Help - 4106 sticking accelerator cable (near Austin, TX)

[technomadia]

Greetings -

Midway through our drive into Austin on Saturday, I noticed that the accelerator peddle in our 4106 was feeling off.  Soon I realized that the accelerator was sticking a bit, lagging behind a bit when I'd lift off my foot.

By the end of the drive it had gotten worse, and it would take a full 5-10 seconds for the peddle to rise back to neutral from fully depressed.

Once stopped I disconnected the throttle cable from the engine, and determined that the stuckness isn't in the engine governor. I am now trying to figure out where the stuck is. I can't yet determine whether it is up under the driver, back by the engine, or somewhere in between.

I find it really puzzling that it happened mid-drive. Saturday was a very cold (for Texas) day with lots of humidity and freezing rain. At first I thought it might be ice causing the sticking - but it was still sticking this morning when I tried cycling the peddle by hand, and we are now well above freezing.

It is really tight to work in the front chamber under the driver - I think I might be able to get the front accelerator linkage dismantled to free the front end of the cable to further isolate where the sticking might be, but it will be tricky. Before I try taking it apart I might want to track down a nearby shop or busnut for help.

Before I dive deeper into this - does anyone have any tips on dealing with this issue, or on repairing or replacing a 4106 accelerator cable?

Is this a good time to change to an air throttle? What would be involved in doing this?

Does anyone have any recommendations for mechanics near Austin, TX that might be able to help?

Happy Thanksgiving, btw!

  - Chris

[Len Silva]

Assuming that it's just like a 4104, it's not a big job.  Disconnect the cable in the front and pull it out from the engine compartment.  Flush out the tube with your weasel piss of choice, clean and lube the cable with white lithium grease, and stuff it back in.  It's easy....unless......
the tube is compromised and you cannot get the cable back in, then you're just screwed.  Naa, it's not that bad, but if the tube is worn through at some point, it will have to be repaired.

Air throttle is fine if you have converted to an automatic, with a stick, the mechanical is better.

[technomadia]

Air throttle is fine if you have converted to an automatic, with a stick, the mechanical is better.

We do have a V730 automatic.

I'm curious why he mechanical throttle is better with the stick though.

Thanks!

  - Chris

[TomC]

Air throttle has about a second lag to it-takes time for the air pressure to go from the front to the back-making shifting a manual almost impossible. I have a V730 on my bus with air throttle. I wouldn't have anything else-since the pedal pressure is light. I set up a King Cruise control with the unit under my dash with the pull cable looping under neath so to pull down on the gas pedal. I did that since just hooking the cruise control to the engine governor control would bypass the transmission modulator-which is also air powered. This way it pulls down on the pedal and everything works properly. I just drilled a big enough holl in the extension plate I bolted to the pedal so to allow the cable to slide through when the cruise control was not used. Good Luck, TomC

[luvrbus]

Fleet Maintenance on E 7th should be able to fix it if they are not booked,and you can try Star Charters they do outside work Walker has been around for long time if he is still around

[technomadia]

Greetings everyone, and thanks for all the great advice.

Before diving deeper into dismantling, I decided to try cleaning and lubricating a bit more.

I picked up some Liquid Wrench chain lube at AutoZone that was recommended for throttle cables.

I squeezed into the chamber under the driver and cleaned the decades of accumulated gunk off the works as best I could, and then saturated everything with the chain lube while cycling the throttle to work it all in.

And...  It worked!

The throttle is now moving smoother and easier than it ever has since we bought the bus.

Score!

Thanks so much for the replies, and we hope all of you had a great Thanksgiving!

[RJ]

Air throttle has about a second lag to it-takes time for the air pressure to go from the front to the back-making shifting a manual almost impossible.

Tom -

Bless your heart, my friend, but I beg to differ.

Shifting a manual transmission coach equipped with an air throttle just requires more finesse.

Add to that a wet-clutch and it quickly separates the professional bus drivers from the "wannabes."

Plus it drives ex-truck drivers absolutely batty!

Thus the time, effort and expense to swap the manual for an automatic.

The throttle is now moving smoother and easier than it ever has since we bought the bus.

Chris -

Glad you've a throttle again!  Motorcycle chain lube is miraculous stuff, albeit lightweight.

Suggest once you get down to Cedar Key, that you do as Fast Fred and a couple other suggested (pulling out & lubing the cable), after which you'll probably never have to do it again.

FWIW & HTH. . .

[harleyman_1000]

Air throttle has about a second lag to it-takes time for the air pressure to go from the front to the back-making shifting a manual almost impossible. I have a V730 on my bus with air throttle. I wouldn't have anything else-since the pedal pressure is light. I set up a King Cruise control with the unit under my dash with the pull cable looping under neath so to pull down on the gas pedal. I did that since just hooking the cruise control to the engine governor control would bypass the transmission modulator-which is also air powered. This way it pulls down on the pedal and everything works properly. I just drilled a big enough holl in the extension plate I bolted to the pedal so to allow the cable to slide through when the cruise control was not used. Good Luck, TomC

Tom, do you have pictures of your setup, so I can try and do something similar.

[Lin]

For preventative maintenance on my 5a, I wanted to lube the accelerator cable.  I do not remember what lube I used; it may have been tranny fluid.  I kept injecting the lube into the cable housing and trying to blow it down line with compressed air.  I really do not know how thorough it was since there was no real problem to begin with.  I personally would be very leery about pulling the cable though since I would be absolutely amazed if it would slip back in without finding a hole in the housing to run through.

[TomC]

Scott-I will get pictures on Sunday when I go out to the bus. Good Luck, TomC

[chessie4905]

   Usually the only place where you get perforation eventually is at the very rear where it makes a bend. A few here have had to replace that piece. I believe it is made of brass tubing. When ours failed there, we used brake line tubing. Not too bad to replace if you can get under there. Pretty good design as most are still working fine even after 60 years.

[luvrbus]

The boat people lube those without removing the cable with a piece of hose clamped to the housing they fill the hose with Marvel Mystery oil  and blow the oil in with 50 lbs of air pressure it works

At one time there was a tool that clamped on the housing and you used a grease gun filled with oil to pump the lube in but I haven't saw one of those in years but I have saw them made on the cable

[oldmansax]

The boat people lube those without removing the cable with a piece of hose clamped to the housing they fill the hose with Marvel Mystery oil  and blow the oil in with 50 lbs of air pressure it works

At one time there was a tool that clamped on the housing and you used a grease gun filled with oil to pump the lube in but I haven't saw one of those in years but I have saw them made on the cable

I made one for the shift cable  on the Wanderlodge. It got so hard to move I would bang my hand up every time I put it in Drive. I disconnected the transmission end, removed the clevis, and connected a hose to the housing with a hose clamp, just as Clifford said. Pumped it full of gear lube using an old lube pump in a 5 gallon bucket. Don't try this on a cold day, Wait til summer! 

TOM

[bevans6]

The throttle cable on my MC-5C was a Belden pull cable, around 1/2" outer diameter, steel wrapped outer with teflon liner, and a 1/8" or so stranded steel inner cable.  It had 1/4" threaded ends swaged on to the inner cable.  You can't pull the inner and lube it, nor is lube needed for the life of the cable - the teflon inner lining does the job until it wears out.  Changing the cable is both hard and easy - the cable runs through holes in many bulkheads along the belly of the bus, and it would be simply impossible to feed a cable through after pulling the old one out.  At the end of the day I used a threaded link nut to bolt my old and new cables together and pulled the new one in with the old one.  I had huge issues - one of the bulkhead holes right around the front of the front luggage bay is only .515" in diameter and the ends on the outer sheath of the new cable I bought were .550"  so I had a lot to do to slim them down so I could pull the new cable past that restricting bulkhead.  The failure on my MCI cable was the cable had frayed almost through all of the inner cable at the point where it exited the outer sheath in the engine compartment.  Only a few strands were left intact.

My understanding is that the GM throttle cable runs through a solid metal tube and the inner can be slipped out, cleaned, and fed back in.  Very different from the MCI cable on my bus.

Brian

[luvrbus]

 Brian,GM's are a bitch  to remove also it's not a easy as it sounds if you are paying a shop a air throttle is cheaper IMO