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View Full Version : 3:73 3:90 or 4:10


Karlfly
05-10-2003, 05:12 PM
Does anyone have an opinion about what Gear ratio to install. I intened to drive this car a Texas World Speedway from time to time. I heard that you can easily hit 145-150 in the straight away. I don't intend to drive the car over 120 very often, I just don't want to be fast in the corners and get passed in the straight away.

I heard that 4:10's in this car will limit you to a top speed of 120???

tcrews
05-11-2003, 12:11 AM
You've heard wrong then....4.10s will give you the ability to pull to 160mph, you can't do that even with the stock 3.27s.

For road-course/auto-cross driving, most prefer 3.73s as it allows for you to stay in 2nd gear longer and exit the turns a little stronger. 4.10s will allow you to pull a higher top-end though.

If you prefer dragracing, then minimum 4.30s and they are still a great street gear.

3.90s could be a good compromise for open-tracking between the the 3.73 and 4.10 gears....but I don't know anyone running them.

redsnake99
05-11-2003, 09:14 AM
I really like the 3.55's I put in my 99 Cobra. This is the same ratio in the stock 2003's. It allows me the all around use of daily driver, track car and occasional drag strip use.

What I like best about this ratio is that it puts the 2200 RPM resonating drone noise out of the most used speed ranges, something that the stock 3.27's used to really bug me with.

It really depends on what your primary use or primary goal is with your car. More drag strip - higher ratio. More open track use middle range.

:D

Bartman01
05-11-2003, 11:48 AM
I am writing this from memory (and I running a temperature with a splitting headache), so please jump in if I am getting the technical details wrong:

The 4.10's will only limit the top speed of the car on a dyno where there are no aerodynamics to worry about. With the stock 3.27 gears, the top speed you can attain on the street is in 4th (drag limited). If you take the top speed with 3.27's and run the numbers, 4.10s probably do seem to limit it.

By switching to 4.10's, 5th is now cabable of overcoming the drag limitation it had with 3.27's and becomes the gear in which top speed is attained. You may decrease the top speed you can attain with 4th, however you can now accelerate in 5th. In a real world environment (ie on the track), you should be able to attain a higher top speed with 4.10's.

At some point, taller gears will limit your top speed.

BadMoFo
05-14-2003, 08:19 AM
I just had the 4.10's installed in my 99 cobra and I almost wish I had gone with 4.30's. but I plan to add some power later so I will be content for now.

johnbasf
05-14-2003, 11:24 PM
160 mph with 4:10's would be possible in perfect conditions like no wind or drag. I run these gears and hit the rev limit at 130 mph in 4th gear. 5th gear is pretty much useless.

Cobra-R
05-15-2003, 12:46 PM
Originally posted by johnbasf
160 mph with 4:10's would be possible in perfect conditions like no wind or drag. I run these gears and hit the rev limit at 130 mph in 4th gear. 5th gear is pretty much useless.

I agree. If you are, or plan to be making gobs of power in the future, go with 3.90's (Steve Reagan is adding them now) or 3.73's.
I run Road America a couple times a year and 4.10's are good for the straight aways, but if I ran the car more at shorter tracks (ie: slower & tighter) I would have gone with 4.30's. I think the additional pull out of corners outweigh's the additional few mph you "may" get from more less gear.

Brian

johnbasf
05-15-2003, 07:04 PM
Originally posted by Cobra-R
I agree. If you are, or plan to be making gobs of power in the future, go with 3.90's (Steve Reagan is adding them now) or 3.73's.
I run Road America a couple times a year and 4.10's are good for the straight aways, but if I ran the car more at shorter tracks (ie: slower & tighter) I would have gone with 4.30's. I think the additional pull out of corners outweigh's the additional few mph you "may" get from more less gear.

Brian

Dang, somebody finally agrees with me on this.

Bartman01
05-15-2003, 08:09 PM
Originally posted by johnbasf
160 mph with 4:10's would be possible in perfect conditions like no wind or drag. I run these gears and hit the rev limit at 130 mph in 4th gear. 5th gear is pretty much useless.

OK, now I am confused. I have seen people claim that they could pull in 5th after they installed 4.10's. Now you are saying that for you 5th is still useless with them. Is this a difference in the model years? Do the 99 and 01's react differently than the older cars?

One thing to always consider is WHAT you are going to use your car for. 1/4 mile monster and twisty king are two very different applications with differing setups.

johnbasf
05-15-2003, 08:16 PM
All I know is at Lowes Motor Speedway last year the car would not accelerate in 5th. If I was at the Salt Flats it might get to 160mph.

97whitevert
05-15-2003, 10:56 PM
Originally posted by johnbasf
Dang, somebody finally agrees with me on this. agreed... oh and let us know when you want ot do the swap....

Big Daddy
05-16-2003, 01:52 AM
Originally posted by Bartman01
OK, now I am confused. I have seen people claim that they could pull in 5th after they installed 4.10's. Now you are saying that for you 5th is still useless with them. Is this a difference in the model years? Do the 99 and 01's react differently than the older cars?

One thing to always consider is WHAT you are going to use your car for. 1/4 mile monster and twisty king are two very different applications with differing setups.

Well I can pull in 5th with 3:73's in my car so maybe it is just a matter of horse power! :D ;)

White Venom
05-16-2003, 01:54 AM
Originally posted by johnbasf
160 mph with 4:10's would be possible in perfect conditions like no wind or drag. I run these gears and hit the rev limit at 130 mph in 4th gear. 5th gear is pretty much useless.
same here

tcrews
05-16-2003, 10:53 AM
Only problem is that is has been done. Wish I could remember his name (actually I know two people) but he pulled 160mph in 5th gear, 4.10 rears and a stock Cobra. He does the cross-country high-speed racing.

5th is not useless with 4.10s and a stock Cobra, it will just take you a LONG time to pull your top speed since it's an overdrive gear.

Again, it really depends on what you use the car for....daily driving, dragstrip, auto-x, etc.....

Karlfly
05-16-2003, 11:16 AM
I'm sure with a supercharger you wouldn't have a problem pulling in 5th gear even with stock 3:27's. However, I don't plan to ever have one. This car will probably never have more than about 360H.P. I plan to drive it on the street mainly and spend about 4-5 weekends a year at Texas World Speedway on the road couse.

As soon as I get a lawyer to fix the ticket I got the other day for going 37 mph over the limit, I'll let you all know what I get and how they pan out.


:cussing:

sn8kbit
05-16-2003, 06:14 PM
Just got the car out of the shop last night, really haven't "played" with it any yet, but the 3.90's feel great. If the chip is right for the gear and wheel size, 2700 in 5th at 70 mph. I also had an aluminum flywheel installed, so that car seems to pull fine in 5th, well, a lot better than it did before. Won't know how it is on track till later this summer, but for now, I feel it's a good compromise gear between the 3.73 and 4.10.