Front wheel removal of 1998 Prevost XL

[Joe Camper]

A semi at 80000 lb on 5axles is averaging 16000lb per axle. A bus that's 54000lb on 3 axle averages 18000lb per axle and that has to be considered.

What r u refering to when u mentioned u replaced the master cylinder??

R your disc brakes Rockwell on the tag and knorr bremse on the steer? Either way those bolts attaching the knorr bremse caliper bracket to the axle housing r for sure some of the most difficult bolts any mechanic will ever encounter. You have to pull it to get the rotor off. They also carry no locking fasteners. They r installed to spec with massive amounts of locktight. That's how they come from the factory. Separating rotors from hubs on Rockwell disc is also very very physically demanding. If u preformed this repair u r stronger than the average guy.

What seal on the drives is leaking? The axle gasket on the outside or the inner hub seal?

Although I would never stab the brakes to test them on a motorhome for all the obvious reasons I'm not entirely confident if I had to that the antilock would actually come to play. Or im not completely confident it is possible on dry road to activate the antilock.

Has anyone out there ever had to panic stop on a dry road and felt the antilock opporating? Ive driven many loaded semi and many different prevo and a loaded semi can stop more comfortably than any prevo motorhome I ever drove but I've thankfully never had to make a real hard panic stop with a bus. My comparison can only be based on normal to slightly harder than normal stops.

[Gil_J]

Ben,

There are 2 different treadle valves and here is what Bendix states:

"The E-10™ dual brake valve (Figure 2) is similar to the E-6™dual brake valve except that a metal coil spring housed inan upper body assembly replaces the rubber spring used inthe E-6™ valve. The use of a metal coil spring (and the upperbody assembly) provides greater treadle travel and, therefore,provides the driver with a less sensitive "feel" whenmaking a brake application. The E-10™ dual brake valve isgenerally used on buses, where smooth brake applicationscontribute to passenger comfort."

So, the question is which one is suppose to be on your bus? I'll try to look that up later. Before I do, Joe probably has the answer.

[Joe Camper]

Ive never replaced one Gill. Every now and then air will leak out the exhaust port that is located on the bottom of the valve up on the ceiling of the steering bay that fools many and has people replacing them because of it. If u ever hear leaking from there its almost for sure one of the 3 R12 brake relay valves.

Your description of the E10 characteristics could explain both questions. First my thoughts on engagement of antilock on dry road. Maybe it can of u push that hard at speed. It would answer and also explain the soft pedal feel as well.

I've never had any truck or bus that needed this replaced.

[Ben Neumann]

Joe, it is the treadle valve and the new one is an E-10 like Gil is describing. The leak on the drive axle hub is on the inner seal. I took the big brake drum and seal to my local parts supplier for turning the drum. They are unable to do it locally and are shipping it to Sacramento, CA. I live about 50 Miles from Sac. half way between Sac. and South Lake Tahoe, CA.
Hope to get it back on Monday. The drum was very uneven and has hundreds of small heat cracks to the extent that I am worried it might be rejected for repair. The passenger side probably will look the same. When replacing the front bags I also noticed these fine cracks on the front rotors. I think I mentioned that I completely replaced the drivers tag axle brake rotor and brake pads. They were completely destroyed. I am hoping, when I get my brake drums back, that I will see an improvement. When you feel the inside of the drum, it feels very wavy inside. I also have to get new shoes for the one side because of the oil on the brake shoes.
The reason I am so concerned about the stoping power of this bus is, because I had an incident where I almost rear ended a young women in an TOYOTA . I was in Pomona,CA and was driving my Eagle Bus from one Freeway into the Hwy.10 headed for Palm Springs, CA. While trying to merge into the #10 from my on ramp I had the foot all away on the throttle and was looking over my left shoulder to merge. The traffic on the on ramp in front of me was moving freely and when I looked forward again, the traffic had competly stopped. I must have been going at approx. 45MPH and hit the brake as hard as possible. I got the bus to stop less then a foot from the TOYOTA. I ended with flat spots on all eight tires. If I had been in my Prevost at that time, I do not even want to think what the outcome would have been. I am alwys thinking about it and something tells me over and over again "my bus is not safe because of the brakes". I hope I never get in to a sitiuation like that again.
Ben

[Joe Camper]

I wouldnt turn a brake drum. Ever. I wouldnt buy brake components for prevo from anywhere than prevo. If u do not send the hub with the drum for turning there is the possibility it will run out when reattached to the hub.

If u do not like it replace it. When u turn a drum u have to use oversized brake linings. Don't like that either.

When u do the brake linings on prevo the linings and shoes and hardware, its all seporate. Lots of labor.

Im not saying u cant I'm saying experience has taught me different.

Small cracks in the brake drum r common, small cracks. Saturated linings can be dried out with brake parts cleaner with great results.

Did u index the bearing retaining nuts before u loosened them so u r sure it goes back togeather correctly?

I'm thinking your disc brakes r different on the steer and the tag. Correct?? I think your year is one that has the brakes on your 3 axles all configured different. Bremse front, drum drive, rockwell tag.

If u pull the front rotor it is knorr bremse unlike the tag that's rockwell. Be sure to locktight the mounting bolts for the caliper bracket on the front if u do.

There is a gasket that goes with the inner seal on the drive hub. Were those screws tight? That could have been the leak. Do u have the replacement gasket?

When reinstalling the axle be sure to tighten the studs with the cones first.

These vehicles r the safest things on the road but u cant drive them like a car. They r so smooth they lul u into a false sense of security. If u make that mistake it could cost u severely. Idiots who stop on freeway entrance ramps should have their lisence suspended, indefinitely.

[Joe Camper]

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This is the backside of a drive axle hub.

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Here is a shot of how the inner seal is designed on a prevo drive axle. This is different from truck stuff and most other hubs for that matter. On most the seal is pressed in directly to the hub. Prevo has chosen to add a another element with a flange and a gasket that is held in with Phillips screws that can come loose and make a leak. A common rookie mistake would be to reinstall the seal without first inserting the inner bearing. LOL

We have all done it.

[Ben Neumann]

Thank you Joe for your input. I have a different hub then the one you are showing on the pictures. I wished I knew how to post photos. Still something to learn for me. My hub does not have the small removable top peace like yours. It has a large encasing over the entire back part of the hub. I took a picture with my IPad. Also, when I removed the hub, I noticed, that the bearings had really been torqued down hard. I thought something like that should not have more then 50 foot pounds. It took some power to loosen it, but I do not know exactly how tight it was. I had no idea that it was important to know that. My old brake drums where made by Meritor and I am getting the exact same ones. I ordered them from my local parts house and will get them on Monday. I also ordered new brake shoes for both sides. These brake shoes are supposed to be a little bit different and I hope it will make a difference in braking power. At this time, I am thinking of removing the front wheels again and purchasing brand new brake rotors. Remember, I have a new rotor on my drivers side tag. I am also thinking of replacing the brake pads with the same type of lining I am getting on my drive axle.
I hope all of this will make the improvement I am hoping for. If it does't, I am really thinking of changing the front brake pods. I think they are #24 and replace them with 30th. This is just a thought at this time and I am not sure if it's even possible.
Currently I am stuck because I am out of parts and still need to replace the bags on the passenger side. The bag replacement on the drivers side is complete and it was an easy task. I will continue Tuesday, after I receive the new drums and brake pads.
Ben

[dale farley]

Ben,

This link will walk you through posting photos. If you have a problem, just let me know. http://forum.prevostownersgroup.com/...-Post-Tutorial

[Joe Camper]

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I guarantee that u have the same hub. The only way they configured the drive axle hub for almost 20 yr that I'm aware of possibly longer.

I'm confused now because u have to have removed the dust cap. Its the only way u can get the leaky seal and then the inner bearing out. First remove the dust cover then the ring that holds the seal.

If u pulled the hub for leaking at the rear this is the only way to remove the seal that is causing the leak. If U did not pull the dust cap what was your plan of attack? How did U get the seal out. How u gonna put the new?

Another thing, u r not thinking correctly if u r even thinking about changing the front brake diaphragms from 24s to 30s. I do not even know they will fit and that's just unheard of. You would be wise to reconsider that.

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Many prevo hubs have the ring that keys the inner nut to the spindle but do not have the second washer that bends over the outer nut to also lock it. SO the outer nut has to be really tighted down vigorously or u run the risk of it getting loose. Once u free the outer nut the inner nut can or SHOULD be able to be turned off by hand. That is the critical adjustment going back together that should ave been noted before it was removed to either A verify it was either put on at the factory and correct OR installed later and wherever the prior mechanic put it at.

U do not put ANY torque on the inner nut much less 50lb. There should be 1\1000 to 5\1000 play in the hub if the inner nut is set correctly.

U better be carful it seems to me u r treading in deep waters.

I'd be very interested in learning where u sourced the brake shoe and linings for the drive axle as an assembly. If I had a chassis that the preformance of the brakes were in question and less than desirable I would not be going to outside sources for their replacement. Like I said earlier I never put brake components on prevo unless they come from prevo.

[Ben Neumann]

Joe, thank you again for posting the pictures of the hub. I just pried the old seal out of the hub without removing the dust cover just using two big screwdrivers. There was so much crust and oil on the back side of the hub that I did not see the screws holding the cover. I looked for it after I saw your pictures. You are right, my hub is identical to the pictures you posted. Getting the seal out without removal of the cover was pretty easy and took only a minute, but definitely the wrong way of doing it, but I will do it correct the next time when doing the passenger side and also installing the new seal into this hub. Thank you for correcting me. In regards of increasing the front brake cylinders on the front axle, that would be an extreme. I really have not checked this out at this time and it might not even be possible. Right now I am hoping that all the repairs will get satisfactory results. If not, I will go back to the front and one remaining side of the tag to change rotors and the pads.
Also, you are talking about purchasing parts from Prevost only. The drums I am replacing are made by Webb and so are the new ones. If they are not 100% identical, they are going back. The new lining is made by Apex and is supposed to be a little better then the old ones. I am hoping for some good results so that I do not have to think "extreme " again.
Ben