I am posting a couple of photos of my ring and pinion gear pattern purely as a sanity check. I'm looking for a few opinions.
I have now dismantled the differential 5 time to add a 0.006 shim to get the gear pattern right. 3 time since the rear axle was mounted back in the truck. I now have 0.036 worth of shims. The backlash is currently 0.008. I kept adding a shim and checking the gear pattern in hopes of getting rid of the light whining sound when I lift up on the accelerator pedal.
Additional information All the bearings are new. It took some time hunting them all down. The former pinion bearings could NOT be reused as they were badly chewed up. The former forward pinion bearing was literally missing a couple of balls on both rows.
The ring and pinion gears are new from Jim Carter Truck Parts. They appear to be made in China.
______ It's still making a light whining sound when I lift up on the accelerator pedal. I have found the new forward pinion bearing (dual row ball bearing) to be rather tight. Perhaps it needs time to wear in. ______ During the summer of 2024 my room mate invited me to park pickup in the driveway. It is a fairly steep slope to the street. I estimate a 3"/12" pitch. I parked backed in. Had I known what would happen I would have never have parked there.
What I figured happened is the gear oil flowed up the torque tube and seeped into the transmission. I found the transmission (SM420) to be over full, and I put 1-1/2 quarts of gear oil in the differential which only hold 4-1/2 pints in total. By this time it was already too late. The differential was making growling and popping sounds. The forward pinion bearing was wiped out and the others were in rough condition.
Your second image doesn't look too far out of the right range to me, however...some questions: 1 Are these new ring & pinion gears? If they are old gears getting them adjusted so they don't whine might not be possible. Sorry to be the bearer of bad news but that is the truth as I've learned it to be over the last 60 years. They get worn and they get happy. When you change them, they make noise. 2 How are you generating that pattern? By that I mean are you adding drag to imitate a load?
You want the pattern as centered in the ring gear teeth as possible. As you may know it is not easy to have this go perfectly your first (or even second or third) time. A tight pinion bearing can and will make noise. If it is too loose, it will make noise on deceleration. If it is too tight, usually it will cause it to get hot and there will be a constant whine...sort of like the distant whine of an older style fire engine siren. Deceleration puts a backwards load on things...reverses the load that is put on components during acceleration. Not always easy to track down in my experience but I've seen failing bearings in the differential cause this. You are putting on them a load they don't normally get and that will cause a weird howling.
Please tell us more.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I try to get them just slightly off center so under a load they center up. I also have a heavy piece of teflon that I can bolt to the houseing while rubbing on the ring gear, this really loads it down when turning the pinion for checking tooth patterns. I always had trouble holding the gear tight while turning. With it really dragging you get a better pattern.
Yours is really close, pulling the drive side a little more to the center would be better, but its likely close enough as is.
Look at the wear pattern on the teeth where there is no marking compound. If that pattern is close to the same as what the compound area is indicating, I'd call it good. If it whines a little bit, loosen up one of your valves so that the ticking covers it up.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Your second image doesn't look too far out of the right range to me, however...some questions: 1 Are these new ring & pinion gears? If they are old gears getting them adjusted so they don't whine might not be possible. Sorry to be the bearer of bad news but that is the truth as I've learned it to be over the last 60 years. They get worn and they get happy. When you change them, they make noise. 2 How are you generating that pattern? By that I mean are you adding drag to imitate a load? Please tell us more.
I added information that I should have put in my original post.
All the bearings are new. It took some time hunting them all down. The former pinion bearings could NOT be reused as they were chewed up. The ring and pinion gears are new from Jim Carter Truck Parts. They appear to be made in China.
I left the tire on and the drive line was hooked up. This provided some drag on the gears.
Depending on whether you have enough drag, you may be about where you need to be right now. As Joe up there said, moving it closer might help, but it is hard to say for certain. More drag might bring the mark where it ought to be. If you aren't getting a fairly loud howl from the ring/pinion, you may be about okay. I can't say about the pinion bearing, though. I'd need to see & feel it.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Depending on whether you have enough drag, you may be about where you need to be right now. As Joe up there said, moving it closer might help, but it is hard to say for certain. More drag might bring the mark where it ought to be. If you aren't getting a fairly loud howl from the ring/pinion, you may be about okay. I can't say about the pinion bearing, though. I'd need to see & feel it.
The pinion bearing is an NOS New Departure 5306W. The grease had hardened in it, I used used motor oil, penetrating oil and a little action from a propane torch to get it to loosen up. It doesn't spin freely and its still very snug.
The whine is not very loud. I put the OSB board I've been using for a pickup bed back in. I can still hear a faint whine in the direction of the transmission as if the sound is traveling up the driveshaft to the transmission.
I'm going to proceed under the idea it's the pinion bearing making the whining sound. I decided I am going to go ahead and drive it very careful strictly around town for a while. I have put a tube of Liquid-Moly for Gears in with the oil along with a 1/4 bottle of STP oil treatment to thicken the oil up a little in hopes things will gentle break in and the whining sound cures itself.
I needed replace the ring and pinion in this 56 pick up. Got feed up with chasing nos parts. We plan on keeping this truck so I ordered this currie 3100 9 inch rear end built for 1955 59 chevy trucks. Ya I'm aware you can go to the junk yard and piece stuff together and I have done that in the past.
