Intermediate Shaft Al Gear Chamfering

[HaroldMHedge]

Ordered a new intermediate shaft gear due to pitting on the old one found during rebuild. The new gear 930-105-136-00 (0) does not have the ends of the teeth chamfered.

Old Gear



New Gear



I noted that the old gear end face seems to be machined and the new one is smooth. On the new gear I do not feel any burrs. By gear end face, I mean the face with the gear code 0.

Looking at Pelican's new gears it appears some are chamfered and other are not.

Is the difference something that I should be concerned about?

[Walt Fricke]

Interesting. That aluminum gear isn't going to wear the steel crank gear, so that wouldn't be a problem

[stownsen914]

I'd rather see the chamfering, but I don't know how much it matters.

[OCG911T]

I am not a Porsche engine building expert like a lot of the guys on here, bu I wouldn't worry about it. The gears shouldn't move fore and aft and as Walt mentioned the aluminum intermediate gear will slightly wear-in with the steel crank gear, if anything wears at all. I would bet the de-burring process the manufacturer uses is to blame for the more aggressive chamfer on some of the gears versus your new gear. The winch and reduction gears aboard ships that I am used to that are anywhere from 1' to 6' (plus many that are even bigger!) in diameter are chamfered only as much as that first picture, if at all, and we do not have any issues as a result. As long as you are using the same size gears and they are lubricated during use you should be fine. The slight wearing of the gears and bearings and degradation of motor oil over time is the reason we all perform oil changes and use nice oil filters on our rigs, as I know you are aware... any wear of that aluminum gear will get passed through the system and caught in your filter and will be disposed of on your first oil change.

[HaroldMHedge]

Originally Posted by stownsen914

I'd rather see the chamfering, but I don't know how much it matters.

Agreed. What I've found would seem to indicate that chamfering should be done.

Gearing Up to a Better Chamfering and Deburring Process

[OCG911T]

Great article... I can now understand the benefit, as far as protecting the contact surfaces from chips or dents on the edge. What are you going to do? Get new gear or try your hand at chamfering with a small file?

[HaroldMHedge]

OCG911T,

I spoke with the supplier and it appears that new gears are not being chamfered so I'm going to do it myself. I have some new Dremel tools, aluminum bar stock and a couple of old gears to practice on.

[stownsen914]

Originally Posted by HaroldMHedge

OCG911T,

I spoke with the supplier and it appears that new gears are not being chamfered so I'm going to do it myself. I have some new Dremel tools, aluminum bar stock and a couple of old gears to practice on.

Just be careful. It'll be easy to slip and mar one of the gear faces, and do more damage than good.

[gsxrken]

Looks more like a deburring than a chamfering to me... obviously skipped for operational savings. As my nearby neighbor in Ossining suggested, I’d go slow, and completely manually. Aluminum is ease to gouge.

Intermediate gears can be the source of some tapping noises... I’ll post this just in case you haven’t come across it from the '84-'87 911/ 930 Tech Spec book:

[HaroldMHedge]

Originally Posted by stownsen914

Just be careful. It'll be easy to slip and mar one of the gear faces, and do more damage than good.

Thought about this overnight and will be checking with the local machine shops to see if they can do the work. Maybe one has a machine like this: Redin gear deburr chamfer: deburring transmission gear

Ken,

Thanks for your guidance and reference.

[reclino]

The only shops that are going to be set up with that type of machine are shops that typically cut gears, it's unlikely your going to find that. The non directional finish on the end of the new gear looks to me like it was blanchard ground. Take a look at the edges with a 30x loupe and if you can't see any burrs I would leave it well enough alone. It's an aluminum gear, so even if it gets loaded out at the tips, the metal will just naturally wear away. I think the function of a heavy chamfer is for hard steel on steel gears where the edges of the gear teeth may chip off causing problems if that chip gets back between meshing gears or bearings.
I like getting OCD more than most, but I really don't see that spending money on this has any return on investment.

[HaroldMHedge]

Reclino,

You have some very good information. I did check around at various machine shops. Most here would not work on it or wanted to make a brand new gear.

Speaking with my old mechanic at Black Forest in San Diego, they said the that they are not having any problems with new gears without the deburr/chamfer.

Being OCD myself, I found an acceptable gear that has a deburr/chamfer.

Thanks to all for your help.

[r lane]

As quality and detail specifics to the products being manufactured is receding, I am frequently looking for used pieces that measure out properly that were manufactured before China was able to turn this game upside down. A very unsettling proposition. All I know is the car market, I can't imagine what is happening in the thousands of other areas of manufacture.