The 9" rear in my '41 Merc has a slight howl (very slight) at 25-35 MPH under light throttle, let up on throttle and the howl goes away. Should I just turn up the radio or is there a fix for this?
Double check your pinion angle with weight on the vehicle, I had an OT leaf spring car that I street raced, when I had the pinion angle set to zero it was quiet and smooth but didn't hook hard, I started moving the pinion angle down so the car would hook, at 2 degrees down so the car would hook and got a howl about 30-40 mph, at 3 degrees down the car hooked really hard and had a howl. I was willing to live with it cause I was winning races. That was before I learned to start tuning leaf springs by changing leafs and moving clamp points, got it hoking hard at 1 degree down.
If the bearings were failing wouldn't it howl all the time? How tight should the pinion nut be? How about preload?
The 9 incher in my 27 has a slight whine, especially when I lay off the gas. It has done it since day one (rebuilt unit/4.30 gears). I've put thousands of miles on it with no problems so I just run with open headers as much as I can. Don
Noise descriptions can be deceiving... because a lot of people don't know how to properly describe noises. A bearing makes a roaring noise, not a whine. Gears make a whining noise. http://pictures.dealer.com/motorcarsvolvovcna/bf762c930a0d028a013816e0da69d3c7.pdf This list has a good description of noises and in terms most people can relate to. The whine in your rear end... gear pattern noise. Perfectly normal and it will live forever. "A common problem is worn carrier bearings, as indicated by a low-pitch rumble above 20 mph. On vehicles with C-clip axles, the noise may vary while negotiating turns. Worn pinion bearings can cause whirring noises at all speeds, under deceleration and/or acceleration. Pinion bearings tend to whir, rather than rumble, because the pinion is turning several times faster (depending on gear ratio) than the carrier. Badly worn bearings can also cause howl if they do not support the gears correctly." Randy's R&P
If the nut backs off it unloads the pinion bearings and the pinion will move into the crown causing a howl when you back off the gas the pinion moves forwards against the taper and the howl stops. Check the nut they do come loose sometimes. Take it off put some blue locktight on and tighten to 50 pounds or so, you don't want to change crush.
Thanks for the input but my howl is just the opposite of what you described...it howls with light throttle and goes away when I let off the throttle...
Sounds like gear noise to me (***uming that it is the rear end). On accel, gear contact will run outward towards the edge of the ring gear. One reason the pinion shim & checking gear contact is important before you install it. Those things aren't light. If you have an ***ortment of pinion shims, pull your pinion out, measure the one you have in it & put one in 0.004 thinner. You may get lucky.
Mine had the same symptoms you described. Turns out there was a crack in the pumpkin around the rear pinion bearing. So much for 9" indestructability.
OK, the comma makes all the difference...will try your suggestion, thanks, *******. (had to put the top up yesterday, we finally got some rain here on the desert. yippeee!)
80% of the time a "howl" whether on the throttle or off can be found to be in the gear set-up. Bad patter, pinion not shimmed correctly, poor backlash, ect. Seldom will you ever find a bearing problem unless it is more like a "growl". The 9" Ford rear ends are one of the easiest to set up but because of this they can be one of the easiest to screw up. Pull the third member out, check the pattern and go through the set up again if you know what your doing or take it to someone who does.
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