///// Help.... My helper screwed up my 2 speed rear /////

Andyinchville1

Expert Expediter
Owner/Operator
HI All,

I have 1985 S1900 international with a 5 sp and 2 sp rear (yes, and oldie BUT a goodie!)

My helper supposedly knew how to work the 2 speed BUT I swear I heard an awful lot of Clicking as the 2 speed struggled to shift (I was not in the truck at the time but rather following behind with the windows down).

I'm not sure what he did or didn't do to cause all that (I later suggested to him just to run the truck in low range 1 to 5 on the tranny and only use the high / low in 5th on the highway (we were running light and I figure the less he used the 2 speed the less potential problems there would be).

Anyways, after much practice and reading he claimed he had the hang of it so I sent him on a long distance run with the truck (100 miles out 1 way mostly highway until the pick up then back).

We he go to the destination the truck cut off unexpectedly but he managed to get a jump to get him going again....

I told him NOT to shut the truck off until he got back (it has a manual cut off so no problem running without juice in the batteries)....

Anyways, he told me the 2 speed was not working and he was stuck in low range...This made for a 45 MPH run for 100 miles on the interstate.

We got the truck back to the shop and I stuck a battery charger on it.....Batteries pretty much dead.

Turns out the alternator was bad so it is being replaced.....

I figured the 2 speed rear was not shifting due to low voltage so after charging the batteries for a day, I took it for a test drive and to my disappointment, it would not shift into high range ....UGH.

When I pulled up on the switch and clutched there was no shifting into high range.....It just went into "neutral" on the rear end (i.e. I could be in gear on the trans but if I pushed on the accelerator it's as though the rear is in "neutral").

When I pushed the switch back to low range, the truck runs fine.....except for being in low range only in the rear end...

So what happened ? .....Did all the grinding mess something up (I am assuming it did).

How to fix this situation (is it a "normal" thing that happens when inexperienced people use the 2 speed?)....

Admittedly, early on in my 2 speed learning, if I ever got to having the rear make strange noises or not want to shift quite right I always had the presence of mind to push the clutch in to help the shift (I usually use the clutch even when I don't have to when operating the 2 speed rear to make it "easier" on the motor etc...).....My helpers usually seem to apply more power to "fix" things....Ugh....

Thanks in advance for any and all help.

Andrew
 

piper1

Veteran Expediter
Owner/Operator
There is usually a cover you can take off the actual shifter/motor unit and see what is going on. The motor is possibly bad from being fed a diet of low voltages or the spring in the shifter/motor unit is broken. In my experience... 99% of 2 speed rear axle problems were solved by a shifter unit repair or replacement (not expensive either) The stuff inside the axle very rarely fails....even with rookie abuse.
 

BigStickJr

Veteran Expediter
Retired Expediter
Haven’t had any two speed rears since the 70’s.
As cheap as they were, no idea of the pricing now, I’d think just save your time, throw a new one on, relieve all doubts.

About $250 today. I think $40 back in the 70’s.
 
Last edited:

Andyinchville1

Expert Expediter
Owner/Operator
HI,

Thanks for the input....you're right ....probably best to get a whole motor unit and replace...

I may try rebuilding the old one to have a spare "just in case"

Thanks!

Andrew
 

ucfd608

Veteran Expediter
Owner/Operator
Man the last two speed rear end I drove was an old fire truck that was at one of the vol stations it was a chore to drive
 
Top