Front end binding when accelerating in 4wd hi or Lo

[Richard Payan]

A worn idler arm which can be checked in 5mins or less is not causing binding in the front end. A worn idler arm causes the right wheel to toe out of alignment and causes the tire on right wheel to wear excessively.
You need to jack front wheels just off the ground in 2wd and turn them and make sure your front diff is not locked in for some reason and while you got the frontend in the air you check the idler and pitman arm for excessive wear.
Have someone grab right wheel at 9 and 3 oclock and rock wheel inward and outward while you are under there watching idler arm. It should not be jumping up and down like it is in the attached video.

Hey thanks for the feedback but i will check havent had my truck in a few weeks been at the paint shop but if you thats not causing the binding then what is ?

 

[rockola1971]

Hey thanks for the feedback but i will check havent had my truck in a few weeks been at the paint shop but if you thats not causing the binding then what is ?

Does it do it in 2wd? If not then I would suspect the Tcase has a problem on its output side to the front. Likely a bearing locking up or loose drive chain. Check fluid level in Tcase.

 

[Mudsport96]

Does it do it in 2wd? If not then I would suspect the Tcase has a problem on its output side to the front. Likely a bearing locking up or loose drive chain. Check fluid level in Tcase.

This is a good possibility. My old blazer did something similar. Seemed like it was binding in low, when really it was the chain jumping because of slack.

 

[Mudsport96]

There can be slight differences in the diameter of the tires which means they will turn a slightly different speed. In 4WD, it tries to make all the tires turn the same RPM which binds everything up.

Yes and no. Yes this can happen when tire diameters are different. But they have to be more different than new vs worn tires of the same size.
I know this because MY daily work truck is an older Ford 4x4 and from the factory it had a 3.55 rear and a 3.54 front.This was commonplace as 4.09 was the front for the 4.10 rear. Because the TTB (IFS) front dana didnt have the spacing for a 3.55 tooth count. And i have driven (accidentally) 40 miles on pavement locked in 4 high and not hurt anything.
So yes if someone has lets say 285/70r17s on the back and 255/70r17s on the front you will get binding. But half to a quarter inch of wear difference on the same tires is highly unlikely to cause binding.

 

[Richard Payan]

Does it do it in 2wd? If not then I would suspect the Tcase has a problem on its output side to the front. Likely a bearing locking up or loose drive chain. Check fluid level in Tcase.

It only does it in 4wd but I already took off both front axles and the transfer case is smooth can hear anything abnormal. Just changed the fluid like 3 months ago.

 

[rockola1971]

It only does it in 4wd but I already took off both front axles and the transfer case is smooth can hear anything abnormal. Just changed the fluid like 3 months ago

I need more info. Did you drive the vehicle with the front axles (cv halfshafts) disconnected and it still did the binding? Did you try pulling front driveshaft and testing (Driving on road)?
Im trying to narrow down between front diff and Tcase.

 

[Richard Payan]

I need more info. Did you drive the vehicle with the front axles (cv halfshafts) disconnected and it still did the binding? Did you try pulling front driveshaft and testing (Driving on road)?
Im trying to narrow down between front diff and Tcase.

Yes i drove the truck with no cv axles in 4wd and it drove fine, i havent disconnected the front driveshaft yet i will need to try that next when i have time. And i just rebuilt my front differential thinking that was the issue but it did not help.

 

[Mudsport96]

Did you happen to get numbers off of the front ring and pinion set for the gear ratio?
That way you could pull the rear diff cover and compare, to make sure one or the other haven't been replaced over the years. Assuming you aren't the only owner.
Because if in 4 high and no front cvs you aren't having the issue, and if you dont have the issue with cvs in and driveshaft out.. i would lean towards ratios don't match

 

[rockola1971]

Alright you drove without cv halfshafts (that aint good since the hubs are torqued to around 180ft lbs when shafts are installed for a reason, to load the hubs by design). Removing halfshafts and no problems tells me output of Tcase is free to turn and so is the front driveshaft along with the front diff. As Musdport96 mentioned, this test does not remove the chance that the front diff is not the same ratio as the rear for whatever reason OR you have one or more halfshafts bad. There is a remote possibility that your ball joints are so hosed that they are causing this but they would have to be pretty bad. I would expect major tire wear on inside edge and/or outer edge of tread if that is the case.

Also check your halfshaft for a ABS target ring toward the axle nut end of the halfshat that could be binding against the lower ball joint. Some universal axles came with this ring but the ring is NOT needed for our chassis.

 

[Richard Payan]

Did you happen to get numbers off of the front ring and pinion set for the gear ratio?
That way you could pull the rear diff cover and compare, to make sure one or the other haven't been replaced over the years. Assuming you aren't the only owner.
Because if in 4 high and no front cvs you aren't having the issue, and if you dont have the issue with cvs in and driveshaft out.. i would lean towards ratios don't match

Ive been having that same gear ratio for 3 years already never had any issues. Before i changed the gear ratio i had 3:73’s now i have 4:10’s but like i said i never had any issues. And if im not mistaking im the second owner i got the truck back when it had 76k. But i am going to remove the front drive shaft and see if the problem is still there.