Differential Clicking Noise

[Kenneth T.]

I have a noise and I am trying to determine the cause before I go any further.

It's a 1968 BB 3.08 Posi rear. I get a clicking noise under low speed no load conditions.

The slightest touch to the gas and it is quiet. If I take it out of gear and coast at low speed it is even louder.
It is not the U-Joints on the half-shafts or drive shaft, that has been eliminated.

I would appreciate any help from the experience of the board, thanks.

Ken

[Steven B.]

Re: Differential Clicking Noise

A few years ago I had a clicking in my 3.55 posi. I could hear it at low speed but not higher, probably because of the headers and Monza mufflers. After a mile or so I stopped and flatbedded the car. A bolt had snapped in the diff.

[Kenneth T.]

Re: Differential Clicking Noise

Thank you Steven. I was hoping for, "just add friction modifier" but I will choose discretion as the better part of valor and take it apart for a good look.

Lots of stuff to come down. I will have to hustle it as the driving season is here.

[Jim T.]

Re: Differential Clicking Noise

Thank you Steven. I was hoping for, "just add friction modifier" but I will choose discretion as the better part of valor and take it apart for a good look.

Lots of stuff to come down. I will have to hustle it as the driving season is here.

Before you take it apart there is one other area that could be a source of the clicking. If your rear discs are not rivetted to the spindle like they came from the factory, the clicking could be the disc brake pads being moved by runout of the the discs.
Easy check to watch runout and listen is to remove the tires but support the control arm in a manner that matches the car sittiing level with the tires on. For safety have jack stands under the frame on each side.
Start the car and put it in gear and observe the brake disc pads for movement. If you have movement, you should be able to hear them.
You could also try driving the car at a low speed and hearing the clicking lightly apply the brakes to see if it quits.

[Kenneth T.]

Re: Differential Clicking Noise

Jim,

Thanks for the reply. I had it up on jacks, not the parking brake, it is coming from the diff.

Ken

[Gary R.]

Re: Differential Clicking Noise

Clicking from the diff could be the posi spiders,open case hole/shaft,broken clutches.

[Kenneth T.]

Re: Differential Clicking Noise

Gary,

I know you are the gear guy, so thanks for the response. I will take off the rear cover and have a look to see if it is something obvious.

Thanks,

Ken

[Gary R.]

Re: Differential Clicking Noise

Sure take some pictures if you have it out let me know. The 68's should have the 1st design Eaton in it and those were prone to crack. Be sure to check the case by shooting some brake cleaner on it and blowing it off, if it's cracked it will show up. They also used the weaker 10-18 spiders and those I would look at close too. How much endplay is there in the axles?
If it still has the original clutches they will be solid steels, not likely to break like the later "snowflake" clutches used in the 70's. Of course someone may have replaced the internals by now too.