4.10 gears illegal in CA??!!

I got off the phone with ford dealership and I asked how much it was to install 4.10 gear differential and he said that it was illegal to change the ratio of gears to any car in california. Is this true? Did i just talk to a dumb mechanic or is he telling the truth. I see that there are people in CA with these gears. How did you get away from emissions? or is this ford mechanic telling me lies?
 
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No actually they are right. Changing the gear ratio means that they might have to shift out of 2nd gear on a loaded (dyno) smog test. Also you have to reprogram your computer to account for the new ratio, and any programming must have a CARB EO number.
 
tell me about it makoto. its bad enough trying to save money to mod up your car, it's even worse not being allowed to cuz of emissions. I couldn't even buy a CAI of my choice cuz most are illegal. I think there were only 3 I could choose from. And dont remind me about cams and heads. theyre also illegal. it blows
 
tell me about it makoto. its bad enough trying to save money to mod up your car, it's even worse not being allowed to cuz of emissions. I couldn't even buy a CAI of my choice cuz most are illegal. I think there were only 3 I could choose from. And dont remind me about cams and heads. theyre also illegal. it blows

Wait wait WAIT. Certain CAIs are illegal?!!??!




crap...
 
I have never heard the 4.10s are illegal here in Cali. When I was getting prices for gear install for 4.10s, not one place including the three dealerships I talked to-Mossy Ford, North County Ford, nor Heller Ford said anything about them being illegal. There labor charge should have been illegal though.
 
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I know this is an old thread but after reading it I just had to post.
Someone has their head way up their a$$.
I know its not a mustang but I just smogged my hemi ram with 4.56 gears, underdrive crank pulley, CAI, electric fan, Superchip, and headers.
CAI and headers have EO numbers. Pulley they didnt even care. fan is not a smog item so it doesn't matter. I also have real duals instead of the factory 2 into 1 exhaust. That doesnt matter since its after the cats.

As long as the tuner does not turn off anything it will pass the smog test. They will not even know its there.
Gears do not matter because the test is at 15 & 25mph within certain rpm ranges.
At 15 my truck was at 2300rpm which tells me it probably never got out of 1st because of the shifting I set up.

My brother was a smog tech for 15+ years till he moved to a shop that didn't do smog.
If you get a truck with big tires or gears just test in whatever gear you need. He had one that had to be done in 3rd for the 25mph test but it worked and passed.
 
They still smog test cars in CT too, the state privatized it a couple years ago so that regular garages can do it if they buy the stupid machine. It's $20, if you fail you can't register the car. They won't do new cars for the first few years, but after that it is every couple years.