eaglescout526 Posted July 21 Share Posted July 21 No. I am not doing away with it. HOWEVER! I am going a different route. Probably one not seen or talked about as it sounds crazy. Selec-trac, with a command-trac case, but the selec-trac vac switch controls the front axle shifting. Crazy? Brilliant? I guess what I am after is some opinions. As it stands I can have a selectable drive via the vacuum actuated system, but I can have 2wd low. Am I going to run into any issues with this set up? Am I gonna lose an NP207? or a front axle? Or a whole drive train? 4wd is still very new to me but not complex to where I can not understand what all is going on. Granted if I absolutely need to, 2wd operation on the 207 is still available. Let me know what you guys think. Link to comment Share on other sites More sharing options...
zomeizter Posted July 21 Share Posted July 21 Consider this: "The only difference between selec-trac and command-trac is that selec-trac offers full time 4wd mode. Full time 4wd allows you to run 4wd no matter what the road conditions. The only difference between part time and full time 4wd is that in full time the center diff/transfer case is "open" which allows the front driveshaft and the rear driveshaft to turn at different speeds, and in part time the transfer case is locked and the driveshafts turn at the same speed." JEGER Link to comment Share on other sites More sharing options...
89 MJ Posted July 21 Share Posted July 21 I know @pizzaman09 wanted to do something similar. Link to comment Share on other sites More sharing options...
gogmorgo Posted July 21 Share Posted July 21 Basically you’re just wanting to use a vacuum switch to manually actuate the CAD? Can’t see any reason it wouldn’t work. It wouldn’t be any different than the “posi-lok” cable CAD shifter thing. As long as you shift out of 4x4 it shouldn’t cause problems if you leave the CAD engaged by mistake, no different than any of us with the thing locked in permanently. It’ll just use a modicum more fuel. Running around in 4x4 with a failed CAD that’s not engaged doesn’t blow things up, either, you just don’t actually have 4x4 when you want it. I’m not sure how the early manually vacuum switched systems work, but no reason you shouldn’t be able to just run new vacuum lines to the switch. I don’t know if the factory vacuum switches are readily available in working condition either, or if you might be better off with an aftermarket switch. I wouldn’t really call it a selec-trac system though. The defining feature of Selec-trac is a centre differential that allows you to run 4x4 on high-traction surfaces, not the vacuum shifting. I’m also not completely sure what the advantage of 2wd low range is. But maybe this is a conversation for a different time. I think the only situation I’ve been in where I might have wanted it was for parking a heavy trailer with a stick shift. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 21 Author Share Posted July 21 I can safely say it’s faux selec-trac haha. I am glad I do not have much to worry about at all. 8 minutes ago, gogmorgo said: I’m not sure how the early manually vacuum switched systems work, but no reason you shouldn’t be able to just run new vacuum lines to the switch. It’s pretty neat actually. It’s literally a switch that sends vacuum to one line or the other. Rudimentary but it worked on the NP228/9 which I sadly couldn’t use. But I have mine set up and it’s working to where vacuum just either vents on 2wd or it goes to the actuator on the axle to shift. But I understand all the definitions better. Thanks guys for the input! Link to comment Share on other sites More sharing options...
pizzaman09 Posted July 21 Share Posted July 21 6 hours ago, 89 MJ said: I know @pizzaman09 wanted to do something similar. I do very much want to do this. I frequently hook my truck up to trailers or move heavy trailers around, a selectable 2WD low would make it much easier. My CAD system is about 70% reliable, I think it jambs the collar on the axle too far over for 2WD mode and get is stuck on the splines. Sometimes I have to rev the truck up real high and snap the throttle closed to generate enough vacuum to actuate it, other times it shifts instantly and easily at low vacuum levels. That said, I imagined a rocker switch on the dash that operated a solenoid that would either block the vacuum to the diaphragm or switch the input and output of the diaphragm. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 21 Author Share Posted July 21 30 minutes ago, pizzaman09 said: That said, I imagined a rocker switch on the dash that operated a solenoid that would either block the vacuum to the diaphragm or switch the input and output of the diaphragm I’m using the old 84-86 selec-trac switch. I imagine if you found an Eagle or an SJ with the same set up, you could use it the way you’d like. Link to comment Share on other sites More sharing options...
zomeizter Posted July 28 Share Posted July 28 I have the complete vacuum system sitting in a box, lonely, collecting dust...if someone wants it, holler. Link to comment Share on other sites More sharing options...
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