View Full Version : has anyone done gears on an 03 or newer?

Dave B.
03-17-2005, 11:04 PM
I am looking to put in 373's on monday, are they enough?
the shop is trying to talk me into 410's but a whole other group of people say to stay with the 355's.

I do not drag race at all, but I also do not drive on the interstate all the time either,

03-18-2005, 07:05 AM
I had bought 3.90 gear for mine. Still havent put them in. Probably will send it back. Found out how much it would cost to have it installed. :eek:

03-18-2005, 08:18 AM
I would most likely stick with the 355's b/c of the instant torque you receive with the Eaton...just wait til you get close the 500rwhp range and you'll see what I mean (with 410's, you'll roast the tires even more)...plus, I was told it would be at least $500 to install...

03-18-2005, 02:46 PM
Dave, I agree with Cobra1, I have almost 500 RWHP now and it is tought to keep traction in 1st, 2nd, and sometimes 3rd with the stock gears. Just an F.Y.I.

03-18-2005, 03:35 PM
355's my vote....I could not imagine 410's with my setup.

Dave B.
03-18-2005, 09:01 PM
The performance shop I dea l with has about 3 differant customers they have put 410's in and all of them and I mean all of them swear by them,

But on the other hand theres a whole other group (you guys) who say not to do it,

is there no one out there with an 03 or newer who has 373's or 410's that can tell us something?

03-19-2005, 12:02 AM
If you are not drag racing then why do you need to change gears? I drag race and I still plan on leaving the stock gears in! :thumbsup:

RF Cobra
03-19-2005, 12:09 AM
JLT Cold Air Kit
Magnaflow catback, Cobra Floor Mats, Snake in grille, MGW Shifter, 2.77 @ 110 mph, 397 rwhp 365 rwtq (STD)

Tony, you ran the quarter in 2.77? Man you're good and that's one quick '04! ;)

03-19-2005, 12:11 AM
Nah... It was a 12.77, the system just truncated the one so I thought I would leave it like that. :rotf:

Dave B.
03-19-2005, 12:11 AM
see thats the thing man,,,,,,I got these guys here where I live telling me they all think putting gears in there car was hands down the biggest seat of the pants kick in the A_ _ they ever felt from there car.

Thats why we are talking about this and once again, I must ask is there anyone out there who has put gears in an 03 or newer?????

Until we find someone who can tell us directly, its all just talk. but I hear what your saying.

03-20-2005, 02:22 PM
I put 4.10's in my 03 when it had o/r exhaust and a CAI mod. Perfect combo. But, when I started adding pulleys I was trapping well over redline. I switched the 4.10 for a 3.90 running 484 rwhp SAE and 530 rwt. It ran 11.39@122 at FFW in Richmond summer before last on a 100 degree day carrying a full tank of pump gas, the fastest pass for an 03 that weekend. I have had people argue with me there was no way I could beat an 03 with the same power and a 3.55 gear. I ended a lot of that talk that weekend. On Sunday I was lined up against Tommy Godfried (F8LBITE), good buddies with a guy that gave me a lot of grief over the gear. I missed the first round of qualifying and I let Jim D'Amore drive it in the second on the stock tires. When I took it down in round three on a set of borrowed ET Streets I had a JDM modded car making more power than I had by 2-3 cars when I blew my 2-3 shift and went into fifth and he blew by. On Sunday F8LBITE showed up and they let him run I guess since they only had five 03's. My dial in sucked at 12.41. They gave Tommy a 11.50 and they lined him up with me. There was no way I could run a 12.41 consistenty. I told the guys I was with I didn't want to run to begin with. Jim had talked me into it. I told them I was going to turn it loose and to show what it would do and break out and park it. Tommy saw that I broke out and he hit the brakes before th line. But if you look at 1/8 times when he was full into it, I had him with my 7.31@96 to his 7.67@94. That got some people looking at gears. I had people all over my 03 when I parked it inlcuding F8LBITE. A guy I was with told them I designed a few things for the rear twisting with their melons. F8LBITE had a 2.76 Reinhardt upper, six pound lower, BBK LT's, BBK o/r h-pipe, 2 chamber Flows, JL CAI and JL tuned chip. He said he hadn't dynoed it. I was running 2.80 upper pulley, four pound lower, homemade CAI, JBA 99/01 Cobra shorty headers, 99/01 Cobra Bassani o/r h-pipe and catback and a JDM tuned chip. I'd say he had me by about 20 rwhp and maybe 30-40 rwt. If there was a 500 rwhp car that could beat me with a 3.55 gear I would like to see it.

Today I'm running a KB at 19 psi well over 600 rwhp. I'm dynoing it this week since I went up two pounds. I run 315 BFG KD's on 10.5 AFS wheels. That's al ot of mass. I gave a 99 Cobra a ride yesterday. In third gear at 70 mph I can mash it about two third throttle and the car will go side ways and will not bite till you let off. In first through third at any speed around 3500 rpm I can roll the tires like the car was on wet pavement with just throttle.

I thought when I was crossing the line with the 3.90's I was well over 6200 rpm at 122 with the Eaton. Some have said no way I was near redline. We have done the math with a 26 inch tall tire, 3.90/4.10 gear crossing in fourth(1:1) and it comes to around 130 mph. That's not what I saw. Maybe I didn't know exactly where the line was at Rockingham. I'll test it out in a few days. I haven't ran the KB yet but it should trap 130. I'm going to a solid axle in a few weeks and I need to know myself what is the perfect gear. I know what the math says but when you have a tire under load with 8 psi I'm not sure it makes the travel equivalent to one circumference of a 26 inch tire not under load at 32 psi.

Here's what I think for the street,

Stock to 400 rwhp - 4.10's
400 to 450 rwhp - 3.90's
450 to 500 rwhp - 3.73's to 3.55's

03-20-2005, 08:49 PM
I guess most 03/04 Cobra owners would fit in the 450-500 rwhp category which brings me back to square one, stock 3:55's. I currently have 397 rwhp but when I reflash the computer and put in a 2.80 pulley, I should be over the 450 rwhp mark. :) Down the road will either be a whipple or a KB. :thumbsup:

Dave B.
03-20-2005, 08:55 PM
S o I guess the bottom line is to just leave the 355's alone uh??
from what I gather that seems to be the recomendation from those most of you, I would have liked to hear from two more of you that have put other gears in these cars but I thinks so far its clear,,,,,,just leave the stock gears in the car, put the money else where.

03-20-2005, 08:59 PM

The Ford place charges at least $75.00 an hour to install gears, not including the parts. If you are a hard charger race guy then maybe change them. But at 10.1 hours at $75.00 that's a pretty penny to spend on a gear set installation. Even if you got the gears with install kit for $250.00, you're looking at over a grand for a gear installation in your IRS. To me, not worth it. But that's just my opinion...

Dave B.
03-20-2005, 09:05 PM
well I have a guys thats done all my work and he is willing to do it for a flat $950 for everything, gears,parts,labor the works,,,,,I just dont know if its the right thing to do.

03-21-2005, 09:26 AM
seat of the pants difference...yes, b/c your gearing is lower...if you're looking for seat of the pants difference, I would try the TB/Plenum switch before dropping over $1000 on gears...I noticed a considerable difference in pedal response when I got my Accufab...just a thought, it's personal preference...I just think that if you're planning on going higher in the HP range, keep the stock gearing...good luck :thumbsup:

04-09-2005, 02:01 AM
I guess every one has a something to say about the gears. I have the 3:73 gears and love them. I wanted 4:10 but the rear end shop said to much, with out a rear end build up and slicks, and still would not be able to get fuul potential from the boost due to hitting rpm so fast. I stayed with 3:73 and no complaints. How ever if your not looking to do insane things then yes stay with 3:55. I can go from 2 to 3rd and darn near 360 the car if i keep my boost up. I do not drive the car with the t/c off, unless im out in a secured area, then it is all fun. I have scared my self several times, since putting the gears in, so be carefull with the choice you make. I put in Ford Racing gears and it was approx. $4 bones to have it install. day and a half to do it. total of about $700 for everything.