1969_Mach1 333 Report post Posted April 3, 2017 I have a close ratio toploader trans in my Mach 1. I recently replaced the 3.89:1 rear axle gears with 3.70:1 so I can at least go 50 MPH without the motor screaming at me. Initially I thought I had rear axle gear whine on acceleration but now I am not sure. The noise only occurs in first and second gear. Shift into third and the noise stops instantly. Fourth, no noise as well. I rarely drive the car, but I don't remember that noise before. I installed Motive Performance Series Gears. They setup easy, set the pinion depth and backlash, and the contact pattern is where it should be. I've used them in the past with good luck but that doesn't mean much these days. I don't know if it's trans noise or rear axle noise that coincidently happens at speeds in first and second gear. Before I pull the third member out to double check the setup, do the close ratio toploader trans typically make gear noise? Or do they only make gear noise when something is worn out? It was rebuilt at a local trans shop when I was initially restoring the car. They didn't replace any gears. They replaced all needle brgs, front and rear main brgs, thrust washers, seals, blocker rings, and lastly a new input shaft. Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted April 4, 2017 block the front tires and put the rear on jack stands and stat it up and put it in second gear and crawl underneath and see if you can hear it from the trans or diff . you may need to turn the idle up a little to get it up to speed to make the noise. when finished, lower the idle down then put it in neutral then turn it off. Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted April 4, 2017 Thanks, I have s stethoscope I use all the time to find noises. I never thought of doing that. I'll stay away from the driveline and rear tires. Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted April 5, 2017 I couldn't hear any noises from the rear axle or trans using my stethoscope with it running on jack stands in any gear. Probably because of no drivetrain load. I think I'll go back to the 3.89 rear axle gears that I don't recall having any noise issues with. I'll post the results after that. 1 barnett468 reacted to this Quote Share this post Link to post Share on other sites
