Mirror Finished gear teeth.

[redwraith94]

Awhile back, before the forums crashed a member suggested to me that mirror finishing the gear teeth on the trans may improve efficiency. After doing some research online. I found articles from universities, and such that claim the same thing. I eventually want to have car dynoed, but for now it is being reassembled.

Here are some long overdue pictures of the ring gear, and the quaife, that I polished:









I will try to add a write up in a couple of days as to how I did it, if you guys are interested.

 

[Kens1992mtxSHO]

wow... shiny.

looks good. Keep us posted on how it's working out for you once installed.

 

[hawkeye18]

Common sense says that the smoother two parts that touch each other are, the less energy will be lost to friction... looks good! I can't wait to see the results! Looks like we might have to revise the transmission loss figures after this...

 

[Toolman]

Did you have it dyno'd before? Also, any plans to up your HP substantially?

Looks cool.

 

[redwraith94]

I would really like to boost compression eventually. I think I would start with new pistons, and then maybe do something with the valves. That, and boosting the rpms. I want to switch it over to e85 / e100 only, but for now I need to assemble her, and get some steering / suspension components.

I wasn't able to have her dynoed, the original owner grenaded the differential, and he was still driving it! I haven't cracked it open yet, but I'll post some pics when I do. It had lost 1st / 2nd, and 5th gears (it wouldn't shift into them) probably because some piece of the differential was blocking the way.

I ran a compression check on the engine, and the lowest cylinder was 184, the highest 196, with 217,000 miles she seems to be just broken in. I think the engine should be near stock power, but it does need the valve adjustment done.

 

[somedude_001]

Common sense says that the smoother two parts that touch each other are, the less energy will be lost to friction... looks good! I can't wait to see the results! Looks like we might have to revise the transmission loss figures after this...

That is what I thought at first too, but upon thinking that I think I came up with the "debate" of polishing the gears.

the metal gears don't actually touch each other. there is a layer of oil between the gears. If you remove all of the rougher texture from the gears then the thick factory spec oil may run right off the gears because it has nothing to grab onto. This makes me think that you may have to go with a slightly thinner oil to compensate. So since the gears ride on a cushion of oil will having smoother gears make a difference? I don't know i'm not a engineer but they sure do look good!

 

[n8rsk8r]

I am going to do this to my trans once apart.. I think this is an excellent idea :woot:

 

[Northwestvoodoo]

That is what I thought at first too, but upon thinking that I think I came up with the "debate" of polishing the gears.

the metal gears don't actually touch each other. there is a layer of oil between the gears. If you remove all of the rougher texture from the gears then the thick factory spec oil may run right off the gears because it has nothing to grab onto. This makes me think that you may have to go with a slightly thinner oil to compensate. So since the gears ride on a cushion of oil will having smoother gears make a difference? I don't know i'm not a engineer but they sure do look good!

Do we have a "stirring the *** icon"? The man has a point.

 

[NovaSS]

Gears are cut with a specific "roughness" , its part of the process of metal being torn away during the machine process. What this leaves is microscopic hills and valleys. As the gears first come into contact under load the hills are smashed down. Its like peaning down with a hammer. THIS MAKES THE SURFACE HARDER
Its called "work hardning" Its the same thing that happens when a new cam shaft is broken in. This why when you pull a gear set apart they is a shinny spot were the gears ran in contact.

I have no idea what the polishing effect will be in your situation as far a longtivity but Im sure you will no see differance in power transfer.

 

[redwraith94]

http://scitation.aip.org/getabs/ser...00122000001000354000001&idtype=cvips&gifs=yes

Finishing from .4 micrometer Ra (roughness average) down to .05 micrometer Ra resulted in a 30% reduction in friction.

 

[MerkXRTurbo]

This is a similar subject:

http://videos.streetfire.net/video/SEMA-2006-Crane-Cams-with_80927.htm

 

[LeddZepp8687]

By polishing the gear teeth you will reduce friction and bind, which will not only be more efficient, but also decrease the ammount of heat generated.

Why do people shot-peen thier gears? Same principle.

It may decrease your drivetrain loss ever so slightly....Will it be noticeable? Maybe... You will see more difference and fluctuation between dyno runs than you will in overall increase in power.

Im all for it however, I just wouldnt expect any kind of large increase in power. Looks great though!

 

[NovaSS]

I guess I was a little misleading in my responce. I guess we are talking about two different things, strength and friction reduction. You can make gears all day long that will have low C/F numbers but will they hold up to a load? Will they break in correctly to prevent failure?

Shot peening is doing the same things as work hardening, It has nothing to do with friction reduction. Since cracks start on the surface of the metal shot peening makes the surface harder, hence cracks are less likely to form.

Listen to the link stated above, Cranes NEW process is just a form of shot peening, it just happens to leave a nice "Polished look" but its not polishing.

 

[redwraith94]

I think that shot peening is done to compress the surface of the gear. It won't heal cracks that are already there, but by leaving the surface with a net compressive force, when a tooth is bent, the bending force has to overcome the compressive force, before the tooth starts to see tensile force.

It's for the same reason that automotive glass is so much stronger than regular glass. They do an ion exchange. Take Soda Lime glass, and dip it in a molten potassium salt, and the potassium ions force their way into where the sodium ions were (below the melting point of the glass), and this leaves a compressive stress on the surface, because the potassium ions are larger than the sodium ions were. Shot peening is the same principle.

I don't know how much more if any power will be noticed, but I am hoping for a few percent more at the wheels.

 

[LeddZepp8687]

You guys are right, Shot-peening is different than polishing.... I shoulda done some more research first.....

I still stand by what I said though, just not the shot peening part...