diff question

[benno440]

guys i am asking this question as i know close to nothing about diffs and was looking for some advice.

i changed out my 741 one wheeler in my 8 3/4 and i bought a brand new 489 case with eaton true trac unit and also some 33 spline axles straight from a company in the states it arrived as a complete unit. it utilises the new green bearings etc.

now when it got here i just installed it straight in and everything seems to spin fine (hasnt been on the road yet) but i was wondering was there anything i needed to check or adjust prior to installing or are they just a bolt in thing, there is a slight howling when i spin driveshaft but i think that might be the park brake is over adjusted slightly.

what do you guys think?

thanks

 

[cr8crshr]

Do you have a Factory Service Manual/FSM? If not then get one as it will help you out here. The reason being is that you will have to adjust the "end play" of the axles which will require following that procedure and right off the top of my head I cannot remember what it is. The "end play" must be adjusted so that when the axles turn when under a driving load, they expand and heat up and will bind against one another which will cause catastrophic breakdown. But the FSM is easy to follow and the procedure is spot on when you follow it. If you need further help just ask here on FBBO...cr8crshr/Tuck

 

[RustyRatRod]

Did you put gear oil in it?

 

[benno440]

Did you put gear oil in it?

i thought your supposed to put sand in that little hole

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Do you have a Factory Service Manual/FSM? If not then get one as it will help you out here. The reason being is that you will have to adjust the "end play" of the axles which will require following that procedure and right off the top of my head I cannot remember what it is. The "end play" must be adjusted so that when the axles turn when under a driving load, they expand and heat up and will bind against one another which will cause catastrophic breakdown. But the FSM is easy to follow and the procedure is spot on when you follow it. If you need further help just ask here on FBBO...cr8crshr/Tuck

i have a manual it is on a cd i will have a look tonite, thanks

 

[RustyRatRod]

i thought your supposed to put sand in that little hole

I was bein dead serious. A lot of people assemble them and forget. It happens more than you know.

 

[benno440]

I was bein dead serious. A lot of people assemble them and forget. It happens more than you know.

i thought you were taking the piss out of me, i put 80w90 castrol gear oil in as i was told the conical gear true trac doesnt need lsd oil.

 

[RustyRatRod]

That's correct. Since it's a gear operated LSD instead of having clutches, there's no need for an additive. Also, keep in mind tha tuntil you actually test drive it, the gear oil is not properly distributed. Once driven under power, the oil will have a chance to splash lube everything and it will probably quieten down. Plus, don't forget, it needs proper breakin after which time it will get even quieter.

 

[bm02tj]

did you reset to have the same exact gear pattern if not it will be noisey

 

[benno440]

That's correct. Since it's a gear operated LSD instead of having clutches, there's no need for an additive. Also, keep in mind tha tuntil you actually test drive it, the gear oil is not properly distributed. Once driven under power, the oil will have a chance to splash lube everything and it will probably quieten down. Plus, don't forget, it needs proper breakin after which time it will get even quieter.

thanks rusty

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did you reset to have the same exact gear pattern if not it will be noisey

sorry i dont understand?

it originally was 3:55 30 spline
now is 3:55 33 spline

 

[RustyRatRod]

Did you remove the pinion gear? If not, then you are probably ok, or at least close. How much backlash does the ring gear have?

 

[benno440]

didnt remove anything, everything in the 489 case was brand new and came as a complete unit i used nothing from the old 741 unit

 

[RustyRatRod]

didnt remove anything, everything in the 489 case was brand new and came as a complete unit i used nothing from the old 741 unit

Ok. I understand now. Then here is what I would do. I would get it running and drive it. If it makes noise then, contact who you purchased it from and let them know and go from there.

 

[67 coronet]

Do you have a Factory Service Manual/FSM? If not then get one as it will help you out here. The reason being is that you will have to adjust the "end play" of the axles which will require following that procedure and right off the top of my head I cannot remember what it is. The "end play" must be adjusted so that when the axles turn when under a driving load, they expand and heat up and will bind against one another which will cause catastrophic breakdown. But the FSM is easy to follow and the procedure is spot on when you follow it. If you need further help just ask here on FBBO...cr8crshr/Tuck

if the new rear has a green bearing setup dont be surprised to find no adjuster.

 

[benno440]

okay thanks guys,
yeh definetly has green bearings as wilwood can only use the green bearings for there brakes, "axle end play" i never checked if there was any but when i put my brakes on i dont recall having any play in that area.

 

[cr8crshr]

OK...Then that is correct about the end play if Green Bearings are used. When I swapped out my 741 case 2.76:1 to a 741 case 3.91:1 sure grip rear 3rd member, I didn't change out the bearings as I was using drum brakes on the rear. So far it sounds like you have all the input you need to start driving it. And like what was mentioned if it makes any noise or causes you concern then I would contact whomever you got it from for assistance. Keep us posted cause there is help here...cr8crshr/Tuck