Quadratrac engaged or not?

[MountainBoy]

I have a 1978 J10 360 with Quadratrac and low gearing. Here's the question. I have the standard glove box quadratrac switch. When I put the switch to the left and in "normal" the dash light comes on stating it's in "Emergency" mode. When I switch it to the right (Emergency) mode, the dash light goes out.

Does the dash light somehow get a signal from the vacuum line or is it an electrical conection in the switch. Do I switch vacuum lines and see what happens.

Whatdaya think?

[PlasticBoob]

There's a switch on the transfer case that gets pushed in and grounds out when the center differential locks via the vacuum motor sliding the shift fork, thus completing the circuit and illuminating the light.

So yeah, switch the outer two vacuum lines or make it look like this:

[MountainBoy]

If I read you correctly my friend, you are stating that the transfer case "MUST" be in emergency mode for the circuit to be completed and the light to come on. Therefore, regardless of where the switch in the glove box is pointing, if the light is on, it's in emergency mode, yes?.

Thank you for your response and making it so easy........... assuming I stated it correctly above, lol

[PlasticBoob]

That's right! Your particular light goes off and on depending on the position of the glovebox switch, so it sounds like everything is working and your switch on the transfer case isn't stuck.

So the lines are either crossed in the glovebox, or crossed on the control diaphragm on the transfer case. Or maybe someone mounted the glovebox switch to the placard upside down, if that's possible. Or maybe the set screw got loose and the knob needs to be re-clocked (see above diagram).

I'd check everything to make sure it looks like the diagram above, just to make everything "standard." Plus it will give you a chance to inspect the lines - they rot out and cause vacuum leaks in addition to failing to shift into Emergency Drive. Later models like yours had metal tubes running some of the way, and I've seen a few of them that were completely rusted out and needed to be replaced with long runs of vacuum hose. My '74 had no such tubes from the factory as far as I know.

You can also tell if it's in Emergency Drive for sure by seeing if the truck grips and slips and jerks when making turns on pavement while applying some throttle, but this puts stress on the system so it's best to try it on dirt or gravel.

If the light is on and you're not getting any tight steering and binding when turning, then there are some deeper issues like a broken shift fork, etc.

[MountainBoy]

OK, I checked the vacuum hoses at the transfer case and glove box switch. I was pleasently supprised to see that the hoses were connected to healthy metal lines just on the other side of the firewall and ran all the way down to the transfer case. I attempted to wapped them at the firewall but the aged rubber fell apart. I will purchase new lines soon and give it a try. Thanks a ton for your help and I will let you know how it goes.

[rang-a-stang]

Woo Hoo! I hope it's working! If you take it out and your front wheels are not receiving power, then the xfercase and/or front hubs need a rebuild.

[MountainBoy]

Thank you boys, its all working AOK after switching the vacuum lines. They were pretty crusty but I moved them and took a test drive and appears to be working as expected. Picked up 10' of 5/32 hose today and will switch it out real soon. THANKS AGAIN!

P.S. Now, once all is updated, I will start a new tread asking for a link to a site that explains, "how the quadratac 4x4 system works for dummies". All reading to date just doesn't get me there ..... sorry

[Curly5759]

Have you looked at the Jubilee jeep site? Lot of Quadra track tech there. https://jubileejeeps.org/


If you do FB, there is a quadra track page there as well.

[MountainBoy]

WOW!, just hit your link, lots of reading there. Thanks, maybe I won't need to start the thread afterall. Will read it all this weekend