Can't seem to locate a growl

[Colonel Biggs]

A couple of years ago I started picking up a low growl in second and, particularly, high gears. I lived with this for a bit, but I’m a perfectionist (unfortunately). The growl to me seemed bearing related, but I had restored the vehicle from the ground up only 400 miles earlier. The intensity of the noise was greatest around the transmission area of the car, but it also extended down the torque tube somewhat to the differential.

In explaining my situation to Tom K. at Bratton’s (who rebuilds their transmissions) and to Les Andrews, both seem convinced that it was a transmission-related problem (no doubt the second and high sliding gear), as opposed to a rear end problem. I concurred, so I performed a total rebuild of the trans – with both Tom K. and Les offering outstanding advice. Needless to say, after installing the trans and cranking up (car still on jack stands), the growls were still there.

In using one of NAPA’s stethoscopes, the noise appears loudest at the front of the torque tube where the drive shaft roller bearing is situated, but there is also some noise down at the differential. (There is almost no noise at the trans nor at the universal joint.) I did a total rebuild of the rear end at the time of the restoration (replacing bearings, bearing cups, pinion gears et al), so I am “hopeful” that the noise is not emanating from the rear of the car and coming up the torque tube (refer to my article in the January-February 2004 issue of The Restorer, if you are so inclined, but it’s bedtime reading only!).

I could start by pulling the rear end back again and checking the drive shaft roller bearing, although I don’t think that this bearing receives that much stress. The growl does cease when I throw out the clutch. I’m trying to think of other tests that I might conduct before gyrating to the differential.

This one has me baffled!

Gordon

[garyaodell]

Dose it growl with the transmission in natural and the clutch engaged? could it be the speedometer gear?

[tbirdtbird]

tighten your rear hubs back up to 80-90 ft-lbs. Some say 100 but IMO that is too much for the undersized 5/8 threads, which should have been 3/4 like it is on other vehicles of the period

when u rebuilt the tranny (again) did you find anything amiss?? Prolly not.
I have had several occasions where a growl was slightly loose hubs. Noises can fool you and telegraph all over the place.....

on your rear end overhaul we assume you followed Tom Endy's procedures well.

[Tom Wesenberg]

I would eliminate the speedometer gear by just removing it for a short test drive.

Is the noise there both while accelerating and coasting with engine braking?

[H. L. Chauvin]

FWIW:

Model A differential growls with worn new or old differential gears can be strictly differential RPM related.

It very well could be that both second & third can get enough differential RPM's to create the growl; however, in first, you may not create enough differential RPM's to make it growl.

I have a differential that will growl from 30-35 mph in third -- this sound was my speedometer to avoid getting a speeding ticket in a 35 mph speed zone in the 1950's -- once passed 35 or under 30 mph, all of the growling stopped.

On a Model A differential rebuild, take very cautious note of not only drive pinion gear/ring gear contact in center of teeth on forward drive; but also notice the curved ring gear to pinion gear center contact on coasting.

Just sharing one "past" growling experience.

[Colonel Biggs]

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No noise in neutral, first or reverse. The speedo gear is out of the car, so it is not a factor.

Is the rear hub torque of 80-90 a Ford spec, or just a thought? There was no problem with the pre-rebuild rear end, except for a slight leak. That was eliminated when I retrued the left rear axle flange. Rear end ran quietly for about 400 miles.

Growl seems to dissipate when accelerating, but comes back with a vengenace when decelerating.

I blued the ring gear/pinion gear teeth on the rebuild. There is a picture of the wear pattern in the article to which I referred.

[tbirdtbird]

"Is the rear hub torque of 80-90 a Ford spec, or just a thought?"

That is an inflammatory statement. Perhaps you have not followed my postings much; that hot Texas sun can get to you. Bratton's torque table calls for 100 ft-lbs. I maintain you will eventually strip out the threads at that rating and I de-rate to 80-90 ft-lbs. If you want to go to 100, then go ahead.
Facts:
1. a tapered axle/hub needs to be darned tight to function properly. It should NOT be the key that is holding it all together, but rather the enormous surface area of the taper. That is why you should need a puller to get the hubs off.
2. Especially after a rebuild and everything has been apart, the hubs can loosen some as the car is driven. Do NOT assume because it was tight at first that it will stay tight. They need to be rechecked, and this is way easier to do than removing a tranny. You may want to re-consider my suggestion of checking the tightness.

I missed the part where you gave the spec that you torqued your hubs to.


"Growl seems to dissipate when accelerating, but comes back with a vengenace when decelerating."

yep. It is getting worse, too, isn't it? check your hubs

If I am dead wrong you have lost nothing.

"January-February 2004 issue of The Restorer "
This is not available to all of us

Post back and let us know what ultimately fixes the problem

[Colonel Biggs]

No offense intended, senor. I have been assisting a daughter restore a 1720 home for the last year plus up in Mass., so I haven't been on this forum for quite some time. A lot of new names to me. In past years, there was some detailed info dispelled as gospel, but until you learned who the players were, one tended to confirm some of the specs cited.

I never even thought to look in Bratton's catalog. I will dig out the torque wrench and give 80 ft. lbs. a shot. I originally torqued the hubs to "very darn tight," but certainly not to the 100 ft. lb. level.

Which is worse: the Houston heat and humidity, or the Dallas heat? I think that Houston takes the cake. But, this is why I started this restoration some ten years ago up in New Jersey.

Thanks for the comments.

[tbirdtbird]

OK. I am sure you know this, but here goes. This has been commented on several times. Once you get to 80, or 90, or 100, or whatever you are gonna use, note whether you are able to use the closest window on the castle nut. Often you can't. The best approach is to neither loosen to the prev window nor tighten to the next window. Instead, remove the nut and grind slightly on the face of the nut on the SIDE of your grinding wheel. Then re-apply nut and re-torque and see how things line up. This is trial and error, but you will get exact results. It doesn't take much. Good luck

Oh, and be sure to use the specially hardened flat washer up against the hub. If you don't have them they can be ordered or just get grade 8 washers from your local hdwe store. Anything less will not stand up to the forces and the nut will just dig into the soft washer and the washer will continue to deform and your hubs will loosen as a result

[Colonel Biggs]

Yes, I am well aware of the castle nut alignment drill for cotters from my restoration process, but reminders never hurt. I have also been known from time to time to place a series of cotters, but forgetting to return to spread the ends. Reminders are always welcome.

When I return to the Roadster I will set the torque on the rear axle nuts and report back. But, I am suspicious why this noise condition, which is very pronounced in high, occurred all of a sudden. Since I replaced all of the hardware in the differential when I undertook the rebuild, and meticulously performed all of the required measurements, and becuase the rear has been silent for the last 400 miles, I am hesitant to open it up without first exhausting all other possiblities. There is always the possibility of a failed bearing, even if new, although it has never happened to me.

[Colonel Biggs]

Tbird -


Finally got back to the Roadster. Would you beleive that the torque on the rear axle nuts was down to 35-40 foot pounds? Set them back up to 70 for starters, but no impact on the noise situation. But, the reminder was well placed!

Tomorrow I will drop the differential again to gain access to the front of the torque tube. My last hope is noise around the area of the front roller bearing. With a stethoscope, the noise is a little greater there than down by the pinion bearings at the other end.

Thanks for the torque reminder!

[tbirdtbird]

sorry it wasn't as easy as I had hoped. At 40 lbs they should have been making quite a racket. Good thing you checked tho 'cause the hubs can get wallowed out as you know from looseness, and you can mess up the keyway pretty bad on the axle. Keep an eye on them.

That front roller bearing is a little hokey for what it is supposed to do...keep the shaft from whipping around due to the universal

Good luck. Let us all know what eventually makes it right.

[Tom Wesenberg]

Oh come on now, what's this nonsense about a loose axle nut causing keyway damage?

This axle was given to me due to the keyway damage. Sometime I hope to weld up the missing metal.

[SteveB31]

I think when you pull apart that differential you will find the two thin pinion nuts have come loose. Here is why I say that. When you aceelerate, the pinion is pushing in to the ring gear and you have no noise. When you decelerate the ring gear is pushing the pinion forward causing the noise you hear. We rebuilt a couple differentials that had this problem earlier this year.

Steve Becker
Berts Model A Center

[Tom Wesenberg]

I agree with Steve that the noise is most likely loose pinion bearings. I set them so they have a light drag, like about 10 inch pounds (NOT foot pounds) of torque to rotate the driveshaft.

I wouldn't do any more driving until you check it out because you could quickly do much more damage to the gears and bearings in the rear end.

[tbirdtbird]

If what Steve suggested turns out to be true, along with tightening, add some blue Loctite

Isn't there a tool that allows you to remove the pinion and its double sided race without dismantling the entire rear end? He could use that.

[d.j. moordigian]

Originally Posted by SteveB31

I think when you pull apart that differential you will find the two thin pinion nuts have come loose. Here is why I say that. When you aceelerate, the pinion is pushing in to the ring gear and you have no noise. When you decelerate the ring gear is pushing the pinion forward causing the noise you hear. We rebuilt a couple differentials that had this problem earlier this year.

Steve Becker
Berts Model A Center

Along with Steve's comment which I think is valid we had this problem.
The Hyatt bearing area at the front of the drive shaft,...the drive shaft
was worn and bouncing around off the Hyatt. This was in a cut down
V/8 rear end with a Columbia in the back..but it's the same parts.
Just something else to inspect....

[Colonel Biggs]

Thanks for the many comments. I like Steve's thought about the pinion nuts. What I don't understand, though, is that if the lockwasher tabs were set correctly the first time around (about eight years ago), I'm not sure why the nuts would loosen.

Today I moved the rear end back (again) so that I could get a look at the roller bearing at the front of the torque tube. Naturally, the bearing is in great shape, so it looks like I will have to perform another rear end rebuild. Out of curiosity, I measured the pinion bearing pre-load, although I still had gaskets mounted on the axle housings. As I recall, these measurements are supposed to be taken without gaskets in place. The torque came out to about 70 inch pounds, well above the 20 level recommended. But, as I noted, I had gaskets mounted since I haven't started the disassembly yet, so the measurement may be meaningless.

Bob Rentz once made a holding fixture for the axles, which simplified life somewhat. Does anyone sell such a tool today?

Again, thanks for the thoughts expounded.

Gordon

[tbirdtbird]

Does Tom Endy want to chime in here??

[tbirdtbird]

On the Fordbarn the pros here consider Tom Endy to be the master at rear ends, he has done hundreds of them.
This is a link to his methods; perhaps you will find it of some use:
http://www.ocmafc.org/techarticles/T...0Re-Edited.pdf

From the section on pre-load:

"Continue adding and subtracting gaskets until you can move the ring gear with your finger, or can measure 20-in. lbs.
on a dial indicator using the spider yoke tool"