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Discussion Starter #1
How important is it?
 

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I definitely believe it’s worth noting, but until I see a problem with what I have, I don’t believe it’s worth correcting, if that makes sense.
 

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The higher (numerically) the ratio, the softer the hit on the tire. Especially in a high torque situation. I run a small 26 X 8.5 tire and found that getting the car to 60' was easier with a 4.10:1 gear than it was with a 3.73:1 rear gear. The taller gear (lower numerically) shocks the tire harder. It is counter intuitive but works. It is leverage at work. Not every car is going to experience this same scenario.There is a lot to be said about having the rear suspension set up right to begin with. If the rear set up is wrong, then it does not matter what gear is in the car, it still is not going to work the way it should.
 

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There are many variables that come to play. What are you doing with the car? Race only or the street strip combo. The weight of the car. the power the motor makes and where. A power adder car makes more torque down low for the most part. The trans weather a stick or auto and what gears are in it. Tire size and so on.
 

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Discussion Starter #5
There are many variables that come to play. What are you doing with the car? Race only or the street strip combo. The weight of the car. the power the motor makes and where. A power adder car makes more torque down low for the most part. The trans weather a stick or auto and what gears are in it. Tire size and so on.
I'm planning on hitting the strip for the first time ever. I have a million questions but I'm pacing myself. Lol.

The car will be street/strip.

I haven't weighed the car. It's a '95 GT with power everything and A/C. The hood is fiberglass along with aluminum heads and no smog or cats. That's about all of the weight loss the car has seen. I weigh 195.

In good air; the car has made 400RWHP at 5900. Engine is N/A. No adders.

For now I'm using a stock T5.

Rear gears are 3.73.

Tires are 25.7" Nitto 555R (315/35-17)

My plans are to use Strange 10 way struts and shocks. Coilovers will be used up front.
In the rear; I'll be using stock GT coils cut to my liking.
I have new J&M uppers and lowers.
I'll most likely use relocation brackets in the rear for the lowers as I'll be lowering the car somewhat.
I'll be installing M&H or M/T drag radials. I don't want to run slicks until I decide if I'm going all out.

The reason I posted this question is that I'm second guessing my rear gear choice. I was using 4.10's and swapped them out to 3.73's. Maybe that was a bad move?
 

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If the 400 RWHP is a real number you should be running low 11s or high 10s in the 120-125MPH range (assuming a 3100 lbs race weight). A 4.10/28" tire would work great in that combo.
 

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Discussion Starter #7
If the 400 RWHP is a real number you should be running low 11s or high 10s in the 120-125MPH range (assuming a 3100 lbs race weight). A 4.10/28" tire would work great in that combo.
I'm sure the car weighs a few hundred lbs more going by the delivered weight found in a search. Then add my weight. I'd love to run a 28" tire as it looks much better on a SN95 but it seems that the majority like the 26" tires. Old Grumpy Jenkins use to say that the number one mistake that racers make is running too much tire.
 

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Discussion Starter #8
I found a post where the car was nearly identical to mine with the difference being that I have a fiberglass hood. His car weighs 3300 without him in it.
 

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Starting line ratio (SLR) and gearing a a bit of a different thing...

There are multiple ways to achieve the same SLR.

In basic terms of rear gear changes. going up numerically in gearing, slows the rotation of the tire down, but increases the torque applied to the tire, and lowering reverses it.

So the hunt for optimal SLR is figuring out YOUR COMBO's ideal wheel speed/torque ratio. There will never be some universal SLR.
 

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The higher (numerically) the ratio, the softer the hit on the tire. Especially in a high torque situation. I run a small 26 X 8.5 tire and found that getting the car to 60' was easier with a 4.10:1 gear than it was with a 3.73:1 rear gear. The taller gear (lower numerically) shocks the tire harder. It is counter intuitive but works. It is leverage at work. Not every car is going to experience this same scenario.There is a lot to be said about having the rear suspension set up right to begin with. If the rear set up is wrong, then it does not matter what gear is in the car, it still is not going to work the way it should.
Not the case... it's only slowing the wheel down. Torque (mechanical advantage) is going up.
 

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If you have not bought the drag radials, unless you have an adjustable clutch or clutchtamer, I would get slicks. Radials are not easy to launch with a standard clutch and a 5 speed. Tire type is more important than gear ratio if you have never been to the track.
 

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Automatics and sticks are different worlds. The last thing I look at in an auto is starting line ratio. In an auto, the torque converter acts like a hydraulic gear set. It can have in the 2.5 ratio when the stator is locked by the sprags, and as the stator releases and starts to freewheel the torque multiplication falls and input to output RPM ratio drops.

The converter is more important than the SLR at the start.

In a manual, you have engine bog and torque curve, and how well you can drive the clutch, to contend with. SLR is way more important in a stick.

There isn't a thing in the world wrong with a radial until you have a ton of power on poor prep. Then when you get a certain power level you'll see the lower pressures in a slick will help get a more consistent hit and let you bring power in earlier on mediocre prep.

The first thing I look at is stuff the tallest widest tire I can fit that suits my driving and the track prep. Then I set the gear for peak RPM through the traps. Then I see how the car behaves off the line and decide if I have to change the converter, clutch, or low gear. I've had everything from stock to a 8 second 1/4 mile stick and a 7 second auto.

I have a 1.69 low gear right now with a 4.10 rear gear in a single T4 midframe car that has a class legal "76mm" for most races. At 3200 lbs it does a 1.15 60ft on 10.50 28 tall Pro Bracket radials (I've been as low as a 1.13's) and a low 1.2 on stiff wall slicks with tubes. The biggest difference between radials and bias ply slicks is on poor prep where I can run the bias at 10 lbs (until it ruins sidewalls and rubber in 10-15 passes) and run the radial at 13-14. The radial is clearly better down track as it stays flatter and does not knock off like a bias. The bias worse for knocking tires at speed but better on crappy track surface.

If you have a lower power car you won't have any of these issues. Everyone around here that is somewhat fast is pretty much changing to a radial unless prep or track surface is bad. Even stick cars. Everyone real fast is using radials as much as they can unless on some of the rough tracks.
 

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TomR, I am sure you are correct. I have never had bias tires. But I have broken a axle and twisted a driveshaft with a stock motor on radials.

Something has to give clutch slip, tire spin, side wall wrinkle, I wish I had started with slicks and not radials.

I think Radials are for street cars and experienced drag racers, not newbies trying to learn how to go a to b
 

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Discussion Starter #14
If you have not bought the drag radials, unless you have an adjustable clutch or clutchtamer, I would get slicks. Radials are not easy to launch with a standard clutch and a 5 speed. Tire type is more important than gear ratio if you have never been to the track.
The clutch tamer was suggested to me early on and I plan on trying one. I like the concept.
 

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Discussion Starter #15
Automatics and sticks are different worlds. The last thing I look at in an auto is starting line ratio. In an auto, the torque converter acts like a hydraulic gear set. It can have in the 2.5 ratio when the stator is locked by the sprags, and as the stator releases and starts to freewheel the torque multiplication falls and input to output RPM ratio drops.

The converter is more important than the SLR at the start.

In a manual, you have engine bog and torque curve, and how well you can drive the clutch, to contend with. SLR is way more important in a stick.

There isn't a thing in the world wrong with a radial until you have a ton of power on poor prep. Then when you get a certain power level you'll see the lower pressures in a slick will help get a more consistent hit and let you bring power in earlier on mediocre prep.

The first thing I look at is stuff the tallest widest tire I can fit that suits my driving and the track prep. Then I set the gear for peak RPM through the traps. Then I see how the car behaves off the line and decide if I have to change the converter, clutch, or low gear. I've had everything from stock to a 8 second 1/4 mile stick and a 7 second auto.

I have a 1.69 low gear right now with a 4.10 rear gear in a single T4 midframe car that has a class legal "76mm" for most races. At 3200 lbs it does a 1.15 60ft on 10.50 28 tall Pro Bracket radials (I've been as low as a 1.13's) and a low 1.2 on stiff wall slicks with tubes. The biggest difference between radials and bias ply slicks is on poor prep where I can run the bias at 10 lbs (until it ruins sidewalls and rubber in 10-15 passes) and run the radial at 13-14. The radial is clearly better down track as it stays flatter and does not knock off like a bias. The bias worse for knocking tires at speed but better on crappy track surface.

If you have a lower power car you won't have any of these issues. Everyone around here that is somewhat fast is pretty much changing to a radial unless prep or track surface is bad. Even stick cars. Everyone real fast is using radials as much as they can unless on some of the rough tracks.
Thanks for the great reply; Tom.
I'm curious; would you run the tallest and widest tire on my car? I think I'd have to run 4.56 gears to hit the trap at 5900 with a 28" tire.
I like the challenge of running drag radials with a stick and many guys do just that.
 

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I'm planning on hitting the strip for the first time ever. I have a million questions but I'm pacing myself. Lol.

The car will be street/strip.

I haven't weighed the car. It's a '95 GT with power everything and A/C. The hood is fiberglass along with aluminum heads and no smog or cats. That's about all of the weight loss the car has seen. I weigh 195.

In good air; the car has made 400RWHP at 5900. Engine is N/A. No adders.

For now I'm using a stock T5.

Rear gears are 3.73.

Tires are 25.7" Nitto 555R (315/35-17)

My plans are to use Strange 10 way struts and shocks. Coilovers will be used up front.
In the rear; I'll be using stock GT coils cut to my liking.
I have new J&M uppers and lowers.
I'll most likely use relocation brackets in the rear for the lowers as I'll be lowering the car somewhat.
I'll be installing M&H or M/T drag radials. I don't want to run slicks until I decide if I'm going all out.

The reason I posted this question is that I'm second guessing my rear gear choice. I was using 4.10's and swapped them out to 3.73's. Maybe that was a bad move?
I just went to a 315/35-17 MT on my car going to make a pass in the next few weeks but can only help a little till I see the difference than my slicks. I did run radials 15 years ago on another car.

Car is a street car so less gear is better for the street.

Now as far as track like has been said its all about what you trap. You want to be just falling off max HP in fourth gear when you trap.

I am on a 26in tire running a T5 with 331 gears running 11.3s but the 331s are perfect for trapping just right at a 10.9-10.8 pass and thats my goal. Also being its a 95% street car the 331s work great. 3,360 race weight.

BTW get ready to buy a T5 on radials it want last long unless you are very easy on it at the track.
 

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Discussion Starter #17
I'm planning on hitting the strip for the first time ever. I have a million questions but I'm pacing myself. Lol.

The car will be street/strip.

I haven't weighed the car. It's a '95 GT with power everything and A/C. The hood is fiberglass along with aluminum heads and no smog or cats. That's about all of the weight loss the car has seen. I weigh 195.

In good air; the car has made 400RWHP at 5900. Engine is N/A. No adders.

For now I'm using a stock T5.

Rear gears are 3.73.

Tires are 25.7" Nitto 555R (315/35-17)

My plans are to use Strange 10 way struts and shocks. Coilovers will be used up front.
In the rear; I'll be using stock GT coils cut to my liking.
I have new J&M uppers and lowers.
I'll most likely use relocation brackets in the rear for the lowers as I'll be lowering the car somewhat.
I'll be installing M&H or M/T drag radials. I don't want to run slicks until I decide if I'm going all out.

The reason I posted this question is that I'm second guessing my rear gear choice. I was using 4.10's and swapped them out to 3.73's. Maybe that was a bad move?
I just went to a 315/35-17 MT on my car going to make a pass in the next few weeks but can only help a little till I see the difference than my slicks. I did run radials 15 years ago on another car.

Car is a street car so less gear is better for the street.

Now as far as track like has been said its all about what you trap. You want to be just falling off max HP in fourth gear when you trap.

I am on a 26in tire running a T5 with 331 gears running 11.3s but the 331s are perfect for trapping just right at a 10.9-10.8 pass and thats my goal. Also being its a 95% street car the 331s work great. 3,360 race weight.

BTW get ready to buy a T5 on radials it want last long unless you are very easy on it at the track.
Wow! 331 gears? Are you boosted? I take it that your current M/T tires are bias ply?

In an ideal world; I'd love to run one set of tires for street and track. I may not even like racing. I guess in reality; I'm looking to play on a budget until I know which direction I'm headed.
 

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Wow! 331 gears? Are you boosted? I take it that your current M/T tires are bias ply?

In an ideal world; I'd love to run one set of tires for street and track. I may not even like racing. I guess in reality; I'm looking to play on a budget until I know which direction I'm headed.

At first I was running 308s, On Nitrous, They are the S/Ss.

I drive it like a daily but I have a few other cars/toys so It gets like 10-15k miles a year. I don't drive it in the rain unless I just have to.

If you go to the track setup on that light and go you will love it. No need for drugs thats all the drug you will ever need.

My build if you just want to see more info I will be post info on how the S/Ss do at the track soon.
https://forums.corral.net/forums/member-build-up-projects/1580346-my-93-cobra-build-gt40-heads.html
 

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Discussion Starter #19
Wow! 331 gears? Are you boosted? I take it that your current M/T tires are bias ply?

In an ideal world; I'd love to run one set of tires for street and track. I may not even like racing. I guess in reality; I'm looking to play on a budget until I know which direction I'm headed.

At first I was running 308s, On Nitrous, They are the S/Ss.

I drive it like a daily but I have a few other cars/toys so It gets like 10-15k miles a year. I don't drive it in the rain unless I just have to.

If you go to the track setup on that light and go you will love it. No need for drugs thats all the drug you will ever need.

My build if you just want to see more info I will be post info on how the S/Ss do at the track soon.
https://forums.corral.net/forums/member-build-up-projects/1580346-my-93-cobra-build-gt40-heads.html
Like you, my car is a toy. It has 70k original miles.

I think you're right about getting hooked on racing. The only thing I fear is breakage. Who doesn't? Lol.
Guys complain that they can only get a few runs in on tune nights. At that rate; it will take a year to get things sorted out.

Good for you on pushing the nitrous envelope. That juice scares me. My buddy is trying to sell me a small NEX dry kit. Let's see, suspension, tires, nitrous, timing regard box, two step, clutch tamer....$$$$$$
 
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Spent the weekend at the track....'57 Chevy with radials. Had bias slicks on it previously. 29x10.5.

The radials suck. No matter what we did to the car as far as the chassis & suspension, it didn't like the radials. Not at all. I drove back home in the truck (about 60 miles), got the bias slicks, bolted them back on and was .13 quicker in the 60 without a single other change. And MUCH more consistent (bracket racin').

So the statement that radial cars are faster/better on radials isn't entirely true. May be on a car that's newer and on a better chassis/suspension but on this older build, not so much.

I don't see a need for radials unless dictated by the rules of the class you're running.

Starting line ratio is a TOOL that one uses to help adjust the launch. Basically, the lower the horsepower, the higher numerically (9.00+) you can get away with on the SLR. With lower power, the mechanical advantage offered by numerically higher SLR helps get the car rolling sooner. AND...it's not entirely true that a numerically higher SLR hits the tires "softer". The initial hit is harder but it falls off quickly as RPM and speed build. The more power it's got the more likely the car is to wheel stand or spin with a higher SLR. BUT...again...it all depends on the car. Turbocharged cars "like" to have the turbo(s) loaded initially and they can get away with a numerically lower rear gear and work quite well, but a N/A car of the same horsepower level may not "like" it at all. Has everything to do with the entire combination and not as much to do with internet hearsay, and in the end, there's no substitute for test & tune at the track to see what your setup "likes". Ever wonder why there's so many used parts for sale?
 
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