Stillen 3.90 Gear Info


dbk

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Jul 30, 2005
15,242
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While I was in California I got a chance to talk to Steve Millen about their 3.90 gear. Here's what they laid out for the forum, and I'll post my thoughts below:

Stillen said:
3.9 Gear Ratio

Stillen has finalized the R&D process on a 3.9 gear ratio upgrade for the venerable Ford GT. We are interested in your feedback before we begin production. It is our goal to produce the type and quality of products that you are most interested in for your vehicle and want to focus our efforts accordingly. Do you see value in this product? Would you be interested in purchasing such an item? This is your chance to help bring an amazing product to market.

Why would I want to change the drive ratio?... you ask:
During development of the GT, Ford set many performance goals some of which were for the sole purpose of achieving specific “paper” milestones. As almost every driver knows paper goals don’t always jive with real world practicality and fun. One such “compromise” was Ford’s insistence that the car reach 60mph without a shift. This was to insure that any editor, journalist or critic that got his hands on the car would achieve blistering 0-60 times by removing as much driver input, and potential error, as possible – a paper goal.

The compromise with the shift-free 0-60 goal is that gaping spans of rev’s must exist. This results in large RPM drops between gears forcing the engine to work much harder in the unavoidable low rev’s as the car claws its way back up into power. The GT currently overcomes this obstacle with brute force. This is all the work of the stock 3.3 ratio that creates something of a no-mans-land at speeds and shift points that are critical in the real world. Track days and spirited driving benefit most from a nimble drive ratio that allows the driver to keep the car in peak horsepower range as often and as quickly as possible. One should not have to decide between pinging the rev limiter or plunging the RPM under the power band and waiting as the supercharger hustles at full boost to push the car back up into power.

Now you don’t have to. Steve Millen, fresh off his grueling, week long, track experience with the GT, had had enough of this torque shuffle and teamed up with Ricardo to develop a gear ratio more befitting a car that demands to be driven. After all, the world is not paved exclusively with straight lines, turns are inevitable. In fact true enthusiasts typically seek them out. The race prep of Steve’s GT included Penske coil-overs, Eibach springs, an AP Racing clutch, AP Racing 6 Piston front calipers with 2 piece cross-drilled and slotted front & rear rotors, Stillen performance exhaust and race pipes, and a Stillen/Eaton blower upgrade, and yet the car’s performance still suffered substantially from the black holes in the drive ratio. Immediately upon his return Millen and Ricardo put to work at solving this deficiency. The result is a perfectly balanced 3.9 ratio upgrade that can be installed on any GT by STILLEN’s specially trained master technicians. Why? Superb agility and more fun from a car that sets a high standard right out of the box.

This product is near production ready and we would like to know what you think before we invest in mass production. Please post your opinions here or, if you prefer, please email them to smillen@stillen.com. Thank you for your interest and participation.

Factory 3.3 Ratio Redline Speeds
1st: 62mph
2nd: 95mph
3rd: 131mph
4th: 171mph
5th: 210mph
6th: 255mph

STILLEN 3.9 Ratio Redline Speeds
1st: 53mph
2nd: 81mph
3rd: 112mph
4th: 146mph
5th: 180mph
6th: 220mph
 

dbk

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This has been discussed before on here, and here's pretty much what I think: the notions put forth above are pretty much dead on.

It's clear the mag 0-60 time was a benchmark that led the team to make sure the car hit 60 in first. Even with the 3.90 gearing, you can see that the car still gets a long way before shifting. You'd be right in the power in 4th if you were a drag racer with the 3.90s.

With the stock power, you're stuck shifting at absurd intervals. This is great for the 0-60 time and also makes the car great for top speed runs. 6th is worth over 250, but with stock or anyone near stock power the car won't pull over 180mph. I know this is a big concern for most of you :lol Even with the gear change you're still at 146 mph before you get out of fourth. That's crazy! In my Z06 with 3.90s I was shifting to 5th right at 130!

I've been the beneficiary of gear changes on other cars in the past, and I think the GT is probably the ultimate candidate. Changing to a 3.90 in my Z was the biggest change to the way the car felt, and it had a 422ci stroker in it. This is only conjecture, but my guess is that you would knock serious time off the GT's quarter mile with 3.90s. Probably in line with something like the Carrera GT. Better yet, for street duty you'd get a lot more kick in the pants and there would be a lot more "driving" to do. Alot of times I find myself just sticking the car in 2nd and being done with it.

That would translate heavily to the track. In the hands of once-a-year track day Joe, leaving it in a higher gear and relying on torque to yank you around the track is a pretty good deal. But with the 3.90's, if you know what you're doing, you can really hustle the car around the track with those ratios. I talked to some people at SVT and they agreed. You're in the power, more often, more often when it counts. I'm sure this is why Steve chose to go to Ricardo with this proposition in the first place, being a Rally racer.

You could always just add more power, but adding gears isn't going to add any additional stress to the motor, it's not going to make the car more apt to overheat, and it's not going to blast the tires off even in 3rd gear from a roll. Traction will go down, but nowhere near what adding a Whipple or something would do.

Anyways, those are my thoughts. It's going to take commitments to get it done. If you're interested or have questions, fire away and the Stillen people will answer away.
 

AZGT

GT Owner
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Dec 20, 2005
1,354
Scottsdale, AZ.
I know in an earlier thread about ratios, 3:90 seemed ideal.

I agree in general driving startng in first gear with the 3:90 would be far easier and less clutch slipping than the current ratio. I do hate being slowed to a mere 200 though :biggrin Like DBK, I find myself not really "driving" the car, rather just sticking it in a gear and going. "Running through the gears" naturally is something you can't really do, unless you are looking to hit 160 on the way to the grocery store.

I think the idea is right on the money. It will most likely come down to THAT basic question, how much bucks $$$$$$$$$$$

Since it is not a simple drop the third member / quick change, I am afraid of what a transaxle ratio change would cost. Is there any estimate on that? Would the entire transaxle need to come out and make it a two day job (or whatever), or can it be done in a couple of hours and a couple of hundred bucks?

If the price was right (what ever that is), I would definitely consider it.
 

B O N Y

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Any idea on costs installed?
 

dbk

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Jul 30, 2005
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Because of the nature of the transaxle and the delicacy of the install, the pricing will be more than the average car. I paid 2k or so for my Z06. Relative to the price of the car though, what I'm hearing is not that high. Nowhere near a $15,000 Gallardo clutch change.

I'll let Stillen answer that.
 

B O N Y

MODERATOR & FGT OWNER
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Lambo clutches are muy expensivo...

Any confessions you care to make DBK will be held in the strictest of internet confidences.

Bony
Mother superior
 

ViperJoe

GT Owner
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Aug 17, 2006
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Washington Crossing, PA
Bragging Rights - You Bet

For a 3.90 gear, please define the top speed, in which gear, and at what RPM with a 3.90 gear.
 

KJRGT

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ACR Joe, isn't DBK's first post on this thread what you are looking for?
 

gtkurt

GT Owner
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Scottsdale, Arizona
I would like to know the speed to gear break out shifting at 7000 RPM?
How much will it cost and how long will my car be down?
With that said I am sure I want one ASAP. Kurt


This and some stronger half shafts should guarantee a 9 second pass.:banana
 

ViperJoe

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ACR Joe, isn't DBK's first post on this thread what you are looking for?
I was under the impression that the top speed shown was theoritical and not actual. Has this setup actually been tested?
 

dbk

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Jul 30, 2005
15,242
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I was under the impression that the top speed shown was theoritical and not actual. Has this setup actually been tested?

This is theoretical as far as I know. Stillen will have to come on and answer that question. I know what you're saying though; the car will definitely haul ass to 180, but will it continue on in 6th gear past 200...right?
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
With a Whipple or TT it should pull to 220 in 6th, but the traction will be a handful in the first two gears!
 

tmcphail

GT Owner/Vendor
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Apr 24, 2006
4,103
St Augustine, Florida
With a Whipple or TT it should pull to 220 in 6th, but the traction will be a handful in the first two gears!


That would be an understatement. :biggrin :biggrin
 

nota4re

GT Owner
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Feb 15, 2006
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I too believe all of the background described here and the driveability benefits that a 3.9 would provide. It would no doubt make the car a whole lot more enjoyable to drive (assuming that is possible!)

While tearing into the transaxle itself would probably best be left to the experts at Stillen, there a number of shops that may be able to do a very competent job in R&R'g the transaxle itself. Therefore, it would be great if Stillen could consider to potentially team up with a trusted shipping company and offer a service that would include the upgrade, comitted turn-around time, and return shipping.

The other factor here which cannot be ignored is the halfshaft bolt failure issue. I am sure anyone contempating this upgrade would want some kind of assurances that they wouldn't somehow void their warranty if, in fact, Ford does come out with a solution. This would be especially true if the Ford solution was otherwise very expensive/involved. I am assuming we will learn about this soon enough....
 

Empty Pockets

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Excellent points, Kendall. :cheers
 

Gierkink

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Wellington, FL
The other factor here which cannot be ignored is the halfshaft bolt failure issue. I am sure anyone contempating this upgrade would want some kind of assurances that they wouldn't somehow void their warranty if, in fact, Ford does come out with a solution. This would be especially true if the Ford solution was otherwise very expensive/involved. I am assuming we will learn about this soon enough....

I agree with this however I've only got a year left on my warrantee. I'm guessing that by the time this is available for installation my warrantee, and that of many other owners, will have almost expired.

This sounds like a great modification for the car!

Rob
 

fjpikul

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Gee whiz, I don't want to ruin my gas mileage.
 

werewolf

GT Owner
Oct 30, 2005
49
 

ViperJoe

GT Owner
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Aug 17, 2006
1,305
Washington Crossing, PA
This is theoretical as far as I know. Stillen will have to come on and answer that question. I know what you're saying though; the car will definitely haul ass to 180, but will it continue on in 6th gear past 200...right?
Correct
 

cobrar1339

GT Owner
Mark IV Lifetime
Feb 2, 2006
956
Diamond Bar, Ca
Build it :thumbsup

I have the same comparison as DBK with a 3:42 to 3:90 in the Z06. The car is simply much quicker, nimble, spirited everywhere. On a road course or twisty road it is a blast. It's pretty hard to go 200mph around here. It will make you feel like you added 100hp and 100ft lbtq IMO. On the Zo6 it made 4th as strong as 3rd, 5th almost as strong as 4th and It will even pull in 6th. Around town and mixed the mileage got a little better. I'm guessing mucho quicker to 180 with ease. Our motors are much smoother and more refined than the C5 ZO6, I would think it will feel great. Roll on's would just pull like mad.

Not4re - brings up some good concerns on the actual deed that I would like some feedback on though. If it is as painless as the ZO6 was, I would be in line early.