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Author Topic: 4104/4106 Question - mountains  (Read 4675 times)
RnMAdventures
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« on: February 12, 2011, 01:07:46 AM »

A few years ago I had a 58 4104. I didn't do the traveling I would have liked to in it. I am in the market for another bus and I have been thinking seriously about a 4104, 4106, or a MC5A. However, I never really knew how well the 4104 would handle the Colorado mountains with a spicer 4 speed?

How about a 4106 with an Alison automatic?

Any feedback is appreciated.

Mike
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Mike & Rosemarie
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« Reply #1 on: February 12, 2011, 03:18:35 AM »

Mike     We have a 4106 with the V-730 auto & have been all over the western Mtns. Temp rise on long
pulls used to be a prob. until the new radiator, now never attempt's to heat up. We also pull a full size
chevy impala while traveling.  06 Bill 4106 2741
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Barn Owl
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« Reply #2 on: February 12, 2011, 05:59:37 AM »

I took a fully loaded 4106 with a V730 through the Rockies without a problem and I didn't stick to the beaten path either. Many 10k to 12k passes and long steep grades. The only thing I wished I had was the 6v92 turbo. High altitudes gives the 8v71 lots of smoke and reduced power. My bus has an over-sized radiator (seven core vs four) and the larger cooling fan (eight blade vs six). After seeing some transmission temps that were on the high side while there I bought a Hayden 1290 off of Ebay this winter to supplement the oil/water cooler, and expect to have it installed before I head out this summer. I believe that of the three buses you have listed, the 4106 w/ the v730 is the easiest one to modify for the mountains. That's one of the reasons I have one, it's the only bus that I could reasonably get to my house..... which is in the mountains.
« Last Edit: February 12, 2011, 08:03:56 PM by Barn Owl » Logged

L. Christley - W3EYE Amateur Extra
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« Reply #3 on: February 12, 2011, 06:31:57 AM »

Personally-I would stick with a 4106 or MC5 with automatic, with a turbo engine.  You'll be amazed (just like I was when I turbo'd my 8V-71) at the difference in performance-especially in the big hills we have out west that can be over 11,000ft.  On a bus, the only manual I would consider would be at least a 7spd with 10spd being preferred.  Good Luck, TomC
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« Reply #4 on: February 12, 2011, 07:59:47 AM »

Is there a ten speed trans. that will replace the 4 speed on a 4106  '64
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« Reply #5 on: February 12, 2011, 09:19:50 AM »

PapaTony -

With the GMC V-drive powertrain, you have your choice of three transmissions:

1. Stock manual 4-spd.

2. VS-series two-spd automatic

3. V-730 three speed automatic.

If you want to put a 10-spd in one, you'd have to completely rebuild the rear of the coach to convert it to a T-drive configuration.

Sorry.   Cry

FWIW & HTH. . .

 Wink
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RJ Long
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« Reply #6 on: February 12, 2011, 09:22:29 AM »

Mike -

The simple answer to your question?

Fine.

You just get to putter along climbing the grades out here in 2nd gear, while enjoying the beautiful scenery!

Think "The Tortoise and the Hare" if it's a 4104.  The other two will be a little faster, but not much.

FWIW & HTH. . .

 Wink
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« Reply #7 on: February 12, 2011, 10:00:14 AM »

From everything I have read and witnessed any bus built for revenue service will do  the job.  I have crawled,,,and i mean crawled up some steep steep hills in an old '04 in Mexico.   The mex hills are way steeper than anything I have seen in the US or Canadian rockies.  My 2 cents is get the bus that is ready to roll in good condition and go from there.  The '04 is slower, but the inline 6 is way easier to work on.  "Startability" is a bit of an issue but as long as you are rolling you should keep going.  I personally prefer the simplicity/reliability of a manual trans, wish my '04 had a splitter, but so it goes.
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« Reply #8 on: February 12, 2011, 04:36:37 PM »

Thanks for every's response.

I do like the simplicity of the DD671, but the part that I didn't like was it could get stuck when the back tires would "cup". Thats the part that worried me at times. I learned to dig it out and park more stategically. I would wonder what would happen if I was on a steep grade on mountain pass and for what ever reason I had to stop? However, I was able to take off from some very steep hills, so I suppose it wouldn't be so bad. I love the sound of a DD671.

My wife will be driving the bus as well (she insist). I figure the experience would be better for her if it is an automatic, but she told me she can drive either. There is a 4106 I plan to look at soon that has an automatic. It's a quality conversion and I almost purchased it years ago. I am ready to take the family on some traveling adventures.
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« Reply #9 on: February 12, 2011, 07:57:34 PM »

Mike,

I've driven my 4104 round trip across the Rockies six times in five years with no problems other than going very slow upgrade!!

The problem is not a 671, it is the poorly geared Spicer. Mountains are not the problem, a too high first gear is the problem.

You have to be very careful about where you stop whether on a mountain grade or a steep incline out of a parking lot!! You just can't start from a stop on anything steep or soft without damaging the clutch and doing possible harm to the engine. Slipping the clutch is a no-no although sometimes you have no choice.

The upside of the Spicer is good fuel mileage and good engine braking on downgrades. Also it is kind of fun to shift when it and the clutch are properly adjusted. When the clutch is out of adjustment it is miserable.
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« Reply #10 on: February 12, 2011, 08:23:14 PM »

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long as you are rolling you should keep going.

Good strategy but Murphy's Law will kill any good plan. Start overheating on one of those long steep grades and you are going to stop to cool off, like it or not. Or let a bear become visible from the road and every gawker in front of you will stop to take a photo and cause you to have multiple stop/starts, no matter how much horn blowing everyone is doing. The list goes on but you get the idea. I don't find the 4106 very difficult to work on. The starter would be the only thing that is not accessible from the back. I like the fact that you can raise the rear engine lid and work standing up without getting rained on. GMs are a dream to turn wrenches in compared to some other manufactures. Yes, I am biased to GM for these good reasons and some others that might just make no sense at all. Owners tend to think that their manufacture is the best ever and I am no exception. I will say that I could be happy with just about any decent conversion regardless of manufacture.
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L. Christley - W3EYE Amateur Extra
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« Reply #11 on: February 12, 2011, 09:39:29 PM »

I was told by a well experienced 4106 pilot that starting a Spicer on a hill was a cinch. Huh  So here is the procedure....

First, you have to modify your engine to allow the fast idle to be  engaged AND be able to put the trans in first gear.  Normal mode, I am told is that the engine will drop out of fast idle when the trans is shifted into gear.  I think safety is the reason for that lockout.

On the hill, while stopped, you engage "fast idle".  You then shift into first.  Ease the clutch out and let the governor walk you into the start.  Absolute minimum clutch slip.  Add some throttle to come up to speed and switch off the fast idle and shift when possible.  I have never done this nor have I driven a 04/06 but that man has street cred with me and I will repeat this "lie" with confidence.

I once described this "method" on this board and was come down on like a ton of bricks from a couple old salts.  I am not smart enuf to argue with anybody DD savvy or truck wise....so I won't.  They never did come up with an explanation of just why this procedure was "crazy", their word, or why DD had locked out the fast idle while in gear.  That is the advocated way to start out on the level but not using the fast idle.  Remember being advised "let the governor get it moving and save the clutch"?  I was told that starting on a 6% grade was a non event and that you could easily start on a steeper grade using the Governor.  Like I said though, I never did it.

BK?  Tom?  BW?

Good luck,

John
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« Reply #12 on: February 12, 2011, 10:43:00 PM »

Hi, John.

I'm afraid that I'm the one that told you about using the fast idle for getting rolling on an upgrade. For some reason, our fast idle was working when we got the coach and the circuit to shut it off when the emergency brake was released had been bypassed. In the process of learning to drive our coach, I discovered how to use the fast idle.

First off, I rarely use that method because it does raise some safety questions. But, if I don't think ahead when stopping on an upgrade and the coach doesn't want to get rolling with a dead throttle start, the fast idle will do it. One thing that isn't obvious, is that the 8V71 in stock configuration will produce 90% of maximum torque at around 800 RPM, a little less than the fast idle speed.

The other thing is that the clutch will try to buck or chatter some when letting the it engage at an idle. When the fast idle is turned on, then the clutch engagement is smooth. I think that the engine moves around a bit on the cradle, changing the length and throw of the linkage slightly. With the fast idle, the throttle has no effect on the governor, because it is locked.

To use the fast idle to get rolling, I have to ease the clutch all the way out in first, shut the fast idle off and hit the throttle at the at the same time. If I do it right, there's only a slight lurch while shifting from fast idle to normal throttle.

While the engine is not hard to stall when idling at about 450 RPM, it's another story altogether on fast idle. I expect that's the reason that the fast idle is usually disabled when the parking brake is released.

That's probably more than you wanted to know about the fast idle operation.

Tom Caffrey
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« Reply #13 on: February 12, 2011, 10:44:13 PM »

 JohnEd,
  Your description of using fast idle and starting the coach on a grade in first is what I do when I start the bus on a grade.....works great for me and I have got the 4104 rolling on some pretty steep grades here in the Ozark Mountains.  And please before anyone jumps in and starts the old "your in the Ozarks, there aren't any steep grades in the Ozarks" argument...... yes Helen there are some very steep grades here in the Ozarks. Wink  I say this and I have traveled a lot in the Mountains of Colorado, Wyoming, Arizona and New Mexico.
There is a saying here, our mountains may not be very tall but the valleys sure are deep.
 I do not know if my coach has had any thing done to it to allow the use of fast idle when in gear I just assumed it was normal. I can get the coach rolling using fast idle and throw the fast idle off as I engage the foot throttle to pick up speed..Works great.

Rick
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« Reply #14 on: February 12, 2011, 11:01:47 PM »

Hi Tom,

I remembered where I heard it and having ridden with you I can attest that you know what you are doing behind the wheel as far as my "feeling" goes.  Didn't want to take unauthorized use....

So what is the "dangerous" aspect?

Rick,

Do you need to be extra cautious to switch off the fast idle when you depress the throttle?  Can't you just sw off and depress throttle?  More casual like?  Thanks for your contribution.

Considering I used to hear that if you got stopped on a hill you might have to back to the bottom of the hill and get a run at it this takes on new meaning.  A three mile "back down the mountain" might sound like a real pain in the tookus but now just consider the ramifications if you are alone and pulling your toad 4 down...or even 2.  Now that is a bonefide delema in my book.  I think many will benefit from this discussion and if you need to be special careful...well, so be it.

Thanks again for your comments and thanks to Tom one more time.
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« Reply #15 on: February 12, 2011, 11:29:23 PM »

If higher engine RPM's are required to get started, you may just use the throttle pedal instead.

If the fast idle is rigged, that works, but I suspect that with a little practice, you can get it moving on a slope with less wear to the clutch by way of less throttle than fast idle.

Your goal for longest clutch life is to have as little difference in rotating speeds between the engine and the drive train in order to get the coach moving, or while shifting gears.

Just think of there being a big grinding wheel in there, the faster the rate of spin, the more material you remove.

Hence, the much encouraged dead throttle start, with the engine only on the idle, and the governor to keep it there, has the lowest spin speed in relation to a stationary drive train.

As for the safety of a fast idle feature able to be engaged while underway, I suppose that if we can think of an inopportune time for the engine to be allowed higher rpm's, or to have the throttle pedal locked out with the parking brake released, that would be it?

happy coaching!
buswarrior

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« Reply #16 on: February 13, 2011, 12:33:32 AM »

To add a little more confusion to this fast idle start thing:

All the GMC parlor and transit buses up thru the 4106s came from the factory with "Johnson bar" mechanical parking brakes.  All later model GMs came with push/pull air-operated parking brakes (DD3s).

The fast idle circuit is wired into the parking brake with a switch that kills the fast idle when the bar is moved beyond a certain point as you release it.  Or, at least that's the way it was wired when it came from the factory.

As Tom mentioned, his switch apparently has been by-passed (Gus's & Rick's too?) by a previous owner.

Every bus I've ever had any experience with that was equipped with the push/pull parking brake always killed the fast idle when the brake was released.

While working in revenue service with manual transmission coaches, I never ran across a situation where I couldn't get the bus rolling in first gear on most small inclines.  Even when having to stop on a grade to hang chains on the drive axle.  I will admit to stalling the engine a few times, but with more practice, stalls became fewer and the starts more smooth.  It's all in the techique, training and practice.  I happened to have a great instructor early in my bus driving career - she taught me well!

Tip:  Remember that the service brake release delay can be your friend when starting on a grade.  (Think about it!)

FWIW & HTH. . .

  Wink

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RJ Long
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« Reply #17 on: February 13, 2011, 02:29:55 AM »

While it sounds like it is possible to restart up a grade with a 4104 or 4106 with a spicer tranny, would a 4106 with a Alison auto be the "best" case scenario? One of your replies mentioned having to back down the mountian... with a toad. That would be a nightmare.

On the flip side of this, how well does a Alison V-730 handle going down the mountain?
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« Reply #18 on: February 13, 2011, 10:20:08 AM »

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how well does a Alison V-730 handle going down the mountain?

There is no "free-wheeling" with the v730, it shifts up/down by rpms, and will hold it's gear for the rpm range it is in. It also locks up in 2nd and 3rd so there is a solid mechanical coupling just like a manual. Tom can actually do a better job with these details. I have Jake brakes on mine, and with the light weight of the 4106, they allow long steep descents without ever touching the brakes. There is no disputing the fact that it is a great mountain setup, and an inexpensive one at that.

I have never driven one, but I understand that the VS series Allison will give an exciting ride down hill. Maybe someone who knows can clarify how it performs.
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L. Christley - W3EYE Amateur Extra
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« Reply #19 on: February 13, 2011, 09:39:02 PM »

Hi, John.

We have never been bothered very much by backing down a hill , except by an impatient motorist who couldn't wait to go around us. Part of the reason is that we have never towed. Backing in good light is not much of a problem. Doing it at night is another problem, altogether. Good backup lights are needed that did not come on the 4106.

The danger of using the fast idle would be the amount of damage a bus could do if the driver lost control on fast idle. If it stayed on slow idle, it wouldn't take much damage to kill the engine, by comparison.

We go up slopes that break over 20%, but I consider it mandatory to run the coach against the governor, starting from the beginning of the steep part and going all the way to the top without easing up on the throttle.

Powerful solutions have powerful hazards is the way I see it. Take care.

Tom Caffrey
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« Reply #20 on: February 13, 2011, 09:57:30 PM »

20% boggles my mind.  I had a hill like that stop Wendy and I was only pulling a 2800 pound Datsun Z car.  To her credit and my amazement, I found the next day that she had shed a plug wire so she quit half way up on 7 but probably would have squeaked over the top with all eight firing.  Want a fun time?  Try unhooking a car while it is dangling off of a ball.  Now don't insult me with "you should just have....". Embarrassed Grin  I'll repeat the story in OT some time in the future and till then I would actually appreciate yours and anyone's suggestion on how to achieve that separation of "iron".

John
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« Reply #21 on: February 13, 2011, 10:07:38 PM »

To me "fast idle" is no more than part throttle except that you can have it while you are parked without having to have your foot on the accelerator.

My bus doesn't have fast idle but even if it did the last thing I would want when starting out is "less" control of the throttle which is what you have on fast idle. When I have to start on a grade I give it some throttle(more than usual) and engage the clutch as fast as possible without stalling it. And as I am letting out the clutch I am also easing up on the throttle aiming for the quickest "full clutch engagement" as possible.

Riding the clutch (or part engagement) to me is the worst thing you can do.

Fred Mc

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« Reply #22 on: February 13, 2011, 11:16:33 PM »

What always worries me about an automatic, is how slow you can go before the converter unlocks. Most automatics I've drive (newer buses) can't seem to go below 30mph before unlocking 2nd. I'd be really worried about overheating climbing a long steep grade with unlocked automatic.

My bus is fortunate enough to have a 6.1:1 crawler 1st, so I can easily start on just about any gear. In 3rd at around 25mph and 2100rpm, my little 6v71 would climb almost ANY grade, partial throttle, no smoke and no overheating, for any lenth of time.
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« Reply #23 on: February 13, 2011, 11:20:17 PM »

RoyJ -

Quick - better post what make/model bus you have to give Paul (artvonne) more info to compound his bus search!

 Wink
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« Reply #24 on: February 14, 2011, 12:58:56 AM »

 Wow, a lot of different thoughts here, seems the method I described in my earlier post is not a very popular procedure.

 I will try and give a better explanation of what I have done several times when starting my 4104 out on a grade. It has worked for me with no clutch slippage several times in the past.
 
 I set the brakes (spring), put the clutch in, put the transmission in first, engage fast idle and as I let the clutch out release the brakes and as soon as the coach begins to move quickly switch off fast idle and get on the foot throttle. It all happens pretty quick and is a very smooth start with no clutch slippage. Maybe this is not the correct way but as I said it works great for me.

 I drive a big truck 5 nights a week hauling US Mail, just got in tonight with a 75,000 lb load and have used a method close but somewhat different to this for years to get the big truck moving from a stop on a grade when I have a heavy load. No clutch problems as of yet. 

Rick
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« Reply #25 on: February 14, 2011, 02:33:01 AM »

I set the brakes (spring), put the clutch in, put the transmission in first, engage fast idle and as I let the clutch out release the brakes and as soon as the coach begins to move quickly switch off fast idle and get on the foot throttle. It all happens pretty quick and is a very smooth start with no clutch slippage. Maybe this is not the correct way but as I said it works great for me.

Your method sounds good to me. If you used the spring brake, do you have to use the fast idle to get the RPM's up since you don't have to use the air break? When I had my 4104 I don't remember using the mechanical break on an incline, so I really don't know how well it would work.
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« Reply #26 on: February 14, 2011, 06:13:43 AM »

does anyone know what it would cost to have a jakebreak installed on a 8v71?
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« Reply #27 on: February 14, 2011, 06:54:01 AM »

 The few times I have done what I described in my last post I have been in heavy traffic on a short but pretty steep grade with a car stuck like glue on my rear bumper..... a situation where I had to stop somewhere I normally would not stop. It is not something I do or feel I need to do everytime I start the coach rolling on a hill.

 It usually happens to me in the Branson Mo. area. If you have ever been to Branson I think you will know what I am talking about....I avoid Branson's highway 76 strip but any time I am up there it seems to happen, I get stopped on a hill in traffic somewhere I would rather not be.  This has gotten me out of a tight spot more than once but I would recommend practicing it a few times without the traffic and the mental pressure the traffic and finding youself in a bad situation will put on you.  I am no expert here just telling what has worked for me.

Rick


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« Reply #28 on: February 14, 2011, 07:40:33 AM »

Just as information, not any criticism of anyone or thing...

On my MCI the fast idle can only be engaged if the parking brake is on.  If you release the parking brake, fast idle is automatically disengaged.  Also, when fast idle is on the accelerator pedal is locked out.  You cannot use the accelerator pedal for anything other than a foot rest when fast idle is on.  Given those two things, using fast idle to help you start on a grade is a non-starter, it just can't happen.

What I have done in the past is use the parking brake.  On my bus (may not work on all, although I am developing a technique that needs field trial...) I can engage the parking brake with the push pull valve and disengage by pushing it in and the DD3's release on their own with no brake pedal application.  That lets me feather the throttle up and engage the clutch at a slightly higher rpm.

Of course being a racing car driver I also have a tendency to heel and toe the brake and the throttle simultaneously, although that is kinda hard with those pedals...


Brian
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« Reply #29 on: February 14, 2011, 08:42:25 AM »

RoyJ -

Quick - better post what make/model bus you have to give Paul (artvonne) more info to compound his bus search!

 Wink

   HAHAHAHAHAHA.  Thanks for thinkin of me RJ. Would it compound my search, on "confound" my seach. You should check my math for me on the thread about 8V71 vs 6V92T, lol.

   Rick, did you ever get the parking brake/johnson brake parts for your Bus?

  
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« Reply #30 on: February 14, 2011, 12:26:17 PM »

Paul,
 No hand parking brakes as of now, I need to find the parts..
Rick
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« Reply #31 on: February 14, 2011, 02:17:14 PM »

Unlike Rick's, my '54 4104 has no fast idle nor is there any mention of it in any of my manuals.

It did, however, come with a hand throttle which shows as original equipment in my Driver's Manual. I use it both for fast idle and as a cruise control on long straights.

It has been converted to spring parking brakes, thankfully!!
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PD4107-152
PD4104-1274
Ash Flat, AR
JohnEd
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« Reply #32 on: February 14, 2011, 03:04:08 PM »

It seems to me that some don't fully grasp how the fast idle actually works.  The rpm, in fast idle, as I understand it, is CLOSELY controlled by the governor.   The governor applies and subtracts throttle much much faster that a human could if he were standing at the engine with his hand on the throttle.  Add in the delay associated with the throttle linkage, and air throttle is much quicker than cables or rods, and you end up with a somewhat hopeless situation of "lag" in injecting corrections and you end up with a over revved engine that is frying the clutch or you stall out.  The process has you engage the clutch at the absolutely lowest RPM and in the shortest time so as to not fry the clutch.  You use the closely controlled "governed" fast idle to just get things hooked up and then, because fast idle will not apply full throttle, you switch out of fast idle and then depress the throttle to get WOT.  Wallah!  "Huston, we have movement that doesn't involve Exlaxx." Grin

Now, this is just my grasp of things having heard them in various levels of detail over the years.  Please correct me in any way for the sake of those others that don't really understand.  God knows that I shouldn't have the last word around here.

If you don't have fast idle and you have a stick 4 or 5 speed you would benefit from get it installed.  If you have it and it is locked out with the handbrake or any other mech I would suggest you modify your system.  Bus companies often hired less experienced drivers and everyone needed protected from their rookies.  We have a lot of safty systems around us that "Real Men" don't need to be successful with the ladies.

John
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« Reply #33 on: February 14, 2011, 08:08:53 PM »

FWIW, when we try to "feather" the clutch while trying to get rolling against a grade, the coach starts to buck. I attribute this to engine movement causing throttle changes by changing the length of the linkage path when a load is applied. This doesn't have any noticeable effect when the clutch is out.

On the other hand, the governor on fast idle doesn't produce "any" of the bucking, even with a heavy load.

Regarding clutch wear, we have .380" and .408" disc thickness after around 80,000 miles and we're nowhere near the rivets, yet. The worst thing that I remember doing to the clutch was climbing the coach rears up on high blocks at Ted Campbell's place when we were trying to fix a vibration problem. It didn't seem to bother him.

If I can get the coach moving without using the fast idle, I do. It normally works very well.

Tom Caffrey
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Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska
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