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Discussion Starter #1
First off hey everone. I have had 3 XJ's so far and its seems like the newer the worse. My first was an 85 pioneer 4 banger which was balls out in any condition, My current 96 is ok and my 99 sucks donkey balls. I know the 85 had the vaccum 30 in it so I am assuming all vaccums were limited slips ? The 96 has 3.55's with an open rear and most likely open front because it is a non vaccum 30 and in snow its so so. My 99 has a limited slip rear and open dana 30 ? I assume at least. They are 3.07's. So basically was my 85 so perfect cause it had taller gears due to the 4 banger and a limited slip front ?
 

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Discussion Starter #2
Oh yeah my 99 is absolutely awful in snow. I never thought I would say this but I hate my 99 and would love to have the Eighty fiver back.
 

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jeep never offered limited slip front axles in our cherokees, they're all open.

the disconnect was a "fuel saver" for the earlier vehicles that was done away with because of chronic system failure, and of course, it didn't save fuel.

welcome to the club by the way. I have some advice regarding jeeps...don't make presumptions based off of another one, because no two are the same, and Jeep did ALOT of wierd things with them for their customers (for example, a tow package suspension and tow gearing...with no tow package)
 

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Discussion Starter #5
My buddy has a 99Ram with a vaccum disconnect front axle and he swears that tire gets power in mud and snow.I am not buying the fuel thing. After all there is only like a foot and a half of axle disconnected.If anything they should of put in like a electric hub lock and unlocker now that would save fuel.
 

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My buddy has a 99Ram with a vaccum disconnect front axle and he swears that tire gets power in mud and snow.I am not buying the fuel thing. After all there is only like a foot and a half of axle disconnected.If anything they should of put in like a electric hub lock and unlocker now that would save fuel.

you're "not buying" that the disco was for fuel saving?

well, go talk to a MOPAR tech who's serviced them all his life, and he'll tell you FLAT OUT that that is all it was for. period.

they did away with it because it was extra crap to brake and it maybe made a difference of 1mpg.

the reason it could "save mpg" is that with both shafts being solid, connected end to end, it spins the differential and therefore the driveshaft at all times under motion. Common sense and mathematics prove that yes, rotational force DOES add drag, and therefore the AMC techs who designed the system decided to make a disco...since the Dana 30 didn't have lockouts.

In the end, the disco was wasted time, and they found that it didn't save anything, so circa-1990 they switched to solid non-disconnect axleshafts.

that is the reason, no way around it, and you do not have limited slip up front.
 

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My buddy has a 99Ram with a vaccum disconnect front axle and he swears that tire gets power in mud and snow.I am not buying the fuel thing. After all there is only like a foot and a half of axle disconnected.If anything they should of put in like a electric hub lock and unlocker now that would save fuel.
The disco was to save fuel... BUT... it only saved a minimal amount... I doubt even 1 mpg under most conditions...

But the vac disconnect was problematic and created more stuff to break...

Electric disconnects are the same thing... more useless junk to break. Ask anyone who had a full size Ford with them...

Or even better lets use GM's genius idea of the heated gas disconnect hubs....

And as far as a limited slip in the D-30... Im gonna have to go down to the basement and dig out my old sales lit... I am about 80% sure there was a Trac-loc for the D-30 offered, in the early pre-Chryco days.
 

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I dunno how you guys have such trouble in the snow in your 99s. I have a 99 and its a tank in the snow. Maybe its just the driver? I drove home 2 days ago in an ice storm without using 4X4 and had no problems at all. Get some have decent tires, and in the winter the skinnier the tire the better off you are. "more rubber on the road" does work in the snow.
 

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Discussion Starter #11
First off if chrysler did away of the vaccum in the 30 because it broke alot and did not give better gas mileage then why do newer dodge rams still use them ? And second if it was used to reduce drag then why would there be drag on a open differential if one axle is just there for looks ? Not steppin on toes here but heres an example for you. Last year a 87 Xj in front of me took a sharp right on 4 inches of snow in front of me and whipped around the corner. I tried it in my 96 with limited slip rear in it and almost slid across the intersection. So obviously there is something going on here with that vaccum 30. Like I said my 85 was a frickin tank and my rest have been ok. All have had the 231 transfer case.
 

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First off if chrysler did away of the vaccum in the 30 because it broke alot and did not give better gas mileage then why do newer dodge rams still use them ? And second if it was used to reduce drag then why would there be drag on a open differential if one axle is just there for looks ? Not steppin on toes here but heres an example for you. Last year a 87 Xj in front of me took a sharp right on 4 inches of snow in front of me and whipped around the corner. I tried it in my 96 with limited slip rear in it and almost slid across the intersection. So obviously there is something going on here with that vaccum 30. Like I said my 85 was a frickin tank and my rest have been ok. All have had the 231 transfer case.

Your attempting to equate 2 different situations here....

Chrysler did away with them due to the problems. BUT Chrysler was(is) desperate to raise the fuel economy of their truck fleet to meet the CAFE standards. So they revert to tricks like this. Its the same reason as why you are seeing full synthetic lubes coming from the factory in trucks. Not because they want your truck to last longer. But they are desperate for even the smallest increase of MPG.

Second, in 1985 AMC/Jeep used either a NP207 transfer case or the NP 228 transfer case. The NP231 wasnt introduced until 1987.

Third, you are misunderstanding how a limited slip works. When an open diff begins to slip all of the power goes to the slipping wheel. Allowing all kinds of possibly bad consequences.

In a limited slip system, when one wheel begins to slip, the clutches continue to transfer power to the wheel that is not slipping, keeping your jeep chugging along. It feels and handles different in slippery,snowy,icy conditions. Its one of the BIG reasons people without experience with them NEED to go out and practice to see how a limited slip rear reacts in bad weather.


Your example of the intersection demonstrates nothing about a limited slip system. Its says lousy tires in the snow.
 

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my tahoe has a limited slip rear. when the rear locks for better traction, it likes to push the front tires and swing the rear around in the rain and snow. i learned to keep off the gas in turns to keep the limited slip from kicking in. made it a whole lot better in the poor weather.

my 01 xj does great in the snow. but i run 31" mtrs, they bite great!
 

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Discussion Starter #16
First off I know how splines, limited slips , opens and so on work. Not an idiot here OK. Well I guess my Very new Bridgestone Dueler Revo AT were obviously not as good as the guy I followed around the corner ! Hey Mudbogger what setup is yours with gears ,tires and so on ?
 

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First of all don't accelerate or brake through the intersection. Coast. I've driven my 99 XJ in the since I started driving. I rarely use 4X4. When the rear locks it should go just fine. I live in western PA so we get ice and all that crap here, i live in the mountains i go up and down them all the time, and drive icy roads daily. Get yourself some good all seasons and you'll be fine. Goodyear wrangler is an excellent all season tire.
 

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My setup is completely stock. I had a 98 XJ which I had 31" on, lifted and all that shit. My dad hit a deer and totaled the front end in it when i let him borrow it to go hunting. I still have the stock gearing in my 99. Everything on the drive train is all stock, rims tire size everything.
 

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And just to add to that, bridgestone duelers aren't a good snow tire, at least not in my mind. When I got this jeep it had a set of all seasons "national" tires on it. I forget what they were called. But i ran it all last year before replacing the tires this year with those on and still did great in the snow. What tire size are you running?
 
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