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Author Topic: MC-8 Manual Trans. Shifting  (Read 3944 times)
DavidInWilmNC
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1978 MC-8 as I bought it May 2005




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« on: July 05, 2007, 07:10:15 AM »

When I drive this bus, I usually grind gears during downshifts and occasionally during a downshift.  The fact that I can occasionally shift it smoothly makes me think that it's my 'technique' insteat of a problem with the bus.  I double-clutch every change.  I shift at or right at governed speed.  It feels like the clutch isn't completely disengaged... at least that's how a car I had felt prior to an adjustment.  I've turned the adjustment knob 'til I felt pressure, then backed it off like instructed in the manual.  That helped some, maybe.  The vagueness of 'until pressure is felt' or whatever in the manual doesn't help.  Should it be completely without pressure then any pressure is when one stops turning the knob?  Some shifts are as smooth as my Toyota's automatic, and sometimes I can't get it into gear.  Sometimes, if I'm stopped, it'll grind a bit when put into first or reverse.  I can generally upshift fine to second, have an occasional grind into third, and the shift into fourth is usually smooth.  I believe I'm following the shifting tips posted on the 'other' forum correctly.  I guess I'm wondering how long it generally takes to master shifting these old buses.  Thanks for any tips or suggestions.

David
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Dallas
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« Reply #1 on: July 05, 2007, 09:48:00 AM »

David,

Mostly it just takes experience to learn how the different components should feel at different shift points.

A couple of months ago I broke the shift rods on my bus and had to replace them.

Before I broke them the shifter was stiff but sloppy, so while I had it apart I tightened it up and greased everything.

I was use to the way it shifted before, but now I have to get use to it all over again. The tower is tight and the shifting mechanism is smooth.

All the way from the Flea Market where I fixed it to the state park where we camped I missed probably 75% of the shifts!


Take a look at RJ Longs article on shifting:

http://www.busnut.com/bbs/messages/12262/16204.html?1167073154
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buswarrior
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« Reply #2 on: July 05, 2007, 01:18:55 PM »

Smooth shifting is mostly a matter of timing.

All the internals are changing the speeds they are rotating at, and you are trying to nail the meshing of gears, the sliding of a spline on a shaft, many feet of skinny linkage on both clutch and shifter at pretty much the precise moment that they are spinning at the same speed. That instant passes, as they go from too fast to too slow to engage with one another.

Get it right on, you might wonder if it even went into gear, a little knock is you being close, a rattle is further away.

Former truckers sometimes have trouble with how slow the shift has to be compared to a 10 or more speed tranny due to the great RPM drop between the gears on a 4 or 5 speed bus tranny.

Car drivers, used to synchros, have never had to think about timing, the tranny helped get the gears together for them.

happy coaching!
buswarrior
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DavidInWilmNC
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« Reply #3 on: July 05, 2007, 01:59:19 PM »

There are a couple of things that are strange to me about shifting this bus.  One is that it seems to shift better (less grinding) soon after starting it as opposed to shifting it after running for a few hours.  This could also just be me getting tired of fighting the shifter for a few hours!  Wink  Another thing is that it often grinds a bit putting it into reverse or first when stopped.  It's not a bad grind like trying to fight it into gear, but more like the grinding is slowing the gears down enough to engage.  That makes me think that something isn't adjusted correctly... like the clutch.  How does one tell if the linkage is adjusted properly?  With the clutch in and the engine running or the engine off, it shifts smoothly and seems to drop into gear, making me think that the linkage is o.k.  Other times it engages so smoothly that, like BW says, I wonder if it even went into gear.  Sometimes it grinds a bit but the clutch engages very smoothly, which makes me think that I had the RPM's matched (mostly) correctly.  I can deal with it taking time to get smooth with shifting this transmission, but I worry about damaging it.  If I heard somebody shifting a car or small truck that I owned like this, they wouldn't drive it again!  I can handle shifting cars and motorcycles, and, although entirely different, surely I can master shifting the bus.  Thanks for the input, guys.

David
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DrivingMissLazy
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« Reply #4 on: July 05, 2007, 02:19:06 PM »

David, it is entirely normal for it to shift better when it is cold. The lube in the tranny is thicker and the gears slow down faster.
If you are sitting with the clutch out, the gears in the tranny are spinning. When you push in the clutch to put it in gear, you have to wait for the gears to stop spinning. Many times you can try and slip it into fourth gear first and you will have little gear raking. Then without releasing the clutch, slip it into first or reverse. It should go in without any problem.
Richard

There are a couple of things that are strange to me about shifting this bus.  One is that it seems to shift better (less grinding) soon after starting it as opposed to shifting it after running for a few hours.  This could also just be me getting tired of fighting the shifter for a few hours!  Wink  Another thing is that it often grinds a bit putting it into reverse or first when stopped.  It's not a bad grind like trying to fight it into gear, but more like the grinding is slowing the gears down enough to engage.  That makes me think that something isn't adjusted correctly... like the clutch.  How does one tell if the linkage is adjusted properly?  With the clutch in and the engine running or the engine off, it shifts smoothly and seems to drop into gear, making me think that the linkage is o.k.  Other times it engages so smoothly that, like BW says, I wonder if it even went into gear.  Sometimes it grinds a bit but the clutch engages very smoothly, which makes me think that I had the RPM's matched (mostly) correctly.  I can deal with it taking time to get smooth with shifting this transmission, but I worry about damaging it.  If I heard somebody shifting a car or small truck that I owned like this, they wouldn't drive it again!  I can handle shifting cars and motorcycles, and, although entirely different, surely I can master shifting the bus.  Thanks for the input, guys.

David
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
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« Reply #5 on: July 05, 2007, 02:27:51 PM »

I know on truck clutches they have a clutch brake that stops the gears from rotating so you can get into gear from neutral without grinding.  It works by depressing the pedal all the way to the floor then push moderately on it to activate the brake.  Not sure if buses have this feature.  One way to tell if the clutch is adjusted right is to push the clutch all the way in and get it in gear.  Then with the clutch pedal still pushed on the floor, put it into neutral for a second or two then put it back into gear (don't let up on the clutch).  If it grinds alot, the clutch is dragging.  If you get just a couple of bump grinds, then it is adjusted right.  Technically the transmission should shift easier when warm since everything will be loosened up.  The fore mentioned cold oil slowing things down could be a factor in cold shifting ease.  When shifting, make sure you push the clutch pedal all the way to the floor or else you might drag the clutch which will make shifting more difficult.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #6 on: July 05, 2007, 02:32:12 PM »

My 4104 always shifted better when I first started out and when the tranny was cold. I always assumed it was due to the thicker oil.
Richard

I know on truck clutches they have a clutch brake that stops the gears from rotating so you can get into gear from neutral without grinding.  It works by depressing the pedal all the way to the floor then push moderately on it to activate the brake.  Not sure if buses have this feature.  One way to tell if the clutch is adjusted right is to push the clutch all the way in and get it in gear.  Then with the clutch pedal still pushed on the floor, put it into neutral for a second or two then put it back into gear (don't let up on the clutch).  If it grinds alot, the clutch is dragging.  If you get just a couple of bump grinds, then it is adjusted right.  Technically the transmission should shift easier when warm since everything will be loosened up.  The fore mentioned cold oil slowing things down could be a factor in cold shifting ease.  When shifting, make sure you push the clutch pedal all the way to the floor or else you might drag the clutch which will make shifting more difficult.  Good Luck, TomC
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Busted Knuckle
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« Reply #7 on: July 05, 2007, 05:22:18 PM »

David all the things said above are true! First of all I applaud you and anyone else who can double clutch properly! I have owned and driven semi-trucks, buses and just about everything else with manual transmissions all my teen & adult life and have never been able to successfully double clutch any of them! I have always had better luck with a single push on the clutch or simply floating the gears altogether with out using the clutch for anything except 1st and reverse! I have tried many time to get the hang of it but never been able too! And I've even had a company I leased a truck to once send their shop foreman out with me for a road test in my truck. And he got upset with me because I could perfectly and smoothly float the gears, but not double clutch with out grinding the heck out of them! I asked him what difference it made since A) it was MY TRUCK, and B) because I could shift perfectly the other 2 ways ! His response was "We want all our drivers to double clutch our trucks, and if your truck ever breaks down and we rent you 1 of ours til yours is back on the road, I want you too be able to shift it my way!" Well after about 15 minutes of trying to show me how he gave up, and told me "just shift the way you know how, because you do a fine job of it that way! LOL"! When we got back to the office the company owner asked him "well is he good to go?" and his response was "yeah, but let him shift his way and don't ask me why!"
Anyway after I got outta trucking and into buses my uncle tried to get me to double clutch and eventually came to the same conclusion and told me "do it your way! I won't have to replace any tranny's or clutches that way"!

Bottom line is if you can double clutch, do it! But there are ways that work better for others!

Anyway if you have time this coming week you ought to look up my dad! The reason I say to look up my dad, although he may be a little rusty/outta practice but he has always been able to shift a manual transmission bus better than anybody else I seen! He might have time to give you some pointers!
I can't guarantee that though as he's hauling the CIA some of our regular customers. And from what he tells me they keep him hoping! The CIA (in this case is  Christians In Action, a youth group that performs at different churchs, senior homes, youth group homes, and such as they travel. And in return they get a meals, or place to stay.)
He'll be in Wilmington Tuesday thru Thursday 7/9-12/07 I don't know the exact times but he will be at or around St. Matthews Lutheran Church @ 612 South College Rd, Wilmington, NC. The group will be staying there at night in their Family Life Center. Call me if you'd like to get dads #, or if you'd like to catch one of the CIA's shows! FWIW! BK

PS I wanted to drive this trip, but this group specifically requests mom & dad!
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Busted Knuckle aka Bryce Gaston
KY Lakeside Travel's Busted Knuckle Garage
Huntingdon, TN 12 minutes N of I-40 @ exit 108
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lostagain
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« Reply #8 on: July 05, 2007, 06:01:14 PM »

You can't hurt your trans. if you don't force it. Just use your fingers, lightly. Grinding going into 1st and r. is normal. Don't force it. It just takes miles to get good at it. Back in the seventies, driving every day for a living, I could shift those 4 speeds without looking at the speedo at any rpm really smoothly. Now, getting out only once in a while, it takes a few miles to get the hang of it.
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JC
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« Reply #9 on: July 05, 2007, 09:52:43 PM »

I do pretty much the same as BK, I only use the clutch for first gear when starting from a dead stop. I, too, found that I didn't shift any better using the clutch, double or not, than with no clutch at all in both directions so why wear out the clutch??

I have the same problem as you when stopped. It is easier for me to just stop the engine, shift into first and restart than to wait for the gears to stop. When I roll up to a stop sign I push in the clutch and gently drop it into first with no grinding. You must be almost stopped to do this. When I can I stop on a slight incline and then can leave it in neutral and let it roll slightly when ready to shift into first, it doesn't take much.

On my Spicer 4-sp there is no grinding going from first to reverse when stopped or when going back to first from reverse. Once you get it into first you have it made.

It takes a bit of practice and patience between gears going up but going down needs to be quicker. I usually just hold down the throttle a bit in neutral when going down and it slips right into gear. Sometimes not!!

When shifting without the clutch you must back off the throttle before taking it out of gear in both directions, this unloads the gears.

I never have a day of all perfect shifts. I've driven a bunch of trucks, including 18 wheelers, and none of them are as  hard to shift as my bus.
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PD4107-152
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RJ
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« Reply #10 on: July 05, 2007, 10:05:49 PM »


I believe I'm following the shifting tips posted on the 'other' forum correctly.  I guess I'm wondering how long it generally takes to master shifting these old buses.
 

Since I wrote that article on BNO you're talking about, I'll share that, IBME, that it takes anywhere from 3,000 - 5,000 miles of experience before you can hit your shift points, both up and down, 95% of the time w/o bumping a gear.

IF you've got the touch.  Some folk never seem to master double-clutching (BK admits to it!), yet can drive them extremely smoothly w/o a lot of grinding.  For others, it comes quickly - my son, when he was 16, figured out upshifting our 4106 easily, but nine years later, he still bumps the gears on downshifts - which is the more difficult of the two.

An awful lot is "feel" and knowing your coach.

No wonder automatics are so popular, eh?

FWIW & HTH. . .

 Wink
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RJ Long
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DavidInWilmNC
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« Reply #11 on: July 06, 2007, 05:12:26 AM »

Actually, I don't really care whether or not I use the clutch just as long as I don't grind the gears!  I haven't tried shifting w/out the clutch, although I have done it in cars and on my bike (motorcycle).  If it takes 3,000+ miles to 'master' shifting, I guess I'm not doing so badly.  I can up-shift fairly smoothly about 60% of the time, very smoothly (like my car's automatic) maybe 15% of the time, and rough as hell the remaining 25%.  I'm able to start, get up to speed, make turns, stop, and manage to up- and down-shift functionally.  It mainly bothers others riding with me, as they think something is wrong with the bus.  I'm not sure that they'll feel any better knowing the problem isn't the bus but is me instead!   Wink

I probably would have bought an automatic, but I think I got a decent deal on this bus.  The exterior is in very good shape, except for the damage I did on those roots, the tires are decent, and the engine was rebuilt 30,000 miles ago and runs great.  I certainly understand why some would wait and pay more for the good condition of this one plus a good automatic. 

Thanks for all the comments.  I don't feel so bad about it now.

David
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Busted Knuckle
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« Reply #12 on: July 06, 2007, 08:33:07 AM »

You'll do fine as soon as you find YOUR groove!
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Busted Knuckle aka Bryce Gaston
KY Lakeside Travel's Busted Knuckle Garage
Huntingdon, TN 12 minutes N of I-40 @ exit 108
www.kylakesidetravel.net

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TomC
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« Reply #13 on: July 06, 2007, 08:55:58 AM »

David- the nice thing is all is repairable.  You're close encounter with the roots will be a bit laborious to repair, but I'm confident it won't happen quite as easily next time.
Shifting is a pain (this from a truck driver that drove nothing but 13spds and for 1.3 million miles).  Maybe somewhere down the road you'll want to change to an Allison.  I was personally ruined when in 1982 I went to a Detroit Diesel/Allison (when they were still together) ride and drive at the Rose Bowl here in L.A.  I drove a Kenworth with a 500hp 8V-92TA DDEC and a 5 spd HT755CR ATEC with the truck loaded to about 67,000lb.  It felt more like driving a pickup pulling a big Airstream behind than a truck.  From that day forward, always lusted for an Allison in my truck.  In fact before I became a new truck salesman at Los Angeles Freightliner, I had a Freightliner Argosy (cabover) with a small sleeper (101" cab) all spec'ed with a 430/470 Series 60 and the HD4060 Allison with a long wheelbase to facilitate a 12ft drom box that would have been converted into a sleeper.  But I smartly did not ultimately order it.  Would have been fun though out accelerating all the trucks, even loaded, from the signals. 
Enjoy your bus-they're absolutely the best way to travel!  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #14 on: July 06, 2007, 07:16:08 PM »

I agree with most that has been posted here. I have driven the old International  549 gas engines with 5 speed main and 3 speed auxiliary, Mack triplexes (3 transmissions, 3 sticks), 5, 6, 9, and 10 speeds, 10 over, 10 under, 15 over and under, 15 double over and some autos; and, this Spicer 4 speed in my MC7 is the orneriest  transmission I have ever tried to shift in my life!  Before I got it, I prided myself on smooth shifting. Now I am thankful to get it in a gear. I drove a lot with my Father and other family members whose favorite expressions were "When you shift, I don't want to feel anything except the change in the engine!" and "If you can't shift it right, I CAN, & you can GET OUT right HERE!"   Angry I am afriad if Dad was with me now, I would be left standing on the side of the road!  Embarrassed

But I'm working on it, and I believe I will get it right before I lose the tranny.  Grin
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