I have located a drop box and a set of 3.73 (or 3.36 gears) for my MC5C.
I would like to replace the slow gears I have now (2200 rpm at 65 mph), with the higher speed gears, so that I could cruise at a more reasonable 1600 to 1800 rpm at 60 mph, to save fuel and wear and tear on the engine.
Chuck Daugh of Sattelitebus in Penhold, Alberta, has a dropp box and the gears off a 5B that he wants $3500 for.
I would like to have the drop box in my shop as a spare if I ever needed one.
Assuming it is in good shape, what do you think of the price?
JC
Several years back I had the rear end rebuilt with new 3:36 gears - cost with out remove and replace labor was $4400.
JimH
JC, you have 1 gear in the drop box that cost 3200 bucks the pinion drive gear is over a 1000 buy that sucker it is really a good buy if a 3:36 fwiw drop boxes are not hard to rebuild if the gears are good
good luck
Thanks, sounds good. I am going up that way soon and will take a good look.
JC
JC,
I will be watching your change out. I have the 5C and would like to improve the fuel economy. I run 24.5's so I kinda cheat that way. But I need to lower the rpm's.
Good Luck !
Gary
Gary,
I run 24.5 tires too.
I need the bus every week-end for the next month or more, so this will be a winter project, so I won't know the results untill next spring. However, I remember driving 5s in the seventies. The ones with the high speed gears went 75 mph, with the 8V71 and 4 speed.
The guy selling the drop box and gears told me I should be concerned about running high revs to keep the rad fans spinning fast for cooling. I don't have a cooling issue now, so I know I could go down the highway in high summer temps with no problems. When going up a hill, I'll be down in 3rd and 2nd and keeping the revs up. I'm also thinking about adding a trans cooler. ( I have the Allison HT740). So I don't really see a problem. It is all in how you drive it.
JC
JC, I bought my 3.36 w/ dropbox 7 or 8 years ago for less than that. But Luvrbus is right, they are selling for mre now. What engine are you running with the 740? Thanks Tom
Tom,
Detroit 6V92.
JC
I picked up the diff gears and drop box this week-end. It is a 3.36 to 1 highway gears, great. It looks in good shape with no visible wear on the teeth. It is a complete assembly including the drop box and carrier with diff gears, as well as the drive shaft. I started boning up on rebuilding it: new bearings, gaskets, etc. I'll post a picture soon.
JC
JC what ever you do do not use silicone it will leak
good luck
Thanks, where do I get the gaskets?
JC
JC, I get the gaskets and shims from Jefferson in OKC 1-800-813-8367 talk to ED if you need shims for the bearing cones on the inside you have to make those I haven't been able to buy those lately they are easy to make with shim stock
good luck
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This is the diff and drop box, separated and cleaned up, checked out and ready to go up into the rear end. It is all easy to do other than it is really heavy: the drop box is around 100lbs and the diff must be 200 to 300 lbs. I will rent a transmission jack that looks scookum enough. First I have to loosen the nuts on the one on the bus now to come off.
JC
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The flange on the lower right is where the drive shaft bolts on.
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.
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JC
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
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
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
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
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
You are going to love that 3rd gear JC with a 3:36 lol watch the speedometer in 3rd lol
good luck
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
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
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.
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
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
With a 740, i wouldn't have a problem either, but with a 4 speed Spicer first gear can seem a little high sometimes... ;D
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... ;D
Brian
Yea I keep forgetting some still have 4 speeds with the screwed up reverse :o
The guy who sold it to me said "manly men drive standards" or some such hogwash, and I believed him... :D
brian
Paul, even though she hasn't posted here for a while, i don't think that Nellie will appreciate being called "old". ;D Brian, "Real" men don't feel the need to conform to what others define as "Manly". And they don't care what those people think of them either. ;D
Ed, where were you when I was buying a bus with a 4 speed Spicer? That was the time for advice on personal philosophy! ;D
The 4.11 gears (now sitting on my shop floor) were fine. It is that I was spending all day at 65 mph top speed and 2200 rpm. So now with the 3.36 it will be easier on the 6V92 at 1800 rpm, and hopefully some fuel savings. I have the HT740 so startability is not an issue with torque converter 1st gear. We used to drive MC5s all over the Canadian Rockies up some steep hills with no problems. Some had slow gears, some had the fast rear ends. I don't remember how often they replaced clutches: we just drove 'em, lol.
JC
Quote from: bevans6 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. 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
My very first car was a 1966 Pontiac GTO. It had a 421HO, six pack carbs, 4 speed, and a 6.13:1 posi. It got around metro Duluth just swell, ease the clutch out in third from a stop on just about any hill, and if it wanted to argue you just lit em, lol. POS car but was fun while it lasted.
I always just thought the road coaches with sticks stayed out on the highway, inner city stuff was all 2 speed autos. But yeah, if you had low gears like that and stayed in town it would make more sense. Maybe lower gears than that yet in a town like Duluth. When I was young I used to like watching the semi trucks climb Thompson Hill at 20 mph. They got a lot more power these days lol.
JC, i ain't no expert but i think you will see a bit better mpg and a higher top end. :) I also think that you will find that a 55 mph speed limit sucks because at 55 you will either be in 3rd gear up around 21-2200 rpm or in 4th at about 1500 rpm. :( Therefore, to keep from lugging it in 4th you need to be running about 63 mph or more. Leastwise that is what i have found with my 8v71, Allison 644, and my 3:36 gears. :)
1500 rpm at 55mph doesn't cause a problem on a 92 series that is in the peak torque curve fwiw starts at 1300 rpm
good luck
Sooooo not to change the topic or be a thread theif... but does anyone have a recommendation for my 1965 tdm 5303 fishbowl 6v91 with the 4spd spicer for a similar set up for hwy travel? Her top speed is about 65 but the detroit is sccreamin pretty good at that speed....
Ed, is your 644 ratio 1 to 1 in 4th?
The only concern I can foresee with cruising at 1500 rpm in 4th is keeping it cool on a hot day, is that is what you mean by lugging it. So I guess I could down shift to up the revs and I also have rad misters I can use.
GMC5303: assuming you have a 6V71 (not a 6V91). The 71 series doesn't mind revving on the governor all day as much as the 92 series.
Another point is the economical justification of swapping diffs is questionable at best. The diff and drop box cost me $3500. If I sell my take out 4.11 gears for half that, I still have a spare drop box. I did it "just because". I might see a little savings in fuel. And some have said that it will be easier on the 6V92, extending the intervals between overhauls. But at 10 to 15000 miles a year... I didn't do it for the return on investment. I'm just looking forward to the improvement in drivability.
JC
JC, yes it is 1:1 in fourth. And for optimal cooling for a 5A with a 8v71 i read somewhere that the rpm need to be in the 1700 range. 1500 rpm in any gear, (lugging), and my temp gauge will start to rise and i can see more unburned in my exhaust. As Clifford pointed out, and i hadn't noticed that you had one, your 92 series will be a little different. :)
Quote from: lostagain on October 14, 2011, 06:53:28 AM
Another point is the economical justification of swapping diffs is questionable at best. I might see a little savings in fuel.
JC
What were you getting for fuel economy with the 4.11 gears?
If you can run 10 to 15 miles an hour faster and not burn anymore fuel, the time factor alone could be worth it. I think you made a good choice, and if you ever need that drop box youll be smilin.
Back in the 90's there was an around the world tour for antique cars (none newer than 1955). We up met up with them going through Duluth Mn. (after they had crossed Africa, China, Alaska and Canada) and one that stood out was a 1926 Bentley. What I found interesting were the various extra mechanical bits, driveshaft, etc., that were bolted under and around the car. You likely would never need the whole box, but a few choice pieces out it could be a lifesaver far from home. I still havnt given up a trip to Alaska someday, so thats how im thinking (the worst possible problem), lol. Like bolting a good cylinder head to the bottom of the floor somewhere.
JC
That is very true......it would take a lot of miles too offset the difference in cost of fuel. Being my fish will probably only get. 5k miles or so a year ill prolly just leave er stock
I think the concept of economic justification in this hobby is an oxymoron... You should do the upgrade if doing the upgrade will make you happy. Happier driving the bus, more fun, spending the money doesn't make you cry, useful maintenance anyway, you always wanted to change a diff gear and you could cross if off your "bucket list"... ;)
Brian
What were you getting for fuel economy with the 4.11 gears?
I don't know. I just fill it up when it needs it. I think around 6 or 7 to the Cnd gallon = 5 or 6 m/USgal.
I am not going to carry the spare drop box on the bus with me, but if I ever need it, I could get the neighbour to ship it to me.
JC
:)
Finally all buttoned up, wheels back on this afternoon. And test drive.
Running great, as expected, and FAST.
This is the GREATEST improvement I have done to this bus. It now drives like it should: 40 mph in 2ND, 60 in 3rd, and 80 in 4Th (yes I tried it, ;D) at 2200 rpm. 1800 rpm at 65 mph. And the loss of power is hardly noticeable.
I am so happy about it :). Well worth the effort.
JC
Make sure you use the flat brass washers. There are a few of those bolts that go thru. the casing. First one I did I used new lock washers and had several leaks. I started putting a little sealant on the threads with the flat washers and no leaks.
Thanks, I used the flat washers and Permatex Ultra Black on the bolt threads. So far no leaks.
JC
The brass washers are on the 2 bearing housing 3/8th bolts on the back of the drop box or front depends on how you are looking at it and they will leak LOL
good luck
JC
Glad it worked out and you are happy with the results!
Like I said, on the way home I really started to freak that mine wouldnt make it up my driveway. On paper it just wasnt going to climb a 22.5% grade with those high gears. But its sitting up here alongside the house right now so so much for paper and opinions, lol.
Glad you got it changed out and working, it should be much more enjoyable now, if not more economical to boot.
great news, a fun bus to drive! life is better.