Automatic Transmission or Differential Backlash (Play)

Question

I noticed that my car has what it seems to be significant differential play. I have a 1993 Acura Integra with automatic transmission. What I mean by play is simple: say I jack up only one front wheel and leave the other one on the ground. Then I can turn the wheel that is in the air probably close to 20 degrees without significant resistance. There is no noticeable backlash between the wheel and the axle and also no bearing noise. I can also replicate this by going under the car and turning the axle by hand, with identical results. I am guessing this backlash is coming from the differential, but I really don't know enough about the inside of automatic transmissions to be confident.

My question is twofold: what amount of backlash is normal in an automatic transmission/differential and at what point should I get worried? Second, what are the most likely reasons for too much backlash and are there any (relatively) easy things to try and fix it before opening the transmission up for an overhaul?

I should mention that all the above applies when the transmission is in park. The other symptoms that might be related and make me worry that this is excessive play are a slight clunk when changing into drive/reverse and also a slight readjustment (sliding forward or backward) after putting the car in park, shutting the engine and releasing the brakes.

Answer 1

What you are describing is a normal condition. The drive axle is connected to the Drive Pinion Gear which is meshed with both Differential pinion gears. As you turn the wheel both of the differential pinion gears rotate around the other drive pinion gear since it's being held by the other wheel on the ground. This turns the Carrier which is attached to the ring gear (AKA Final Drive Gear), which turns the pinion gear attached to the countershaft that's attached to the parking gear that is being stopped by the parking pawl.

What you are seeing is a accumulation of all of the play within all of those parts. You can check the backlash of the differential but it requires disassembly of the transmission. Again what you have is a normal condition.

If you are having symptoms like a clunk when shifting into drive or reverse there may be an issue to troubleshoot.

I have added an image to illustrate the play in the parking pawl alone.