dannydoo said:
i dont wanna jack your thread but i wanna ask a question
the pinion pre load...or the back lash..what does both mean?
my real question is my rear is awsome but....sometimes at 40mph when i let off the gas it will wiz a little..and ay 60mph when i let off the gas it will wiz.as soon as i give it slightly a little gas it will stop wizzing..
what is causing this?i know the gut used the old pinion <washers>i forget the name of the things.and crush sleeves..any idea?
:OT:
Pinion pre load is the amount of torque required to turn the pinion gear without anything attached. i.e. No carrier & no driveshaft, just the pinion gear. When you do a gear swap, you install the pinion gear by itself (with the shim/crush collar/pinion seal/pinion nut/pinion flange of course), then you measure the torque required to turn the pinion. If it's too low, you brace the pinion flange (prevent the pinion gear from spinning) and turn the pinion nut further, which crushes the crush collar, which increases the amount of torque required to turn the pinion.
Backlash is the distance between any pinion tooth, and an adjacent ring gear tooth. So, for instance, you have someone put a ratchet on the pinion nut, and have them hold the ratchet still so the pinion can't move. Then, with the carrier installed, you wiggle the ring gear back and forth. The carrier will move slightly, which is refered to the play, or backlash. The backlash can be changed via the shim size on each side of the carrier. The stock carrier shims are huge, with one on each side. So you can't change the backlash with the stock shims. You need a shim kit, which has smaller shims. You then measure the stock shims, add the total together, and that total is the shim thickness you have to work with. i.e. if both of the stock shims measured .025, then you would have a total thickness of .050. So you can put .030 on one side, and .020 on the other, which still adds up to .050. By putting smaller size shims on one side, and bigger on the other, you have shifted the ring gear closer, or farther away from the pinion gear, depending on which side you add/subtract from. You must retain the total thickness, or else the carrier will be too tight, and will probably spin the carrier bearings. By changing the size of the shims on each side you tighten/loosen the backlash.
Make sense?
Now onto your question. If the guy used the same pinion shims and same crush collar, your backlash & pinion depth may be seriously off. That is all I can tell you. You need to pop the cover of the differential, clean it off well, and put some "Prussian Blue" on the ring gear. Then rotate the ring gear across the pinion gear, and this will show you the wear pattern. Hopefully you will be able to discern the problem, and adjust it accordingly.
If you have your stock gears, you can measure the pinion head depth on the stock & new pinion gears, and use that to calculate the correct shim size for the pinion gear. Then use a dial indicator, and measure the backlash. Then there will be no need for the gear marking grease to check for the wear pattern.
But at a bare minimum, you need to replace the crush collar & tighten the pinion nut until you get the correct amount of pre-load. I can't believe he used the stock crush collar. That's Frickin moronic!
Scott
, my mrand new pinion seal was good, differential cover gasket was leaking , but not any more, I just come back from garage
