Drop box and diff gears

lostagain · September 14, 2011, 02:37:14 PM

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

busguy01 · September 14, 2011, 02:41:39 PM

Several years back I had the rear end rebuilt with new 3:36 gears - cost with out remove and replace labor was $4400.
JimH

luvrbus · September 14, 2011, 02:56:18 PM

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

lostagain · September 14, 2011, 04:31:19 PM

Thanks, sounds good. I am going up that way soon and will take a good look.

JC

Gary '79 5C · September 14, 2011, 04:50:45 PM

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

lostagain · September 14, 2011, 05:05:01 PM

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

Tom Y · September 14, 2011, 05:27:23 PM

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

lostagain · September 14, 2011, 05:31:26 PM

Tom,

Detroit 6V92.

JC

lostagain · September 27, 2011, 08:42:12 AM

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

luvrbus · September 27, 2011, 08:58:56 AM

JC what ever you do do not use silicone it will leak

good luck

lostagain · September 27, 2011, 11:48:41 AM

Thanks, where do I get the gaskets?

JC

luvrbus · September 27, 2011, 12:04:33 PM

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

lostagain · October 05, 2011, 11:26:40 AM

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

lostagain · October 05, 2011, 11:28:58 AM

lostagain · October 05, 2011, 11:30:39 AM

The flange on the lower right is where the drive shaft bolts on.