Differential clunk

[KevAndAndi]

I had noticed a "clunk" coming from underneath the car when backing out of the garage. I assumed it to be the differential, which is not otherwise noisy. (I recently replaced the giubo, the center support bearing, and the u-joints on the drive shaft, meaning that those were not likely culprits.)

I decided to change the oil in the diff, replace the gasket, and have a look. This is what I heard when I moved one of the wheels back and forth:

https://youtu.be/vwNWueh3zVI

Otherwise, everything looks to be in decent shape. There's nothing broken that I could see, and there wasn't anything in the bottom of the case or on the drain plug magnet other than some small shavings.

I buttoned it back up and refilled with oil, but I'd like to know the diagnosis. (Please keep in mind that I know next to nothing about differentials.)

1) Is it time for a new ring and pinion?
2) If so, who does that kind of work - a transmission shop? Would they need special Fiat tools?
3) Or, do I live with this until it gets noisy and/or something breaks?

[DieselSpider]

It may just be the need to replace the input bearing, seal and crush washer which a good transmission shop should be able to take care of along with set the lash and pre-load. Let it go too long and then hard parts could require replacement costing much more to repair.

[seabeelt]

Hmmmmm, I may have started to develop a similar noise. A definite clicking as it goes around

[KevAndAndi]

It may just be the need to replace the input bearing, seal and crush washer which a good transmission shop should be able to take care of along with set the lash and pre-load. Let it go too long and then hard parts could require replacement costing much more to repair.

Is this done with the axle off the car? I'm going to be replacing shocks and trailing arms this winter, anyway, and so am inclined to remove the axle and bring it to the shop. There's one in Livingston, NJ called Euro-Tec that advertises transmission work as one of their specialties. In addition, on their Facebook page this month they showed two classic Fiat Spiders that they had just serviced.

[DieselSpider]

Yes it can be done with the rear axle still installed in the car however many like to pull them to clean and refinish them while they are at it.

[KevAndAndi]

They told me to bring the whole car in, so I may have them install the trailing arms and shocks that I have, since they're going to be back there anyway.

Maybe I'll get to see the Fiat Dino they just finished restoring!

[KevAndAndi]

I'm giving this post a bump. I decided to wait and bring the car to the shop in the spring. But it occurred to me that a condition that our car had when we acquired it may have led to his problem. The center support bearing was completely shot, and it's likely that it was original to the car. Who knows how many miles were put on the car with no center support on the drive shaft. What kind of damage, if any, can this do to the differential? This may help narrow down the diagnosis when I take the car in for service next year.

[spider2081]

I know most of the parts are available for what you are talking about but if there is any hang up that happens in the spring it would be a disappointment not to be able to drive your car. Especially that first sunny top down day. Just a thought.

[KevAndAndi]

I know most of the parts are available for what you are talking about but if there is any hang up that happens in the spring it would be a disappointment not to be able to drive your car. Especially that first sunny top down day. Just a thought.

That's a good point.

I'm going to try to get done what I need to do this winter (brakes, trailing arms, wheel bearings, etc.), and get to the shop as soon as the salt is off the roads. I'd like to at least try to do some more diff diagnosis on my own before I take it in. Open up the inspection plate and move things around again, to try to see exactly what is clanking.

I had already "put the car away" for the season, but since we've had some nice days, I've burned through half of a full tank of Sta-Bil treated gas!

[spider2081]

Still driving ours also. I hate to put it away.