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upin1212 03-27-2013 02:04 PM

yj 4wd
I just recently sold my 02 tj and bought a 89 yj. my question is can I shift into 4h on the fly or do I have to be stopped? I also have lockers on both axel's can I engage them at any speed? thanks for your help im new to rock crawling but good in mud. so any tips help..

OverkillYJ 03-27-2013 03:25 PM

No, not a good idea. The TC can handle it, but the front axle and split shaft can not.

upin1212 03-27-2013 04:08 PM

So no on shift to 4wd h on fly. And no on lockers?

OverkillYJ 03-27-2013 04:23 PM


Originally Posted by upin1212 (Post 3560377)
So no on shift to 4wd h on fly. And no on lockers?

I am guessing you have selectable lockers then. I would check the documentation for the lockers you have specifically, but I would not, even if it said I could.

upin1212 03-27-2013 08:57 PM

Yea I can select front or back or both. I have dana 88 axels chrome Molly.

Square_Eyes 03-27-2013 09:14 PM

You can shift into 4hi on the fly just fine, i would not however turn on the lockers while on the fly. Im not familiar with selectable locks so much but it just doesnt sound like a good idea lol 4hi fine, lockers no. Just my .02

OverkillYJ 03-27-2013 09:32 PM

I accidentally not thinking shifted mine into 4x4 going about 10mph one day and thought the ring in the axle was going to break. Sounded loud as hell. Now that I have a solid shaft I can shift on the fly though. I wouldn't do it over 10 though

wrangleryj90 03-27-2013 09:36 PM

I just let off the gas when I shift and I never have a problem

upin1212 03-27-2013 11:37 PM

Cool ill just do it at 10mph or lower I don't want to mess anything up. As for lockers I guess I'll mess with those when at a stop before I climb anything. Thanks for your time. I can't wait to get this jeep out there. My 02 was good but this 89 is super clean and built really good. It's a beast ill put some more picks up soon. The guy who owned it before me never took it in rain or snow so it's clean. I know mud messed alot up in my 02. And was a pain to clean. So I decided rocks are clean lol.

Square_Eyes 03-27-2013 11:45 PM

The 4x4 system in the YJ is made to be safely shifted from 2H-4H up to 55mph, says it in the manual that comes with the jeep

Gohot 03-28-2013 06:31 AM

Let me ask out of ignorance.... when your driving down the road in 2H is the front drive shaft spinning?

sirchadley 03-28-2013 07:13 AM


upin1212 03-28-2013 10:47 AM

I would say no also. Only in 4wd would it spin

Xpress 03-28-2013 10:55 AM

The front driveshaft freewheels. Even though the passenger shaft is disconnected, there is still enough friction in the system to cause it to freewheel near the speeds you are driving at.

Shifting into 4wd HI at speed is not going to hurt anything in the system, it was designed to do that.

sevenservices 03-28-2013 11:00 AM

^ yup.

If the axle is locked (via vacuum pressure in the YJ) then the shaft will spin engaged via the wheel force.

If the gearbox is engaged, it will spin via engine force.

If neither are engaged, it may still spin now and again due to force within the axle. Just keep in mind two systems engage for your 4wd. 1. is the gear box and 2. is the front axle.

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