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Rear-end gearing/ Highway speed? Capttain trips 3-15-04  
My bus is a 1983 IH Thomas body (fully converted and reg Motor Home)
It was used here in the mountains of south-west Virginia and has a low geared rear end. it pulls like a mule but on the highway it sounds like its going a thousand miles an hour but is only going 55.
I will put a 2 speed rear-end in it one day but for right now I have to run this one.
If I slow down to around 50 MPH on the interstate do you think I will be safe to travel long distances? do you think I will have trouble with the state police for going that slow?
Re: Rear-end gearing/ Highway speed? Bolton Peck 3-21-04  
You can drive all day at 50 mph if you don't die of boredom ;-)

Chances are very good that your bus has an Eaton rear axle, for which new gears are commonly available in a variety of ratios. Is it gas or diesel? Auto or manual? If you could put like a 6 speed Allison trans in there that would be better than doing the two speed, however if its a stick shift then the two speed is the way to go. If you are mechanically inclined you could get you a ring and pinion set, an instruction manual and a big torque wrench and do it yourself. Medium duty truck stuff is surprisingly easy to work on.

I have a 1965 Chevy C-60 school bus with a Carpenter coach and a Cadillac 500 V8 which will flatten any grade up to 7 percent, no problem. Except its got a 6.2:1 rear axle (low range 8.4:1) and buzzes the big V8 pretty good at 65mph. If I had the 5.8:1 ratio I'd gain a good 5 mph. Plus, I'd gain a few more miles between fuel stops ;-)
Re: Rear-end gearing/ Highway speed? Mark O. 4-20-04  
Not knowing which engine you have in your bus, it is hard to know how best to advise you.

If you have a gas engine, get a manifold vacuum guage and check what sort of vacuum you are pulling when you are cruising. If you have less than 5" you will most likely end up using more fuel than you are right now if you change to a higher speed rear end.

A 2-speed is rarely going to change your top speed. It will help on the hill climbs sometimes since you will be able to split each gear.

Gas powered IHC buses in the best of condition rarely were able to cruise much faster than 55-60 MPH. The gas V-8's just didn't have that much HP. If you have the 7.3L, again, 55-60 is about the best you can expect. If you have the DT466, regearing will help a lot. They can be regeared to cruise easily at 65-70+ and still climb the hills.

Only you can decide what is the best choice for you.

Good luck.

Mark O.
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