Gears and smaller rims

[shoblock]

I just ordered a new '15, and wanted the ACC, so I didn't order the PP. I drive 33 miles one way every day, and thought the lower (numerically) gears would be better for the highway. I am an ex-Stang banger, and am able to do ring and pinion changes. (I have a lift) I picked a SHO because I found myself looking at GT's with automatics, and decided it would be better to have a bigger back seat and AWD.
I've been looking through the different posts for about a week now, and no one had brought up changing gear ratios, or going to an 18" rim to get the same effect. It would also lower the car at the same time. I was thinking of using the 20's for winter tires, and 18's for a few months in the summer.
Will 18's fit over the calipers on a non-PP car?
Is it a major unit overhall to change two sets of gears?
After it's out of warranty, I'm sure I will go for all of the mods talked about in these pages, but the two mentioned may be invisible to the dealer during a warranty claim, and would make the car more fun.
Thanks

 

[BamSHO]

Don't think gear swap is possible. You would have to tear down the transmission to replace the gear in there and don't think anyone makes gear for transverse applications. 18's should work, cause I think the base Taurus run 18's, but not sure how off your speedo will be. Do you have a tuner friendly dealer, if so, buy the mods now.

 

[shoblock]

Thanks. I didn't think it through. The 18's with smaller diameter tires are likely the way I will go.

 

[Shojeep13]

I have 18's on my '13 pp for snow rim/tire package and the fit fine with a 1/2 inch to spare.

 

[shoblock]

Thanks for the reply, Shojeep13. Are the 18's a standard Ford rim, or aftermarket? Did you tune for the diameter revision?

 

[RealityCheck]

Be careful with lowering and smaller diameter wheels/tires. I have H&R springs and I'm running 245/40-19 Bridgestone RE-11s in place of the OEM PP 20" summer tires. The Bridgestones are about an inch smaller in diameter than the stock Goodyear F1s and the car sits very low. My exhaust scrapes on things regularly. The good news is that PP gearing + smaller diameter tires allow the car to launch much harder. The fact that the Bridgestones are much stickier than the Goodyears doesn't hurt either.

 

[SHOnUup4]

I wouldn't worry about it...non pp here, stock 19" RSA'S and still putting down as good if not better than most in the 60' and 1/8 mile.

Rich

 

[shoblock]

Great replies. Thanks. Now if they just finish building my car and deliver to the dealer before rebates expire.
One question to all:
Does the tire diameter have to be programmed into the tuner to keep the speedometer, etc. in-sync with the rest of the OS?

 

[RealityCheck]

Great replies. Thanks. Now if they just finish building my car and deliver to the dealer before rebates expire.
One question to all:
Does the tire diameter have to be programmed into the tuner to keep the speedometer, etc. in-sync with the rest of the OS?

Yes. I used my SCT X3 to reprogram for the smaller diameter tires. It allows you to select revs per mile. The Tire Rack website has comprehensive specs for all tires they sell - overall diameter, revs per mile, etc. As a point of reference, the OEM 19" SHO tires are 741 revs per mile, the PP 20 inch Goodyears are 729 revs per mile, and my RE-11s are 779 revs per mile.

 

[shoblock]

Thanks RealityCheck, you nailed it.

 

[wuzzzer]

I noticed that when I've driven by the radar stations that show your speed that my speedometer is a good 3 -4 mph too fast. I didn't realize that I could adjust the speedometer in my SCT. Is it changed under the "adjust additional engine options" area?

{edit}I'm running Goodyear Eagle RS-A tires in 245/45/20. Same overall specs as the F1 Supercar tires that came factory. Why would my speedometer be so far off?

 

[RealityCheck]

Even though I reinstalled my summer tires only 2 weeks ago, I can't recall the exact menu options I used on my SCT to adjust for the smaller tire diameter. I do remember that it wasn't intuitive at all. If I recall correctly, you start like you're downloading a tune and at some point it asks if you want to make adjustments. If you drill down to the revs per mile selection, you get a giant list on 5 rpm increments. I'll be swapping my winter tires for my summer tires on my Ecoboost Flex this weekend and will write down the exact steps.

Not sure why your speedometer is so far off the roadside speed indicators. I verified mine against a Garmin GPS and it was spot on. I've never checked against one of the roadside speed setups, mostly because I'm too busy slowing down. If I think about it the next time I pass one I'll see how it matches up to my speedometer.

 

[Shojeep13]

Thanks for the reply, Shojeep13. Are the 18's a standard Ford rim, or aftermarket? Did you tune for the diameter revision?

After market. I have not bought a tuner yet. I am waiting to put the factory 20's back on. Also have a CAI and 3 bar map that I can't wait to put in. Didn't want to make the car any faster with winter tires on.

 

[RealityCheck]

I noticed that when I've driven by the radar stations that show your speed that my speedometer is a good 3 -4 mph too fast. I didn't realize that I could adjust the speedometer in my SCT. Is it changed under the "adjust additional engine options" area?

{edit}I'm running Goodyear Eagle RS-A tires in 245/45/20. Same overall specs as the F1 Supercar tires that came factory. Why would my speedometer be so far off?

.
I put my summer tires back on my Flex today and went through tire revs per mile setting process. You're right, it's under the "adjust additional engine options area". After you select the desired revs per mile, you have to compete the entire tune loading process. If you stop after setting the revs, the change won't stick.