Transmission

A

Albert Roussel

Junior Member
Does anyone know what the cause of a transmission growl in Low gear and a slight growl in second gear, and no growl in high gear? The ****** is full of 600W oil as recommended. Am I looking at problems in the future? My other model A is quite in all gears. Thanks, all barners,if someone knows why.
 
High Gear ("3" on the knob) is direct drive "through" the transmission input shaft to output shaft - without any internal gearing part of the equation.

2nd Gear uses one of the cluster gear "steps."

1st Gear uses another of the cluster gear steps - as in probably one of the smallest gears (I haven't traced this in my mind.)

What you are hearing is probably some issue with the cluster gear. It may be simply "worn gears" generally, or (more likely) some issue with the cluster gear shaft or bearings.

When the cluster gear is engaged in 1st or 2nd, there is a force "tangent" to the shafts as the gears attempt to separate (i.e. this caused by the "pressure angle" of the gear which I believe on the Model A is 14-1/2 degrees.) More force for 1st gear than 2nd, which accounts for your graduated noise levels.

Its sounding like you want to remove the transmission, do a tear down, and examine all parts for tooth wear or particularly the cluster gear shaft and the two needle bearings for physical damage. You'll see the damage on the "needles" as "brinnelling" (i.e. "cracks" lengthwise on the needle.) The cracks may be "mirrored" on the surface of the cluster gear shaft or the inside bore of the gear.

Quality issues have been prevalent on this shaft and the two bearings in the past (There are actually three bearing of this ilk if you include the "nose" bearing between input shaft and output shaft - right in the center of the transmission.) Aftermarket shafts have been found to be "soft" and likewise, the needle bearings have been found to be "brittle." Many original transmissions have needle bearings where the needles are done as tightly wound "springs" in the "Hyatt" pattern. Alas these seem more durable but today are rarely found.

Hope this helps. Keep us posted to your progress as we're ALWAYS interested.

Joe K


77040.jpg
 
Last edited:
It will go until it doesn't.

What may happen is the needles will break into pieces and then work their way out of the gear/shaft/cage, and end up in the bottom of the transmission to do MORE damage.

A magnet drain plug (3/4 pipe thread) might be a good and cheap investment.

But - transmissions can still be found for fairly cheap money, parts used are plentiful, and you may be able to run for quite a while as you are.

I would get the stiffest oil you can find to put in the box. I tend to like straight STP oil additive (comes in a can with a "peel off top") but many here will say "THAT IS NOT A LUBRICANT." Which admittedly it is not - but might be "better."

Don't use grease. Some people advocate John Deere "Corn head grease" (search term) for use in steering boxes. It might work but I would try to get by with STP first.

Joe K
 
If someone rebuilt the transmission with good but mis-matched gears that transmission will most likely be a bit noisy. First thing I would do is drain the box and see if there is any metalic particales found.
 
A dishonest way to quiet the gears when selling a car is to put sawdust in the transmission. The 600 W transmission oil is not as good as modern 85W-140 GL gear oil. That oil has an additive that will reduce the wear on all parts. The additive binds to the metal surfaces and wears instead of the metal.
 
Last edited:
Just rebuilt a transmission that was real real noisy in first, second and reverse but quite in third. Thought sure that the bearings were bad or a chipped tooth. After taire down we found that the gears were worn real bad and the bearings had some wear but not what we expected. Replaced all the gears and bearings and quite as a mouse now.
 
Not saying you were, and not suggesting sawdust. I just posted that as an interesting comment. Dishonest people have actually done that, but it was 60 years ago.
 
You must log in or register to reply here.
Back
Top