Opinion on gears

[jking32]

I have been autocrossing for about 2 years. I drove my 03 Cobra the last three events of 2006 and the entire 2007 season on street tires (2 different sets). I have run 6 events so far this season on Avon Tech R's. I have learned alot and have along way to go, but I am having a blast.

Autocrossing is very humbling, getting your butt kicked by 2 to 3 seconds by top runners in my class and 4 to 6 seconds by the top event runners is always an eye opener and makes you strive to learn more and get quicker.

I know the key is seat time..............and I continue to get more and more. My mods are in my signature. As most of you know, driving Mustang's and Cobra's in autocross can be especially challenging. I always find it interesting when I walk the course with guys who talk about mashing the gas and going full throttle in areas where it just isn't possible in my car, unless I want to spin out or create a cloud of smoke and lose more time. Learning to modulate the throttle is very important.

I am always looking for more grip/acceleration. Lets face it, high horsepower cars are very challenging to drive quick.

I am planning to put in a True Trac carrier in this winter and am considering changing the stock 3.55 gear ratio to a 3.73 gear while I am making the carrier change. I currently never run out of RPM in second gear on any of the courses I have run. I was close on one course. I know this will probably make traction even more challenging, but the hope is the increase in acceleration will outweight the traction issue. What do you think?

 

[golden_eye]

My friend has an '01 GT that he autocrosses with and he just swapped his 3.27s for a set of 3.73s. he's pretty satisfied with them and is able to wind out 2nd a bit more. He still rarely hits 3rd except for the longer courses. His times have actually stayed somewhat the same though because even though he has the steeper gears, his tires seem to break loose even easier now, but they are pretty worn to start with.

I'm still running my stock 3.08s and I really could benefit from a steeper gear as I usually have tons of room to go as far as RPMs, even with the lower redline compared to the DOHC 4.6.

FWIW me and my friend are both pretty much stock otherwise and run on street tires.

 

[Conechaser]

It would help to know what class you are trying to stay in. If you are already running aftermarket calipers I'm guessing you're not in ESP or a lesser class. (I don't believe you can go to a 3.73 in ESP as there isn't anything on the same line that came with it from the factory) If you are already in CP or SM... then the gear choice is wide open.

Before you spend the money to do the swap, have some of the "fast guys" in your region drive your car and see what they can do with it. If they are pulling 2+ seconds faster than you... I would save your money.

Just be happy that you don't have 2.73's like I do in my 97 GT that I run in STX. It's rare that I have to shift INTO 2nd gear!

 

[jking32]

I am in SM2. I was originally told to go ESP in 2006. At the end of 2006 I spent alot of time reading the rule book and realized there was no way I fit in ESP with my Alcon brake calipers. In the 2006 rule book I did not fit into SM, but in SM2. I have been there ever since. I checked with the SCCA and asked for their opinion on what I fit into and they said I can run in either SM or SM2, my choice. Since I already have class letters made up for SM2, I just stayed.

I have one guy in my region who is pretty quick in his Cobra. I will have to see if he is willing to run it in fun runs.

 

[Conechaser]

I am in SM2. I was originally told to go ESP in 2006. At the end of 2006 I spent alot of time reading the rule book and realized there was no way I fit in ESP with my Alcon brake calipers. In the 2006 rule book I did not fit into SM, but in SM2. I have been there ever since. I checked with the SCCA and asked for their opinion on what I fit into and they said I can run in either SM or SM2, my choice. Since I already have class letters made up for SM2, I just stayed.

I have one guy in my region who is pretty quick in his Cobra. I will have to see if he is willing to run it in fun runs.

I wouldn't just look to other Cobra or Mustang drivers... look for someone who is fast in ANYTHING RWD with hp/tq. Vettes, M3, Camaro.

Where do you run? KC, Topeka, Wichita? Isn't Iola someplace in the middle of all three?

 

[TroyV]

I have 5 years of autocross in my 03. The Devens facility in Ayer Ma. is a very big place, so we use 3rd gear more often than the typical autox venues elsewhere.

My suggestion to you is to look at a tire change before looking at gearing. Tech R's are a terrible autocross tire. They don't heat up quick enough for short course work, and they over heat too easily for long course work.

Not to nit pick the poster above me, but none of mentioned platforms, short of the Camaro has nearly as much weight over the nose as an 03 Cobra does. To be effective the car needs a stickier tire. The V710 is ideal as it maintains good grip for the amount of weight you are carrying. It heats up relatively quickly, and stays in for some time before over heating. Having run everthing out there that can fit my car, I can say V's are a lot faster than Tech R's. Even Hoosier R6's are quicker than Tech's. A6's are very quick, but won't last long, especially if you are over driving the car and sliding around a lot.

Another tire you can look at is the Hankook Z214 C71. They are almost as quick as Hoosier A's, but last just a tad longer.........watch out though... they are easy to flatspot as they get older....even with ABS. Ask me how I know.

In short, V710's are the fastest tire I run that last an entire season for me.

 

[jking32]

Conechaser, I run the KC region at Arrowhead. Great place to run. I could probably autocross in some region around me almost every weekend, but then I would also be broke and divorced.

TroyV, thanks for the information. I have found there does not seem to be alot of people autocrossing 03/04 Cobras. I bought the tech R's because I got them new for $100 each. I figured I could get started on them and change up next season.

The cost to create a trailer hitch that is completely hidden on my car, buying a small trailer, harness, alternate wheels, tires................was as much as I could handle this spring. As far as I have to drive to get to my events makes it impossible to drive on what I run.

I have learned alot on these tires. The street tires I ran were very stable and predictable, they lacked the grip of R Comps, but were great when it came to learning car control and learning not to overdrive what you have. The Avons stick very well in the turns but don't handle heavy breaking very well. I want the 710's, but that will have to wait until this season is over. I am enjoying my seat time and learn something every event I attend.

 

[TroyV]

Wow. That looks familiar.... did the same thing this year..

http://www.snaptom.com/gallery/4804401_4jCGu#285455768_42NH9-A-LB

I wish I had a better pic of this trailer, but it is a nice one... all aluminum with lockable box, and room for an easy up between the tire rack and the box.

I would consider roving the NASA or SCCA forums for V710 scrubs.. These tires are out there for cheap with half life in them.. It's a good deal if you can find an installer who can mount and balance for cheap.

 

[TroyV]

BTW I'm not looking to steer you away from gears. I had great success moving from 3.27 to 3.73 with my 99 GT years ago. I'm just saying that between the two, you will get a more positive result from a better tire than from gears.....especially if you are doing short course stuff..

 

[jking32]

TroyV - I'll have to see what I can swing this winter. I have seen some out their for sale before. They definately don't stay around too long.

 

[Conechaser]

I have 5 years of autocross in my 03. The Devens facility in Ayer Ma. is a very big place, so we use 3rd gear more often than the typical autox venues elsewhere.

My suggestion to you is to look at a tire change before looking at gearing. Tech R's are a terrible autocross tire. They don't heat up quick enough for short course work, and they over heat too easily for long course work.

Not to nit pick the poster above me, but none of mentioned platforms, short of the Camaro has nearly as much weight over the nose as an 03 Cobra does. To be effective the car needs a stickier tire. The V710 is ideal as it maintains good grip for the amount of weight you are carrying. It heats up relatively quickly, and stays in for some time before over heating. Having run everthing out there that can fit my car, I can say V's are a lot faster than Tech R's. Even Hoosier R6's are quicker than Tech's. A6's are very quick, but won't last long, especially if you are over driving the car and sliding around a lot.

Another tire you can look at is the Hankook Z214 C71. They are almost as quick as Hoosier A's, but last just a tad longer.........watch out though... they are easy to flatspot as they get older....even with ABS. Ask me how I know.

In short, V710's are the fastest tire I run that last an entire season for me.

Troy, no problem on your comments. My thought was to not limit his driver choice to just Mustang/Cobra drivers but to include the guys who are fast in ANYTHING they drive. There are some seriously fast guys in KC to choose from. I would still first look toward people in RWD cars that have power. I haven't run a KC event for a while but Jim French, Jim Harrison, Debbie Pruett, Randy Herrick, and maybe even Chris Conant come to mind. If someone unfamiliar with the car jumps in and goes 1-2 seconds quicker... it's not the car.

 

[TroyV]

Good point. I have been "schooled" in my own car before, by non Cobra drivers no less. Every region has its hot shoes.

My intent was to look at ways to drop time (seat time not included) that would be cost effective and keep from cracking a gear box open and applying labor to an end that may or may not produce the intended result.

 

[Conechaser]

Good point. I have been "schooled" in my own car before, by non Cobra drivers no less. Every region has its hot shoes.

My intent was to look at ways to drop time (seat time not included) that would be cost effective and keep from ing a gear box open and applying labor to an end that may or may not produce the intended result.

I'm with you there as well. Even though a gear change isn't "that" expensive... it's still a process and just as expensive to undo if it doesn't have the intended results. I think a 3.55 is a pretty decent gear for AutoX. Too much gear will just make it more difficult to get the power down to the ground.

My thought was to see where the driver is compared to the "fast guys" If they can go faster in the car as it currently sits compared to the owner... then seat time is my first mod. The nice thing about doing the driver mod before the car mod is that the improvements last a lifetime instead of staying with the car. Instead of working on accelleration... work on momentum and throttle input. There are times when you can be fast and times when you have to be slow, the hard part is knowing the difference and how to make the car do what you want it to..

Now, if the hot shoes can't go faster, then it's time to work on the car. Tires, alignments, gear, weight reduction, etc...

 

[David Hester]

For what it's worth, I've been autocrossing since '84. http://www.rheacermotorsports.com/racerbios.html
Altenburg and Pobst were still autocrossing back then.
Lot's of people seem to think R compound tires are evil, but we have used Yokohama, Kumho, Hoosier, BFG and Goodyear over the years (Formula Vee and Formula Ford slicks).
I vote for using the stock gearing to your advantage. Slightly higher stock gearing will lessen tire spin off corners and you have plenty of torque.

 

[brkntrxn]

So bear with my rambling, I think I have a point here (but maybe not).....

Going from a 3.55 to a 3.73 is a minimul change and will gain you a bit of gearing advantage as far as acceleration goes (and about 4mph is the difference at the top of 2nd gear with the T56 gearing). A shorter tire will do the same for you since a shorter tire will change your effective gearing (a shorter tire will have the same effect as numerically increasing your gear ratio). I am making the assumption that your are running 275 tires on a 9" rim and the norm for 275 tires is a 275/40/17. So, ideally, you would be able to find a 275/35 and have a similar effect as changing the rear gearing. But, I do not see any 275/35 tires for sale by anyone, anywhere, in any type; so that won't help you. Bad example maybe...

I did notice that Kuhmo Ecsta V710s 275/40s are 25.4" in overall diameter as compared to all of the other 275/40s which are 25.5" in diameter. That difference is almost neglible, but does decrease the top speed of 2nd gear by about a 1/2mph. Which is ever so slightly increasing your gearing advantage. I am sure that when you are looking for ever single advantage in autocrossing, the little things like this may make a difference. LOL, of course, a variance in tire pressure can fully negate the size difference.

 

[speedfreak440]

Either one of you guys have pics of how you mounted that trailer hitch? Sorry for going off topic but I would love to have a hitch on my Cobra.

 

[jking32]

Here are a few photo's. This only applies to 03 and 04 Cobra's as they are the only 2 year and model cars with a curved rear bumper. All other Mustang's that I have looked at have straight bumpers.

I used 1 1/4" diameter square tube that is 3/8" thick. I bought the 1 1/4" receiver online. If you look at how all the other Mustang hitches are mounted, I mounted to the same locations. The end straps are bent at an angle that allows the tubing to be recessed into the gap between the trunk pan and the bumper. The curve in the rear bumper allowed me to fit the receiver vertically in between steel tube and the bumper. I used the 1 1/4" square tube because the receiver tube is 1 1/2", and there is only about 2 5/8" of space between the center of the bumper and the trunk pan.

I cut and bent the straps then put the mounting holes in them and then loosely mounted them to the car, layed the square tube on top of them until I was happy with the fitment then tack welded them on. I welded on the receiver at the height you see, then cut off most of the length above the weld. I only left about 2 inches above the square tube. I used truck bed nuts to mount to the bumper. Unbolt and finish weld it, add a couple of safety chain loops, grind and paint or powder coat if you like.

The ball hitch is an 1 1/4" X 3/8" tubing that is just cut and welded to the demensions that fit the way you want. One important note is to make the ball height the same as the receiver mounting point. Too low or too high, will create lever on the piece mounted to the car and possibly damage it due to the encrease leverage the ball hitch will place on the receiver. I added a little extra bracing to mine for peace of mind. The piece the ball is hooked to is 1/2" thick steel.

Obviously holes have to be drilled......you get the idea. I pull my tire trailer and it weights about 750lbs fully loaded. I have pulled my trailer about 30 hours of travel so far most of it at highway speeds and inspected my setup after each pull and all is looking great so far.

 

[speedfreak440]

Thanks a ton man! The closest track to me is about 1.5 hours away so maybe this way I can pack up a little trailer & get all my stuff there without wearing out sticky tires on the interstate. Thanks :beer:

 

[jking32]

That is why I do it. I am an hour and forty minutes south of where I run.