Prevost tag axle brake rebuild

[bobofthenorth]

I don't think there's anything particularly earth shattering about my brake rebuild last week but maybe there are a few pearls of wisdom buried in the effort.  We decided that we should do the rebuild after doing a BC safety inspection last fall.  I had lots of brake pad left and plenty of adjustment left but when they did the inspection they put a dial gauge on the brake cam and measured the total travel.  "In spec" is 110 degrees and we measured around 90 or 95 on the curbside tag.  Everything else was much lower.  The inspecting shop didn't offer any advice - it passed so they were OK with it but it bothered me all winter.  I try to get the bus into a friend's shop every spring so I made sure to do that and his mechanic immediately recognized that I had some wear on the cam bushings on that axle that was contributing to the excess travel.  My drum was also run out which I should have been able to notice myself - all that takes is a finger inside the drum to feel for a lip.  My pads were hardly worn at all - likely the last fix before we bought the bus consisted of installing new pads to compensate for the drum wear. 

Lessons learned:
- check your cam bushing wear by releasing the pressure on the slacks and then trying to wiggle the slacks side to side - if you can feel any significant movement you are likely out of spec

- use lots of Never Seize when putting everything back together.  I did that 2-1/2 years ago when I replaced all the shocks.  They didn't last worth a damn but that's another matter unrelated to the Never Seize.  This time we replaced all the shocks with Gabriels and every last one of them slipped off easily.  Last time we used a sawzall and the red wrench to get pretty well every one off and then had to beat or cut the mounting bolts out in order to replace them as well.

- buy all the parts from Prevost.  We thought we were being smart by purchasing from NAPA but even with their deepest discount most of the items were still more expensive than Prevost.  We didn't find that out until after the fact but it has been my experience in the past as well so I should have known better.  You guys that have access to Mohawk don't have to worry about this but for us Canucks the frenchmen are clearly our best source for parts.

- Prevost's parts book for my coach is wrong.  Left tag is right tag when it comes to brake cams and vice versa however there is a Preost partsbook online.  Its a royal PITA to use but it does work if you have a Prevost parts account.  And if you don't have an account getting one is a simple as phoning Prevost.

- Chinese manufactured brake shoes are not perfect.  We got everything together the first time only to discover that the guides for the rollers had enough of a burr to prevent us from putting the drums on.  Even after polishing out the burrs on both sides the curb side drum still dragged on the outside of the top shoe and we ended up grinding a bit of the pad off.  The Meritor drum also was slightly out of round - enough that we could notice it when we rotated the drum against the too-tight shoe.

- We should have bought the cam bushings and seal kit from Prevost (see above).  The Prevost kit has better seals and (likely) bronze bushings - the NAPA kit had seals that worked but didn't match the originals and it had all plastic bushings.

- And finally a lesson that we had learned before but ignored.  Use CR seals - don't use Stemco.  Because we ignored this rule I get to remove one drum and hub today in a campground and replace the seal.

- total cost including all new parts and a token labour payment to Darrel ($900) was just over $4000 Canuck but that includes close to $1000 for all new shocks so more like $3200 for the brake job on both tags.  We'll probably do the drives next summer and thanks to the parts book error I have a spare set of brake cams that will also fit the fronts whenever we get around to doing them.

[mikelutestanski]

Hello  Bob:
   So for my mci tag rebuild I spent about 750 and the labor was on me. THat includes new drums from ABC in winter haven and mohawk parts with shocks.  The bearings and seals were ok.
    BOb are you planning on FLorida this winter?   We wll be heading for Texas  to see the grandkids.
    SO we send our regards to Marilyn and yourself.   
     happy busssin    mike