Rear End Backlash Rated G for general audences...I promise

[Ed Saniewski]

I am in the process of assembling 2 rears, one a standard 3:78 rear that will go in my 160B with a 4 speed O.D. transmission. The other is a 3:54 that I will put in my 29' CCPU. The question I have is I was able to get the backlash to come out great in the 3:78 rear, but there seems to be a lot more "slop" or play in pinion to ring gear of the 3:54 rear. A friend that was helping thinks that it is because of the space between the gears. He feels the 600 wt. oil will make up the difference. When we put the marking grease on the gears it looks O.K. but you can feel a little more play in the gears then the 3:78.
Has anyone else found more play in the high speed rear then a standard rear? Dose this make any sense??? Thanks, Ed Saniewski

[Hicktick]

If you have a matched gear set , the gear ratio has no effect on backlash .

[1931 flamingo]

Is not the backlash "controlled' by the gaskets used on each side of the banjo?? Brent in Tenn has mentioned that he's come across warped bells that he's had to resurface.
Is the pinion sitting where it's supposed to be??
Is it a "matched" ring and pinion??
Others will chime in I'm sure.
Paul in CT

[larrys40]

Ed,

Typically the repro 3:54 sets in my experience have been very good. Once your carrier preload is determined you should be able to get your lash adjusted. I would make sure your double pinion race is seated in all the way, and that there aren't any issues with the housing mating surfaces that would cause any issues. It could be a faulty set... who knows.. but I would check all the details and other things first. Remember you have to move gaskets to get your lash ( I assume you're already doing that), and it may be you have no gaskets on one side with whatever the distance ( thickness) of gasket (s) are on the other. A think RTV is good. I have had some I've had to do with no gaskets and only a skim coat of rtv.

As I tell folks with multiple Model A's and they all want them to run the same.. they are like kids.... as much as you want them all to be the same or "behave" the same, they do not. They individuals and are all different. Rear axles, transmissions, engines.. etc
Keep us posted for an update. Would love to know outcome on this. that's how we all learn.
Thanks Ed for sharing your problem.
Larry Shepard
St. Charles, MO

[pat in Santa Cruz]

if you have an early 29 housing, the bearing clearance was too great to get proper pre load while still using a gasket. So Ford altered the housings in order to tighten up the clearance. There are spacers made that go behind the carrier bearings to tighten the clearance if you have the early housing

See Marcos page on this and 3:54 gear specifically:

http://www.abarnyard.com/workshop/rearend.htm

[Ed Saniewski]

Sponsored Links (Register now to hide all advertisements)

Thanks for the replies. It is strange that we have almost all the gaskets on one side of the banjo. I will try moving the last one over to the other side so all the gaskets are on one side and see if that sets right. My friend that was helping wondered if there was any adjustment for the pinion gear depth, but it seems to be set tight. I am not sure what year the axle housing is, I got it from a guy in my club to make a spare rear.

[pat in Santa Cruz]

you could have an early 29 housing on one side, thus the gaskets all on the opposite side. Measuring the depth of the race seat and comparing it to the blueprint on Marco's page will tell you that. Placing a shim on the carrier bearing which is on the less gaskets side will change all that and it will increase the total thickness of gaskets required as well. Most parts suppliers sell shims for this purpose. Additionally, if the bearings have spun on the carrier, the shoulders of the carrier can be worn, requiring a shim to set the bearing back closer to its original location. You were lucky with your first axle. Its not uncommon on these old parts to have to assemble, breakdown, then re assemble a differential several times before you get it. Not difficult to understand, but physically tedious nonetheless. The pinion depth does not adjust, just the pre load.

BTW, If you have not read Tom Endys treatise on axles, its worth a look.
http://www.ocmafc.org/techarticles/T...0Re-Edited.pdf

[1930artdeco]

I just read Marco's page about the bearings. He mentions to not chase the housing bolt threads. And that if they can screw in by hand then not to use them. Do they make larger bolts or do you use RTV to seal them up.

Mike

[Ed Saniewski]

I don't think the axles are early type, I decided to take every thing apart and start over again. When I assemble the rear without any gaskets the ring gear will not turn. I started adding gaskets and now have it so the gear will move with some resistance. This time I am using less gaskets. I think I had too much gasket the last time. I reset the pinion gear and white greased the gears and reassembled everything.Tonight I will start checking for backlash and moving gaskets.

[Tom Endy]

Reproduction ring & pinion gear sets, such as the 3.54 you are trying to set up are often found machined incorrectly. The pinion sleeve where the two bearings mount should be machined to two different diminsions as were the originals. The dimension nearest the gear should be such that the bearing mounts with an interference press fit. The area where the second bearing mounts should be a nominal .0015 smaller. This allows the second bearing to slide on with very little pressure. This is important as the second bearing is where you set the pre-load on both pinion bearings.

I had a conversation with Walt Bratton a number of years ago and he advised that he and Snyder's are aware of this requirement and the R&P sets they sell are machined in this manner. That is true. However, whoever is doing the maching for them does not always get the first dimension correct. It is sometimes more of a press fit than needed. The second dimension being .0015 less is still a press fit. With both bearings a press fit it is almost impossible to set the proper pre-load.

When dealing with a reproduction R&P the first thing I do is run my finger nail over the center of the sleeve to see if there are two dimensions there. I then attempt to press the first bearing onto the pinion and if I hear and feel that familiar "crunching" sound of interference as the first bearing passes the area where the second bearing will install I stop and remove the bearing. I have a tool made from the tapered end of a discarded rear axle. It allows the pinion to be chucked up in a lathe or drill press for machining. Often all that is needed is the application of emery paper where the second bearing installs.

If you not able to slide the second bearing into place and easily set the pre-load you can end up with thrust clearance and it will affect the backlash as the bearings are not properly seated.

Tom Endy

[pat in Santa Cruz]

Originally Posted by 1930artdeco

I just read Marco's page about the bearings. He mentions to not chase the housing bolt threads. And that if they can screw in by hand then not to use them. Do they make larger bolts or do you use RTV to seal them up.

Mike

we had a bunch of original bolts cad plated, which made them tight, even in a bore with loose threads.

If I had none, and facing the situation you describe, I would clean the threads of all grease and oil and use loctite on the final assembly. Then check it regularly to see if it holds. I have not tried this, as I have access to tighter bolts, its just a thought about what I would try in a pinch like you describe. RTV tends to soften in long term oily situations.

[Ed Saniewski]

Tom you are right on the money. One of the ring and pinion came from Mikes and I had my machinist cut down the pinion sleeve so the second bearing would slide on. The other set came from Walt Bratton and that was dead on the correct size to fit the bearing.

[western77]

Remember the pinion can also be shimmed in toward the center of the banjo. By doing this you also tighten up the backlash. Make sure to check the fit with dye after doing this. I have used up to .020 shim on some repro gears before. JB

[Ed Saniewski]

How do you shim the Pinion?

[JBill]

This thread might have started rated "PG," but it got to "R" real fast!

[Milton]

Originally Posted by Ed Saniewski

How do you shim the Pinion?

By placing a round shim on the pinion shaft before the bearings. This will move the bearings away from the pinion gear which allows the pinion to mesh deeper in the ring. To move the other way place a shim in the banjo before the double bearing cone. This will cause the pinion to mesh towards the out edge of the ring.

I just received a 3.78 ring & pinion from Mike's and the pinion gear diameter is the same from one end to the other. It is still better than what I have though, and the difference in price will still make it a deal.

[Ed Saniewski]

After taking every thing apart, I discovered that with just the pinion installed in the banjo it dose not turn smoothly. There is a bump or gap feeling when I turn the drive shaft back and forth. I removed the upper bearing and found it was out of round. I checked the lower bearing and it seems round. So, I reinstalled the pinion with a new upper bearing and have the same loose feeling after I torqued the nuts. I will take it apart this weekend and press off the lower bearing and replace it also. The only thing I can think of is I did not have the drive shaft straight when I tightened the nuts.

[western77]

When you say ' I torqued the nuts' are you referring to the pionion adjusting nuts? If so, you don't torque them. They are used to add preload to the bearings and the driveshaft is checked with a torque wrench for rotational torque in inch pounds. If you get the preload to tight, loosen the adjusting nut and rap the end of the driveshaft to drawback the bearing and check the torque again. The two bearings keep the driveshaft straight so don't worry about that.JB

[Ed Saniewski]

Western, I tourqued them to 20 inch pounds with an inch pound wrench. I got the other bearing of and will try again this weekend. Thanks, Ed Saniewski

[Milton]

Originally Posted by Ed Saniewski

I tourqued them to 20 inch pounds with an inch pound wrench.

Like Western said, you don't torque the nuts. You tighten the nuts until the pinion requires 20 in/lbs to rotate. Then you lock them against each other while maintaining the 20 in/lbs rotational resistance. Then bend the tabs on the washer that goes between the nuts. One tab per each nut.

Use the toque wrench on the drive shaft or the pinion nut to measure the preload.