TR2/3/3A diff free play tr3

[TRclassic3]

In the process of getting 3 ready for a trip I was checking the u joints and they seemed fine. However I noticed when turning the drive shaft that there is some freeplay before things engage. What if any freeplay is acceptable. Or put another way how much movement can exist before its time for a rebuild?

 

[TomMull]

I don't know if any specs exist but from my shade tree experience, it is not unusual to be able to turn the diff flange 5 to 10 degrees or so with no motion visible at the wheels and no resistance at the flange. If there are no other symptoms, I would not worry. Tom

 

[CJD]

If the dif does not "howl", then your free play is correct. The pinion is set to an exact tolerance with the ring gear..like...to the thousandth of an inch. If it is off, you will know it. It will start with a slight howl at certain speeds, and increase to a growel at all speeds as the gears wear themselves. It will only make the noise when loaded in the drive and/or coast direction. The noise will go away when you "float" the accelerator pedal between drive and coast.

So, the short answer...you have nothing to worry about.

John

 

[TRclassic3]

Tom,

Thanks for the response. That puts me at some ease as I would guess the movement to be in the neighborhood of 10 degrees. No other symptoms that I have noticed.

 

[bobhustead]

It would be unusual not to have what seems a worrisome amount of play in an old rear axle system. Acceptable bits of lash develop in the upper and lower pinion bearings, the pinion to ring mesh, the spider/axle gears themselves, the little cross pin the spider gears rotate on, the holes in the carrier that the cross pin fits into, the differential carrier bearings, and the fit between the axle splines and the axle gears. In the aggregate, they seem to go on forever when you turn the pinion. Specs for new builds are not helpful and you can't measure most of them except as you assemble or disassemble all the parts, but you can find several specs in the Haynes workshop manual. If its not howling and you can't feel much side to side or up and down motion by pushing the yoke on the pinion gear around, you are probably fine.
Bob

 

[TR3driver]

FWIW, my TR3A had a rather enormous amount of play in the differential when it came to me, over 1/4 turn at the input flange, and worked fine for over 100,000 miles. Although I never pulled it apart to check, I now believe the play was caused by wear in the curved brass thrust washers that carry the spider gears; likely caused by using a gear oil with the "active sulfur" EP additive.

 

[TRclassic3]

Thanks to all. That is very reassuring! At the risk of starting another fluid debate, what is suggested for gear oil without the active sulfur EP?

 

[TR3driver]

Lots of good choices; but I use Valvoline Synpower
https://www.valvoline.com/products/brands/synpower/gear-oil/59

Last time I checked, my local Autozone had the best price, about $8/qt.