Rear Axle Build Help. RTH (1 Viewer)

Tank5

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So I need some help. I am assembling a custom rear FF Axle and elocker that uses all 80 series parts, the housing and axle shafts being the only custom parts.

I have the assembled housing under the truck now but when I try to spin the wheels by hand, they are hard as hell to spin. I have tried it both locked and open and it does not seem to make a difference. The diff spun freely and easily prior to install. The hub spindle is torqued to FSM spec. and the hub tension on both sides is at 9lbs. Hubs spin easily prior to the axle installation. After I install the axles the hubs are very tight and tough to spin by hand. I have already taken it back apart and checked everything once.

What could be wrong here? I am wondering if the axle shafts are slightly long would this cause the issue?

Thanks in advance for your help.
 

duggy

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Something is binding. Did the locker actuator arm drop when you took out the axles? Can you shine a flash light through to see if it is cock-eyed in anyway?
 

Tank5

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I pulled the small cover of the locker where the sensor plugs in. I can see and operate the locker and it appears to be operating just fine. I can see it engage and disengage the gear.
 
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I know you said the housing is new, so I'm assuming it's not bent. Is it possible the shafts are bent slightly causing the to rub on the inner tube? Also, did you grease the inner seal liberally to make sure that's not giving you extra drag?
 

Tank5

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I pulled it apart again and the only thing that appears out of place is that as soon as I loosen all of the axle flange nuts, the hub and flange separate by about an 1/8th of an inch. If I loosen the hub nut more it will be out of spec. so that does not make sense to me. All I can figure is that the end of the shaft is getting some push back. It does this on both sides.

Any ideas?

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Tank5

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I would not expect the housing to be bent but the builder screwed up most everything else so it is possibe. If it is bent is is not obvious, how would I check that? I have greased everything very well.
 
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Also, when Yotamasters built my 3rd the diff was very tight. It would spin easily from the pinion but turning it with the shafts was difficult until I got the wheels mounted. They said it was because the bearing preload is set pretty tight for new bearings. When everything is together does it turn easily from the pinion side?
 

Tank5

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When it's out the 1/8" and still coupled to the flange is it easy to spin?

Good question, I wish I would have tried that.

Also, when Yotamasters built my 3rd the diff was very tight. It would spin easily from the pinion but turning it with the shafts was difficult until I got the wheels mounted. They said it was because the bearing preload is set pretty tight for new bearings. When everything is together does it turn easily from the pinion side?


When the wheels are on it is easier to spin but harder than I think it should be. I can easily spin the diff by hand with the axles out but I did not try it with the axles in and the flanges unbolted. I may have to try that tomorrow and see if it makes a difference.
 

Tank5

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Sorry, one more obvious thing to check, are your brake pads and rotors dragging or maybe your ebrake?

I tried it with the calipers off. The ebrake cable has is not connected, I checked the shoes and they are not dragging.
 

Tank5

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I am tempted to put oil in and take it for a short drive to see if it loosens up a little after a few miles. Does that sound like a bad idea?
 
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I am tempted to put oil in and take it for a short drive to see if it loosens up a little after a few miles. Does that sound like a bad idea?

Yes it sounds like a bad idea.
If the axles are out 1/8" per side, and thus is a CUSTOM housing as I believe you stated, then either the axle shafts are too long or the housing is too short. Either trim the axles or have someone rework the housing.
 

Tank5

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If the axles are out 1/8" per side, and thus is a CUSTOM housing as I believe you stated, then either the axle shafts are too long or the housing is too short. Either trim the axles or have someone rework the housing.

What is the best way to measure for determining the proper axle shaft length? How far into the housing are they supposed to extend? What is the best way to cut them if I can determine that is what I needs to do?

Thanks again to everyone for all the help so far.
 

Tank5

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Did some research, cutting the shafts looks like something I can do. I am still trying to figure out how to measure the proper axle length for my housing.

The differential is centered in the housing, and I am using a STD elocker Diff.
 
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You will typically cut axle shafts with a grinder/cutoff wheel.

There is a clearance (tolerance) for the tip of the splined end into the side gears in the differential. What is your diff? Toyota Open? E-Locker? ??? There are the things that should have been researched prior to "building" a custom axle housing.

I will defer to other experts on the forum: @landtank @jcardona1 and many others.
 
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Do you have stock FF axle shafts? If not, maybe cut a dowel and insert at same length as stock shafts.
See what actual internal measurement you have. Maybe someone here can provide that length for you.
someone up above said to see how it spins when sitting at the 1/8" position. Try inserting 1/8" spacers between the
flange and hub and tighten it down. Then see how it turns. That might indicate shaft length issue??

My info is the 60 FF and 80 FF have same specs. So re: bearing setup. The wheel bearings are initially tightened
quite high, around 60 ft/lbs. Then according to FSM spin them, then release the wheel bearing torque and retorque to
a final ~ 40 ft/lbs and set lock screws. I'm reciting this from memory, but if the bearings were tightened at the higher
setting and not released and reset at lower torque there would be a tight feeling. Off hand, I think you have a
problem with shaft length, but felt I should throw this in just as an FYI. Maybe it helps.
 

Tank5

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Thanks for the help. I am going to go unbolt the shafts again and try to spin them with the 1/8th gap to see what I learn.

The differential is centered in the housing, and I am using a STD/low pinion elocker Diff. With the centered differential design the axles shafts are the same length. The axle shafts are not stock. They are Nitro shafts measured and ordered/supplied by the vendor that built the custom housing.

I did do the the initial preload of the bearings, release and retighten to spec. using the specs. out of a 1993 FSM.
 

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