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28" W/ 3.15 gears

13K views 59 replies 11 participants last post by  OzzyLiriano 
#1 ·
Will it be enough? I finally got my 275/60/15 mt street installed but im wondering if i need higher gears to spin those tires? 3.31 is becoming more of an option everytime i see these auto at the track.
 
#2 ·
I have 3.31 on my manual, if you hit the wetbox before trying to sticky up the tires before a run, I can assure you will spin.

Edit: And by higher, do you mean numerically?
 
#5 ·
Agreed^^^. Backing in the wetbox and you should be able to break them lose no problem.

Assuming your mustang has basic bolt-ons, why go with a 28" tall tire? You should be able to finish the quarter mile in 4th with a 26" tall tire and those 3.15 gears. Although, ore mods or 4.10 gears will make the 28" drag radial more practical.

Let us know how things go at the track!

Shane
 
#7 ·
Tires were given free and rims were a great price when i got them, thats why i have 28"

---------- Post added at 06:22 PM ---------- Previous post was at 06:17 PM ----------

You shouldn't have any problems. I run a 295/55-15 which comes in at 27.8" tall and spinning the tires isn't a problem. On the street I still have to feather the throttle. The 3.31 wouldn't really make a big enough difference but a converter would. I would see how you do with the 3.15's first before making a decision.
Yes, im not changing gears till winter when well its not really winter in miami, but i would like to go to the 1/4 mile strip by then, i will keep practing here at the 1/8 till then.
Where should i be at with these mods/specs at the 1/8?
Stock with 235/50/18 all season tires base rims i ran 8.4

Now that i have bama tune, x pipe and bmr lca and 275/60/15 mts, what is the goal i should be aiming for? 7.9?
 
#6 ·
You shouldn't have any problems. I run a 295/55-15 which comes in at 27.8" tall and spinning the tires isn't a problem. On the street I still have to feather the throttle. The 3.31 wouldn't really make a big enough difference but a converter would. I would see how you do with the 3.15's first before making a decision.
 
#8 ·
Guarantee you that if you brake stand it you will spin the tires, if not rev it higher lol. I'd install a launch assist and play with launching at 2500-4000rpms with that set-up. Your 13 might even have it already.

Switching from 3:15 to 3:31 isn't going to save you a considerable time on your et. Even switching to 3:55 isn't going to make that much of a difference. A guy could line up next to you with a supercharger/ nitrous on street tires in his 5.0 that has a 3:15 auto and blow your doors off.
 
#9 ·
Guarantee you that if you brake stand it you will spin the tires, if not rev it higher lol. I'd install a launch assist and play with launching at 2500-4000rpms with that set-up. Your 13 might even have it already.

Switching from 3:15 to 3:31 isn't going to save you a considerable time on your et. Even switching to 3:55 isn't going to make that much of a difference. A guy could line up next to you with a supercharger/ nitrous on street tires in his 5.0 that has a 3:15 auto and blow your doors off.
Thats true, i liked my car stock more than tuned, but lets blame it on my 20s for now right lol
 
#12 ·
If I break down and get some, I'm going with a 29" 325/50 mainly for looks, I like a big tire that fills the wheelwell, and for more rubber on the ground. My 3.15's should still work good enough for a while.
 
#15 ·
Again you've made a compromise choice that won't work like you want.

You'll spin them in the box or on really ****ty track prep, that isn't the issue. The issue is you have put a 28 inch tall tire on a stock converter with lazy rear gears. Even with the steep first in the 6R80, you are giving away 60' time by a good deal. Every tenth lost here is 2-4 at the top end.

I'm a running a 28' tire on my 91 tuned MT82 car, to keep it off the limiter so I can finish in 4th. I can pretty much do a 5000 rpm clutch drop launch and dead hook if there's any sort of 1/2 decent track prep.

So, envision what I am saying for you. You can brake-torque the stock weak converter to about 2000-ish rpm. You let go and the engine's basically dead for power production. This mean big bog, uhhhhhh-wahhhhhhhh as it catches up. This is a recipe for slow times, something you're already familiar with.
 
#18 ·
Again you've made a compromise choice that won't work like you want.

You'll spin them in the box or on really ****ty track prep, that isn't the issue. The issue is you have put a 28 inch tall tire on a stock converter with lazy rear gears. Even with the steep first in the 6R80, you are giving away 60' time by a good deal. Every tenth lost here is 2-4 at the top end.

I'm a running a 28' tire on my 91 tuned MT82 car, to keep it off the limiter so I can finish in 4th. I can pretty much do a 5000 rpm clutch drop launch and dead hook if there's any sort of 1/2 decent track prep.

So, envision what I am saying for you. You can brake-torque the stock weak converter to about 2000-ish rpm. You let go and the engine's basically dead for power production. This mean big bog, uhhhhhh-wahhhhhhhh as it catches up. This is a recipe for slow times, something you're already familiar with.
So what is your solution in my case?
 
#19 ·
**** man, a 26" tire is fine for an auto car with the stock converter.

Stop dycking around, think it through and build a package that will do what you want. There's more than enough information out there to make buying things once and right, easy.

You have several options here, all cost more money, sadly in the wake of what you've wasted already:

26 inch tire will take best advantage of the soft gearing and flabby stock converter. Probably the cheapest option. Still not ideal but cheapest.

Put a steeper gear in the back to prop up the tall tire. The stock converter still won't allow a stall speed to take best advantage of that but, it will get it out of the soft zone faster making for better 60s. Cost level #2.

Put a converter in to allow a flash to higher rpm stall that will get this motor into a power producing range for best acceleration, parts and labour probably the most expensive single option.

Option four is put a bit more gear in AND a converter and rock out. Definitely most expensive option but addresses the most shortcomings: the tire, the gear and the converter pretty much in one setup.
 
#21 ·
**** man, a 26" tire is fine for an auto car with the stock converter.

Stop dycking around, think it through and build a package that will do what you want. There's more than enough information out there to make buying things once and right, easy.

You have several options here, all cost more money, sadly in the wake of what you've wasted already:

26 inch tire will take best advantage of the soft gearing and flabby stock converter. Probably the cheapest option. Still not ideal but cheapest.

Put a steeper gear in the back to prop up the tall tire. The stock converter still won't allow a stall speed to take best advantage of that but, it will get it out of the soft zone faster making for better 60s. Cost level #2.

Put a converter in to allow a flash to higher rpm stall that will get this motor into a power producing range for best acceleration, parts and labour probably the most expensive single option.

Option four is put a bit more gear in AND a converter and rock out. Definitely most expensive option but addresses the most shortcomings: the tire, the gear and the converter pretty much in one setup.
S
Option#1 would means i cant use my 15x10 rims with any set of tires? I need to do some research but im in the hospital till tomorrow, got a throat infection so if u can answer this it would be great if not ill look tomorrow.

Option #2 what gear?
Option #3 what is the best converter?
Dont want to make another thread, im sure i can look it up if anything
Well ption 4 i get it that one with 2 and 3
 
#26 ·
There are a lot more tire choices in the 26" height range than in 27, 28, 29, etc.

Be aware also not to expect too much out of ET Streets, particularly if they are used. I find that tire touchy and when it goes off, it goes off badly. It needs very little burnout to heat and if you do it too much it gets greasy.

You should really use a dedicated drag tire if you're going to the trouble of using specific rims. I drive my Hoosier drag slicks out to the track and back no issues. I don't even air them up. I prefer a bias slick but, that's b/c I have an MT car. You could get a drag radial which would make the car easier to drive at the track and off it. With a bias slick, you have to fly the ship all the way down track and that can be intimidating for some, like the guy who put his $200,000 Olds 442 restomod into the wall at the top end of my local track last week.
 
#28 ·
Thanks a lot! I think i need to stop worrying about gears so much and just save up for the paxton kit....this might be a stupid question, but is their a option of turning off a converter when your driving on these streets? This is my best looking ride at my house, i debating on just waiting a couple more years to make the car a "drag car". Im just going to finish the suspension and get the right size tires
No, the stall rpm is set at the factory.
 
#30 ·
It would be nice if they made a variable ratio coverter like in some turbos. Adjust the vanes according to what you want to do.
 
#33 ·
My advice is to stop spending money until you internalize some of the advice you've received here and chart a proper course ahead. Now you're talking about another set of tires and spending 6000 bucks + on a blower kit without any sense of the implications of either decision, as far as I can tell.

If you insist on going for another set of tires, go with a real drag slick this time. That will maximize your traction, repeatability and support future changes of plan, even FI.

I see guys like you at the track all the time. Mortgaged the kids' college fund into pretty but not so well thought out modifications, rather than maximizing what they have and working from there.

Understand me, if I hadn't done exactly the same thing repeatedly, I wouldn't be so hard on you for making the same mistakes.
 
#36 ·
Nope...I'm smarter than that...no kids. :thumb:

Left me plenty for my own Masters' plus a little fun with the 5.0. I'm about doing it well, for as little $$$ as possible. So far, so good. I'm into this car for about $1000 bucks in perf mods and I'm knocking right on the door of 11s. Pretty happy to keep chasing that 11 with what little I have on the car, as it'll come on the right day.
 
#47 ·
Did you see that guy casper and his black 5.0, he had great times
He didn't have great times, the shop he dropped off his car did. He wasn't even driving it. A few things about his car. Lots of weight reduction. It was done on a closed track with excellent track prep. And in -1500 DA. That's some incredible DA. With normal DA they've been unable to get his car out of the 11's now.
 
#50 ·
They are elastomer rubber but much smaller than stock with heavier sleeve and no voids in them to soften them up.
 
#52 ·
It should be within reason. Roush cars are set up with about a 1+" drop at the rear from the factory anyway and this piece is engineered for a lowered car. Every car is slightly different in this regard of course.

On 55D springs on my car, pinion angle measures about -1.5, for what that data point's worth, especially since I didn't do any before and after measuring. Regardless, the much stiffer bushing much more strongly resists the wrap up effect anyway so one doesn't need as much negative pinion angle.

Keep in mind also, this link articulates both up and down, side to side and rotationally around the yaw axis. This is murder on a poly bushing and can lead to weird handling effects or breakdown of the bush itself. Poly likes to stay in one plane, if possible and, over time, they need to be monitored carefully for lubrication and damage. This part is in and forget it; it passes Ford's stringent oem durability testing, same as the stock part, because it is a stock part.
 
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