After I see the pricing on the 05 I have ordered, I am truly tempted to ask the dealer to install, on day one, a 3.73 set of gears over the stock 3.55's. (direct from Ford Racing Parts)
http://www.fordracingparts.com/parts/part_...rtKeyField=5701

My background on this is that I owned a 1987 GT, which I prompty wrecked (being stupid) after 2 months of "spirited" driving. I don't recall the rear end ratio, but it was higher than the 1988 I replaced it with. I will always recall how much more deeply the '87 dug when I punched it. It was a great deal of difference between my two otherwise identical cars.

I am also tempted to have them install another Ford Racing item, the Torsen Differential: http://www.fordracingparts.com/parts/part_...rtKeyField=2521

I know that Torsens won't lock at ALL if you have zero traction under one tire. This can mean that if you get wild slip in a drag race, you don't get much torque at all. I'm willing to live with that, because I'm not going to live and breath by my slip times.... I'm just tired of burning up Traction-Lok clutches (on my 88 and my '97 Explorer).

Your comments? Gimme the good, the bad, and the ugly.

Thanks.

 

By the way, another factor in this mod would be to make the car unique from day one... some people like parts that look fast, some people like parts that sound fast, I like parts that go fast...

 

You have to see what the next gens shift points at certain speeds are, and how the standard bolt ons work first. You may end up sticking yourself with a 3-4 shift 200' before the line you never had to make with the stock gears. This motor breathes much better then the 2v, I doubt going up .25 is going to help. Most likely going with a 3.90 or even higher will work better. A lot of it is SOTP 'speed' I have seen cars go slower with higher gears if it does not take advantage of the motors torque curve. Let someone else be the guinia pigs and over time people will figure out what works best.

 

Good advice...

I have to weigh the "who's the guinea pig" factor against the "include the options in the loan" factor



Any opinion on the Torsen? I've wanted to try one for years... I've read great things about them, and also bad things (mainly from hard core draggers, which they are not optimized for).

 

My oppinion on 3.73's for this car with larger tires and 3.55's already, dont bother. Between gears and the speed calibrator you'll spend 500 easy for no measurable gain.

 

I was just looking up old stats for the 87 and 88 I owned, and it looks like they had 2.83's and 3.08's from the factory.

Man, talk about tall gearing.

Yes, wait and see is a good approach. In order to compare apples to apples, I'd need to see the tranny gearing and figure the overall ratio for my old cars in order to get any sort of comparison.

 

Are the gear ratios for each of the five speeds known at this point?

 

I would doubt they changed em for this car from 04.

 

3.55s

 

Assuming that you are talking about a MTX< I agree with Kevin that going from 3.55 to 3.73 is not a large enough difference to justify the cost of the new gears.


If your objective is to just have the feeling of more power when you punch it and you are going to go through the expense of gears, put in 4.10s. Becuase the tires are larger in diameter, 4.10 gears in an 05 Stang will be the same as 3.73s in a 99-04 Stang. At 70 MPH with the 4.10s you'll be turning 2200 RPM vs 1900 with the stock 3.55s.

Kevin, if the 2005 Stang uses the same system as the Lincoln LS, there will NOT be any recalibration of the spedo required. The new Ford system uses one of the wheels sensors for the speedo, so changing the gears will have no effect on the speedo. If you back up a Lincoln LS you'll note that the speedo reads normall, just as if you were going forwards and the odo also runs up whenther you are going forward or backwards. :worship:

 

3.55 gears are really a good gear, In my 90 GT 1st gear was short and 2nd was just awesome, it really pulled hard in every gear, even 5th gear pulled good on hills less down shifting when just cruising.

 

Another thing to consider is how the new trans is geared also. Mod motors do like lower gears.

 

You have to consider the tire diameter. The 05 Stang has significantly larger diameter tires than the 99-04, so 3.55s on the 05 will act virtually the same as 3.27s on the 99-04.

Also, as you said in your next post, you have to consider transmission ratios. The MTX on the 05 (T3650) is the same tranne and has the same ratios as the mid year 2001 - 2004 Stangs. The very tall 0.62 OD ratio lets you put in some pretty tall gears and still have reasonably low RPM when cruising on the Interstate (80 MPH 5th gear with 4.10s will be only 2500 RPM (verses 2180 with the stock 3.55s.)

Again, if you want to make a significant speed improvement, I think 4.10s are the way to go, don't bother with 3.73s. But if you are interested in 1/4 mile times follow Kevin's advice and figure out your shift points to make sure that you won't need to make an extra shift just before the line which will give you a slower 1/4 time.

 

Well, if the gear ratios are what I think....

Then the 6000rpm redline in 3rd comes up at about 102mph, with 3.55 gears, 97mph with 3.73s, and at about 88mph with 4.10s.

If I did my math right that is (LOL)

So it looks like it's close enough to a 3-4 shift that we're really going to have to see how it runs.

(I'm pulling numbers out of places online and calculating this stuff... please pardon me if I fudged something along the way)

 

Assuming that you are talking about a MTX< I agree with Kevin that going from 3.55 to 3.73 is not a large enough difference to justify the cost of the new gears.


If your objective is to just have the feeling of more power when you punch it and you are going to go through the expense of gears, put in 4.10s. Becuase the tires are larger in diameter, 4.10 gears in an 05 Stang will be the same as 3.73s in a 99-04 Stang. At 70 MPH with the 4.10s you'll be turning 2200 RPM vs 1900 with the stock 3.55s.

Kevin, if the 2005 Stang uses the same system as the Lincoln LS, there will NOT be any recalibration of the spedo required. The new Ford system uses one of the wheels sensors for the speedo, so changing the gears will have no effect on the speedo. If you back up a Lincoln LS you'll note that the speedo reads normall, just as if you were going forwards and the odo also runs up whenther you are going forward or backwards. :worship: [/b][/quote]
Possibly, but it also uses the standard T3650 from the 04 stangs.

Figure the cheaper way, they already have the hardware for the 3650, and all it needs is a line of code in the computer to interpret it.

 

But the '05 Stang uses the Black Oak PCM system from the LS, which also controls the 5R55S trannie. The traction control system is supposed to be updated, probably again lifted from the LS. The 05 prototype I sat in had an Advance Track section on the setup display, so A/T may be a future option. And according to one of Ford's press releases the '05 Stang uses the same communications bus that the LS uses. If the '05 Stang already has most (if not all) of LS's electronics it sounds to me like it will be simplest (and lowest cost) to use the wheel sensor for the speedo & odo just like the LS does.

 

here you go fellas.... check this out. When you do find out what the gear ratios in the tranny will be, you can see what speeds you'll get out of which gears and with what rear ends.

http://www.f-body.org/gears/

I'll say, though, that I had 2.73s in my '98 from the factory.... I wound up in a fortunate situation and got a free gear swap. I had a pinion seal leak that I didn't notice until I went out of town for about a week. I rolled the Stang outta garage and saw a spot about the siz of a quarter of diff fluid. Long story short, I didn't let them get away with just pressing in a new seal, I made them tear the thing down, which was good because the carrier pin was sheared and floating around, and the carrier bearings were all shot, but my buddy that worked in the parts dept hooked up a swap to 3.73s... going up a full bean was a huge difference. I could spank a Cobra or Z28 off the line, and they didn't catch up until about mid way thru 3rd gear.... I felt pretty proud of myself... but yeah.... I agree with V-10 on the point that it's going to feel like 3.27 with 18" wheels... you have to remember that it takes more torque to turn bigger tires.... even though you have a larger circumference, you still have to have more power to turn it as fast.... it's not mathmatics, it's physics... Get on a mountain bike, put it in the largest gear and then peddal your hiney off up a hill.... you'll like the lower gears much better.... and the car will be the same way.... I'm thinkin' a 4.10 will be a better gear for this model... but it will dog your MPG (on the highway) and it will take about 25mph off your top speed.
But heck.... how many people open their car up all the way more than every once in a while?

 

Well, when I had my '87 and my '88 GTs, I would drive them up to 100mph every day. When it only takes a few seconds (and a clear stretch of hiway without any cars to get in the way), it only takes a few seconds to get up to 100 from 60

 

OK, I need to understand something. I know that gear ratio and tire size play a huge role in what to choose for the rear-end, but everyone keeps referring to tire size. What size are you referring too? Overall height or width? I am guessing that if I replace my 17" rims with 18" rims and a lower profile tire that gives me the same stock height, it shouldn't matter how wide the tire is. Am I right or way off?

 

You are correct adrenalin.

What we are referring to is that the tire diameter (size) on the 2005 Mustang is significantly larger than the 99-04 Stang. 27.2" vs 25.7"

The point was that you're favorite gear ratio for your 99-04 GT Stang will not be the right ratio for an 05 GT Stang.