View Full Version : Any of you 03 guys changing rear end gears?

Dave B.
09-13-2004, 12:32 AM
I have heard some pros and cons for putting 410 gears in the rear,,,,,, has anyone out there done this?,,,,, this question only applies to the Supercharged 03 and up Cobra, if so, what do you think now?,,,, was it worth it?,,,,,, did it make a big diff,,,,, talk to me buds,,,,thanks

09-14-2004, 07:28 PM
Not me. We like to head out for the beach alot and that is a 175 mile drive on I-40. If I went to a gear like you mentioned, it would be unnecessary wear and tear on the engine for no reason. I don't race mine at the strip or street, but if I did, I would be satisfied with it's present performance.:flag:

09-14-2004, 08:22 PM
I just got my car back tonight from getting 4:10's and a pro 5.0 shifter. All I can say is AWSOME AWSOME. I am totally happy I went throught with it. The car totally rips. I got bad milage anyway so I didnt sweat that part of it. I think the 4:10s are the way to go. Just my opinion though. best of luck with what ever you choose.


Dave B.
09-14-2004, 08:32 PM
Please tell me,,give me some ideas of what your tach say when crusing in 6th on the interstate?
also, how does is work down low, tell me all about it please?

09-14-2004, 08:47 PM
I cant really tell because my speedo is out of wack now until I get the diablo predator. My wife was beside me and I called her to see how fast we were going. She said she was doing about 70 - 75 I was at 2200 rpm. 1st through 5th is boom boom boom. tachs right up to 4k like nothing.

Dave B.
09-14-2004, 09:04 PM
to talk to you for a min if I could, I will give you my number if you want to call me, or I can call you on my dime, I have a ton of stuff done to my 03 I dont know if you have seen the photos I had on here some time back, it is 9:03 pm here, I am a serious night owl if you can call me, I have so many things I would like to ask you about the gears, plus I have a predator..

09-14-2004, 11:30 PM
I wonder how much effect the gear change has on your top end speed?:doubt:

Dave B.
09-14-2004, 11:53 PM
Well thats one of the questions I want know if our partner in crime will call me but he has not,,if your out there bud, I am up till 3:00AM EDT call me.

Also I am afraid it may use up the power too fast, I have a few years ago and Suzuki TL1000R a high performance V-twin super bike, it was kind of like these things, it had high torque and a low red line of 11500 RPM which is low campaired to the 4 cyclinders like the GSXR1000. any we put a one (1) tooth smaller sprocket on the front with a stock 39 tooth rear, well what happened is it used up all the power too fast, it would just peg the red gear after gear giving the impression of more bottom end.

It was slower, so what we then did is put took the 16 front sprocket off and put the stock 17 tooth back on and then just went up one (1) to a 40 tooth rear sprocket, what a hugh differance, it hard hugh torque, the best way to discribe it is that the high torque V-twin now could throw the bike further down the road. it had the torque to pull the higher gear ratio and basicly had a stronger throw, now thats what I mean when it comes to going to the 410's
are we going to be using up the power too fast just as I discribed with the motorcycle.

09-15-2004, 03:37 PM
dave, call anytime 781 316 4098......cya, phil

09-17-2004, 09:00 PM
Dave, got your message last night but I was sleeeping. I work at 3 A.M. so Im in bed early. I went out on the Highway, at 80 I was a hair under 2500 . I could probally go 81 - 82 at 2500 hope this help, Phil

Dave B.
09-18-2004, 03:37 AM
I dont see how those numbers can be as I was just the other day going
80 MPH with the RPM right at 2500 RPM

So something is not right in you test,in fact I can even tell you that with stock gearing 85 MPH is exactly 2750 RPM orit may have been 90 MPH maybe,

So you should at 80 MPH be around 3000 RPM or higher. check it out and let me know, thanks

Dave B.
09-23-2004, 11:49 PM
Hey I just today went out with my stock rear end gears and ran 80 MPH in 6th gear and my tach was exactly at 2300 or 2350 something like that.

There one thing I did not take into consideration though, I have a set of Toyo 295/35 18 inch tires on the rear, I wounder if there profile could have changed the speedo??????,,,,,,,anyone know??

09-26-2004, 02:24 PM
You have to decide what you want to do in the future and if you are drag racing the car at a strip. On a stock car or around 420 rwhp, then 4.10's are fine. Here is my progression of mods after my car arrived on June 5, 2002:

First day: I drove from the car home from the dealer and installed an 99/01 Cobra Bassani catted x/pipe and catback, drop in K&N. This was my thrid Cobra so I ordered the exhaust to be here before the car arrived. Dynoed 395 rwhp SAE and 370 rwt 900 miles later.

First of July 02: Installed 4.10 gears. Heck yeah. It ran 8 flat on F1 tires with 2.0 sixty footers.

End of July 02: Added 2.93 pulley and JDM chip. 454 rwhp SAE and 450 rwt. Still heck yeah. Bought a set of ET Streets and it went 7.60's with 1.67 60 footers. The car was trapping over 7k rpm in third, not really good by the power curve. Never ran a 1/4.

August 02: Added 2.80 pulley, JBA 1 5/8 headers, nine inch Powerstack filter. Dynoed 478 rwhp SAE and 460 rwt. Ran slightly better on the 1/8. Ran it at Rockingham and it went 11.58 at 123 taching well over 7k in fourth. The car would spin the F1 tires in second at 50 mph with throttle and on cool nights on smooth pavment if you matted the throttle it would break loose in thrid at 80 mph on the stock F1's.

January 03: Swapped out the 4.10's for 3.90 gears. Ran a 11.52 at 123 at Rockingham.

June 03. Added a four pound lower. 503 rwhp SAE and 550 rwt. Forgetabout street racing, something I don't do anyway. F1 tires are useless through third gear. It went 1.52 sixty foot,7.31@97,11.39@122 at FFW in Richmond on a 100 degree day with a full tank of pump gas. The car should now run 10's on a cool night with an 1/8 tank of 100 octane.

If you are going to stay around 420 rwhp, then the 4.10's will be fine. But, if you are going to run around 480-500 rwhp and never race, then the stock 3.55's are what you want. But, if you are going to drag around 500 rwhp with ET Streets, then the 3.90's are perfect. I'll put my 03 against any Cobra running the same mods with 3.55's. This winter I'm adding either a KB or a 125 wet shot and I'm pulling my 3.90's and going back to 3.55's. To trap near 130 in fouth, you'll have to have 3.55's.

I run 10.5 AFS wheels and 315 BFG KD's. These tires are big and heavy. They hook better but you still can't just slam it to the floor. I can usually mat the throttle at 40 and get it plenty loose in second. On the interstate, at 90 mph it will pull like a mule when you put it to the floor in sixth gear. I haven't checked my mileage with the 3.90's but I did with the 4.10's. I drove from north of Charlotte to the southside of Atlanta on I85 and I got 23 mpg driving about 5 mph over the speed limit.

Look ahead at what you want in the future before getting gears. Another thing, 4.10's will increase vibe around 80 mph in most cases.

09-28-2004, 08:21 PM
"...There one thing I did not take into consideration though, I have a set of Toyo 295/35 18 inch tires on the rear, I wounder if there profile could have changed the speedo??????,,,,,,,anyone know??"

The thing that most of people increasing their tire size fail to realize is that they are instantly going to increase their RPMs. Hence, slightly more wear and tear on the engine. This perhaps, could be why you are getting that reading.