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Discussion Starter #1
I just bought a 2.47, 9", open rear pumpkin for my 67, 289, C4 fastback from a rear end rebuilder. He used a 2.47 ring and pinion from a Lincoln and rebuilt the rest of the unit. I have two questions:

1) Does this rear end have to be "broken in" in any way, and if so, what’s the procedure?

2) What rear end oil should be used? 85/ 90 or 85/160. What’s the difference between them? It’s my understanding that the first number is the actual weight of the oil, and the second number is the equivalent protection of the oil, that is, the oil will protect to the same degree as the weight oil of the second number. For example, 85/90 oil is the viscosity of 85 weight oil, but affords the protection of 90 viscosity (weight) oil, whereas 85/160 oil is the viscosity (weight) of 85 oil, but affords the protection of 160 viscosity (weight) oil. If this is correct, then it follows that 85/160 oil should be better to lube the rear end than 85/160 oil.

This all sounds perfectly logical, but I’m not sure it’s correct!!! Can anyone out there set me straight on this?

Thanks

Jay67fast
 

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if the gears are used it dont realy need broke in.....the bearings are new (im guessing) so just take it easy for a hundered miles or so as far as oil anything will work well (not a good answer but its true)
 

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Discussion Starter #3
Rebuilt rear end questions

Whoops! Slippsies!
Third line from bottom should read "oil should be better to lube the rear end than 85/90 oil".
Sorry!
Jay67fast
 

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A 75/90 Synthetic Gear Lube is an excellent all year lube, and should last forever. You might also ad a pint or so of friction modifier. If set up right you should have no issues. And NO you should not use just any oil.

Ron
 
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