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Differential Noise

Started by vicbrincat, July 17, 2010, 09:56:43 PM

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vicbrincat

The differential in my 48 makes a loud click or pop every time the car starts to go forward from a stop...or when I accelerate quick. It is the same noise that the differential makes when you shift from forward to reverse or visa versa.

I suspect that there may be excessive wear in the differential ring gear. ..but not sure why the noise occurs every time  I stop. I would think that even when stoped, the transmission should still be trying to turn the  drive shaft and thus keep the diff ring gear and drive gear "under load"...so I can't explain why it happens every time I step on the accelerator

Is it possible that it is a transmission problem???


Any ideas???

Vic


Otto Skorzeny

I think you have a bad universal joint in the drive shaft, not a bad differential.
fward

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vicbrincat

Did some more  investigation tonight....

Jacked the rear of the car up on axle stands.  Started the car and got my son to shift back and forward, accl, brake hard etc. while I lay under the car.

Tuns out the noise  is NOT coming from the diff, driveshaft NOR the transmission.  It's actually coming from the rear right  wheel.
When the barke is applied hard it makes the pop....then not again until you reverse the direction of wheel rotation.

Taping the brake backing plate makes the eaxct  same  sound..  It looks llike something in the barkes not the drive line  itself.<thank goodness!!>

Will investigate rear brakes next week.


Bill Ingler #7799

Hi Vic: You might check the torque on the axle nut. If the nut is not torqued to specs then the axle will turn inside the brake drum just enough so that the axle key will make the clicking sound as it moves against the drum. I think the torque should be 285 with a max of 315.

vicbrincat

Excellent point, Bill. Will most definitely check.

Vic

Whit Otis, 1188

If you remove the brake drum and examine the backing plate, you will see four raised areas or "lugs" for lack of a better description, stamped into the backing plate.  These are located on the backing plate at the outer diameter of the brake shoe (where the lining is located) at roughly 10, 2, 4 and 8 o'clock.... in other words, the edge of the brake shoe table and edge of the lining actually make contact with the lugs.  The lugs are there to stabilize the shoe.  If a car has a lot of miles on it, sometimes the lug will get a groove worn in it caused by movement of the table on the brake shoe against the lug.  If it isn't too deep, you can dress this down.... otherwise you have to remove the backing plate and weld the area and then regrind flat.... usually they are never that bad, though.  Anyway, when you apply or release the brakes, the edge of the brake shoe table catches on the groove and causes a clicking or popping sound.  Sometimes, even if the backing plate lugs do not have a groove worn in them, the shoes will make a popping sound.  Therefore, whenever I rebuild brakes, I always smear a light coating of grease on each lug before installing the shoes..... this makes the shoe slide easily on the lug when applying and releasing the brakes and eliminates the popping sound....  and no, it (the grease) does not migrate to the brake lining.
Whit
Whit Otis -
1941 6219D Custom
1941 6219D
1940 7533F
1986 Mercedes Benz 560 SEL
1999 Bentley Arnage
2019 XT5
Drawing of AP Sloan Custom by Terry Wenger

vicbrincat

Thanks Whit!

I know exactly what you are reffering to. And I will check them when I have the drums off......<been on vacation and haven't done much to address this problem..hope to tackle it soon>

Thanks again

Vic

Guidematic


QuoteJacked the rear of the car up on axle stands.  Started the car and got my son to shift back and forward, accl, brake hard etc. while I lay under the car.

Jeez, you're a braver man than I!

All good points made here. The grooves in the backing plates to me sounds to be the most viable. It's a very common problem with all drum braked cars.

In the past when I have encountered this,  have brazed up the grooves, then ground them down flat. The I also put some anti-seize on the pads. However, there is a newer lubricant out there designed especially for brakes that uses ceramic in the grease and it's good for more than 2000F.

I just can't remember the name of it, and I have a can of it on my bench at work.... If I remember, I'll have a look today.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69

vicbrincat

Problem solved. No more clicks and pops....

It turns out Bill was right. The axle nut on the right rear wheel was not torqued down properly. I was able to turn it off the shaft with almost  no effort.
So I tightened it as best I could...I don't have a way of putting 315 ft/lbs to it ....but I will take it to a garage that can do it properly.


Thanks for all the advise folks.


BTW Mike, "brave" was not the word that came  to my mind....;-)

Vic



Guidematic


QuoteBTW Mike, "brave" was not the word that came  to my mind....;-)

LOL!

Glad you got it worked out and it was a simple fix.

Mike
1970 Fleetwood Brougham 68169
1985 Eldorado Coupe 6EL57
1988 Eldorado Biarritz 6EL57
1990 Brougham d'Elegance 6DW69
1994 Fleetwood Brougham 6DW69