Stranded - Can't put bus into gear - Near Las Vegas

[lvmci]

Hi, get of I15 south to LA, turn west on Flamingo towards Rio/Palms hotels, at end of Palms hotel is Arville stoplite, turn left, south, just past hotel is apartments on left, school district bus yard on right, then a industrial center on left, 1st entrance on left, look for Garys marroon Dodge dually, if you get to Orleans hotel at Tropicana you've gone to far, if you need it, Gary may have used tranmissions available, sometimes he does, tom, lvmci...

[Dlsnow]

I heard a big air leak while under the bus. It's coming from the rear end of the clutch air assist cylinder. There is a petcock supplying the cylinder. Wih it off the air leak stops.

I'm taking off the cylinder, inspecting and bringing it to Gary.

[Ncbob]

It's the same cylinder as the original belt tightener cylinder on the old OTR A/C compressor if you still have that. Parts to rebuild the cylinders are available (I carry a spare set aboard) and Luke has them. Good Luck

NCbob

[bevans6]

The air cylinder is a 2" diameter single action cylinder, and can be easily rebuilt by changing the O-rings.  There is a sponge inside that is soaked in oil, to keep it lubricated.  It has two rod end joints, mine where totally seized but they are common 1/2" rod ends.  The petcock is there so if the cylinder leaks you have the option of shutting off air to it - I just removed mine, because it had failed, and direct-connected the supply to the air cylinder.

There, I feel better now that I managed to get that off my chest!

Brian

[Dlsnow]

I checked the tensioner for the old compressor, it didnt have similar Orings. Ordered the rebuild kit for delivery Monday.  The tech on the phone mentioned the rebuild kit is also for the air cylinder that locks the front door shut.  Mine is disabled, tonight I will disassemble and see.

It is leaking due to the wear in the Oring.  It is shaped more like a D (wore flat against the piston).

Many thanks to Gary at B&B coachworks for helping me out

[Tony LEE]

How does a leaking clutch assist cylinder make the clutch easier to operate.

[Dlsnow]

Tony-It shouldn't it should make it harder. If it works it should be easier. I think it started working (maybe it was seized up or slow leak)

The problem-
--bus can't move, can't get into gear
--when I press the clutch pedal the transmission doesn't slow down to allow me to shift into 1st

History
--I don't think air assist Was working when I got the bus (a year ago).  My first bus ...I thought it was just really hard and that's how it is.
--last 3500 miles clutch was hard to press
--gassed up (bus was warmed up) and I SLAMED the clutch down because I was expecting it to be hard to press
--clutch worked but was easy to operate
--I adjusted the free play dial as there was a lot of free travel and it was nice and easy to shift (bonus)
--I drove about 15 miles from camp to the dump station and noticed the clutch kind of bumped and I pressed and released it
--I did my business at the dump station, started bus and can't get into gear

Notes
--it didnt have a noticeable air leak here before
--it still won't go into gear with air shutoff to the cylinder
--it is possible that I am fixing an unrelated issue (proper air assist may not get me rolling)
--It seems to be an issue with the distance of travel
--I checked the connection at the transmission and the clutch seemed good and tight

Thanks all for being so helpfully and responsive.

[RJ]

Dave -

Just because you cannot put the coach into gear with the engine running doesn't mean you cannot drive the thing.

That's what every friggin' 4905 driver had to deal with, due to GM's use of a wet clutch.

As long as you've got a straight shot in front of you, simply shut off the engine, put it in gear and restart the beast with the clutch in.

You may bump along a bit until the engine's fully running, but at least you're no longer stranded.

You should be able to upshift w/o using the clutch, just the throttle.

Simply pop it out of gear as you roll to a stop, then repeat the process when it's time to get rolling again.

OTOH, enjoy the view where you're staying until the parts come in. . .

FWIW & HTH. . .

[luvrbus]

 What view RJ I bet he is shocked they call that area the Lake Mead Rec Area he won't be looking out over the lake lol

[Dlsnow]

Cant see much of the lake but it is a good view. I mean nothing bad of "stranded".

Btw-bus is pointed uphill and wont roll starting it in first.  If i needed to i could probably roll it backwards down the hill and turn it around.  Ill excersize my patience.

Probably not waiting on parts to find out if this air cylinder repair gets me going.  Im pulling an "ok" Oring from the door claw and will put a heavy oil in there to get a seal and see if this gets her going.

From a "whats changed" troubleshooting perspective its logical that thia may work.  When i look at the diagram and think about the symptoms I worry that thia air cylinder issue isnt the end of it.

Stranded in good weather with the people I love...not a bad gig

[hargreaves]

Adjust the linkage so there is no free play and try again. hold the clutch down for a minute, the input shaft brake may not be working.  if it works slowly adjust so you get some freeplay back.

cheers Gerry

[bevans6]

That setup doesn't have an input shaft brake, unfortunately.  It's a very simple clutch, just a mechanical lever on the outside of the bellhousing, two fingers hold the throw-out bearing which presses the fingers.  The cover plate has about 25 1" diameter springs maybe 2" tall, there is a plate - disc - floating plate - disc - flywheel.  The fingers ride in adjustable trunnions.

Brian

[wg4t50]

Still feel it is a broken center disc plate draging, had same experience on my MCI7, was able to put in gear, start engine, use clutch to get moving (draging heavy) and shift  w/o clutch.   Also, the big MCI shop used a carriage w/wheels that rolled on the frame rails to move transmission back, look for rails inside on bottom of frame rails.
Agree, good time for a 740.
Good luck
Dave

[challenger440]

I can't see how the assist cylinder is going to help in this situation.  On my MC 7, near as I can tell, the assist is only there to make the pedal easier to push in.  It does not make any difference to what is going on inside the bell housing. 
 
Sounds more like your not getting enough travel somewhere.  Broken fingers, worn out throw out bearing, clutch center broken out, etc. 

  Time will tell.   Hard to say if driving it would cause any more damage.  Just  depends on what's broken.
John M.

[Dlsnow]

If i go with a 740 ill probably have to get jakes too for coming down the hills...right?
I went to put the air assist cylinder back in this morning.
Easier to get out than in. Pickjng up a ja k and stands / blocks now.

I worked the clutch more to see if i could find slippage.

The bus wasnt running or aired up and the clutch pedal was real easy to operate (without air assist as its disconnected).  Does this support the broken disk idea?  What provides the resistance i usually feel?