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Unread 09-06-2010, 08:03 PM   #1
AJeep
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1999 TJ Wrangler 
 
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2 questions Q-trac and Transfer case grinding

I have 2 questions I have read up on here about the q-trac system. Which there is some really good write ups explaining what the function does.

My first question is,
I have been playing with the switch in the glove box. I turn it one way and I hear a vacuum noise and turn it the other way it goes away, although I dont feel a difference in driving it. The light stays on saying Emergeny drive which I know is directly tide togother. Since nothing seems to change when I drive it with the switch either way. Is there a vavle that could be plugged, or something else I should check next? I have followed the vacuum all the way thru and it seems to be there.



Next question,
I have been playing with the little lever on the floor next to the drivers seat. It should change it from H-N-L or visa-versa. If I put the transmission into nuetral and move the lever from HIGH to LOW, and then put the transmission into drive it does nothing. When I out it back into PARK to change out of the gear, it grinds and then will make a popping noise before it shifts. What could be the problem? any ideas?

Its a 1976 with a 258, and has a 400 trans, with q-trac.

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Unread 09-07-2010, 12:20 AM   #2
jumbojeepman
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I still haven't mastered shifting mine with the engine running. I find it easiest to turn the engine off to shift from low range to high range or vice versa. Sounds like you aren't getting it from neutral into low.

If you hear a vacuum noise with the switch in any position, you have a vacuum leak, which is probably preventing it from unlocking the transfer case (or locking, but you indicate that the e-drive light is on.)
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Unread 09-07-2010, 10:22 AM   #3
AJeep
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I will give it a try to shift from high to low with the engine off.

Do I understand this right it is full time 4 wheel drive? So it has to stay in high in order to drive around town or highway driving?

Regarding the vacuum switch, does it mean the switch is bad if I hear a vacuum noise coming from it, or does that just mean there is a vacuum leak some where along its path?
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Unread 09-07-2010, 10:25 AM   #4
AJeep
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this just brought up another question.

Does the emergency drive engage or disengage by the vacuum being on or off?
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Unread 09-07-2010, 10:41 AM   #5
mikeumkc
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quadra trac is a full time 4wd system. It has to be in high when you are driving around town. The low gear is used off-road (generally speaking). When in either high of low range, the transfer case acts like a limited slip differential. It sends power to whichever axle (front or back) that isn't slipping. The vacuum operated switch in the glove box locks the transfer case. What this does is send 50% of the engines power to the front and 50% to the back, no matter what kind of conditions you are in. You should never drive the jeep with the transfer case locked on dry pavement unless you have lots of time and money on your hands.

I hope this helped.
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Unread 09-07-2010, 10:49 AM   #6
jumbojeepman
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Quote:
Originally Posted by AJeep View Post
this just brought up another question.

Does the emergency drive engage or disengage by the vacuum being on or off?
Kinda, it the vacuum pulls on either side of a rod on the transfer case. It pulls it in one direction to lock it in e-drive, and pulls in the other direction to pull it out of e-drive. Once it is in one mode or the other, the vacuum is no longer needed to hold it into position. While the switch could be leaky, I'd say it's more likely that a hose is loose behind the switch.

A brief description: A vacuum hose runs from the intake manifold (providing vacum) to the switch. Two hoses then run from the switch to the transfer case, one to engage e-drive and one to disengage e-drive. They attach to the transfer case on the upper right side. When you turn the e-drive knob, vacuum switches from one hose to the other.
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Unread 09-07-2010, 10:54 AM   #7
AJeep
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Thank you for breaking it down for me. Its such a simple concept, I guess thats why its so hard for me to understand (LOL)

So now I know where to go from here. Back to the vacuum lines and all the conections. Thanks for all the help.

Any other ideas will help too, I will check them out while I am all over this thing.
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Unread 09-07-2010, 09:21 PM   #8
bigjoe
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AJeep, just another thing for you. If your vac. hoses are all good and you find no leaks, the shift actuator on the xcase can go bad and not shift either into or out of E drive. But it does sound like you have a vac leak at the glovebox switch.
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Unread 09-09-2010, 06:36 PM   #9
AJeep
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Thanks for all help and ideas, now I understand how it all works and that helps when I am trying to resolve the problems.

The switch for the glove box had the three lines in all the wrong places. So after moving them all around, that was fixed.

After being explained about the shift actuator. I double checked it and there was a vacuum leak fixed it and now it works.

Still cant shift from HIGH to LOW or visa versa, with out shutting it off and then changing gears. Does any one have any ideas on how to fix this? It just grinds if I dont shut it down and then restart it.
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