Topic: Won't Turn Left in 4wd

[79HiluxHillbilly]

There's an old thread already out there but no one posted an answer to the problem. I'm gonna tear it apart this weekend and figure it out but in the mean time if someone wants to save me some trouble I sure would appreciate it. If not I'll post the answer after the fix.

Truck worked fine. Installed a new 3rd member on the front and now it won't turn left past straight in 4wd. Take it out of 4wd and it turns left immediately.  No bad sounds, no bad feelings; just acts like it's on the stop.

Seems to be a birf problem but which and why only left?

[gnob]

Doesn't Really make sense. If you had a birf issue simply unlocking 4wd doesn't really change the relationships.  A broken or damaged birf would still jam a knuckle.
Is the new diff locked?

[mudmaster]

Sounds like you're trying to turn on pavement with a locker??

[79HiluxHillbilly [OP]]

Gnob: I agree. It doesn't make sense! Yes, the new diff is locked. But I that shouldn't be the problem either. Like I said it drives fine with no noise or vibration in 2 or 4. Just doesn't turn left in 4wd but with  1 finger in 2wd.

Mudmaster: On or offroad it makes no difference. It's only when it's in 4wd will it not turn.

Also, I did forget to mention that it's only when the hubs are locked. In 4wd without hubs locked = no problem.

[gnob]

Does it still lock up on jacks?
Sounds like the locker is jacking you up

[mudmaster]

Does it still lock up on jacks?
Sounds like the locker is jacking you up

I agree. Put it on stands and see what it does.

[79HiluxHillbilly [OP]]

Gnob/Mudmaster: I would assume so. I haven't tested but it'll get solved this weekend.

There is no locker. It's a welded diff and like like I said it works great going straight, to the right and back to straight. Just not left, past wheels straight.

Don't see how the diff would causing a turning issue.

[mudmaster]

Wait, so the previous 3rd wasn't welded?

[79HiluxHillbilly [OP]]

Mudmaster: No, previous was the stock diff. New is 5:29's welded up.

Also, during the swap I had to replace a lockout. Other than that everything went right back into place.

[gnob]

Your wheels are turning different speeds and direction when stationary turning. Locker doesn't allow that. Its physics dood.

[79HiluxHillbilly [OP]]

Gnob: The locker/welded 3rd member is a dumb animal. It only knows to spin forward or backwards. It has nothing to do with steering. You are correct tires do change speed when going around a curve (I.e. the inside tire slows and the outside speeds up) and with a locker these tires are "locked" at the same speed. Trouble steering increase as your vehicles' speed increases because your inside tire is forceably having to slip when you corner. Which is why if you've ever driven a vehicle with a locked rear end it "yelps" when you corner. Same concept but having the front makes it way harder to steer as speeds increase. However, it doesn't not effect the ability to turn when not in motion on loose gravel, which I have.

My problem is constant moving or not when in 4wd w/ hubs locked. This is why I'm leaning towards a birf or hub issue. Also, if that were the issue I wouldn't be able to turn right either and anyone running lockers wouldn't be able to go any direction other than forward when engaged.

[Gnarly4X]

... You are correct tires do change speed when going around a curve (I.e. the inside tire slows and the outside speeds up) and with a locker these tires are "locked" at the same speed. .

Negative.  If the axles are locked, both wheels will rotate at the same speed - revolutions per minute.

Gnarls.

[mudmaster]

A true locker does unlock when going around a turn, a welded locker or spool can't do this. Most people don't weld or install a spool in the front for this reason.

[79HiluxHillbilly [OP]]

Gnarly4x: Reread my whole statement. Unlocked tires change speed in curves. But when locked the inside tire must slip when going around a curve or you will go straight. Locked diffs don't effect steering at 0 mph and very minimum at crawler speeds.

Mudmaster: You're correct. I know this. I have a Detroit in the rear. I'm not talking about going down the road at 45mph with the hubs locked and trying to turn. I'm talking about sitting on level ground on gravel and trying to turn.

I still have lockouts so the front is never truly locked in unless the hubs are. Truck drives great in 2wd down the road with the hubs unlocked. No turning issues at all. The issue arises when the truck stopped and the hubs are locked in. Once this is done it immediately will not turn left past straight. Without moving an inch. But it will turn right.

[79HiluxHillbilly [OP]]

Old thread, same problem, no solution

https://board.marlincrawler.com/index.php?topic=54624.0

[mudmaster]

I still have lockouts so the front is never truly locked in unless the hubs are. Truck drives great in 2wd down the road with the hubs unlocked. No turning issues at all. The issue arises when the truck stopped and the hubs are locked in. Once this is done it immediately will not turn left past straight. Without moving an inch. But it will turn right.

This is in 2wd with the hubs locked or I read that wrong?

[79HiluxHillbilly [OP]]

Mudmaster: 2wd hubs NOT locked in = no problem steering.  2wd/4wd hubs locked = immediately will not turn left

[mudmaster]

Hmmm, that's strange it's an issue in 2wd with the hubs locked. Be sure to post what you find.

[blackdiamond]

A true locker does unlock when going around a turn, a welded locker or spool can't do this. Most people don't weld or install a spool in the front for this reason.

A selectable locker like and ARB functions as an open differential when unlocked and a spool when locked which means that the two tires are forced to go the same speed 100% of the time.  A locked ARB will feel exactly the same as a welded differential.

An automatic locker like a Detroit (or lunchbox lockers) never lock the two axles together and instead just don't allow either axle to go slower than the cross pin.  This mechanism does allow one tire to overrun the differential when going around corners which is what make the classic lunchbox locker clicking noise.


For the OP:
It's expected that a welded differential in the front will have a significant impact on steering and I wouldn't necessarily expect it to steer equally well in both directions because I doubt the steering geometry has equal leverage in both directions.

If your hubs are locked the front tires are still being forced to turn at the same speed because there isn't any give in the differential.  The only different 2wd vs. 4wd is in 2wd the front axle is being pushed (i.e. coasting) and in 4wd it is being driven by the front driveshaft.  The bind in the axles between the tires is the same either way.

If your hubs are unlocked then the front tires are free to spin independently and if you are still having binding issues it seems that it would have to be an issue in the steering joints.

If you put it up on jack stands and you don't have a steering issue then it's likely that the primary issue is the welded differential not allowing the tires to turn at different speeds.  If it still has the issue on jacks stands then it's something independent of the welded differential and related axle binding because the tires would not have any resistance.

What's your steering setup?

[blackdiamond]

Mudmaster: 2wd hubs NOT locked in = no problem steering.  2wd/4wd hubs locked = immediately will not turn left

I think it's a steering geometry issue where it doesn't have enough leverage to turn left when the tires are not allowed to turn at different speeds.  Even sitting still the welded differential will make it harder to turn the wheels.

I have a Detroit rear and and an Aussie front and I really only have driveline windup issues when turning left.

[Lewis Hein]

If your hubs are locked the front tires are still being forced to turn at the same speed because there isn't any give in the differential.  The only different 2wd vs. 4wd is in 2wd the front axle is being pushed (i.e. coasting) and in 4wd it is being driven by the front driveshaft.  The bind in the axles between the tires is the same either way.

No, the OP reports this problem while sitting still on gravel, in which case the speed difference does not exist. Steering geometry could still be the issue I suppose

[Lewis Hein]

The other thread linked a little while ago lots of people suggested a cracked or broken birfield joint

[Djencee]

The other thread linked a little while ago lots of people suggested a cracked or broken birfield joint

That is what came to my mind (birf bound or broken? or something wrong with the trunnion bearing potentially. An axle tear down for investigation is what is needed. There are only so many things that could cause this issue & without actually seeing the parts, one could only speculate.

[79HiluxHillbilly [OP]]

Okay so had some time to tinker with it last night and put it on jack stands.  And it looks like its a birf problem...

Procedure:
0)Pulled it in the shop in 2wd (unlocked hubs) --- NO ISSUES
1)Put front end on stands, Transfer case in 2wd, Hubs Unlocked, Rotate tires and turn full L-R-L --- NO ISSUES
2)Lock in DS Hub, Rotate tires and turn full L-R-L --- NO ISSUES
3)Lock in PS Hub, Rotate tires and turn full L-R-L  --- NO ISSUES
4)UNLock DS Hub, Rotate tires and turn full L-R-L --- NO ISSUES
  **At this point I'm really irritated because I cannot get the problem to repeat on stands. So I decide to see if I can get it repeat on the ground again. 
5)Lock in DS Hub (Both hubs locked), Put in 4wd, backed up out of the shop to the left. ---ISSUE: Could not turn left past straight w/ slight trouble turning right past straight.
6)Pull back in shop
7)UNLock DS Hub, back out and to the left --- NO ISSUES
8)Pull back in shop
9)Lock DS Hub & UNLock PS Hub, back out and to the left --- ISSUES: Turned slightly more than past straight but did not like it.
10)Pulled back in shop.

-Brother shows up to work on his rig, so I show him what's happening. We repeat 1-4 again but NOT on stands. ---ISSUE: Truck won't turn left when both hubs are locked, but seems to turn slightly more left if the DS Hub is UNLocked.

-He noticed some binding noises while I was turning the wheel so I had him turn it while I listened and there is definitely something not right happening in the DS birf. I put my hand on it while he turned the wheel and was able to feel periodic vibrations/grinding while he turned L-R-L-, that was not noticed in the PS birf. 

Teardown next. Will keep updating