1977 CJ7 pulls hard left periodically in 4X4

[Rahudack]

I recently bought a 1977 CJ7 with a Dana 30 front axle and didn't notice this issue as I had tested on soft ground. When I shift it into 4X4 it will drive forward and then momentarily pull hard to the left. The steering wheel straightens, drives another ~20 ft and does the same thing. When in 2WD, it drives fine.
I'd appreciate advice on how to troubleshoot the issue. A bad front u joint? something wrong in the differential?
Thanks,
Ray

 

[mtnwhlr]

I think you have a bad u-joint in the axle. I would replace them in both sides.

 

[Lumpy Grits]

Are you on 'hard' ground?
Have you checked your tire PSI.
Are you SURE both front hubs are engaged?
Are you sure the tires are all the same size?
Does it 'pull' under power or when coasting?
What's in the front and rear diffs? 'Hard' lockers, LSD???
REALLY-We need more info on the vehicle.

LG

 

[Rahudack]

Thanks for the replies

1)are you on 'hard' ground? - I noticed it very little on sand, but it was much more obvious on a hard dirt surface.
2) Have you checked your tire PSI. - I'll check.
3) Are you SURE both front hubs are engaged? - They are warn locking hubs, but and I have turned the dial but i am not sure they are really engaged.
4) Are you sure the tires are all the same size? - yes
5) Does it 'pull' under power or when coasting? - it pulls under power. Good question. Now that i think about it, when in 4X4 i did not try to see if it is pulling when coasting also.
6) What's in the front and rear diffs? 'Hard' lockers, LSD??? I am not sure what differentials are in the axles. I assume there is no easy way t tell without pulling the cover?
7) REALLY-We need more info on the vehicle.- fair enough. I just bought it. I'll have to find out.

8) regarding the axle u joints. I did a visual inspection looking for loose caps etc per the link below but i did not see anything.

Symptoms of a bad U Joint - Jeep Wrangler Forum

Any suggestions on order of steps to trouble shoot?

Ray

 

[mtnwhlr]

8) regarding the axle u joints. I did a visual inspection looking for loose caps etc per the link below but i did not see anything.

Any suggestions on order of steps to trouble shoot?

Ray

When mine went bad they looked fine but when I pulled it apart they were frozen and in real bad shape.

 

[Bjasper]

I would jack up the left tire and with the hub unlocked rotate it the ujoint shouldn't be spinning Spin the tire check for a spot that drags could be a brake issue though not likely Are the wheel bearings spinning free no dragging Now lock the hub the ujoint should spin the tire may spin a few times before it locks sometimes thick grease slows the teeth from meshing together quickly Now spin the tire with ujoint turning any thing dragging now I'm thinking ujoint or differential issue but this will narrow it down hope this helps

 

[Lumpy Grits]

Use a steel bar and check the U-joints for play.
If you see ANY play at all-Repace'em, ASAP.
Only use Dana/Spicer U-joints.
Pulling on hard ground is kinda normal. Especially in 4-low.
BTW-Warm hubs are junk(IMNSHO)and can be torn up internally.
LG

 

[Torxhead]

Just to add a few more suggestions: Flexible brake hoses can deteriorate from the inside causing the brakes not to release pressure after applied. I had this happen to a vehicle and it turned the rotor blue from heat. There could be a problem with loose wheel bearings, that can be checked by rocking the front wheels back and forth to check for any play.

 

[Rahudack]

Thanks for all the suggestions. It is a little cold today, next nice day I'll pull the CJ out and see if I can find the issue and report back!

 

[Belizean]

Thanks for all the suggestions. It is a little cold today, next nice day I'll pull the CJ out and see if I can find the issue and report back!

Cold ? It's kind of cloudy and 80 degrees and pretty good jeeping weather here. Probably be summer in a couple of weeks here.