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General Forums => The Mess Hall => Topic started by: jfrabat on December 17, 2007, 03:35:11 PM

Title: 4WD not engaging
Post by: jfrabat on December 17, 2007, 03:35:11 PM
Hey, guys, I went to use the 4WD yesterday, but it would not come on.  I imagine it will be a vacuum line that is not correctly connected, but I have not yet opened the hood or gotten under the jeep to check.  But what do you guys think?  Vacuum line or something else? 

I am actually considering the posi-lock for the front axle, but I dont know if it is worth it.  Any comments on that as well are welcomed!

Felipe
Title: Re: 4WD not engaging
Post by: Rob the plumber on December 17, 2007, 03:50:00 PM
Your vacuum disconnect is probably sticking. The Posi-lock is a great idea. almost a requirement. My disconnect sticks in cold weather. If I heat it with a torch for a second it pops right in.
Title: Re: 4WD not engaging
Post by: jfrabat on December 17, 2007, 03:54:31 PM
Well, I know mine is not sticking as a result of the cold...  I live in Miami, so 60 is FREEZING for us down here, and today was the first day that the temp dropped below 70!
Title: Re: 4WD not engaging
Post by: oldjeep on December 17, 2007, 04:03:18 PM
For the price of a posi-lock you can get a non disconnect D30 from a cherokee.
Title: Re: 4WD not engaging
Post by: Jesse-James on December 17, 2007, 06:08:42 PM
Your vacuum disconnect is probably sticking. The Posi-lock is a great idea. almost a requirement. My disconnect sticks in cold weather. If I heat it with a torch for a second it pops right in.

Mine did this last night, had to bring it in the heated garage at the shop and let the Heep thaw.
Title: Re: 4WD not engaging
Post by: jeepheap on December 18, 2007, 06:49:59 AM
posi lock. but upgrade you fork. mine took a crap recently and it just sucks to have to pull it apart again. in the cold that you lucky..... 60 is freezing. 10 then other night in delaware with the 40 mhp winds. but then again when you guys get winds there usually a state of emergency becuase it a hjurricane!
Title: Re: 4WD not engaging
Post by: jfrabat on December 18, 2007, 07:50:35 AM
Do they sell extended vacuum lines for when you lift the Jeep?  By the way, the part about the Posi-lock that makes me not finalize making the decision is the fact that if I do decide to upgrade the D30, the alloy shafts are not compatible with this system, because they do not have the disconnect.  But who knows...  I may end up doing it anyway!
Title: Re: 4WD not engaging
Post by: Jesse-James on December 18, 2007, 08:15:04 AM
One piece shaft from a TJ D30 eliminates this problem. It's on my list. It's a long list.
Title: Re: 4WD not engaging
Post by: Jeffy on December 18, 2007, 10:05:01 AM
One piece shaft from a TJ D30 eliminates this problem. It's on my list. It's a long list.

Or XJ shafts from +94.  You also upgrade the U-joints since the (pre-94) YJ's use 260x and the later axles use 297x which can be further upgraded to the 500 series.
Title: Re: 4WD not engaging
Post by: jfrabat on December 18, 2007, 12:01:32 PM
Hey, guys, considering my vacuum lines are almost 14 years old, I was thinking since I will be looking into this as a result of this problem, I might as well go ahead and replace them (they are really not all that expensive to replace, from what I have seen).  But I was wondering if there was a kit that came with all the hoses and fittings that I could use.  I saw from http://www.hosetechniques.com/ that they have universal kits that would fit my Jeep (no kits specifically made for Jeep, so I got to go with this one) and the hoses go for about $130, but I need to figure out the fittings that I would need to make all new connections and forget about vacuum issues for a good couple of years.  Any comments on this?
Title: Re: 4WD not engaging
Post by: Jeffy on December 18, 2007, 10:37:50 PM
Hey, guys, considering my vacuum lines are almost 14 years old, I was thinking since I will be looking into this as a result of this problem, I might as well go ahead and replace them (they are really not all that expensive to replace, from what I have seen).  But I was wondering if there was a kit that came with all the hoses and fittings that I could use.  I saw from http://www.hosetechniques.com/ that they have universal kits that would fit my Jeep (no kits specifically made for Jeep, so I got to go with this one) and the hoses go for about $130, but I need to figure out the fittings that I would need to make all new connections and forget about vacuum issues for a good couple of years.  Any comments on this?

That stuff is pretty *bling*.  I think it's a bit thick too.  Maybe 3-4x as thick as the stock lines.
Title: Re: 4WD not engaging
Post by: jfrabat on December 19, 2007, 07:17:25 AM
That stuff is pretty *bling*.  I think it's a bit thick too.  Maybe 3-4x as thick as the stock lines.

Which brand would you recommend, then?  I didn't look too deeply into this, but it was the first vendor I found...
Title: Re: 4WD not engaging
Post by: garydubf on December 19, 2007, 09:24:11 AM
we had the same problem on my boys jeep.  For half the price of any of the posi-lok or stock replacement parts we made a plate to block off the hole were the disconnect mounts and slid a junk yard Tj axle in!  No more problems, no more vacuum lines to get ripped off, no more vacuum leaks!  Took about 3hrs once we had all the parts!
Title: Re: 4WD not engaging
Post by: jfrabat on December 19, 2007, 09:29:53 AM
How does a TJ axle handle the disconnect?  Because if I put a one piece axle, the front shaft will start to rotate during 2H driving, right?
Title: Re: 4WD not engaging
Post by: oldjeep on December 19, 2007, 09:36:41 AM
How does a TJ axle handle the disconnect?  Because if I put a one piece axle, the front shaft will start to rotate during 2H driving, right?

There's no disconnect on a TJ.  Yes  the front shaft will rotate, but that's what they are built to do ;)
Title: Re: 4WD not engaging
Post by: garydubf on December 19, 2007, 09:36:56 AM
Yep!  Both jeep and Dodge did away with the axle disconnect in around 99/2000.  For good reasons!  With the transfercase in 2hi the axle will still spin the driveline!  But the nondisconnect side of the YJ does too!
Title: Re: 4WD not engaging
Post by: jfrabat on December 19, 2007, 11:48:23 AM
There's no disconnect on a TJ.  Yes  the front shaft will rotate, but that's what they are built to do ;)

Then that means less MPG and more vibration (YJs dont have the front shaft balanced)...  That's what worries me.

Felipe
Title: Re: 4WD not engaging
Post by: oldjeep on December 19, 2007, 12:18:46 PM
There's no disconnect on a TJ.  Yes  the front shaft will rotate, but that's what they are built to do ;)

Then that means less MPG and more vibration (YJs dont have the front shaft balanced)...  That's what worries me.

Felipe

Less MPG - I doubt it.   Balancing a driveshaft is about $40 if you are having vib problems.  Realistically with a lifted jeep and bigger than stock tires you can't feel anything from the driveshafts.  Both of mine are home shortened with no balancing and less than perfect runout.
Title: Re: 4WD not engaging
Post by: garydubf on December 19, 2007, 01:25:59 PM
There's no disconnect on a TJ.  Yes  the front shaft will rotate, but that's what they are built to do ;)

Then that means less MPG and more vibration (YJs dont have the front shaft balanced)...  That's what worries me.

Felipe
Should be no noticeable change in MPG.  Your front end already spins while driving! Only have one side disconnected!!  Shouldn't experience driveline vibes either unless yours is allready bent
Title: Re: 4WD not engaging
Post by: jfrabat on December 19, 2007, 01:33:38 PM
And how do you connect the 4WD light to the dash if there is no servo motor to send the signal?
Title: Re: 4WD not engaging
Post by: oldjeep on December 19, 2007, 01:39:26 PM
And how do you connect the 4WD light to the dash if there is no servo motor to send the signal?

Swap out the vac switch on the tcase for the electrical switch used on non-disconnect cherokees.  Wire into that.
Title: Re: 4WD not engaging
Post by: jfrabat on December 19, 2007, 02:00:19 PM
OK, I think I will have to put this down in the list...  Probably after the rear axle is changed (to a D44 or Ford 8.8).  For now, I will try to fix the current system, as I cant afford to change the axle yet (neither one of them, actually).  I got my hands full with the alternator that I should be receiving on Friday!

Thanks to all for the advise, though!
Title: Re: 4WD not engaging
Post by: Rob the plumber on December 27, 2007, 05:29:57 PM
There is also a specific seal need to use a TJ front axle shaft in a YJ. TJ's also use a double cardan front driveshaft, where YJ's use a standard U-joint shaft. There might be a reason for that.
The only thing spinning on a disconnected YJ is the axles (up to the disconnect) and the spider gears. The whole differential, ring and pinion, and drivehaft stay still. Enough parasitic loss to notice? Maybe not.

The good thing about a posi-lock is that you can be in 4-low in tight trails and unlock the front axle to make tight turns easier. (handy in quad trails when you end up in a tight, burmed circle)
Title: Re: 4WD not engaging
Post by: garydubf on December 27, 2007, 07:25:49 PM
enlighten me on the specific seal!  I did this swap on a buddies YJ with no seal changes.  All we did is fab'd up a plate to cover the disconnect hole!  I'm not sure I agree with your opinion about only the spider gears turning either!  The non-disconnect axle will turn the ring and pinion until there is a differential in force, thus turning the drive line.  The disconnected axle acts as a "floater" per say! Therefor no pressure differential, carrier acts like a spool!  Thats the way I understand it!  As for double cardan vs. single U-joint , you're right but the reason is for serviceabilty not balance!


I could be wrong, I've been wrong before! ???
Title: Re: 4WD not engaging
Post by: oldjeep on December 29, 2007, 09:04:42 AM
enlighten me on the specific seal!  I did this swap on a buddies YJ with no seal changes.  All we did is fab'd up a plate to cover the disconnect hole!  I'm not sure I agree with your opinion about only the spider gears turning either!  The non-disconnect axle will turn the ring and pinion until there is a differential in force, thus turning the drive line.  The disconnected axle acts as a "floater" per say! Therefor no pressure differential, carrier acts like a spool!  Thats the way I understand it!  As for double cardan vs. single U-joint , you're right but the reason is for serviceabilty not balance!


I could be wrong, I've been wrong before! ???

If you use the jeep in an off camber situation, all your gear oil runs out the passenger side if you don't have the seal.
Title: Re: 4WD not engaging
Post by: garydubf on December 29, 2007, 09:13:59 AM
Right!  But that seal is all ready there!!
Title: Re: 4WD not engaging
Post by: jfrabat on January 02, 2008, 06:02:45 PM
Well, finally got around to taking a look under the Jeep, and sure enough, the double vacuum connector to the servo motor was unplugged.  I think I will need to make an extension for the vacuum lines, as it seems this will continue to happen as a result of the lift when the suspension is extended...  Either that or go for a Posi-Lock, but the extension seems like a MUUUUCH cheaper alternative!
Title: Re: 4WD not engaging
Post by: Jeffy on January 03, 2008, 01:34:08 PM
You can get a lot more slack if you reroute the lines.  Instead of having them go in front of the engine mount and down, pull the lines back through and have then come down before the engine mount.  I doubt you'll have any trouble with them pulling out unless they get hung up on something.
Title: Re: 4WD not engaging
Post by: jfrabat on January 03, 2008, 01:40:34 PM
That's a good idea!  I did not think about that, but I will give it a shot...  This weekend I will instal a bored out 62mm 4.0L TB, a new 167A alternator, and probably will get to work on the lug nut that I rounded out, so I will get this done as well (seems it will be cheaper than extending the lines!).
Title: Re: 4WD not engaging
Post by: jfrabat on January 05, 2008, 07:09:21 PM
Well, the final solution was even simpler than I thought; I just relocated the collar that held the vacuum lines and signal cables to a lower point on the frame, which leaves ample room for the suspension to extend without pulling on the lines.
Title: Re: 4WD not engaging
Post by: Elyod on February 06, 2008, 02:02:28 AM
I figured I would continue on this thread with my problem:

I have a 98' TJ driven in below freezing temps, all fluids (including t-case) changed recently. 

When I try to take it out of 4wd it does not disengage right away.  I always put it into 2wd while going slow and have tried doing it while stopped and it always takes a while to disengage. I will accelerate and hear the normal added noise that you hear while in 4wd and then it will "pop" out of 4wd and drive normally.  Any clue as to what is causing this? I am not worried about significant problems, this is just friggin annoying.
Title: Re: 4WD not engaging
Post by: Bounty Hunter on February 06, 2008, 06:07:12 AM
The disconnect is not that much of a pain if you know how to diagnose and maintain it.  I actually sought out a disconnect D44 when I swapped in a pair of D44's.  I run a front spool and a cable to the disconnect. I can disconnect the DS axleshaft and run 3wd to make turning on the trail a lot easier.  When locked, it's troublefree traction.  The disco is controlled by an aircraft cable for troublefree operation.  Po'mans Ox Locker.
(http://sija.org/bounty/jeepmods/DSCN3522.JPG)
(http://sija.org/bounty/jeepmods/DSCN3523.JPG)
Title: Re: 4WD not engaging
Post by: Bounty Hunter on February 06, 2008, 06:09:13 AM
I figured I would continue on this thread with my problem:

I have a 98' TJ driven in below freezing temps, all fluids (including t-case) changed recently. 

When I try to take it out of 4wd it does not disengage right away.  I always put it into 2wd while going slow and have tried doing it while stopped and it always takes a while to disengage. I will accelerate and hear the normal added noise that you hear while in 4wd and then it will "pop" out of 4wd and drive normally.  Any clue as to what is causing this? I am not worried about significant problems, this is just friggin annoying.
The mode hub on the TJ is not synchronized like it is on earlier jeeps, so shifts are not as easy.  Below freezing temps will make the TC fluid thicker which makes shifting even more difficult.  Consider a synthetic tranny fluid in the 231 and cold weather shifting may improve.
Title: Re: 4WD not engaging
Post by: Elyod on February 07, 2008, 02:25:26 AM
Thanks for the advice, I will try changing the fluid, I thought this might have been the problem. 
Title: Re: 4WD not engaging
Post by: jfrabat on February 07, 2008, 02:49:27 AM
The disconnect is not that much of a pain if you know how to diagnose and maintain it.  I actually sought out a disconnect D44 when I swapped in a pair of D44's.  I run a front spool and a cable to the disconnect. I can disconnect the DS axleshaft and run 3wd to make turning on the trail a lot easier.  When locked, it's troublefree traction.  The disco is controlled by an aircraft cable for troublefree operation.  Po'mans Ox Locker.

This sounds like an interesting locker option for the front...  You think it would work on a D30?  Or will it kill it (with 33s)?  Does it affect street driveability at all?
Title: Re: 4WD not engaging
Post by: Bounty Hunter on February 07, 2008, 09:47:08 AM
I ran my D30 like that for years with 32" and 33" tires, no spool options so had to weld the spiders.  Invisible in 2wd on the road, slight pull in 3wd but driveable.
Title: Re: 4WD not engaging
Post by: 95yjman on February 26, 2008, 12:40:01 PM
Just a real quick question, I ran into the 4wd drive not working today in the snow.  From what I've read it sounds like it just likes to stick in cold weather.  My 4wd has always worked, so my question is when it warms up outside or just plan old gets warmer will it go back to working normal?  This is the first its done it since I have owned my YJ.  The light was on but the front tires where not spinning :confused:  I can live with it not working once in a while in the cold since winter is almost over, just wanted to know if it was going to go back to normal once summer hits?
Title: Re: 4WD not engaging
Post by: Jeffy on February 26, 2008, 01:49:45 PM
Just a real quick question, I ran into the 4wd drive not working today in the snow.  From what I've read it sounds like it just likes to stick in cold weather.  My 4wd has always worked, so my question is when it warms up outside or just plan old gets warmer will it go back to working normal?  This is the first its done it since I have owned my YJ.  The light was on but the front tires where not spinning :confused:  I can live with it not working once in a while in the cold since winter is almost over, just wanted to know if it was going to go back to normal once summer hits?

Both front tires weren't spinning?  If the light came on then the actuator should have moved.  That actuator triggers the switch that turns the light on.  GM's used to have a problem with their disconnect since they used a thermal wax in them but that was years ago.  Jeeps never had that issue since they are all vacuum.
Title: Re: 4WD not engaging
Post by: 95yjman on February 26, 2008, 02:34:35 PM
Both front tires weren't spinning?  If the light came on then the actuator should have moved.  That actuator triggers the switch that turns the light on.  GM's used to have a problem with their disconnect since they used a thermal wax in them but that was years ago.  Jeeps never had that issue since they are all vacuum.

hmm maybe I wasn't giving it enough gas to spin the tires :lol: I've never been big into the throttle kinda guy.  I'll have to play around with it.  I had it in 4 high maybe 15-20 minutes before that and it was working then.  Its probbley just me being paranoid that it isn't going to work.