Glen McCartney

I have a used auto 13/33 - 2.54 ring and pinion gear set that I am selling.
I had Steve Cattanneo try to install and he never got it in when he rebuilt my transmission. He said he wasn't happy with the mesh, no really sure why.

On the ring gear, there is a stamped number 160090 may be serial number and then two engraved numbers 5981 and F0.18

On the pinion gear, there is a stamped number 160090 and engraved number is either 7078 of F078.

The manual shows different information on the numbers on the gears.
$350 OBO plus shipping.

Pics

slate blue

Hi Glen,

You don't mention the milage on this set, do you know the history of these gears?

Thanks in advance

Glen McCartney

I think they came out of an'89, don't know the mileage. I bought them from Jaeger years ago. There doesn't look like much wear at all. Tried to take a closeup picture, probably doesn't show well -

Vilhuer

5981 and 7078 are pairing numbers. For gear pair to be usable number should be same. These are from two different transmissions. Factory process was to run each gear pair in bench to find out best position to run them. F0.18 is this backslash position for ring gear. Or it was when it was new. When puting these two into one transmission its impossible to know how to set them up using factory method. Best option would be to try to find their correct pairs.

Tony

Perhaps google "5981" or "7078" good luck with that Glen

Randy V

Sounds like you have a nice set of book-ends there, Glen.

GregBBRD

!00% correct.

Non matched pair of gears.

xschop

Good pic too, I've always wondered how many splines are on the auto pinion shaft. Looks like 27.

KenRudd

Actually very cool nugget of information, thanks!

Are there any good write ups on actually changing out a ring/pinion set assuming a matching pair could be found? A quick search turned up bupkus, but worth asking. I realize setting mesh/backlash/etc is not for the faint of heart or impatient. I see section 39-11 in WSM, but RL write ups tend to be more user friendly...

{Edit} Further reading of the WSM procedure is rather intimidating.
{Edit +Edit}Now that I gave some thought to proper search terms, found lots more information here.

Glen McCartney

Ahhh, OK, I bet someone who was supposed to install this for me, who had my car for 2 months over a winter 5 years ago, mixed up the ring gears with gears he had and that's why he couldn't get the mesh right. I know the numbers matched when I brought the set to him. The ring gears have the same number of teeth (2.20 or 2.54).

Ok got some wall art to hang in the garage.

danglerb

Would that be the head of the person who was supposed to swap the gears?

I would be tempted to visit them and see if they have the correct gear.

Glen McCartney

It may be.
Shop is no longer in business, wonder why and he was a MB specialist......

BC

What would happen if someone used an unmatched set. Is it disastrous or just not best practices?

GregBBRD

You'd have to get really lucky to have them work together. Most likely they would be really noisy and wear very rapidly.

The different gears are more than just two gears that happen to work good together and are matched as a pair. They are actually lapped together on some sort of a machine that allows the pinion to be moved back and forth (changing pinion depth) and the ring gear to be moved in and out (changing backlash.) Once the "sweet spot" is found, they are then lapped together and the numbers for correct pinion depth and correct backlash are etched into the pinion and the ring gear.

I believe that this "matching" happens before heat treating....or at least before they get their final heat treat (my crankshafts get heat treated 3 separate times.....so I'm assuming that ring and pinions might also get multiple heat treatments.) The reason I believe this is that the pinion depth number and the backlash number seem to be put onto the gear, with a simple electric pencil. Trying to make a mark in the gears, once we get them, with an electric pencil is a joke....they are way too hard to mark them with much of anything.

When I was actively doing G-50 gearboxes for the 993 race cars, we were getting some very high quality ring and pinions that were not matched together. Apparently, with really high end CNC machinery, it is possible to make ring gears and pinions that all work with each other. These things would come in a big box and you'd just reach in, grab one of each, and go assemble the transmission....getting virtually perfect patterns, every time. Pretty amazing.