore and tired Scotsquatch)
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:54 PM

Sent: 9/21/2006 8:39 PM

Success!  The brake bleed was a complete success!

Yes, you guys were right about one aspect of the vacumm bleed...you see bubbles no matter what...even though I covered the bleeder threads with teflon tape. 

So...I probably wasted a lot of brake fluid.

What I did?  I evacuated the brake bleeders, starting with the hydrovacs, one at a time.  The fluid reservoir of the bleeder is 4 ounces.  I did each bleeder, filling the reservoir twice for each bleeder.  Once all bleeders were done, I pumped the heck out of the brake pedal, and let it set for a few hours.

I then did it all again, two reservoirs (8 ounces) at each bleeder, regardless of bubbles...which must have come from the threads.

The result?  The pedal is right up to the top!  One pump makes it harder, but the pedal is right to the top before pumping!

And it stays, hard, even if the engine is started.

So...the conclusion is that the hand pumped vacumm bleeder thingy works!

OK...after I bleeded the system and pumped the heck out of the brakes, I jacked up the rear, and then the front, and did a final adjustment on the star wheels.

I tightened them until they were dragging, all four wheels, and then backed them off until it was just a whisper of contact...

Lets hope the drive is as good as the parked results!

More pics were added to the Budd Brake album, page 8 of the albums.  Mostly it was tools of the trade, etc.

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:55 PM

Sent: 10/1/2006 9:07 PM

Update!

I just drove 1668 miles, from NJ to TX, and the brakes are perfect!!!

The Ark is braking better, probably twice as well, as it ever has!  And that is pulling the van!  In other words, pulling a fully loaded full size van, I have twice the braking power than I ever did, even when I first bought the Ark, without pulling the van!  I would guess I could even "lock them up" if the van wasn't there!

Thanks Geoff for just the right parts, and thanks Tom for all your help...and thanks to everyone else for all their own brake posts to make the job doable!

And yes...the vacumm brake bleeder is worth the damn money!

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: denisondc on December 11, 2012, 06:57 PM

Sent: 1/8/2008 10:30 AM

And the members with newer motorhomes will be looking forward to your saga/depiction of rebuilding the brake calipers.

I have 'rebuilt' calipers on our familys old cars, and find they work well for several more years - (unlike wheel cylinders for which 'rebuilding' may only get you home from the vacation before they start leaking again). The 'rebuilding' doesnt amount to much work, once you know how to get the pistons out of the calipers, and havent snapped the bleeder screw off while trying to get that loose.

Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 06:57 PM

Sent: 1/8/2008 8:39 PM

LOL Dave!  I don't know if I would bother rebuilding the calipers...the Chevy P30 chassis parts are dirt cheap and easily available.  I would probably spend almost as much on a rebuild kit as buying refurbed calipers, once I turned the old ones in as a core. 

Eventually I want to bleed the brakes on Excalibur...not because they are squishy or anything (they work perfectly!), but I want to change the fluid...lol!  I don't know HOW old this fluid is!  Its not really dirty, but its murky.

My only real mechanical issue right now brake-wise is that the brake booster runs off the power steering pump, and the power steering pump leaks a little!  On the trip from Texas to Florida, about a thousand miles, I lost about 2 ounces of fluid...not TOO bad, but in my experience, leaks only get worse, not better.  It leaks around the steering gear apparatus...I have to clean it all up one day to pinpoint the leak.  I'm too busy in Tom's backyard in the In-Tents Woodshop right now building catapults to do much of anything!

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: denisondc on December 11, 2012, 06:59 PM

Sent: 1/9/2008 7:04 AM

The leakage from the steering box is most likely the top seal, where the steering shaft is. Not easy to reach unfortunately, but better than if its leaking around the pitman shaft. I replaced that top seal on mine when it was losing a pint can of p.s. fluid per 400 mile driving day. But then I dont have hydroboost brakes.
If the leak is from the pitman shaft - Step 2 in the replacement process is to drop the steering box from the vehicle. Step 1 would be locating a replacement Saginaw steering box from another P30.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: toddabney on December 11, 2012, 07:00 PM

Sent: 1/9/2008 8:49 AM

hey gang, what about using silicone brake fluid after everything is re-built? i have been told that the only way to use it is on all new parts.true or false?  thanks to all.i have learned so much reading all the info there.take care,todd
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: denisondc on December 11, 2012, 07:01 PM

Sent: 1/9/2008 6:24 PM

The following is my opinion - not to be confused with fact. As I understand it, the reason for using the silicone brake fluid (DOT-5) is because its not anhydrous - wont absorb water from the air; and the metal parts of the brake system will last longer. But unless you got all of the old fluid out, you could still have water in the system; mixed with the old fluid - that would continue to cause corrosion and make wheel cylinders stick or leak. Since the dot-3 kind of fluids are highly miscible with water, they prevent ice from forming, even when its really cold; thus the reason for their use.
I dont think the DOT-5 silicone fluids mix with water, and I dont think they blend with DOT-3 either. My understanding is that they just co-exist, like the liquids in a lava lamp.

I dont know how I would ever get 100% of the old fluid (& any contaminant) out of assemblies like the hydrovac boosters. Nor am I convinced that all of the rubber/plastic parts (some of them predating DOT-5) inside the current system would be compatible with a silicone based fluid.
If someone else does it, I hope they will give us a report on their results - not just the week after they do it, but a year or so and a few thousand miles later.

I can imagine 3 reasons not to use DOT-5 brake fluid. 1. If it was really the answer to problems with olde brakes, the automakers would be changing already & bragging about the improvement. 2. I dont think there is any foolproof braking system (certainly not air brakes), and its a good idea to open it up,dismantle things and examine the parts every few years anyway. 3. If I am in an accident, I dont want an ins. investigator to be making a case that my modified brake system meant the accident had to be my fault. I have a relative who did that kind of work for his employer (auto insurance firm) before his retirement.

Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: Oz on December 11, 2012, 07:04 PM

Sent: 1/9/2008 9:39 PM

DOT 5 and DOT 3 will not mix.  Like oil and water.  I found that out by accident.  The DOT 5 is clear and heavier than the pinkish DOT 3.  It will rise to the top, or move around the lines like air bubbles.  Also, DOT 5 is very caustic.  I found that out by accident too... and I really don't want to describe the details, it was a horrific mess...
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: Slantsixness on December 11, 2012, 07:05 PM

Sent: 1/10/2008 5:13 AM

this link got deleted:

http://en.wikipedia.org/wiki/Brake_fluid (http://en.wikipedia.org/wiki/Brake_fluid)

Since its wikipedia, I would say only that "you get what you pay for" as  far as the validity of the information provided there. I have found Wikipedia flat out wrong, distant or misinformed in several instances, brake fluid not being the case in those instances.


Brake fluid opinion...from me? Well... I'll say this:

If you change all of your brake lines (like I did) and all of your Wheel cylinders, calipers, proportioning block (like I did)...etc...
Then:

Use whatever is available on the shelf... and use only that. If it's DOT 5.1, then use ONLY DOT 5.1 (ok..I'm taking Wikipedia's word that it's actually called 5.1)
If it's DOT 4.... use ONLY DOT 4. OR use DOT 3 and only DOT 3.

Just don't ever use Castor Oil (no, I didn't say "Castrol" brand... I said CASTOR oil A.K.A. DOT 2 )

Don't mix 3, 4 or 5.1.... there's a reason they have different numbers, the same as why there is "ATF", then DEXRON II,III &IV, TYPE F and +3 & +4.. and you 'd better not mix those, for sure! (or your transmission will be toast).

Can you clean out all the old brake fluid to change over to a newer fluid?
Well... yes...but it's not easy. Just keep the fluid fresh: change it every year. Then no matter which fluid you use, it will remain fresh and "within specification".
 
Alright already....
enough with the borish post.

Tom
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: Slantsixness on December 11, 2012, 07:08 PM

Sent: 1/10/2008 9:43 AM

Has anyone ever gotten brake fluid (not castor oil) in their mouth accidentally..

I can see why it eats paint.... Tastes horrible.

I had a brake line give out on me when I was under a car bleeding the rear wheel cylinders. Got in my eyes, mouth, all over my clothes. It's been awhile, but I can rememder the taste and the stinging in my eyes... really didn't do anything to the clothes after a good wash, though.

What an awful taste. Like ransid olive oil with burnt orange peel in it. Yuck.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: denisondc on December 11, 2012, 07:09 PM

Sent: 1/10/2008 2:09 PM

I have tasted brake fluid (dot-2 & dot-3) over the years, usually when trying to siphon old fluid from a master cylinder reservoir. I dont agree with the Wikipedia article where it says that DOT-2 is "essentially" castor oil. Maybe they meant "Castrol" brake fluid from the 1960s. It was supposedly compatible with DOT-2, but it had a nicer camphor smell. My opinion of Girling brake reliability is about the same as my opinion of Lucas Ignition part reliability. (Not good).
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: kilroy75633 on December 11, 2012, 07:13 PM

Sent: 3/16/2008 7:27 PM

Another way to bleed brakes is, I built this thing after looking on internet one night at brake bleeders.   I have used it on cars but not on motorhome,

I took a 1 gallon pesticide sprayer and cut the spray head off.
Then bought extra master cylinder cap and drilled out top so I could put a fitting in the top. I attached the spray head hose and put a little back flow fitting in the hose so the fluid would only go one way..Put the master cylinder cap on and then brake your bleeder screws at each wheel and fill the 1 gallon jug with brake fluid and start pumping, It will force the fluid down to each wheel and push the air out.And the fluid in the jug will keep master cylinder full.But make sure your cap is on good or you will have a mess. When you see only fluid come out at each wheel tighten the bleeder screw.  Relieve pressure on spray jug take off and put your regular master cylinder cap back on.

Hope this helps some.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: brians1969 on December 11, 2012, 07:14 PM

Sent: 3/17/2008 3:19 PM

I got brake pedal!! I replaced the master cylinder, every wheel cylinder, hoses, shoes, and all the metal brake lines (there is alot of brake tubing on d24!)

I built the power brake bleeder from a garden sprayer (plans are on the internet) and it worked prettty well,except for some leaking around the cap gasket. It got the air out quickly! So much better than the buddy system.

Road trials soon!........
brian
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: ClydesdaleKevin on December 11, 2012, 07:15 PM

Sent: 3/18/2008 5:07 PM

Horray!!!

Isn't it an awesome feeling when you do something yourself, and it works beautifully?  And you have the satisfaction of knowing that the job was done right, and you saved big bucks!

Kev
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: bigoak54 on March 15, 2013, 03:30 PM
HI, new member with a new to me 72 on the same chassis.  we found ours after it spent 20yrs in a barn.  all original, but more work than i had planed to do from it sitting so long.  fuel tanks, all rubber lines rotted out and brakes gone.  i had to replace all of the rubber vacuum lines, master and wheel cylinders.  now it seems the one rear proportion valve is bad and i can not find it anywhere.  does anyone her know the current part numbers for it, a source to get it at or a Winnebago junk yard?  we have yet to drive it and are most anxious to put it all back together and post some pictures. 
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on March 15, 2013, 03:46 PM
Not for sure what you mean by "one rear proportion valve".  Proportion valves are normally only used on disk front / drum rear systems.  Far as I know you have a all wheel drum system like described here: http://dave78chieftain.zxq.net/M375Late.html (http://dave78chieftain.zxq.net/M375Late.html)

If that is not the setup you have, then pick the correct one from here: http://dave78chieftain.zxq.net/DodgeRBrake.html (http://dave78chieftain.zxq.net/DodgeRBrake.html)

Need to know exactly what part you are looking for.

Dave
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: bigoak54 on March 15, 2013, 05:02 PM
Hi, thanks for getting back to me.  it is the M375 late system with the two hydrovac units.  it is the valve between the master and the two back hydrovacs.  it has four lines on it.  two go the back hydrovacs, one to the front brakes and one going in from the master.  it this enough info for you?

Steve
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on March 15, 2013, 06:57 PM
Link to the picture below: http://i286.photobucket.com/albums/ll120/BaileyDave/M375LateFull_zps4f80489c.jpg (http://i286.photobucket.com/albums/ll120/BaileyDave/M375LateFull_zps4f80489c.jpg)

Need to look at the picture full size. Right click on the link and select new window.   Use Control + to zoom in on the picture in the new browser window so you can more easily trace the brake lines in the picture.

There are 2 "tees" shown.  The rear one (outboard the front booster) is actually a Brake Warning switch.  The Brake Warning switch is used to detect an imbalance between the front and rear brake systems.  Also, a leak in the front system will not result in a loss of braking in the rear system AND vice versa.    There is a wire attached to the Brake Warning switch which lights the brake light on the dash.  If your only problem is the dash light is lit, the problem is most likely adjustment rather than a defective switch.  You have to bleed the brakes (front vs rear circuit) in order to get the paddle inside the Brake Warning switch to center position.
Are you sure you are not looking for this? http://www.ebay.com/itm/Mopar-Chrysler-Brake-Proportioning-Valve-P-N-4131254-/281067960473?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item4170f4b899 (http://www.ebay.com/itm/Mopar-Chrysler-Brake-Proportioning-Valve-P-N-4131254-/281067960473?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item4170f4b899)
(https://www.classicwinnebagos.com/forum/proxy.php?request=http%3A%2F%2Fi.ebayimg.com%2Ft%2FMopar-Chrysler-Brake-Proportioning-Valve-P-N-4131254-%2F00%2Fs%2FOTI3WDE2MDA%3D%2F%24T2eC16JHJFoE9nh6m%2BEuBR%21ZC3fvug%7E%7E60_58.JPG&hash=a135efef975ea3a4c145b914aaf9aad3e741a53f)



(https://www.classicwinnebagos.com/forum/proxy.php?request=http%3A%2F%2Fi286.photobucket.com%2Falbums%2Fll120%2FBaileyDave%2FM375LateFull_zps4f80489c.jpg&hash=35ac38e9fa05d201f24b085cbb7ac7133b9e8667)

Dave
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: bigoak54 on March 15, 2013, 07:29 PM
wow, are you Mr. Winnabago or some rv god?  i will get out to the winnabogo tomorrow morning and see if that is the right part.   i will let you know.  thanks again!!
Steve
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: bigoak54 on March 18, 2013, 02:25 PM
Good morning Dave,

you were right, i have ordered the part.  with luck we will have it by spring break and we can get our for our first trip.  we will post some pictures once we get everything cleaned and put back together.  thanks again for your help.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on March 18, 2013, 02:43 PM
A Brake Warning Light on the dash which is used to indicate when there is a loss of brake fluid pressure to the front or rear brake system.  When this loss of pressure occurs, the brake imbalance switch in the Brake Junction Block/Prop Valve (disc brake systems) will be pushed off-center within the valve and trigger the brake warning light on the dash to turn on.  This is a safety feature to let you know that there is a problem with your braking system that should be given immediate attention.  First, figure out the problem (leaky wheel cylinder, damaged brake line, new Power or Disc Brake Kit installation, etc.).  Once the problem has been fixed, the brake warning light can be reset by bleeding the front and rear brake systems.  If you have bled the front and rear brakes and the brake warning light is still on, you will need to bleed either the front or rear brake system additionally until the brake pressure valve has been reset to center.  To do this, follow these instructions:

1.  Check the Brake Master Cylinder and make sure the fluid in both reservoirs is within 1/4″ of the top of the reservoir.

2.  Turn the ignition switch to On so that the brake light switch is lighted up.
DO NOT START THE ENGINE!!!

3.  Have someone sit in the driver’s seat to control the brake pedal while bleeding and to keep an eye on the brake warning light.

4.  If the problem that caused the light to trip was in the front, start at the rear wheel cylinders.  If the problem was in the rear brake system, start at the front wheel cylinders.  Start by bleeding one of the wheel cylinders and attempt to bleed it until the brake pressure valve resets and the light goes off.  If the light turns off and then back on, you have bled too much and will need to bleed the opposite wheel cylinder to compensate (if you were bleeding the rear wheel cylinder, you will need to move to the front and vice versa).  If the light does turn off, have the person in the driver’s seat hold the pedal in that position and tighten the bleeder screw.  Once the bleeder is tight, release the pedal and pump it a few times to make sure the light stays off.  If the light stays off and the brake pedal is firm, the job is complete.  Make sure your master cylinder reservoirs are refilled after the bleeding.

5.  If the light does not turn off or has turned off and then back on, you will need to bleed the opposite side brake system (If you were bleeding the front, you will now bleed the rear and vice versa).  Follow Step 4 with the opposite wheel cylinder until the light turns off.  So long as the pedal is firm and the light is off, your brake fluid system should be good to go.  If the pedal is not firm, then there is likely air in the lines and you will need to continue to bleed the brakes until this air is completely removed from the brake fluid lines (it is also possible with drum brakes that the brake shoes are out of adjustment which can cause excessive pedal travel).

Dave

Courtesy: http://www.tomsbroncoparts.com/pages/schematics/bronco-schematics/drivetrain/h-blockprop-valve-brake-warning-switch-adjustment/ (http://www.tomsbroncoparts.com/pages/schematics/bronco-schematics/drivetrain/h-blockprop-valve-brake-warning-switch-adjustment/)
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on February 03, 2015, 08:22 PM
Full system:
Bleed MC at pedal
Bleed booster MC(s) [Early 375 one booster; Late 375 two boosters]
Bleed RR drum - If I recall correctly, the top feed bottom cylinder so bleed the bottom cylinder (always the last one in line)
Bleed LR
Bleed RF
Bleed LF

Many people do gravity bleed but a pressure bleed works just as well when you have an assistant.

Dave
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: Jonbbrew on May 28, 2016, 01:09 AM
Any place to get a new brake warning switch?
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on May 28, 2016, 08:17 AM
You will most likely have to search for NOS https://www.google.com/?gws_rd=ssl#q=mopar+4131254 (https://www.google.com/?gws_rd=ssl#q=mopar+4131254)

These switches rarely go bad though.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: dkaven on June 01, 2016, 02:57 PM
Hey All!


Thank you so much for sharing your work and thoughts! I'm starting on my 73 Indian M375 / 400..I'm still very green on this RV. I've done alot of working getting it ready. New Tires on the Budd Wheels, in refer, water heater plumbing etc. I was under the RV last Friday to jack it up to put on the new tires and notice the rear wheel Cylinders leaking on the LT. I did order some new wheel cylinders from a local Auto Parts Store. Some were I notice the parts numbers on Dave's web site. I do have a question the 2 parts numbers / parts have 2 different wheel cylinder bore sizes,   1 3/8" or 1 1/2"..could someone help me on the correct size?


Thanks you,
Danny
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: dkaven on March 03, 2017, 10:24 PM
Dave,


Thank you for your info / data on the brakes. I did order the correct kits.  1 3/8 are correct size.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: dkaven on March 03, 2017, 10:30 PM
The Cylinders bore were to far gone.  So I had to open up the bores and install / machine SS sleeves.
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: DaveVA78Chieftain on March 04, 2017, 10:42 PM
So all is well now?
Title: Re: Rear Brakes, M375/400, 5 Lug Budd
Post by: dkaven on March 05, 2017, 08:42 PM
Yes Yes! I well have the wheel Cyl's done this week and will reinstall bleed etc.


Thank you!