makin 97 4wd into 98 2wd limited

[willardauto]

so this is what ive gotten myself into.... took a 97 4wd sr5 complete chasis and stuck it under a 98 limited 2wd body... runs and drives good...BUT the 4wd is stumping me.... did a little research and im thinking that the "on-the-fly" engagement is screwing me.... I kinda bypassed the vacuum switch with my own but the front axle does not engage.... ANY HELP IS GREATLY APPRECIATED!!!

also having hard start problem...crank FOREVER when cold but no issue after it warms up and turn it off to restart.... runs smooth and great after runnning

 

[ChildrenOfBodom]

So you know that ADD is not just an electrical system, the front diff needs vacuum to actually make the switch. How did you make your own?

Did you test the front diff vacuum line that goes to the vacuum tank/solenoid? If not, you can test the switch with your mouth. Try to see if you can engage/disengage the ADD. Both front wheels off the ground, front driveshaft off. Both wheels should spin when you turn the driveshaft flange when engaged.

The stock vacuum system works great for shift on the fly. I was able to convert my 2WD 99 to a 4x4, wiring took 3 weeks, but I added 4WD and manual trans stuff to my existing harness. Shift on the fly works like stock.

If you don't want to deal with the wiring, manual locking front hubs are an option. You could just leave the ADD switch engaged. Won't really have shift on the fly, but it would be easier than wires.