howling

[wheelspin]

the other night I noticed a slight howling from the rearend under deceleration. So I changed the diff fluid and it seems to be a bit louder. but it only seems to be when Im not on the gas as soon as I lift coming up to a stop sign i hear it. and a few time it seemed louder when I made a right turn . I no its not good. and yes it a 7.5 3.42 auburn posi. is it the gear mesh? or bearing . any thoughts are MUCH appreciated.

[Melonhead]

By chance, did you or had someone change the pinion seal or mess with the pinion nut? What it sounds like is one or more of your bearings are screwed. The best thing to do is take off the cover and inspect for damage. There will more than likely have metal in the bottom of the housing. If you hear more on the pass side, check the axle bearings also. Any bearing that fails will leave debris in the whole system to cause a chain effect.

[wheelspin]

thanks for the input. rear ends scare me to death to work on. but Im gonna a give it a go.now, my axle bearings are they at the end of the the housing by the backing plate? and if I have to change I know there c clips to take out to remove the axles. wish someone had some pics what to take apart as far as the posi unit to get them out. also are axle bearings slide on or do I have to have it done? thanks for dealing with all the questions.

[stroker1]

If the pinion nut is loose, you can grab the driveshaft and wiggle it and it should show alot of loose play. When you remove the cover on the differential you can look at the wear pattern on the ring gear and it will tell you more than anything. You know you need to put the limited slip differential additive to the gear oil for the unit, right?? Most conventional gear oil does not have the additive for the posi unit.



Check Richmond Gears web site, or Google search Randys Ring And Pinion. They have a real good web site. Probably got some pics on proper wear patterns. I know my Yukon Gears had a good illustration on this stuff when I bought them. They also where purchased from Randys Ring And Pinion. BTW, Randys is not a Nickel-Dime business either. They are pretty top notch. The have an excellent parts department and tech support.



Stroker1

[wheelspin]

hey stroker thanks for the input. could you be a lil more clear on that nut being loose. leave it in park and just wiggle the driveshaft or try and hold the end by the pinion? it does have a slight like by that front seal too. but I have never tried to tighten it thanks man for taking the time to help

[stroker1]

Yeah with it jacked up and in park you should be able to feel the drive shaft wiggle a little if the nut was very loose. In other words the yoke that slides onto the pinion shaft will likely be loose enough to wiggle it if the nut has backed off. In any case you can hold the yoke with a big pipe wrench and torque the pinion nut again.



Stroker1

[wheelspin]

cool thanks I will do that. is there any specs as far as ft lbs. I should torque it too or just tighten it up if its loose? I owe ya beer for all the questions

[stroker1]

Yes there is a spec, but I don't remember what it is. You could find it in a shop manual or call Randys Ring And Pinion, they will tell ya. Also they have some pretty good auto-math calculators for gears and RPMs and that kinda stuff.



I have always went by the instructions that come with gears when I have done a gear change but I don't recall the torque spec.



Could be different on a 7.5 than a 8.5 or 12 bolt and 9 inch ford. I dont know but would assume they are different.



Stroker1

[mzoomora]

There is no spec for the nut itself, you have to torque the nut to obtain approx. 15 in/lbs rotating torque on the pinion if you are using used bearings. Also, you should use a new crush sleeve since they are one time use only.



Usually decel whine is from improper bearing preload or too much backlash. If the setup on the gears has not been changed I would look at bearing preload first. You bearings may be worn.