I have a 2004 F550 4x4 at work that had a 6.0L in it. We converted it to a 12 valve about two years ago. We were using the stock Ford transmission which we replaced numerous times. We have now gone away from the Ford trans and installed a 47RH. This combination has worked very well but we are having trouble getting the transmission to go into 4th gear.
This is what I have done. I was told to install a preasure switch to activate the 4th gear at around 40 mph. Before I put in the preassure switch, I hooked up a preassure guage to see exactly what the preassure is at about 40 mph (I was told 1 psi for every mph). At 40-45 mph it was running about 90 psi (strange). So I installed a 90 psi preassure switch. The problem is that when you get to your desired cruising speed (in 4th) and back off the throtle to maintain the cruising speed, the preassure drops and it goes back into 3rd gear.
I am now thinking that if I can tap into the speedometer so that at a predetermined speed, it would put power to a silonoid and in turn activate the fourth gear.
Is this possible or should I go a differant direction?
Paul
This is what I have done. I was told to install a preasure switch to activate the 4th gear at around 40 mph. Before I put in the preassure switch, I hooked up a preassure guage to see exactly what the preassure is at about 40 mph (I was told 1 psi for every mph). At 40-45 mph it was running about 90 psi (strange). So I installed a 90 psi preassure switch. The problem is that when you get to your desired cruising speed (in 4th) and back off the throtle to maintain the cruising speed, the preassure drops and it goes back into 3rd gear.
I am now thinking that if I can tap into the speedometer so that at a predetermined speed, it would put power to a silonoid and in turn activate the fourth gear.
Is this possible or should I go a differant direction?
Paul