Hi,
Thanks to all who helped out with information on the assembly of a '34 Rear Axle.
There is a lot of information available out there in various location, but I thought that a summary of it and my learning may help others.
I actually found the whole process straightforward once I understood what I was doing, I'd first attempted the assembly in the wrong order and made life difficult for myself!
So in summary:
1. Getting the pinion preload and backlash right is the easy bit, the tough bit is sorting out the carrier preload. So don't be tempted to assemble the pinion into the banjo before this is sorted.
2. Don't assemble the axles into the carrier until carrier preload is sorted either, taking the axles in and out of the housing repeatedly could damage the seals.
3. Assemble up the carrier without axles and assemble the 2 housings to the banjo with 2 0.009" gaskets. Torque one housing up first to 30 ft lbs and then slowly tighten up the other housing, all the time testing to see if the carrier assembly locks up (you can turn it through the pinion opening). If you get the second housing up tight and the carrier is still very free, then disassemble and use thinner gaskets. Repeat this until you can feel a lightish drag caused by the preload. If you want to be precise then from the literature its seems that about 12 in lbs of drag is what you are looking for. So if you wrap a piece of string around the ring gear, pass if through the oil drain plug and hang a 3 lb weight from it this should just be enough to turn the assembly.
4. A little too much carrier preload is probably better than not enough. On other axle designs prelaod is often about 25 in lbs. Other recomendations for cars of the period often described the drag as feeling 'heavy' when the bare axle was turned by hand.
5. One you have got the total gasket thickness sorted out that gives you the right carrier preload, then the pinion can be fitted and preloaded. One tip is that the lock nut does affect the preload, so its a bit trial and error. The pinion preload should be between 12 and 17 in lbs.
6. Assemble up the whole axle with half the gaskets on each side. Torque up to 30 ft lbs.
7. The pinion backlash should be between 0.006" and 0.010" measured with a dial indicator tangentially on the spline flank. This is, coincidentally, 0.6 to 1.0 degree of backlash at the pinion. If you haven't got a dial indicator, then clamp a 12" long pointer onto the pinion shaft and measure the backlash at the end of the pointer. It should be between 0.130" and 0.217".
8. If the backlash is outside the range then gaskets will have to be moved over from left to right or vice versa. As a guide, for every 0.010" of gasket, the backlash will change by 0.003" as measured at the pinion spline flank, or 0.065" measured at the end of the 12" pointer.
9. If you cannot get the backlash down to tolerance with all the gaskets removed from the right side, then you will need to shim under the right side bearing seats. Whatever thickness you shim under the bearing, remember to add the same thickness of paper gasket to the housing in order to retain the carrier preload.
10. As a final check on preload, the drag measured at the pinion as a result of the carrier preload should have gone up by approx 3 in lbs. For example, if you measured pinion preload as 14 in lb then when it is driving a correctly preloaded carrier this should have gone up to approx. 17 in lb. (this will differ with the gear ratio... based on a 4.11:1 setup).
Hope this is of help. If done in the correct order, then the whole process doesn't take too long at all. My first attempt involved assembling everything together, including the axles and pinion. I then spent a few hours messing about moving gaskets around until I stripped it down again and started again from scratch!
Hope this all helps!
Mike
Thanks to all who helped out with information on the assembly of a '34 Rear Axle.
There is a lot of information available out there in various location, but I thought that a summary of it and my learning may help others.
I actually found the whole process straightforward once I understood what I was doing, I'd first attempted the assembly in the wrong order and made life difficult for myself!
So in summary:
1. Getting the pinion preload and backlash right is the easy bit, the tough bit is sorting out the carrier preload. So don't be tempted to assemble the pinion into the banjo before this is sorted.
2. Don't assemble the axles into the carrier until carrier preload is sorted either, taking the axles in and out of the housing repeatedly could damage the seals.
3. Assemble up the carrier without axles and assemble the 2 housings to the banjo with 2 0.009" gaskets. Torque one housing up first to 30 ft lbs and then slowly tighten up the other housing, all the time testing to see if the carrier assembly locks up (you can turn it through the pinion opening). If you get the second housing up tight and the carrier is still very free, then disassemble and use thinner gaskets. Repeat this until you can feel a lightish drag caused by the preload. If you want to be precise then from the literature its seems that about 12 in lbs of drag is what you are looking for. So if you wrap a piece of string around the ring gear, pass if through the oil drain plug and hang a 3 lb weight from it this should just be enough to turn the assembly.
4. A little too much carrier preload is probably better than not enough. On other axle designs prelaod is often about 25 in lbs. Other recomendations for cars of the period often described the drag as feeling 'heavy' when the bare axle was turned by hand.
5. One you have got the total gasket thickness sorted out that gives you the right carrier preload, then the pinion can be fitted and preloaded. One tip is that the lock nut does affect the preload, so its a bit trial and error. The pinion preload should be between 12 and 17 in lbs.
6. Assemble up the whole axle with half the gaskets on each side. Torque up to 30 ft lbs.
7. The pinion backlash should be between 0.006" and 0.010" measured with a dial indicator tangentially on the spline flank. This is, coincidentally, 0.6 to 1.0 degree of backlash at the pinion. If you haven't got a dial indicator, then clamp a 12" long pointer onto the pinion shaft and measure the backlash at the end of the pointer. It should be between 0.130" and 0.217".
8. If the backlash is outside the range then gaskets will have to be moved over from left to right or vice versa. As a guide, for every 0.010" of gasket, the backlash will change by 0.003" as measured at the pinion spline flank, or 0.065" measured at the end of the 12" pointer.
9. If you cannot get the backlash down to tolerance with all the gaskets removed from the right side, then you will need to shim under the right side bearing seats. Whatever thickness you shim under the bearing, remember to add the same thickness of paper gasket to the housing in order to retain the carrier preload.
10. As a final check on preload, the drag measured at the pinion as a result of the carrier preload should have gone up by approx 3 in lbs. For example, if you measured pinion preload as 14 in lb then when it is driving a correctly preloaded carrier this should have gone up to approx. 17 in lb. (this will differ with the gear ratio... based on a 4.11:1 setup).
Hope this is of help. If done in the correct order, then the whole process doesn't take too long at all. My first attempt involved assembling everything together, including the axles and pinion. I then spent a few hours messing about moving gaskets around until I stripped it down again and started again from scratch!
Hope this all helps!
Mike
