Rear End Housing Assy Question

[RockHillWill]

I would assume that you would want minimal axle shaft end play. What is recommended maximum?

I understand ring gear to pinion back lash, but do not know how it is checked on the Model A rear end. Any ideas? Can someone that has done this figure out a way to equate it as degrees of rotation on the drive shaft while holding the ring gear stationary?

[BRENT in 10-uh-C]

Will, I do not have time to look for a picture at the moment but do you recall us driving up the road a few years ago and me telling you how we have a pipe that we made that we slip over the end of the axle and pull the axle outward during set-up? Later you actually made a drawing and sent to me making sure this is what I meant. That is the way you lock down the ring gear with the necessary preload in the side bearing. Now the diff housing can be installed on the housing and a dial indicator can be used (we don't) where the pinion can be rocked back & forth against the ring gear.

As far as axle end play, we go with anything under .030". In some instances we will find the diff. case is worn but usually new diff. (spider) gears will correct the end play.

.

[Kurt in NJ]

I have some specs for V8 rear in my notes--
backlash between axle gears and diff pinion --.010
clearance between diff pinion gear and spyder shaft -- .005-.008
axle shaft endplay --.003-.006

My brothers rear made with nos and parts not showing wear came out in those ranges of play---barely perceptible play with no binding

--I have not seen ring gear--pinion backlash ever expressed in degrees ----but I don't see why it couldn't be figured

On a V8 the edge of a pinion spline is used, a tab clamped to the driveshaft with vicegrips can be used on the A

[Tom Wesenberg]

I blue the ring gear and look at the pattern of contact and when it's good to go the backlash feels fine. As Kurt mentioned, I've never seen it expressed in degrees, and I just go by feel.

[H. L. Chauvin]

As mentionned above, one can develope a "feel" for the required 0.008" - 0.012" ring gear backlash; however, in terms of rotational degrees, this should equal to about 0.15 degrees of rotation which is a very close degree number to that of the backlash amount.

After trying several materials, I found one of the best materials to accurately show the "exact" centered" pattern of contact on the ring gear between the pinion gear & the ring gear, (on both the drive side & coast side of the ring gear), is to mix about a 1-1/2 ounce mix of a small amount of either white or yellow alkyd paint with axle grease until the grease is close to the color of the paint but still thick like grease.

Then apply one thin coat to both sides of several of the ring gear teeth with a paint brush. Rotate pinion in forward & reverse to check both sides of ring gears.

The pinion/ring gear pattern between the dark ring gear steel & this light colored mix has a high level of contrast on edges of patterns which is very clear & most distinct for achieving the "centered" pattern results between lands & grooves and between toe & heel.

There is no rush in working with this mix because this solution will not dry on the ring gear; & furthermore, it wipes off very easily with a paper towel for trying the pattern after making subsequent pinion gear adjustments to try to obtain the "centered" patterns.

Hope this helps.

[van Dyck]

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From an old Ford Rear Axle Manual
After your pinion bearing preload and depth have been established (preload = 12 to 17 inch pounds) and carrier bearing preload (slight drag felt by hand, before pinion assembly is installed into banjo) assemble rear axle assembly.
Set up dial indicator so that the stem of the DI is tangent to the pinion shaft and in contact with one of the splines. Quote: "Backlash should not exceed the limits of .003" to .008"". FWIW the backlash spec for 32 to 48 ford car and 1/2 tons is .006"to .010".
I hope this is what you need.

[RockHillWill]

Hey guys, thanks for the reponses and the help. I am comfortable about all my readings and setting, but I would just like to be able to quickly read the backlash in terms of drgree(s) because I made a handle to prevent rotation of the driveshaft as I am tightening the lock nuts out of an old universal joint. I made another tool from an old universal joint to adapt to the torque wrench, and after setting both the carrier preload and the pinion preload, it would be very convenient to be able to rotate the driveshaft against a 'fixed position' ring gear and read the backlash in terms of degree(s) at the end of the driveshaft.

All the replies were hepfull, thank you!

I would still be interested if anyone that has set a backlash exactly correct, and then measure it in degrees of rotation. On second thought, if you measured the OD of the pinion, then rotated it around the perimeter by .008", that could be determined to be the angle, correct?

Mr. Chauvin, is that how you arrived at your figure?

Any one have any thoughts on that?

[just plain bill]

Multiply diameter of pinion shaft by 3.1416, divide result by 360 to get rotation in .001 per degree .

Example
Shaft 1.375 x 3.1416 = 4.3197
4.3197 divided by 360 = .01199

So each degree in rotation equals .01199 on this diameter, could/should be rounded off to .012, don't have pinion gear here to measure so these numbers are just an example

[van Dyck]

Would you be using a degree wheel such as engine builders use to properly time a camshaft?
What about the "play"in the coupler connecting the drive shaft and pinion shaft?

[H. L. Chauvin]

1. The helical pinion gear & ring gear should be adjusted to make contact as close as possible to the midpoint between toe & heel of the ring gear & midpoint between lands & grooves of the ring gear on both drive side & coast side of the ring gear; however concentrating on centering the drive side.


2. The diameter (D) of the ring gear's recommended point of contact, (midway between toe & heel) is approximately 7-5/8" = 7.625"; hence the circumference (C) of the point of contact is pi x D & 7.625 x 3.1416 = 23.95"; therefore the point of contact (C) = 23.95".


3. In searching today's gear manufacturer's ring gear backlash settings, one finds many different recommendations; however, an average recommended setting is approximately 0.010" for ring gears covered with auto manufacturer's warranties. I imagined with current technology & ASTM standards, that 0.010" was arrived at with accurate lab testing. Only an opinion.


4. In using 0.010" recommended backlash on a ring gear contact point of (C) = 23.95" where (C) has 360 degrees, 0.010"/23.95" = x/360 degrees; hence, x = approximately 0.15 degrees; hence, measured on a circle where (D) = 7.625" & (C) = 23.95", 0.15 degrees would measure approximately 0.10".


5. If one goes on a CAD drafting program, it would be easy to draft a (D) = 7.625" degree wheel & paste same on something similar to a manila folder, (provided with a centered hole for the drive shaft), & measure the 0.010" backlash & the 0.015 degree movement; or access the banjo lube filling hole with a dial indicator to measure the 0.10" at the center point of ring gear contact; or concoct any other backlash measuring methods using the ring gear or drive shaft.

6. Many just rely on the "feel" method & may find this exact measuring attempt most amusing.

Hope this helps

[RockHillWill]

Thats GOOD info! I will print it. The actual number is pretty small, so maybe my idea wasn't all that good. I amt try to extend that degree figure out over a longer arm and give it a try.

Fitting a dial indicator in the filler hole is a definate possibility as well.

I just wanted to do as good a job as I possibly can and this piece of info was eluding me.

Thanks again for taking the time to respond in that manner.

[columbiA]

I just use the "feel" method for brg preload & backlash & it works for me.

[H. L. Chauvin]

Humble Opinion:

How many modern car auto owners have to order ring & pinion gears today after driving modern cars in excess 150,000 miles?

Nothing wrong in spending time to achieve exact measurements.

Judging on the numbers of Model A ring & pinion gears sold by Model A vendors today, the "guessed at" feel method definitely varied a lot from past feeler to past feelers over the years.

If the U. S. Government ever passed a law that auto manufactirers today had to use the feel method for all differential adjustments on all cars & trucks, no doubt one coulld become a billionaire in a few years by investing in ring & pinion stocks.

Not too many of the millions of today's modern vehicles, (with far more mileage than our vintage vehicles of yesteryear), require ordering & installing new ring & pinion gear replacements.

Not that the feel methods are bad; but, no doubt many individuals have different feelings.

[van Dyck]

Modern crown and pinion gear sets incorporate the Hypoid design. 1928 to 1948 Ford crown and pinion gear sets incorporate the spiral bevel design with the pinion C/L on center with the crown C/L.
Measuring backlash at the pinion shaft is not the same as measuring backlash at the crown gear. It's just simple math: we're talking two vastly different radii. If you measure at the pinion shaft (as Ford engineers recommend), 0.010" is way too excessive. I'm about to set up a 36 Ford gear set and will incorporate the Ford method outlined in their published manual. Just finished setting an 8 3/4" Plymouth, have done numerous 9" Fords for street and oval track and drag racing without a failure. Just saying!
Setting anything by feel is not recommended for the novice:"feel" is acquired as a result of repetition, repetition, repetition doing it the way factory engineers recommend.

[RockHillWill]

van Dyke:

I see your point and I found that to be true when I was looking at that issue today. I did not do this with any sort of dial indicator, but I do believe that a .010" movement on a 2" radius will result in a larger angular change than a .010" movement on a 6" radius. I want to be able to measure this a degree figure at the pinion for that very reason. The same .010" backlash will reveal a larger angular dimension at the pinion shaft than at the ring gear giving a more accurate reading.