I've got a 97 Cobra conv. and I want to somwhat road race it. I also want to dragrace some with it. I was wanting to know what gear I should run in the rear of the car. It is going to be an everyday driver and I was thinking 3.73, 3.90, or 4.10.

Chris

 

If its a daily driver I would NEVER go with 4.10s! In my opinion even 3.73s is close to pushing it. I think 3.55s will be enough for you to definately notice an increase in performance yet still keep it streetable. I don't know what 97 cobras have in the rearend stock but I think its 3.27s (03 Cobras have 3.55's stock), so if you don't mind cruising the highway at higher RPMs and your gas mileage not being as good you should be alright with 3.73's.

 

I would say 3.73 or 4.10s. The 4v really like gears. Scothew has a '96 Cobra and should be able to provide a little more insight. I'm thinking about 4.10 or 4.30 for my Mach . . . unless I decide to blow her.

 

I reccommend 4.10s because the 4.6 DOHC motors love to rev.

 

Please, spare us the details

 

Can't type a long reply at the moment. I will tomorrow morning from work.

 

Ok here we go.

I am running 4.10's in my cobra in which I used as a daily driver for quite some time. Even with the 4.10's, i still get 25mpg on the freeway so lets not go into the "It will kill your mpg" crap. 4v motors love to rev and at 80mph on the freeway, i am still not even in my powerband in 5th gear.

For drag racing, no less than 4.10's. Anything smaller and its going to take you forever up through the gears. Although, with 3.73's I believe you could still cross the traps in 3rd instead of having to shift to 4th. 4.10's acctually put you in a weird spot where you have to shift to 4th about 75ft before the trap, so it acctually may put the car to low in the rpm range. 4.30's would probably be optimal.

For road racing and curves, i've found that on more technical, tight roads, I wish I had better use of 2nd gear. With 4.10's I find myself redlining 2nd, and having to shift into 3rd alot, where as with 3.73's, I could probably stay in 2nd and power through better.

If I were to stay as a straight street car, with some drag race and some road race, go 4.10's, you will be happy. Its a great all around gear.

if you decide to get a blower on the car at any point, stay with 3.73's or less. I know alot of guys with 96-98 cobra's that do have blowers and the cars still daily drive great with 4.10's though.

 

What about 3.90s? I do have the bottle I'm going to put on it. Just about a 100 or 125 shot whatever is safe on the car. My main goal is street and probably corners. Every once in a while I'm going to drag it, like when somebody just pulls up or something like that. It will be at the track sometimes but mostly I will race my coupe at the track. My cobra like I said will be mostly street and everyonce in a while corners. If I get good enuf I would like race SCCA.

Chris

 

I havent had experience with 3.90's, but i have the other 2. I dont think there will be enough of a difference from 4.10 to 3.90 to really notice. Thats why I say go with 3.73's.

Btw, I ran a 100 shot on my car with 4.10's and it was very very fun on the street.

I highly recommend staying with a ford racing brand gear. They have always been the best quality and least amount of noise if any. All the gear installers I know will only use FRPP

 

I don't like the recent issues people have been having with FRPP gears, i have heard of 3 situations where the gears striped, heres a picture of one instance:

 

That had to be something up.. I've ran FRPP gears and know hundreds of others running them and none have ever done things liek that and i and others have put major abuse and power on theirs.

I think that was a bad install personally.

 

This had to be where its a possible rush job.. Not saying the individuals were not qualified.. You know what I mean..

Break-in time with the proper Friction Modifier oil must be used.. Also, a good 500 mile break in should also take place, to make sure its broke in properly..

There could be a number of scenarios which could cause this.. Doubtfull its the hardened gears fault..

 

You guys make a really good point, thats very possible. Here i was thinking FRPP gears were junk