Al-Jabal Al-Akhdar !!
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Senior Member
Joined: Apr 2008
Posts: 974
Likes: 1
From: Oman
Year: 2001
Engine: 4.0
Correct. 4WD will give you some more traction and control if you need it, but don't use the "part-time" modes (4LO or 4HI Part-Time) unless you're dealing with something slippery or shifty - sand, snow, mud, or a good deal of rain. Otherwise, you'll bind up the chain in your transfer case - when it lets go, it tends to rupture the case.
The downshifting from "OD" to "3" in your transmission locks out the overdrive gear, which lets your engine's compression help with braking. On very steep grades, it can help to shift down into "1-2" for more compression braking - but it can dump you into first gear, so keep a weather eye on your engine speed if you do that.
Compression braking is not a substitute for actual braking, but it does help you. This allows you to not use your brakes so much, keeping them cooler, which helps you if you do need them rather suddenly (cf: "brake fade".)
As long as you're on dry pavement, you don't need 4WD, and you're better off not using it. Just pull your transmission down a gear instead, and use your engine to help you slow down (I know - it seems counter-intuitive. Trust me, it does work! It's similar in principle to the "Jake brake" that heavy trucks use - you can look that up as well, if you want to know how it works.)
Enjoy your drive, and do please try to take some pictures for the rest of us!
The downshifting from "OD" to "3" in your transmission locks out the overdrive gear, which lets your engine's compression help with braking. On very steep grades, it can help to shift down into "1-2" for more compression braking - but it can dump you into first gear, so keep a weather eye on your engine speed if you do that.
Compression braking is not a substitute for actual braking, but it does help you. This allows you to not use your brakes so much, keeping them cooler, which helps you if you do need them rather suddenly (cf: "brake fade".)
As long as you're on dry pavement, you don't need 4WD, and you're better off not using it. Just pull your transmission down a gear instead, and use your engine to help you slow down (I know - it seems counter-intuitive. Trust me, it does work! It's similar in principle to the "Jake brake" that heavy trucks use - you can look that up as well, if you want to know how it works.)
Enjoy your drive, and do please try to take some pictures for the rest of us!
many many thanks for this valuable info ...
But my friend still insist on using 4X4 when driving downhill
Thread Starter
Senior Member
Joined: Apr 2008
Posts: 974
Likes: 1
From: Oman
Year: 2001
Engine: 4.0
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Joined: Feb 2009
Posts: 7,244
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From: socal
Year: 2000
Model: Cherokee
Engine: 4.0
it is best to use 2wd unless it is a dirt road or sandy or snowy. if you use 4wd on pavement it will destroy the transfer case when you are taking the corners. and the 3rd gear will be a better gear for steep inclines and declines 
