Shifting a 2 speed axle

[coastlogger]

On my single axle international dump with 5 speed trans and 2 speed axle ,the shifting instructions are ,like on every 2 speed I've seen,the downshift the axle after upshifting main( ie for a split upshift). I wonder why? It makes for a very slow shift and I've tried it the other way,(ie preselecting the axle shift ) and it seems to work just fine.Can anyone enlighten me?

 

[skyking1]

you can get caught in a no-mans-land where the driveline and front part of the two speed spins down and you have to come to a stop to sort it all out. That never happens with the "by the book" method.
if you are happy with your method and it SOUNDS ok, not a crash fest and grinding, I see no reason to worry. The above is a consequence when it does not go right.

 

[John C.]

Been in no man's land with that high pitched ratchet sound a couple of times. Pushing in the clutch when doing the axle shift also can cause it to happen.

 

[terex herder]

You need to be able to enable the shift with the engine speed, can't do that with clutch in or tranny out. When you get right down to it, shifting the two speed is just a spring loaded float.

If the shift is slow, is the two speed working properly? As in good vacuum or good voltage and amperage?

 

[DMiller]

The new style 2spd actuators are better than the old units but not by much, is yours also a 4th/5th main in lo side drop back to 4th for high then fifth?

 

[coastlogger]

Mine is like you say d miller.
The actuator is pretty fast. Guess the rationale must have something to do with an axle downshift needing more revs from driveline,which it's not going to get with a preselect.
my trans is as you say dmiller though I rarely use those upper gears in my work.
Not sure what trans it is but I guess it must have synchromesh of some sort. If the revs aren't about right it won't let you into the next gear,but there's no grinding ever.Not sure how that works either. A lot of stuff I don't know.

 

[Tyler d4c]

For a kid I'm not to bad with a 2 speed rear tho I've made the tach needle make a full 500 degree rotation once the old 8.2 deteoit smoothed out at 5000 rpm

 

[DMiller]

2 spd axle was always pretty unforgiving, rpms had to be right and the driver consistently smooth in transition of gear to N to next gear, these took a moment to align the stars and a double clutch your friend in most cases. They do not respond well to quick slam shifts up or down.

Older GMs had Corporate, Clark, Spicer or Eaton trans in them. Ford was pretty consistent Spicer
IH pretty well Spicer or Eaton, New Process had a number of trans out there, Dodge preferred those as a standard.

 

[John C.]

I haven't driven a two speed axle for years but generally liked the stuff made in the sixties and seventies. I didn't find shifting them to be troublesome at all. The trucks I drove back then were gas powered and had syncro transmissions which worked better using the clutch. The two speed was just better to forget the clutch whenever you had to shift it up or down. With a big load you would say shift from third and high on the axle to fourth gear on the tranny, let out the clutch and then shift to low on the axle and give the engine some throttle. If you were going down you would shift from fourth low to third gear, let out the clutch and then shift the axle to high and again give it throttle till the axle caught the shift. Those extra speeds helped a bunch on those old gas pot engines.

 

[Old Doug]

It looks like they would have built a trans that would have went in the smaller trucks with a 2 speed on the back of them instead of a 2 speed rear end.When you have a almost 60 year old truck with a 2 speed it its hard not to wonder what kind on shape the rear end is in but maybe your better off not knowing.

 

[DMiller]

Easier to do the Rear End, Can still remember shifting Eaton 3 Speed units until one would flail itself to death. Most got converted to Double two speeds shift at SAME time.