3.73 gears going in this Wednesday

[wht_stang]

I'll be having a set of 3.73 gears put in my 07 Crown Vic Interceptor this Wednesday. I'm already planning a trip to Edgewater Friday after work and would love to see some of ya there. I was wondering though if anyone had any ideas of what gains I might be expecting. I ran a 15.934 last time out and stock it has a 3.27 trak lock.

[2Fast4You]

I would expect to see a couple tenths with that swap, it will make a difference.

[draggin50]

Weather plays a big factor as well. What was it like last time you ran the car? The gear itself will get you out of the hole quicker if you don't spin. What tires are you running?

[redfirepearlgt]

Will be looking for ya Friday

[wht_stang]

Weather plays a big factor as well. What was it like last time you ran the car? The gear itself will get you out of the hole quicker if you don't spin. What tires are you running?

Just running the stock tires which I believe are 255/55/R17. I'm kind of figuring I'll be about 15.4 or so. Last time I ran it was hot and high humidity and I believe this Friday is gonna be the same lol.

[CNTLOSE]

Do you have a hand held tuner for it to program it for the gear swap? If not I would not recommend racing it or driving it very hard until you do. If I remember correctly you can grenade your transmission if the computer still thinks you're running the 3.27's. I used the SCT X3 when I did mine and using the performance race tune on 92 octane was a lot of fun...but you will burn the fuel up quick.

[wht_stang]

The SCT X4 is the one I'm looking at, but no I don't have one yet. According to a couple guys on crownvic.net since it's only a two step difference between the 3.27 and 3.73 gears, the computer will relearn shift points, but not speedo. Can't find any more info on it though they say WOT is fine since there's not too much difference. Tune is ideal.

[CNTLOSE]

Now that I think about it I think I might have had the 4 as well...bought it used off one of the CV sites and it went with the car when I sold it so now I'm not sure...lol. I went with 4.10's and mine was still drive by cable unlike yours. The tune will make a huge difference. Mine was a totally different car with it...but like I said it made her thirsty!

[NXcoupe]

The SCT X4 is the one I'm looking at, but no I don't have one yet. According to a couple guys on crownvic.net since it's only a two step difference between the 3.27 and 3.73 gears, the computer will relearn shift points, but not speedo. Can't find any more info on it though they say WOT is fine since there's not too much difference. Tune is ideal.

No it won't learn shiftpoints. The gear ratio needs to be changed in the tune. The trans shifts by mph and rpm. It will still see the mph your speedo sees which will mean very early/short shifts. Get somewhere down there and get it tuned. When you race it, manually shift it so it will shift at the rpm you want it to, otherwise you will have short shifts each gear. jmho.

[wht_stang]

No it won't learn shiftpoints. The gear ratio needs to be changed in the tune. The trans shifts by mph and rpm. It will still see the mph your speedo sees which will mean very early/short shifts. Get somewhere down there and get it tuned. When you race it, manually shift it so it will shift at the rpm you want it to, otherwise you will have short shifts each gear. jmho.

Hmm wonder why those guys said it would relearn with it only being a 2 step difference. I thought it had something to do with the drive by wire on the Crown Vic. It doesn't matter anyhow cause went to have the gears done and come to find out I need a whole new differential. I'm ordering the Ford Racing 8.8 31 spline differential part # M-4204-F318C It's supposed to be the same one used in 03-04 Cobras and I found one on Ebay for $212 shipped. Also if I'm shifting it at the column while racing, should I turn off the OD?

[CNTLOSE]

Yes...turn the OD off.

[NXcoupe]

Hmm wonder why those guys said it would relearn with it only being a 2 step difference. I thought it had something to do with the drive by wire on the Crown Vic. It doesn't matter anyhow cause went to have the gears done and come to find out I need a whole new differential. I'm ordering the Ford Racing 8.8 31 spline differential part # M-4204-F318C It's supposed to be the same one used in 03-04 Cobras and I found one on Ebay for $212 shipped. Also if I'm shifting it at the column while racing, should I turn off the OD?
Because they don't tune for a living, I guess. The computer learns idle and fuel mapping, but only a small amount of fuel change on those cars with narrow band O2 sensors. It can't learn driver demand tables and can't learn gear ratio changes, those are all etched in stone as far as the computer is concerned.

[CNTLOSE]

Also a lot...not all, but a lot...of guys on those CV sites really have no idea what they are talking about. I quit even going to their forums because the info was so bad and everyone wants to get in a pissing match when you offer solid advice.

[wht_stang]

Because they don't tune for a living, I guess. The computer learns idle and fuel mapping, but only a small amount of fuel change on those cars with narrow band O2 sensors. It can't learn driver demand tables and can't learn gear ratio changes, those are all etched in stone as far as the computer is concerned.

Yeah I thought something sounded funny about that hahaha. Well now I'm just waiting for my differential to come in. I'm getting the Ford Motorsport M-4204-F318C. That should work for my Crown Vic right? My CV does have the 31-spline axles.

[wht_stang]

Also a lot...not all, but a lot...of guys on those CV sites really have no idea what they are talking about. I quit even going to their forums because the info was so bad and everyone wants to get in a pissing match when you offer solid advice.

Yeah I kind of noticed that hahaha. Pretty much the reason I got back on here. I know most of the guys on here are very knowledgeable of the 4.6 that's in my car among a ton of other good info.

[CNTLOSE]

Yes that differential should work for you as you should have 31 spline axles. Keep in mind though sometimes with fleet vehicles things get changed out from parts cars.

[wht_stang]

Yes that differential should work for you as you should have 31 spline axles. Keep in mind though sometimes with fleet vehicles things get changed out from parts cars.

When we had it open yesterday it appeared to be the normal 3.27 track lok differential and 31-spline axles so I should be good. Sucks though cause my mech can't get it back in the shop til the 31st, but I can't find anyone that can beat his price of $300 for the install. He's been doing ford rear ends for years so I know he knows what he's doing.

[NXcoupe]

That is a good deal. I charge 350 if you provide the gear and 50 to do the traction lock install, which includes pressing on the carrier bearings. I use the ford pinion depth tool and ford side shims, which cost a ton of money to use, but I believe it nets a better quality install over the shim packs.

[wht_stang]

That is a good deal. I charge 350 if you provide the gear and 50 to do the traction lock install, which includes pressing on the carrier bearings. I use the ford pinion depth tool and ford side shims, which cost a ton of money to use, but I believe it nets a better quality install over the shim packs.

Even $350 is a good deal. Do you have the capabilities to re-program the speedo? I'd like to at least have that done til' I can buy the X4 programmer.

[NXcoupe]

Only way to change that is with a tune. I can tune the car, yes, but I don't use an Xcal to do it, unless a customer specifies that's what they want. I could do it for you tho.

[chris91]

What about just using a Dallas Speedocal or whatever it's called?

[wht_stang]

Only way to change that is with a tune. I can tune the car, yes, but I don't use an Xcal to do it, unless a customer specifies that's what they want. I could do it for you tho.

What would you charge for a tune with the speedo correction?