Topic: Polishing transmission gears?

[Flying J]

In "The Thoughts of hondaman" he mentions polishing the gears can gain you as much as 10% more power. Do any of the racers do this? How do you do it? I have my transmission apart right now and found this at the last minute before i start to button it up.

 I also was looking at Accelerated Isotropic Superfinishing. looks really cool. I think im going to call a few places to see what it cost to have done. I bet its expensive but it never hurts to ask.

[dave500]

considering only one pair of gears is driving at a time i think a 10% power increase might be a misprint?so if you have 35 you gain 3.5 free horse power?looks like a job for a dyno or mythbusters.

[dave500]

lapping gears together is done to mate and bed gear teeth together,,the initial wear is then done "outside" of the enclosure,minimising the amount of break in debris staying within the gearbox or differential or what ever.

[Bailgang]

You might want to pop this question in the high performance and racing forum. I read HondaMan's article as well and considered lapping the gears on my 550 when I had it's case split but I couldn't quite come up with a proper procedure either. I too thought the 10% gain was a stretch in fact almost all his tips had a claim of a 10% gain, maybe once you applied all of his tips you might see a 10% gain but to get it just by lapping the gears is something I'd have to see on a dyno to believe. Don't get me wrong, I'm not trying to dis HondaMan in fact I applaud him for taking the time to share his info with us. Regardless of how much gain in HP you might actually see I think his info in that article is great stuff and worth considering for someone who's trying to get as much HP as they can to the rear wheel.

[GammaFlat]

So far, I've not been let down by any of Mark's advice.   I don't expect that to change. 

[bwaller]

Check out Paulages hybrid build. He set up a remote driver to bed in the gear clusters. If the gearbox is all original and has mileage on it I doubt more is needed.

[lrutt]

Maybe reduce the power loss in the transmission by 10%. And a typical  tranny might have 8% loss so you might gain .8%. There are lots of losses in a trans though, bearings, gear lube, messing gears, etc. I think typical loss through the entire driveline is on the order of 15% or so max I believe.

[NCSUEngineer]

gear engineer here:

To start off with - polishing your gears is going to decrease the surface "roughness" of the tooth flanks (the flank being the involute curve that touches the other gear).  Decreasing the surface roughness -by itself- won't make a huge difference gear meshing efficiency (but it certainly wont get worse).

The big benefit smoothing up the surfaces of the teeth is that it allows you to run thinner and thinner oil which can drop parasitic drag/windage losses of the gears by quite a bit.  You can do this because as the teeth get smoother you can get away with a thinner and thinner oil film between the teeth.

Imagine on a microscopic level the surfaces of the gear teeth look like the rocky mountains.  When two teeth come together, you have two fields of mountains rubbing against each other. Your oil film has to be thicker than those mountains in order to prevent contact from occuring.

Now imagine that you polish your teeth so that the mountains are now just rolling hills or plains.   When these two surfaces come together a much thinner film of oil will separate the two.

Remember - your engine and trans share the same oil so...you may polish your gears (also, how do you plan on doing this?) but unless your engine can use 0-10W oil - I wouldn't make drastic changes in viscosity.

[lucky]

Straight cut gears rather than helical will get you 10% maybe.
Not worth messing with.
Talk to the gear experts.
Then there are the high performance coatings too.

[Flying J]

I like the feed back. Called these guys today but got an answering machine.
http://www.procryo.com/RemGears.html

[dave500]

Straight cut gears rather than helical will get you 10% maybe.
Not worth messing with.
Talk to the gear experts.
Then there are the high performance coatings too.

they are straight cut or spur gears.

[NCSUEngineer]

I like the feed back. Called these guys today but got an answering machine.
http://www.procryo.com/RemGears.html

ISF (Isotropic superfinishing, or just super finishing) is a pretty neat process.  you can get the surface of the gear's down to under 5-6 microinches RMS.  We do this to some of our super high speed gears.  For comparison - we use jet-turbine oil for these...which is super, super thin.