VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Growling noise

My 28 National is growling. Let me describe. It drives just fine with no noise until I let off the gas and then whether in gear or not, I get a growling sound from some place in the drivetrain. If I am in gear and gently apply power, the growling goes away. I plan on cracking open the u-joint housing and taking a look, but would love some advice so that I can avoid the joy of getting greasy twice. I did check the transmission and diff levels and they are fine. I did add a cup or so of 600W to the u-joint because the driveshaft o-ring seal is leaking a bit.

Hi Shawn,

My first comment would have been that your uni joint is a bit dry, which shows itself when you back off, and will dissapear when the lubricant is topped up. As you believe your uni is well lubricated, I would be looking at the condition of the joint itself. Others may have other suggestions.

Good luck, let us know how you get on.

Ray

2 years ago, when I did the clutch, the u-joint looked good. The car has maybe 60 miles on it since then. It was stored off site last winter and as I said the u-joint is leaking to the outside via the slip joint to the driveshaft tube. Perhaps it is dryer than I think. I just order a gasket kit from Gary Wallace and will take it all apart and see what's up.

It might also be the tailshaft bush being badly worn, a common problem.
Another thing (which I had years ago) is the settings of your rear springs, if one spring has sagged more than the other it will cause your uni to rattle on back off as it drags the torque tube to one side putting pressure on the uni.
The way to check this is very easy, bounce the back of car up and down a couple of times and have a look at the angle of your rear shackle plates if one is at more of an angle that the other, this will be your problem and you'll have to get your rear springs reset.
When these cars were made they experienced a similar problem when as power was supplied the engine torgue dragged the torque tube to on side, they fixed the problem by having having different height rear spring saddles.
Chris

Thanks for the guidance, but can you please explain resetting the springs.

A noise that goes away under acceleration is usually a pinion bearing.

i would say the ring gear is loose on the carrier in the rear end . have found this a common thing on the early chevys . easy to check . hope this helps

Wow, so many problems to choose from. I do appreciate all the ideas. Ray, if it is the pinion bearing, is a 307 bearing the right one?

I am on the road now and don't have my reference materials with me.

The pinion bearings have numbers as follows:

Front:double row angular contact type 5305

Rear:maximum capacity ball bearing 1307(same as rear axle
bearing).Modern p/no. NTN BL307

Ring gear carrier bearings:single row angular contact bearing
original p/no. 1208,
modern p/no. 7208.

Thanks. As much as i love dealing with our various vendors, we have a superb bearing shop in town. Nice to not have to pay shipping once in a while.

You may wish to check my posting #214372,as I put the bearing dimensions down for another poster.

Got it. many thanks.

CJP's a walking parts list for old Chevrolets, doesn't even need a book.

Resetting the springs. OK if you put a straight edge form the top of the front and back eyes and measure the distance from the straight edge to top of the leaf that will give you the 'set' measurements. As the spring get old they sag and the distance between the eyes gets bigger and the 'set' measurement gets smaller, and the angle of the rear spring shackle plates gets shallower. Resetting them brings back to the brand new configuration.
Hope this makes sense.
Chris

Makes mores sense now, thanks