I have a Class C motorhome on a '93 Ford E350 chassis and I have had brake concerns since I bought this a few years ago. The PO had the brakes redone and he stated that ever since the pedal has been 'spongy'. I am trying to fix this...I have 2 specific questions - why do I have a solid brake pedal with key off, but when I start the motor, the pedal goes to the floor - pretty much to the floor? I also have a pretty severe brake pulsating when depressing the pedal and I have pulled the front rotors and am having them turned...what is the torque for the hub to rotor bolts?

Any other suggestions on this pedal issue are appreciated...this has RWAL ABS. The camper stops, but it feels 'scary'...

Thanks in advance!
Ryan

 

First, your question......."what is the torque for the hub to rotor bolts?"

Rotor's don't have bolts.

Do You mean.......Hub to spindle torque??
If that's the case, it' 20-25 inlb's, and backed off 1/4 turn.

What your also explaining sounds like a problem with the vacuum booster for the power brakes, with out vacuum, your pedal is hard, with vacuum (engine running) you'll have vacuum.
So, a vacuum test should be done to the booster to see if the diaphragm is shot in the booster.

Another "common" problem is the RABS unit, causing a "soft" pedal, with the removal of the spring in the front of the unit, it will solve the problem with the soft pedal, kind of "by-passing" the ABS unit, and not set the yellow trouble light off.
There are several posts on the forum about this, if you want to check it out.

But, before you go that route, bled the entire system first, including the ABS unit (which is often over looked) and see how the brakes react.

 

Ok, my rotors have bolt holes...they bolt to the hub and I had to remove the hub from the rotor to turn the rotors. 8 bolts, I think - funky 19mm heads....

Just curious what I should torque these to....if it matters...

Also, do you have a procedure for testing the vacuum on the brake booster - or maybe point me in the right direction?

Thanks,
Ryan

 

Your right, I had a 'dud' moment there.........

Your talking about the wheel hub extension for the Bud rims (dully)

I can look up the spec's, I've always use an 1/2" impact on them and punch them up tight, So if the washer lugs call for 140 ftlb's and the bolts are 9/16" I believe, I would say around 90-100 ftlb's.

This link is a good read, you kind of when it the right direction to start.

After searching for your answer, I couldn't find it, so.......

If You hear a hiss sound when the brakes are applied, sign of a leaking brake booster. Also, if your idle is rev'ing a little high, caused by a vacuum leak, disconnect the vacuum line to the booster, and plug it, to see if the idle levels out.
Check for brake fluid leaking around the MC.
Check adjustment of shoes and bleed the rear brakes and ABS unit to see if your brakes "tighten up" The "self adjuster" don't always work correctly.
A quick check would be if the parking brakes holds the vehicle. If not, the rear shoes are not adjusted correctly.

Take it from there, and see what your results are.

What I first posted about the ABS unit spring, solved my spongy brakes, after a inspection "tech" told me my MC was bad and needed replacing, which was about 2 months old at the time.

 

Thank you for your response! I have none of the other issues you discuss in your last post - no hiss, no idle issues, can't see any signs of external leak from the rear brakes to the MC, and emergency brake DOES work just fine. I'm thinking the ABS valve or the Master cylinder - internal leaks...

There is a procedure on this RWAL page for testing the ABS unit or the MC - Kelsey-Hayes RWAL Antilock Brakes.

I will bleed first because I'm thinking it's possible that the ABS unit was not bled when the brakes were redone right before I bought the coach - and then go from there.

A wheel bearing question - I have pulled the wheel bearings and they look great. Been advised to replace them and been advised to just reuse them. Any advice? I mixed them up in removal and cleaning so I do not know which pair go on the right or left wheel...? And I HAVE TO replace the races if I replace the bearings - right?

The pads were not very worn at all, but should I replace them to match the newly turned rotors?

Thanks again,
Ryan

 

Went through that with my 95 E350 this past summer.
Bleed all wheels first, if the pedal is still soft bleed the master cyl, I had to pull mine and do it flat on the table , not very difficult really.
Pedal dropping when engine starts is normal with air in the system.
Sounds like the PO got air in the master.

 

That link was quite the read, very good.

In the diagram, you can see the spring in the accumulator that I removed from mine to solve the soft pedal problem.

Yes, by all means go ahead and bled the brakes, from RR, LR, ABS unit, RF, LF. See what your results are after words.

The wheel bearings........Rule of thumb is, if you can see Any "dull" spots on any of the roller bearings, even one, time to replace the bearing and the races. Yes, the races and bearing should be replaced together.

It's not a real expensive job, and not alot of time to do, and very good insurance.

Pads are "cheap" also, and with the new turned rotors, I would replace the pads at this time, plus with the "warpage" you experienced, the pads might be slightly out of shape too.

And........if you parking brake is working correctly, then your rear 'self adjusters' are also working, there very prong to not work correctly.
Meaning, the shoes are set in the drums good, and not loose and sloppy.

 

If there's any doubt about air in the master cylinder, bleed it first, before bleeding any wheel cylinders--or, the RABS valve. Bleed the rear port of the master cylinder first.

FWIW: all of the literature I have regarding this matter has a kicker that I don't see in the posted link. This is what it says: "If equipped with RABS, bleed the RABS valve in between the left rear wheel and the right front wheel in the sequence."

 

OK, an update. I have replaced the front brakes - new pads, turned rotors and today a friend helped me bleed the brakes. Followed the outlined procedure - RR, LR, ABS Valve, RF & LF. They are better, but still spongy - only noticed a little bit of air from ABS valve and RF.

I did not bleed the MC yet - decided to try and do the wheels first and see if that helped.

Friend thought that I might have a problem with the booster - the pedal makes a very noticeable "swoosh" noise when the pedal is depressed. It's always been like that - since I've had the coach - and it's still doing it. You can hear 'air escaping' - from somewhere, under the dash at the firewall - very noticeable.

Any other suggestions? Should I go ahead and remove the MC and start over?

Ryan

According to my recent Google search the appropriate term would be a "whoosh"...