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Author Topic: Drop box and diff gears  (Read 4643 times)
lostagain
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« Reply #15 on: October 05, 2011, 11:40:20 AM »

This one shows the end of the pinion shaft where 11 37 is stamped. That is the ratio: 11 teeth on the pinion gear, and 37 on the ring gear. I also counted them. 37 divided by 11 is 3.36 to 1 ratio. You would have to remove the drop box to see that if the diff is on the bus.

I might find some time to install it in the nex few days. Really looking forward to the test drive, lol. I hope it doesn't reduce the power too much. Although I don't remember power problems on the 5s with the highway gears back in the old days. They sure had more power than the MC7s with the same 8V71 and 4 speed Spicer. Having the Allison HT740 will help at least in 1st gear.




JC
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JC
Invermere, BC
1977 MC5C, 6V92/HT740
lostagain
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« Reply #16 on: October 07, 2011, 12:07:18 PM »

I am in the thick of it now. The drive shaft is off: had to take the U-joint apart at the drop box end, being an automatic, there no flange, the yoke is right on the input pinion. The axles are off. My plan is to take the drop box off first, then the diff., they are so heavy. I have all the nuts on the drop box loose except the 2 at the top: I can't get to them to turn a wrench. Not a lot of room to work with. And the pass. side DD3 is mounted on the diff., damned engineers, lol. So this afternoon the right hand wheels are coming off. Of course the park brakes are on. How do I take the DD3 off? I'm thinking take the brakes off and disconnect the push rod at the clevis pin. What if the press. goes down enough that the brakes come back on? Although my bus will keep air above 40 or 50 psi for several days. Is there a better way to remove that brake pot without causing trouble?

Anyway I got myself into a BIG job... I remember doing that to my Courier 96 and telling myself never again...

JC
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JC
Invermere, BC
1977 MC5C, 6V92/HT740
bevans6
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« Reply #17 on: October 07, 2011, 01:12:26 PM »

The passenger side DD3 is kinda mounted to the axle/diff housing, but I  don't think it's attached to the differential pumpkin at all.  I was just in there and changed my DD3 can's but I don't totally remember how the mount worked  I really think  it was welded to the axle housing, which is the same piece as the diff housing.  I do remember that the hoses to the inversion valve were clipped to a diff pumpkin stud.  Anyway I changed mine with the emergency brake full on and locked, since there was no air pressure in my bus at all and I put the emergency brake on before I took the engine out.  I was able to undo the two bolts that hold the can to the mount, it moved forward enough to take all the pressure off the slack adjuster so it was all just hanging there.  The clevis pin was totally seized so cut the head off with a grinder and knocked it out with a punch.  then I just undid the hoses and wiggled it out.  I had to move the front shock forward a few inches to get clearance, but you may not have to.

When I undid the two canister bolts, the studs actually came out of the cannister and the nuts stayed exactly where they were, that may have actually helped me get it out not having the studs in the way.  I would definitely take the passenger side wheels off and I think you will find you don't need to take the DD3 off at all once you can see it better.  I would personally take all the rear wheels off, it would make it a ton easier to get at things.  Unless you are in a pit, I guess.  If you do take the canister off, you can reset the pushrod to release the emergency brake by applying around 50 PSI to the locking port, and then pulling the pushrod out a bit, it will release and spring back in to the full off position.

Edit:  Now I think that the DD3 mounting bracket was bolted on to something, and it may well have shared some bolts with the diiff pumpkin.  Gotta look and see, I guess.  Anyway, it is possible to remove the DD3 in the parking brake locked on position.  don't forget to dump all the air out before you undo a hose.

Brian
« Last Edit: October 07, 2011, 01:45:26 PM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #18 on: October 07, 2011, 01:43:22 PM »

Thanks, Brian. I am taking the wheels off now. I will, like you say, have a better look with those out of the way. I'll report back later.

JC
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JC
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« Reply #19 on: October 07, 2011, 03:51:44 PM »

Wheels are off now. I can see a lot better, and get in there from the side. I was able to get at the 2 top nuts (drop box to diff pumpkin) without too much difficulty. The DD3 can on this side (pass.) is mounted to a bracket that is bolted to the diff pumkin to axle housing studs, so it'll have to come off. But anyway, the whole thing looks a lot more doable with the wheels off. I won't be able to get at it now till after the long week-end (Thanks Giving here in Canada). My son is coming home from college and says there is work to do on his truck, plus the outlaws will be here too... so the bus will have to wait...

JC
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JC
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« Reply #20 on: October 12, 2011, 08:42:47 PM »

Spent a couple of hours yesterday removing nuts. None of them were stuck, but it is still hard work, lying on my back. The pass side DD3 brake can came off no problem. Some hoses had to be disconnected, etc.

Today I rented a big transmission jack. It is a good one that not only moves up and down, but the table swivels side to side as well as front to back, which is good for lining up the diff into the housing. I spent all day taking the drop box and diff out, and reinstalling the 3.36 diff and drop box back up. It is a JOB AND A HALF! It takes big tools and also some brute force and ignorance, lol. I hope I don't have to do that again! The diff I took out of my bus is a 9 to 37 = 4.11 to 1 ratio. The manual says that 3.70 was standard. So I don't know if my bus came from MCI with 4.11 gears, or one of the owners before me put it in. I'll be another day or two finishing up, and then I should (on paper) be revving 1800 rpm at 65 mph, down from 2200 rpm at that speed. I'll report back about my test drive...

JC
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JC
Invermere, BC
1977 MC5C, 6V92/HT740
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« Reply #21 on: October 12, 2011, 08:50:24 PM »

You are going to love that 3rd gear JC with a 3:36 lol watch the speedometer in 3rd lol

good luck
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lostagain
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« Reply #22 on: October 12, 2011, 09:12:28 PM »

Yea Clifford, I was doing some calculations last night and 3rd gear should take me to about 50 or 60 mph at 2200, that'll be nice. 2nd to 40 mph. So I am hoping that what I lose in power, I can make up by being able to down shift at a higher speed. I remember the summer of '75, I was assigned a 5A with a fast rear end. Going downhill with a tail wind, I could get 80 mph out of it, lol. I never got a speeding ticket, even  though I deserved one at times, lol.

I guess 2200 rpm at 65 mph with a 8V71 was OK in the '70s. That is what the bus originally came with. Those 8V71s didn't mind revving on the governor all day, and fuel was cheap then.

JC
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Invermere, BC
1977 MC5C, 6V92/HT740
luvrbus
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« Reply #23 on: October 12, 2011, 09:18:56 PM »

Hang on to 4:11 the Eagle guys are always looking for that running the B500 or 4060 with the series 60 probably can get over 1/2 your money back and keep the dropbox not bad huh,if you want to sell it PM me a price and I'll post it on the Eagles board for you 

good luck
« Last Edit: October 12, 2011, 09:21:43 PM by luvrbus » Logged

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« Reply #24 on: October 13, 2011, 11:11:19 AM »

  As some here know, I have a hellaciously steep driveway. But for those who dont, allow me to recount my smaller hillbilly version of "Wolfcreek Pass". Coming off the highway which is at about 6% grade, the driveway is initilly 18% rising to 22.5% within a Bus length, then immediately falls off to average 14% up to the house. Its a steep hump. When I first came to this forum and admitted I wanted a 4107, then a 4104, and explained my driveway grade, many here strongly (some humorously) advised against it and we ended up in all kinds of discussions (opinionating) about startability and grade climbing in a Bus. There were suggestions of winches, pushing with the Towed, pulling it up, or just simply relocate to flatland. In the end I gave up on the 07 and 04 and eventually bought a MC5B. I bought it without knowing what gears it had, believing (praying actually) that being from these parts (the Ozarks) it would surely have the lower 3.73 gears. And even with those gears, on paper the climb would be tough. The 1975 MCI sprang to life, we woke up Mel Tillis.

  Within miles of Little Rock however, I started to realise I was in big trouble, as I was seeing the higher speeds in gears. Near 40 in second, 55 in third, 75 plus in 4th (I think I hit 80 once or twice, or close to it). At first I tried to BS myself the speedo was off, and without a GPS thats all I was doin was guessing. Then I started timing mile posts at 60 per, and uh, negatory on that speedo error there Pig Pen, She's on pretty close. ARGHHHH! You wanna back er on down Earl?

  That last 150 miles home my mind was spinning, should I even try going up the driveway, and if not, where do I go. And I started wondering about a gear change, I think you and I even exchanged some emails about doing that, swapping gears. But I plowed on, and as I drove it, as I watched the miles unwind and as she talked to me, I resolved myself that I would at least try. And the closer I got, especially as I tooled it through Fayetteville double clutchin the upshift and snaking them in slick, and kept making takeoffs from lights, my confidence rose, I just knew it could. But still. The sign said 22.5% grade ahead.

  When I got here I stopped down on the highway looking up up at "El Capitan" and contemplated it one last time. I now knew it had the high gears. I knew on paper and from discussions, it couldnt do it. But with that last 200 miles of experience behind me, I felt the paper and opinions were moot. I dropped the clutch, mashed the pedal down, and aimed old Nellie for the barn. It was totally a non event, she stormed up here throwing pine cones, rocks, and boulders. My wife said she backed way off as I was really sprayin gravel.

  I had my Fire Fighter buddy up here a couple weeks ago. He owns the local trash company and was up to haul some stuff for me, and he spots the Bus next to the house and his eyes bugged out. Being he's been all around these parts haulin garbage, he's seen some whopper driveways, and rates mine as one of the steepest. He says " is that an MCI? Wow, another Bus nut. Next he says "how you get that &%)$#* thing up here?". I said I drove it. He was even more colorful when I related as it was a 4 speed stick.

  4:11 gears, man, I cant imagine what you would ever need those for, cept mayby India, 20,000 feet up on a goat trail. 
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bevans6
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« Reply #25 on: October 13, 2011, 11:25:41 AM »

The 4:11 gears are useful in metropolitan work, where top speeds might be 50 mph most days.  My bus has the 3.7 gears, in town I never get out of third gear, and  I have a problem getting going at a stop light that has a steep approach.  The 4.11's would be perfect for a bus that never got on a freeway.  On the other hand, starting on that steep approach to a light would be a lot harder with the 3.4's.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #26 on: October 13, 2011, 11:34:50 AM »

 A Eagle bus don't have a problem starting on a grade with a 6v92,740 and 3:36 gears and they are a 40ft bus 3:36 or 3:73 were the standard

good luck
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« Reply #27 on: October 13, 2011, 01:18:09 PM »

With a 740, i wouldn't have a problem either, but with a 4 speed Spicer first gear can seem a little high sometimes...   Grin

Too high for a dead throttle start, have to balance brake/throttle and clutch, raining, rush-hour, lost, been driving for 10 hours, allergies kicking in.  You get the picture...   Grin

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
luvrbus
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« Reply #28 on: October 13, 2011, 01:29:28 PM »

Yea I keep forgetting some still have 4 speeds with the screwed up reverse   Shocked
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bevans6
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« Reply #29 on: October 13, 2011, 01:40:36 PM »

The guy who sold it to me said "manly men drive standards" or some such hogwash, and I believed him...   Cheesy

brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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