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 Double-clutching/Downshifting a 5-speed '76 Crown
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hure1200
New Member

2 Posts

Posted - 10/25/2013 :  11:46:49 AM  Show Profile  Visit hure1200's Homepage  Reply with Quote
So I took the plunge! One of my childhood dreams (well, since I was in the 6th grade -- I rode on them from elementary thru high school) was to drive/own a Crown School bus. These buses are real gems, and as you know, they are being taken out of service (and in most cases, crushed, rather than sold (in order for the school district to get the federal and state incentives)). Hereís the skinny: My bus was manufactured on 8 Dec 1976 and delivered to Tustin Unified School District (Tustin, CA in Orange County) as bus #5. It has an A-426-11 (Amidships), Detroit Diesel 6-71 engine, and a 5-speed (Fuller?) transmission.
Although Iíve been driving a stick shift since I was 15 (now 45), this beast is giving me problems... I donít know if itís me or if the clutch needs adjusting. I was told that on this bus you have to double-clutch and get up to a certain RPM before you shift, otherwise you grind the gears Ė and yes, that does happen if youíre not to at least 2000 RPMs before you (up)shift. I have gotten that down pat somewhat, although I miss the gears sometimes, because Iím probably not clutching/shifting fast enough Ė then I freak out. I still haven't figured out how to downshift, though. I drove the bus from Los Angeles to Oceanside (~90 miles down the 57 and the 5), hoping not to hit stop-n-go traffic. It wasnít too bad, although the couple of times that traffic did stop, I didnít downshift, but rather rode the clutch with break 'til stop -- then started again on first. I never once downshifted from fifth, even on the upgrades on the 57Ö I'm sure I stressed the hell out of the engine, but it's a freakin' beast, and it performed flawlessly.
My question is, are there any Crown bus drivers here that can give me some pointers as to what Iím doing wrong? I read another thread that says I need to match RPMs on the downshift as well, but that seems too complicated. If anyone is in the North San Diego area, and is willing to give me a couple of lessons, Iíd be much obliged, of course, thereíd be some compensation Again, very much appreciate any input. Thanks! Jerry A.

misterbill
Advanced Member

United States
302 Posts

Posted - 10/27/2013 :  06:39:46 AM  Show Profile  Reply with Quote
The easiest way to do it is how I was taught in truck driving school back in 86(I mention this because now this is taught as being improper). The method that I was taught is called 'bumping the governor', I am assuming that the bus has a governor or you will get yourself in trouble.

Anyway, you need to figure out at what RPM the bus will go into the next gear. It is probably around 1500 to 2000 of an rpm drop. In other words, if you tack it up to 3000 rpm and shift, it should go into the next gear at 1000 to 1500. What you do is tack it up and push the shifter into the next gear by watching the tack. It is much easier to tack it all of the way up, at some point you won't have to think about it, because it is all about timing(how fast or slow you have to shift).

Here is a hint that I don't want to give you. Most truck drivers do not use a clutch to shift from gear to gear. It is a lot easier to shift that way. The reason that I don't want to tell you this is because you cannot(or should not)do this with the kind of transmission that is in a pickup truck, or in most school busses.

The modern way to shift a truck is called 'progressive shifting'. That means you only tack it up a little for the first seven or so gears. You progressivly tack up higher in each gear to conserve fuel. The trucks that I have been driving for five years have a 10 speed that is really like driving the old thirteen speeds. You skip speeds 1 and 2, so it is really like driving a four speed car or truck. You start in 3rd, push a switch(splitter)to go into forth, push ths switch back and shift into 5th and then switch to 6th. I drove a straight ten speed(five and five)at another job and I could not figure out how to shift it, and I learned how to drive on a ten speed.

Well I hope this helps, I don't communicate very well, this sounds complicated to me. Really, once you figure out the spread on the tack, it just takes a lot of practice.

High School Friend-"Hey! How are you! Well, I guess you can't be doing too well, you're driving a school bus."

Edited by - misterbill on 10/27/2013 06:43:02 AM
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misterbill
Advanced Member

United States
302 Posts

Posted - 10/28/2013 :  10:04:59 AM  Show Profile  Reply with Quote
quote:
Originally posted by misterbill


Here is a hint that I don't want to give you. Most truck drivers do not use a clutch to shift from gear to gear. It is a lot easier to shift that way. The reason that I don't want to tell you this is because you cannot(or should not)do this with the kind of transmission that is in a pickup truck, or in most school busses.



Can I quote myself? Must be able to, cause I am.

I just got out of work and I realized something. I had a truck that didn't like to go into fifth gear for some reason(I haven't driven a truck with under a million miles[no I am not exagerating]in four years). When you shift without the clutch, you can feel how fast the gears are spinning(grinding). When you rev the motor you can feel the gears speeding up or slowing down. It probably would be a better way to learn how to shift.

High School Friend-"Hey! How are you! Well, I guess you can't be doing too well, you're driving a school bus."
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C.HARDY
Advanced Member

350 Posts

Posted - 10/28/2013 :  5:58:45 PM  Show Profile  Click to see C.HARDY's MSN Messenger address  Reply with Quote
I couldnt imagine driving one of those on a route....lol. Practice is the best way to learn i have found. Get out there and take your time and before you know it youll have it down

"Hardybusman"
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hure1200
New Member

2 Posts

Posted - 10/29/2013 :  10:28:56 AM  Show Profile  Visit hure1200's Homepage  Reply with Quote
Agreed. I did take it out this past Saturday for about an hour and drove it around town, but still managed to grind the gears. Seems hit and miss, shifting into 2nd. The higher gears seem to go in a bit easier. I just need to have the foundation/fundamentals down, and for that I probably need someone that has driven these in the past. I understand some school systems here in California are keeping (requesting an excemption for?) at least one Crown with a standard tranny; for training and certification purposes. To your point about driving this on a route, yes, it can be quite a chore, but I do remember the bus drivers back when I was a youngin' seemed to all be little old ladies that had no problem with the manual Crowns (no automatics yet). Still remember one of those ladies driving us on a class field trip to San Francisco (1985) and did an outstanding job going up and down those streets with the steepest hills (some with a 31.5% grade -- Yikes!)... Well, she was calm, cool and collected anyway, and didn't even break a sweat lol She retired the following year (my Senior Year of high school) after 30 years of driving.

Edited by - hure1200 on 10/29/2013 2:42:54 PM
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C.HARDY
Advanced Member

350 Posts

Posted - 10/29/2013 :  4:30:30 PM  Show Profile  Click to see C.HARDY's MSN Messenger address  Reply with Quote
yes they amaze me those little old ladies driving those crowns. I drive a truck part time and it has a 9 speed. I dont drive often enough to keep from scraping from time to time but I have found there is nothing better then road time. Once you figure out what rpm/roadspeed combo works you will be able to do it by ear. Sounds like you have a cool, fun driving bus.

"Hardybusman"
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