Ring gear clearance question

[Reno Speedster]

I am building the rear end for my 26 speedster and i am measuring the gear lash. All the gears are new as are the thrust bushings and the axles. I am using a modern drive shaft spindle setup with the roller thrust and shims. The ring gear is torqued down, no burrs on the differential housing. I have been using the club book on building the rear end. I set the lash to .012 but when I rotate the ring gear I get some variation in lash, with about .0085-009 being the tightest but also .01 and .011. Should I use a smaller shim behind the drive shaft gear to get a little more clearance or is this good enough?

[Mark Chaffin]

Consider adding one spool gasket 2583G with aviation Permatex. You'll be glad you did.

[Reno Speedster]

Thanks Mark. Is that for the spacing, to prevent leaks, or both? I could do the adjustment with the shim set.

[RGould1910]

You always have variation in lash. Yours is better than most but a bit more clearance wouldnt hurt. T rear ends run best with about .015" lash imho.

[Allan]

Morgan, it looks like you not have the pinion gear meshing for the entire width of the teeth with the ring gear. This should be the first step. Then mess with the backlash if needed. That may well be how it was done in the hurly- burly of the production line, but it is not the best way to do it. Backlash is not the whole answer. With the correct rolling fit with the gear teeth, the backlash is then what it is.

If you can get hold of a copy of Tinkerin' Tips 2, you will find all you need to set your gears for best results.

Hope this helps,
Allan from down under.

[Reno Speedster]

Thanks Allan,
Here is a better shot of the gear alignment. It looks pretty good to me and If I run the pinion in farther the lash decreases to between .003 and .005, which is too tight. Once I get a decent lash, I will use some Prussian blue to check gear engagement to be sure I am gettin engagement across the ring gear.

The steel and bronze thrust washers are within speck, but if needed, I could take some off of the bronze washer. I need to do it on the right one anyway.

As with many things on the T, there is a lot of fiddling to get things right.

[Dan McEachern]

Move the pinion in and out until you get a good tooth bearing pattern. You do not want the contact at the toe of the teeth- more to the heel should be your goal. Then move the ring gear in and out to adjust the backlash. You do not want less than about .010 backlash. From your picture my guess is your pinion is too deep, causing the bearing on the toe that you are seeing.

[Allan]

That's a better angle Morgan. You do have room to withdraw the pinion a little. Setting backlash as the way to go is not necessarily the best way to achieve the best gear mesh. Once the depth of mesh is done, the correct mesh across the gear teeth is achieved by moving the ring gear. This means you have to move the diff centre within the housing. This is done by shuffling steel discs and bronze washers from one side to the other.

If your blue shows contact at the outer end of the ring gear teeth, you have too much backlash, so the ring gear needs to be moved towards the pinion.
Contact on the inner end means too little backlash and the ring gear needs to be moved away.

Once you have the gears engaged across the whole face of the teeth, the blue will show this. If that contact is right at the toe of the teeth, then you move the pinion back towards the ring gear. If it is at the bottom of the ring gear teeth, the pinion needs to be moved forward. The best result is when the contact is almost full face on the teeth.

When I build a rear axle assembly, I go through my collection of steel discs to find four with the maximunm variation in thickness. Likewise when tackling the bronze thrust washers, I like to have one some .010 - .012" thicker than the other. That way you can just juggle that 6 piece stack until you get the ring gear in the best place.

It is interesting then to measure the backlash you end up with. The backlash you have is the backlash needed for the best mesh of that set of gears.
All this is detailed in Tinkerin Tips 2.

Allan from down under.

[Jerry VanOoteghem]

Morgan, it looks like you not have the pinion gear meshing for the entire width of the teeth with the ring gear. This should be the first step. Then mess with the backlash if needed. That may well be how it was done in the hurly- burly of the production line, but it is not the best way to do it. Backlash is not the whole answer. With the correct rolling fit with the gear teeth, the backlash is then what it is.

If you can get hold of a copy of Tinkerin' Tips 2, you will find all you need to set your gears for best results.

Hope this helps,
Allan from down under.

YES!!! 100% Correct!

Set the gears for a good rolling fit and good contact area and lash will take care of itself. Do NOT set the lash, set the contact area.

[Reno Speedster]

Thanks guys. It looks like I have been using the wrong book. I think I have a copy of Tinkering Tips 2, but I didn’t know it was the one to use. Time to find it.

[TRDxB2]

Thanks guys. It looks like I have been using the wrong book. I think I have a copy of Tinkering Tips 2, but I didn’t know it was the one to use. Time to find it.

Here you go
In Canada https://www.blueovalclassics.ca/lifesty ... ustrations

Below https://www.amazon.com/tinkerin-Tips-re ... B001U9XEBC

[Reno Speedster]

With a little adjustment this is what I have. Looks pretty even and centered, though it’s a bit hard to see. I still am getting some variation in lash on different quadrants of the ring gear (about .003 high to low). I have about .012 lash at the max, and about .009 at the min. I am going to thin down a bronze thrust washer a few thousandths and see if I can increase the lash.

[RajoRacer]

Run a small piece of copy paper through & check the pattern.

[speedytinc]

Run a small piece of copy paper through & check the pattern.

You should see an even fold across the tooth. The fold should be sharp but not cut the paper or bind the movement.
Contact with the bluing looks good. Spin the drive shaft. You should not feel any dragging spots.
A note of caution. Your drive shaft must be perfectly supported in a neutral position. If not, your actual lash will be off.
I like installing a radius rod to be sure.

[Mark Chaffin]

The gasket and Permatex will help reduce leaking and alow a bit more clearance.

[Reno Speedster]

By fiddling with the spacers I was able to get between .011 and .015 lash. It spins freely all the way around. When I ran a strip of paper through the gears it didn’t bind up, though it took out all the lash. I don’t want to open it up too much more. Next step is to get the spacing sorted between the axle housings.

[Jerry VanOoteghem]

With a little adjustment this is what I have. Looks pretty even and centered, though it’s a bit hard to see. I still am getting some variation in lash on different quadrants of the ring gear (about .003 high to low). I have about .012 lash at the max, and about .009 at the min. I am going to thin down a bronze thrust washer a few thousandths and see if I can increase the lash.

That looks very good. Variation in lash is normal. Don't be concerned by it unless there is actual binding.

[Allan]

Morgan, put the right housing, two steel discs and bronze thrust washer in place and an lightly run up three of the bolts. If you then measure the gap between the two housing flanges, that will give you a guide as to how much you need to take off the bronze thrust.

Allan from down under.

[Jerry VanOoteghem]

Morgan, put the right housing, two steel discs and bronze thrust washer in place and an lightly run up three of the bolts. If you then measure the gap between the two housing flanges, that will give you a guide as to how much you need to take off the bronze thrust.

Allan from down under.

Excellent. I usually do this trial fit by placing spacers/shims between the 2 housings. I adjust the shims until just minimal side play is felt, then note the thickness of the shims and take that much off of the 2nd bronze washer. Essentially what Allan has stated.

[Mark Nunn]

I followed Allan's advice four years ago when I rebuilt my rear axle. It worked perfectly for me. I had a stack of steel disks that I measured and marked each with its thickness with a sharpie. Then I selected disks for the left side starting with the thinnest and swapped disks as needed. That was the easiest way for me to get the best setting.

[Reno Speedster]

Unfortunately, I don’t have a stack of disks to work with. But, I do have a mill and a lathe, so I will get there in the end. I used feeler gauges and shim stock figure out the the spacing and from my measurements I need to take .019 off of the right bronze disk and I will be good.

[Craig Leach]

I have a small piece of a right housing that I bolt to the left of the rear end I'm working on that helps align the drive shaft to the left housing.
One other issue I had was the ends & bore of the tapered bearing housing were not concentric so you could change the clearance by rotating
the spool in the housing.
Craig.