Matching Ring and Pinion

Bill Goddard

Bill Goddard

Well-known member
I need a new ring and pinion set and I have aquired a NEW 34t ring gear but not a matching pinion. I have also found a good condition 9t pinion to make the ratio 3.78:1. How important is it that the ring and pinion be a "matched set"? The original matched set failed. Wouldn't the pair I've put together wear in after a few miles? Thanks for your help Bill G
 
So far I have had 27 views of my question about ring and pinion gear match and no replys. Should I assume from this that no one has any strong feelings and the "match" is an old wives' tale? Thanks Bill G
 
Bill Goddard said:
So far I have had 27 views of my question about ring and pinion gear match and no replys. Should I assume from this that no one has any strong feelings and the "match" is an old wives' tale? Thanks Bill G
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Assume? We all know where that gets you. If you post something in the early AM and have no response a few hours later it probably means you are a bit impatient. Or am I assuming????
 
Bill...One of the final job when making the R/P sets, after heat treat, is lapping the
gears in. They put the gears in a machine and use lapping compound running the 2 gears together. That is why the are called" a match set ". Don't do it , you won't be happy.
Dudley
 
d.j. moordigian said:
BTW....Ford sold gears in sets, not each. Also there should be numbers stamped
on the gears that MATCH each other.
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Hummm, while that might be true in some instances, I actually
have found the opposite as evidenced in the photo below of
a Ford Garage Parts Dept loaded with 'T' parts. Something else
is to verify part numbers A-4209 and A-4215.

Also, when I had no alternatives, I have mixed and matched
parts rebuilding at least three rear axle assemblies (one at the
MARC Nat'ls in Jacksonville, and twice for participants in the
GreatRace) where we were desperate to get back on the road
and used whatever was available. In all instances, the plan was
just to make it to the end and we would properly rebuild them.
The one that was done using used swap meet parts in Jacksonville
is still on the road and as quiet as a mouse. The ones that were
rebuilt in the hotel parking lot all did well too. I think THAT is the
main reason why Ford used such a heavy grease.

Bill, I am of the opinion that I would never 'mix & match' gear
sets while restoring a customer's car simply because it goes
against what seems proper however if you are in a bind and are
willing to take a chance, then go for it. It may surprise you. I
know it has to me on several occasions.


29358u.jpg
 
I have sold several used gears to people in the take a chance position. Seems to be mainly the people that want 4.11:1 at a much cheaper price than the new sets bring. Have several ring gears on the wall of the parts barn as it seems mainly the pinions I find are bad. I would not have a problem playing the mix and match game with them on my own car, but did buy a new set of 3.54:1 for the delivery til I can afford the OD. Rod
 
Rowdy said:
I have sold several used gears to people in the take a chance position. Seems to be mainly the people that want 4.11:1 at a much cheaper price than the new sets bring. Have several ring gears on the wall of the parts barn as it seems mainly the pinions I find are bad. I would not have a problem playing the mix and match game with them on my own car, but did buy a new set of 3.54:1 for the delivery til I can afford the OD. Rod
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Wow, comparing the 9-34 pinion to the 9-37 pinion, there is a definite difference in the pitch angle of the teeth. I am surprised the 9-34 pinion actually works satisfactorily on the 37 teeth ring gears without trying to climb the ring gear teeth.
 
I did not mean mix and match in that way. I meant from different rearends, not being a matched set that had ran together. As you mentioned the pitch is way too different. BTW, did you get my e-mail last week on the back panel. may give you a call to further discuss it. Rod
 
Brent...Yes, I know about the T gears, just doing the apples for apples thing. I just
don't want to give that kind of advice that may come back and bite the customer or
myself in the ***.
Some hotel in Ontario Ca. probable still smells of GL-90 after a trans o/h on the bed
before a 500 miler.
Necessity is the Mother of Butchery......Dudley
 
Brent, You bring up something I hadn't thought about. Are the teeth profiles (P.D, etc) of the 9t pinion the same for the 37t and 34t ring gears.. If not, is there a practical way to know which 9t pinion you have. Bill G
 
d.j. moordigian said:
Bill...One of the final job when making the R/P sets, after heat treat, is lapping the
gears in. They put the gears in a machine and use lapping compound running the 2 gears together. That is why the are called" a match set ". Don't do it , you won't be happy.
Dudley
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Having been responsible for the purchase of Axle components for Ford Motor in my recent past assignment, I can tell you that this statement is accurate. Ring and Pinion gear sets are machined independently and brought together for a "run in" period using an abrasive lapping compound. The objective is to smooth out any roughness on the surface finish and to mate the "highs and lows" of the two components together. After lapping, they will remain a matched pair.

I will say, however, that the tolerances and gear profile design of the Model A ring and pinion are not nearly as precise as they are today. I suspect that is why people can take a chance on a mixed set and not have problems. But consider if the installed alignment of the ring and pinion was such that the wear pattern was close to the inboard center on one set and outboard on another. I believe there might be some serious noise issues for a mixed set with these parameters. So that is why you may be taking a chance on success.

Another interesting Factoid for those want to know more...Many of the European manufacturer designed ring and pinion gear sets are not lapped. They are first machined to size/profile using standard machining processes and then they are "ground" to final profile using thin grinding wheels in machining centers. Because this process is so carefully controlled, the profiles and critical dimensions are very consistent and repeatable. These gear sets do not have to be matched at all. If you think, "Why then don't all of the OEM's used ground gearsets?" there are some downsides to this approach. One is cost - obviously more expensive - not a lot, but more expensive. Another, however, is the potential for the gearset to be so precise that it actually begins to ring like a bell when installed. Axle manufacturers that use lapping claim that their gearset is a "softer" fit and will be, therefore, more quiet. The debate still rages on...
 
Follow the money. If a manufacturer didn't need to lap the gears and serial number them why would they? Can you get away with it if you are lucky, of course.

Charlie Stephens
 
Bill i have some new 9 tooth pinninos here in NZ ,purchased them last time in the states if that helps, Only once did we have a noise problem with miss matched used Ring & Pinnion. The owner had heard that if he lightly blasted them they would wear in, wrong. I beleive new to new would stand a very good chance of not being noisy, Going to Vancover meet, Could deliver. Derek.
 
THAT is why 600 weight gear lube cures all the funny noises!!
ROFL.gif



Although I have never used it on rear end gears, I do believe Timesaver lapping compound would likely work really well on lapping in two mismatched gear sets. I use it on other things and find it works very well.

My experience with R&P on Model A's is that they are fairly soft too, --which allows them to work themselves in and get "friendly with each other" as a former Fordbarner used to say.
 
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Although it is not right,I have done it probably dozens of times over the years when there was no money to fix it right.I have only had a couple of them talk back to me after.It has mostly been on trucks,but quite a few cars also.When working with old junk you tend to set things up a little more carefully.I have done it in a lot of 44,000 pound Rockwell rear ends,just to get a couple of loads done or make enough money to fix it right.I'm not sure if any of those guys came back to get them fixed right.A couple of them were singers,but those were the ones I fully expected it from.A worn out pinion and a worn out ring gear can not be made to perform as expected.I have had a bunch of A rear ends that were put together that way that I bought from some older fellows.They were all fine.A man I used to work for maintained Model A;s for the millworkers for years.The driveways for the mills were steep,and when they came out they would be spinning the tires.When they hit the salted main road they would sometimes snap a tooth off either the pinion or the ring gear.He would put in what they needed,not a matched pair the proper way.I have to say that the results have been in my favor a good 95% of the time.
 
forever4 said:
I am really curious about the results when you do try it. I wonder how the timesaver distinguishes the gear set interfaces from the roller bearing and race interfaces? Personally I would not do it myself, being the skeptic, but am interested in the results of others.
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For me personally, it has more to do with the way we apply it. We mix it up with oil into a paste and I smear it on with my fingers. If you let it set in your cup too long, the gritty-ness goes away so I guess it is soluabl and dissentegrates.

If you have not read all of this, THIS may answer some of your questions. I, like you was skeptical of the stuff until a few years ago I was on a Model T tour and lost a connecting rod on a freshly rebuilt engine. My crank journal had been turned to something like .015" undersized and all I had availble to be was a .020" under rod. Someone on the tour recommended Timesaver, and I was so upset I was willing to try anything. I spend several hours scraping and fitting the rod, and once back together it did remarkably well. I saw the journal once the engine had been torn down and I could not detect any scratches or etc. with a naked eye. I am pretty fond of it on certain things
 
I think I have acquired a used matched pinion and gear set 9/34 ratio from a local collector. The teeth have mirror smooth surfaces with no skratches or chips. I am waiting for a phone call to confirm my find. Thanks for everyone who replied , I needed your input to sort this out. Bill G
 
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