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Mystery device on my bus Dave 10-13-03  
Hey everyone,

I'm working on a 1966 Ford B600 Bus that had been previously converted. When I first drove the bus, I noticed a push-pull type of switch on the stick shift for the manual transmission. When I moved it, it appeared to do nothing. Upon further investigation, it appears something was happening, due to the fact that it would dim the headlights and draw electrical power. I finlly managed to trace the wires to this device, and discovered it was connected to what appears to be a small motor and gear box that's attached to the rear axle on the driver's side of the drive shaft. It has markings indicating that it needs to be lubercated seperately, and seems to move only once when switched. Pull up un the switch knob, it moves for 2 seconds and stops, push down and it does the same thing (presumeably in the opposite direction). I've thought long and hard about what it does and why it's there, but I'm drawing a blank. Does anyone out there have any insight as to what this mystery device may be?

Thanks in advance

Re: Mystery device on my bus IHC Bus Man 10-13-03  
Hi, i do know what that device is as ive driven school bus for 5 years, and my school bus has this i have a 1984 IHC BB 71 pass. what the switch is for is shifting your rear axle from high to low range as you probably have a 4 speed transmission with a 2 speed rear axle. the electric motor in the axle does the shifting when you pull it up or push it down but if the motor isnt hooked up right the axle wont shift. most of the time the button should be up which would be high range to shift it from low to high you have to shift into fourth gear and depress the clutch then pull the knob up and let off the clutch. on my bus i dont have to clutch it i just let off the accelerator in 5th gear pull the button up and then accelerate. you may need to double clutch. but the 2 speed in the older models is used in low range mostly in town and high for highway use.
hope this is helpful. also the 2speed has a tendency to freeze up in the winter and 9 times out of 10 it will freeze up between hi and low range if you mess with it in the winter.
happy busing
1985 IHC thomas 77 pass
1984 IHC Blue Bird 71 pass
1980 Ford B-700 Ward 71 pass
1975 IHC thomas 65 pass
Re: Mystery device on my bus aksmitty 1-6-06  
I have a 1949 ford (f600)with two shift handles. one of the handles does go to the drive axle for two speed, but it doesn't seem to work. Maybe i'm doing something wrong. I try to go fist low then 1st high but doesn't seem to make any difference. any help would be appreciated thanks smitty
Re: Mystery device on my bus Mark O. 10-14-03  
What you are describing in the orginal post is an electrically shifted two-speed rear end. What you are describing in your second post is a Road Ranger multi-range transmission--a totally different horse.

Most 2-speed rear ends allow you to "split" each gear in half. In theory this allows you to climb hills a little faster. In pratice, the reality is most 2-speed rear ends don't split gears exactly and if you don't know what you are doing you can sometimes shift down when you are wanting to shift up.

Most 2-speed rear ends shift 1st low, 1st hi, 2nd low, 2nd hi, 3rd low, 3rd hi, 4th low, 4th hi. Sometimes, if the transmission is a 5-speed with 5-speed direct drive, 5th low is lower than 4th hi. In 4-speeds and 5-speeds with 5th an overdrive gear you may find 3rd hi is lower than 4th low. The only sure way to find out is to try each gear out, preferrably on a road with no traffic behind you.

In order to shift the 2-speed, all you need to do is move the button up or down. When you lift the throttle, the 2-speed should shift. The only time the clutch needs to be used is when you shift the main transmission.

Once you learn the shift points and at what speed the engine needs to be for the optimum shift, your shifts will become as smooth as an automatic. Until you learn the shift points be prepared for a lot of lurching and crashing of gears.

As IHC Bus man has already said, sometimes the 2-speed will stick in between high and low range. That is why you neve ever, absolutely never ever, positively don't ever down shift a 2-speed going down hill. You will get stuck in between ranges and then you will have your bus freewheeling downhill.

With the electrically shifted 2-speeds, sometimes the seal between the shifter and the rear end will leak allowing gear lube to get into the mechanism. When that happens the shifter becomes very slow or will stop operating completely.

As to not working in the winter, that is true only when the gear lube is really cold. When the gear lube in the rear end is cold it will slow down the shifter to the point it won't want to shift. Once things warm up it should shift without any problems. The problem with most school buses is they never go far enough or fast enough when it is really cold to warm things up enough.

Good luck and happy trails.

Mark O.
Re: Mystery device on my bus Mark O. 10-18-03  
More or less, that is correct.

You will need to learn what the ratios are in each gear to learn what sequence you should use.

Many times, the splits become very close in the upper gears and it isn't worth the effort to split each gear.

What you are trying to achieve with the greater number of gears is to make each shift occur in such a way so as to never lug or over rev the engine.

Again, never ever, absolutely don't ever try to downshift the range when going down a hill. Pick the gear you want to be in at the top of the hill and stay in it. You really don't want to ride down a hill freewheeling.

Good luck.

Mark O.
Re: Mystery device on my bus IHC Bus Man 10-19-03  
Dave, you are correct, on some buses the two speed needs to be shifted diferently than others, on my bus the optimum way i shift it is 1st 2nd 3rd 4rth,and 5th low then in 5th gear i accelerate and then let off the accelerator and pull the button up and then slowly accelerate again and then i can here the 2 speed rear end shift to high range. also on my shift pattern on the shifter it has circles with 1-5 on the bottom and 6-12 on the top in the circle. the only way to tell if its working is to be moving but it actually does give you higher gears to work with for highways. you could try shifting it without clutching it from low range to high range but sometimes clutching it will make the rear end shift smoother. the difference between this and a road ranger on a semi is that on a semi you would shift 1-5th gear low and then pull the button up and go back to first gear and shift all the way to 5th again which would be 10th gear. however this is because most semis have 2 tranmissions a main and a auxillery but with your bus haveing only 1 transmission you cant shift this way you would shift the same way as on a car except for you can try going through all the gears in high and low range to figure out whats the best way to shift it. sometimes there will be a shift diagram somewhere like on my bus that will explain how to properly shift your 2 speed but i would take it on the road and try the difernt gears to see whats best as Mark O has said to try.
Good Luck
Happy Busing
1985 IHC thomas 77 pass
1984 IHC Blue Bird 71 pass
1980 Ford B-700 Ward 71 pass
1975 IHC thomas 65 pass
Re: Mystery device on my bus jason 12-25-03  
There is a way you can test that without taking it out on the road. All you need is a heavy duty jack. you need to release the parking brake, and put the trans in neutral so the wheels can spin freely. Simply raise one drive wheel so that it is just off of the ground. Obviously, you have to make certian you use your wheel chocks on the front and observe all safety precautions.
this requires two people.
Perform this test once with the 2 speed rear end in each position: Chalk a line at the 12 o'clock position on the outside of the drive wheel. Crawl under the bus, turn the drive shaft by hand, keeping track of the number of times the drive shaft spins to complete one revolution of the drive tire. (if, for example, it took 2.05 revolutions of the drive shaft to complete one revolution of wheel, then you multiply that by two to get the gear ratio which in this case would be 4:10) If it takes the same number of drive shaft turns to equal one revolution of the tire after switching the 2 speed, then the 2 speed is not functioning.
Re: Mystery device on my bus Dave 10-14-03  

So in theory this acts like a completely new set of gears? For instance...I start in first and move all the way from first to fourth, then put the clutch in and activate the switch. Does this give me a new gear range (5-8)? Or does this just add a higher gear to the mix for better highway driving? And is there any way to tell it is working properly without taking it for a spin on the highway?

Re: Mystery device on my bus Dave 10-14-03  
So in reality, to get the most from the system, you'd alternate as you moved through the gear range...1st low, 1st high, 2nd low, 2nd high, all the way to (in my case) 4-high, using the clutch only to move between main gears on the transmission, correct?

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