allenw

I just had a used front axle (D30) installed by a mechanic on my 2008 Jeep Unlimited and wanted to make sure 4wd was working. I know you shouldn't drive or turn on dry pavement but it just so happened to be raining today so I thought I would try it. I was driving straight on wet pavement about 20 mph and switched to 4H and you would think I was on a carnival ride. The jeep was lunging to one side, rocking back and forth, I had to turn the steering wheel halfway around just to keep the vehicle straight. I pulled over and tried to disengage. The 4wd light went off but it was still in 4wd so I stopped again and put in neutral, same thing. Limped around a corner to a sidestreet and tried to drop to 4L just to try to get something moving so I could get back out of 4wd. Couldn't even get it to 4L after trying several attempts. Finally I pulled into a driveway and slammed the stick between 4H and 2wd and it still wouldn't disengage. I was ready to give up and drive home in 4H but when I put it in reverse and then drive again all was fine - back to 2wd.

Questions - when I disenage 4H and the dash light goes off, shouldn't it be in 2wd. Is there some sort of lag?

What would cause me not to even be able to go to 4L? I was parked in neutral.

Is a jeep completely undrivable in a straight line in 4wd?

Pjohn

May be a silly question but are the gears the same in both front and rear differentials?

allenw

How would I know that? The mechanic owns a jeep shop and he knew the old axle was 3.73. He did however buy this used so he could just bolt it on. I really have no idea other than anything is possible with this guy. I am planning on taking it the dealer next week but would prefer to just find an honest shop that know their business. I wuld not be surprised if he did not check. Would different gears cause what I described.

I already spent $3000 for a used d30 (yes, I am an idiot) and know the dealer is going to love me coming through the door.

rexicon

hmm not sure what your issue is but I can anwser your questions.

there is no lag between 4wd and 2wd the light goes off and your in 2wd

jeeps shift between 4hi and 4lo when they are rolling slowly much better then when stopped

you can drive straight in 4wd even on concrete although it is bad

allenw

Thats what I was afraid of. Something is definately wrong here. Probably used an axle off a jeep liberty or something.

jesse0376

I have had vehicles that had different ratios and they will act like that but 3k for dana 30 wow

Pjohn

From what it sounds like the front gears are different from the rear. when you put the vehicle into 4wd the transfer case engages and then your from tires are moving slower than the rear. the differential kicks in and one front tire is being pushed along and the other is just spinner causing this pulling effect. when you try to disengage the 4wd there is binding or pressure on the transfer case from the rear pushing the front that wont allow it to disengage. when you put the vehicle in neutral i assume it didn't roll backwards to release the pressure and stayed in 4wd even though the light went off. when you finally put the vehicle in reverse the binding or pressure was released and let the transfer case disengage.

I am not 100% sure this is correct since i am not a mechanic but its the explanation i can come up with.

PS your not the idiot. The mechanic is if he installed this and didn't warn you about the gears. unless you just ignored him. You are lucky you found out the way you did rather than on the side of a mountain and falling off. Sounds like neglect on the part of the mechanic and he is liable for any damage done to the vehicle. Here in sue happy CA your mechanic could have been looking at a big law suit. At the least he should be installing the correct gears for free (labor) I would be contacting the better business bureau if he has a legit shop and isn't willing to make this right.



I hope this helps hopefully another member can chime in to confirm or deny my theory.

Sorry for all the spelling errors in a rush to get to the gym

Edited for spelling and added comments.

allenw

Thanks. He offered to switch the rear to 4.10's to match the front. I don't know if I should have him work on it anymore though. I consider what he did to be intentional negligence in that any mechanic should know to make sure the gears match and the fact that he didn't make an attempt makes it intentional. I am thinking this could be dangerous at worst and a future costly repair at best.

u-joint

At least he is offering to make it right... But, it's tough, once you lose faith in a shop, it's hard to trust them anymore.

Go with your gut, don't let him touch your Jeep anymore. You can use it as an opportunity to upgrade your gears all the way around.

Menard666

$3000 for a D30? Wow man.

Also, he is ordering 4.10's for the rear to match the front? AFAIK no D30 came stock with 4.10's, so unless the previous owner put 4.10's in, you will end up with the wrong ratio again.