Technical 9 inch assembly ?

i am trying to assemble a 9 inch diff with mismatched ring and pinion. first, what is a starting point for the pinion depth and where is it measured. top of the gear teeth or the top of the part that goes into the bearing? i have looked at tools to do this and i figure it is measured from the center line of the bearing yes. second, when i torque the yoke down, with a crush spacer, there is a lot of play up and down of the pinion. so, i put in a solid spacer and with and without a .012 shim , like the books say, and it gets to tight. now the part i don't get is, the crush spacer is .504 and the solid is .429. how can the solid one get to tight but the crush spacer not tighten up at all?

 

The solid spacer is bringing the bearings together more than the sleeve is all that is happening.

 

If you mean the pinion is from one gear set and the ring gear from another,chances are it will be noisy since they are run in as a matching pair at the factory. As for your preload,you haven’t crushed the spacer enough yet. The solid one needs shims added to it if it’s too tight.It may take a few times to get it right.

 

When you say mismatched.. are they from different companies, mix of used and new, both new and just not lining up ?

Ha, Marty Vanin beat me to it.

 

If the ring and pinion are mismatched, and each are used, it will be noisy. Depending on the ratio (whether hunting, semi or non hunting) will also determine if the set needs to be timed, although not being a set it may not matter. With "torquing down" the yoke, are you crushing the sleeve? With pinion play, it doesn't sound like it. It takes a much higher torque to get the sleeve to start to crush. With the gears being mismatched, the + or - markings on the pinion will be of little use, and you will have to assemble it with the correct backlash and check the pattern.

 

If they are mis matched due to different ratios, and you set they up with proper clearance, there is a good chance they will bind up. Setting proper clearance may even be impossible.






Bones

 

Doesn’t matter what depth or preload or backlash if the ring and pinion are not a matched set. It will make a ton of noise!

 

Why?

Used, matched gear sets can be a gamble, if they are not set up exactly right.

Used mismatched gear set probably should be best left as wall art, or car show trophies.

 

Bones makes an excellent point. You don't say why the gears are mismatched, but if an attempt to change the ratio, it will most likely lead to failure. Good example- 3.00, 3.25, 3.55, and 4.33 each use a 39 tooth ring gear. The pinions are 13, 12, 11, and 9 respectively. But the gear pitch may differ on each set, since the gears are face milled.

 

Ah, it'll be fine, they eventually self clearance into each other and make their own mesh pattern. Should we talk regular or synthetic gear oil now

 

Synthetic, mixed with 10% valve lapping compound.

 

They've almost always worked for me. The one set that did make noise had a lot of wear.

are scrap metal prices back up?

 

Mix matched .Give it to these guy's.

 

And yes, we need pictures to verify the insanity of it all.

 

I feel bad for the apprentice, he has to stand there and rotate the three jaw for the welder but he gets no welding helmet and then he gets a face full of grinding grit. At least they have a precision inspector, he gave it the educated finger inspection at 7:32 and pronounced it good. It’s a different world out there.

 

^^^^^ What's truly sad (for the "tech educated") is the day modern civilization becomes screwed if ever our current infer structure ceases.

 

maybe you could write a scifi story about it

 

Pass. There's been so many all ready written.

 

Well, you do know how to set them up exactly right.

I just took a bunch of copper, aluminum, and stainless chips from the CNC mill in to the recycle center, and came back with almost as much as we paid for the stock!

 

you wouldn't say that if you saw the yellow paint They've always been forgiving for me.

 

OK. you all have had your fun. now let me tell you where this set came from. i don't understand why you don't understand what mismatched gear sets mean. i am not saying you are all wrong but what you say doesn't jive with what i know about this set. back around '94 i had several 9" diffs. i mixed and matched ring and pinions to get a 4.11 to 1 match. i put it in my bantam race car. that set has been in it ever since. never any problems. i then matched another set that is the one in this post. 2.74 to 1. it was in my brothers '59 ford truck for about 6 years. never any problems. then my brother scrapped the truck. i got the complete rear end. i put it in my Henry J and drove it for 12 years with no problems. then i wanted it to be faster so i changed it to a 3.90 to 1. now i want to put this set back in my J. let me see if i can answer all they post. i don't know how much more i can torque down the yoke. my impact goes to 230 pounds. how can the solid spacer be pulling the bearings closer when it is thinner than the crush spacer. since the crush spacer is thicker how can it not pull the bearings closer. why is it i can't find out how and where you check the depth. is it some top secret knowledge that is only known to people in the diff setup society. most tell you to check gear pattern but i would like to know this heavily guarded knowledge. please don't simply tell me to buy the tools. i have tried youtube but this pos computer just buffers forever.

 

Then do it the old fashion way and read your pattern and adjust accordingly.

 

The spacer goes between the two pinion bearings, thinner spacer = more preload.

I've put new collapsible spacers in the press before to get them "started" as they seem to be stronger than the oem ones, I've also used second hand collapsible spacers with shims from a solid before when I've need to get a diff done sunday night to get to work monday.

As far as taking a pinion from a 2.75:1 gear set and using it with a ring gear from a 3.89:1 gear set, I've never seen it done and don't see how it could even get a decent mesh

 

The tooth profile would be different.

 

The depth gauge I have used had a magnet the you stick to the end of the pinion and the measurement is taken from that point to the carrier bearing center line.
Most 9 inch will have around .022 shim for the pinion.
Using a depth gauge will only work if the pinion is marked with the depth it was lapped in at when machined.

 

A mismatched gear set means that the two gears in the set don't match each other. At least that's what it means to all of us! If it means something else to you, then you probably shouldn't mention the mismatch part, you're just confusing everyone.

As for pinion spacers...on a 9" if I use a crush sleeve, I put it in the press and crush it part of the way to get it started, then clamp the yoke in a big vise, and use a breaker bar with a pipe on it to tighten the nut until the end play mostly goes away. Then I start checking the preload torque with an inch pound torque wrench. I tighten the nut a small bit at a time (with the yoke back in the vise), and then take it out and check preload torque. After you do this a few times you can get a pretty good feel for how to do it, and it's a quick process.

The solid spacer...you start with it too thick, then put it together and measure end play, then take out just a bit more shim than the end play was, put it together, check preload torque with the inch pound torque wrench, repeat until you get the preload torque right. Again, you'll get to be pretty quick at it after you do it a few times.

Pinion depth on a 9" ford...I've never even attempted to measure. If you took the original gears out of a housing and pinion support, and you kept track of the pinion shim, and the gears were marked with a "+3" or something, and then you put in used gears that are also marked, you can probably get the right pinion shim the first try, by doing the math shown in the Ford shop manual. I just leave the shim in the housing that was there already, and put it together and adjust backlash and check pattern, then if it's off I adjust the pinion shim accordingly, and try again. Then when I'm happy I set the backlash/carrier bearing preload as the manual says, and check the pattern again.

 

In my perception here, there would be two different classes of mismatched gears.

The first wold be, for an example, a ring and a pinion, each from a different 3.73:1 gear set.

The other would be a ring and a pinion from different ratio sets.

 

Let me see if I can level this out.

It has been mentioned that "Good example- 3.00, 3.25, 3.55, and 4.33 each use a 39 tooth ring gear. The pinions are 13, 12, 11, and 9 respectively." *I did not check these numbers, but let's assume they are correct for example sake.

If you look at the ring gear from each of these sets you will see that they are respectively marked:

39-9
39-11
39-12
39-13

I believe that if you placed those ring gears in that same order across a table, and gave a quick look, you would quickly see why they are different.

Since they all have the same tooth count on the ring gear, the ring gears all have the same inner and outer diameter, and the pinion location is in the same place on every 9-inch housing (that I know of),

Those dimensions that I just called out dictate the profile of the teeth on the ring gear. So yes, they should be all the same on the ring gear.

Now, you cannot put 9, 11,12, or 13 teeth of the same pitch around the same dimension cone section, and have them meet and mesh with the ring gear. In order to preserve tooth pitch of both the ring gear, and the pinion gear, something has to give.

A 9-tooth pinion gear at the low extreme, and a 13-tooth pinion gear have two very different diameters.


*These are a 3.00:1 and a 6.50:1 sets, respectively, to exaggerate the differences between dimensions.

So what does actually give?

The ring gear thickness.

Since the Ford 9-inch carrier does not have a carrier ratio break, where the mounting flange on the carrier is in a different place for different ratio ranges, the ring gear has to be a different thickness for different ratios, to accommodate the differing diameter of the pinion gears.

More teeth on the pinion, bigger cone diameters, thinner ring gear.


Fewer teeth on the pinion, smaller cone diameters, thicker ring gear.



It might, and it is a big might be able to turn the adjusters to shift the entire carrier with the ring gear on it to catch the teeth on a smaller pinion, or correspondingly move it away from a larger one.

I do not see any way that one could get a proper, as-intended tooth engagement with a set that is mismatched by ratio. The teeth might catch, and it might go down the road, but it would be about as far from ideal as one could get, and still be moving.

I have never even considered it, as that would anger the Gods of Speed, and it is not worth making the sacrifice for $180 for a new set.

 

^^^^^ Basic out line

 

@gimpyshotrods, wouldn't the angle of the teeth be at different angles also, along with the different thickness of the ring gear? Asking because I'm not sure...