Front wheel removal of 1998 Prevost XL

[Gil_J]

The rear are much easier! Did you confirm the bags they sent were the right ones? I noticed my 9u chassis had 3 different bags.

[Joe Camper]

Yes the rears should be a smidge easier.

When u do the rear do as I described up front. All the way up all corners front included. Support the chassis at the lift points with jack stands as tight as u can get them. Dump all rear air both sides. Leave front up. Jack duels just enough to get them off the ground plus just 1 inch. The rims will not be a strain on and off.

U really do not have to take the inner drive tire off unless u want. If u do not just be sure to check the inner nuts for tight even if u have not loosened any often u will found 1 or 2 loose and potentially happening during the outer tire removal but also just plain loose as well. Regardless if u remove the inner drive or not and if u have a valve stem extension the just off the ground suggestion makes putting the outer tire back on and way easier to get the stem extension thru the hole in the outer rim without damage.

When u remove the screws for the rubber flap forward of the drives if u like and if u left the inside duel on u would not remove all the screws. Leave the top inside screw for the rubber flap on and let it lay on the tire it will be out of the way and make going back in easy alignment.

After u have pulled the outer drive tire and before trying to remove and replace the bags drop the jack down at that corner until the inner tire hits the ground this will give u the most clearance.

There is no rhyme or reason to weather the fittings r push in or not. I'd replace any disrupted push in with new old style parker fittings.

Look close at the air tanks attached to each bag for rust at their brackets. Do NOT open or disrupt the drains on those tanks. U will never get any water out of them and ud be potentially creating a suspension leak. I'd plug them get rid of the drains. I'd pull and paint the tanks too if I've got the time.

The top and bottom studs on some bags r the same threads. Some have fine thread on the top and course thread on the bottom. This is so wrong on so many levels but I won't go there!

When installing the new bags paint their mounting plates. Put the bottom in first and compress by pushing down hard and u can push it in, first 1 top stud then the other. U will not damage the threads on the top studs by doing this. Once both studs have cleared the flange position it up. If there is a gap at the top longer than the studs after u have secured the bottom jack that hub back up and the bag will get close enough to get the nuts on the studs. It may be nessessary on the drives to jack the other side up with it . This keeps the suspension carriage square where if u don't u will have to pull and push to get the top studs to line up wit the holes.


If u do replace fittings use Parker only. No home depot no Chinese.

Also if replacing fittings for some reason prevo has half in pipe to 3\4 compression on the front drive bag BUT 1\2 IN pipe to 5\8 compression to the rear drive and tag bags.

That about covers the little things that ud otherwise have to potentially slow u down. If anything else comes to mind I'll add it on the thread.

Gill I'm thinking the drives r 260 the tag is 259 can't recall the steering.

And above all else be careful Ben, do not hurt yourself.

[Ben Neumann]

Yes Gil, I did call Prevost and I have the right bags. They all fit but do look taller and skinnier then the old ones. This is probably because they have never been inflated before. Thank you Joe for your extensive explanation about removal and installation of the rear bags. They are definitly easier to install. When removing the drive axle wheels, I noticed an oil leak on that axle (drivers side) Yesterday I just installed the tag axle bag. Today I need to address the oil leak on the drive axle before I continue with the remaining air bags. I have another issue with my bus. When I purchased the bus about three years ago I noticed there was a problem with the brakes. When stepping on the brake there was always a gap in the brake paddle when stepping on it. In other words, you try to stop in front of a stop light by stepping on the brake and nothing happens. When realizing that the bus would not stop, I would panic and slam on the brake to stop it. When investigating the cause, I found the drivers side tag had frozen brakes and the brake shoes were completely gone to the point there was nothing left and the rotor had 1/4" groves. I repaired this wheel and also checked all the remaining wheels and installed new brake shoes on every wheel. The brakes definitly improved and the gap at the brake pedal disappeared. But still, I feel the brakes are not the way they should be. Last year I changed the master cylinder and it made a slight difference. It is an improved new model whitch looks identical to the old one. Still, I feel these brakes are not save. I need way too much pedal pressure to stop the bus. In an emergency braking I would be in real trouble. I have never driven any other Prevost and therefore have no comparison. I ask my parts supplier for softer brake lining but he tells me it is not available. After I am done with the air bags I am going to attack this problem. At this time I wonder if anyone of you have the same problem. When talking to other bus owners (not nessecerly Prevost owners) I hear comments like "all busses are like that because bus owners do not want to get sued when passanges might get slammed against the front seat if the bus driver hits the brakes to hard. I have heard these comments from several people. I am haveing a hard time believing it and would appreciate your thoughts.
Ben

[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.