Will 4:10s mess up a stock T5 ?

It will be fine go for it. All gears do is put the engine into it's power range quicker.

One thing it might affect is drive shaft vibration. While normally not evident with stock gears, the 410s will spin the shaft faster, and sometimes vibrations come with that. Sometimes not too. At least it will give you an excuse to get an aluminum ds.

Do it

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Gears get you in powerband quicker = multiplying torque which makes you rev quicker...it is the same thing...different words...

The 410's will give the effect on your transmission of more power...it won't mess up your transmission but wear it just that much more...

if its a free T5 that works, who cares. If you plan on getting the tremec, just learn how to power shift on the t5

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raph130 said:

gears dont just get you into your powerband quicker. your multiplying the torque made by the engine. for example going from 2.73's to 4.10's is the equivelent of 80lbs of tq give or take a few. this is why notchbacks with stock motor (cam, heads, intake) can run 12's or faster with only gears(4.10s minimum), suspension work, and slicks. there are guys in stock mustang spec racing that run 11's with stock motors using 5.30 gears.

Click to expand...

I think you mean 4.30's, and probably should also note they run 28" tires.
And, depending on the class, they are either stock motors with very aggressive cam, or, stock cam'd, with plenty of short block work and GT40 heads, cobra intakes.

Back to the original question, 4.10's will not hurt your T5. Stock T5 shifter combined with aggressive driving may tho.

if the gears are installed wrong you will get a vibration

Gears don't jurt T5's, driving does. They should have only been put in four bangers. That being said, there will be more wear and tear, and stress on the U joints- assuming you will be launching harder. (with 4.10's, who wouldn't?) This isn't even discussing the torque multiplication factor, which also works in reverse. The more power you have, the more stres there is on the entire drivetrain, even if it's just the illusion of power you get from a gear swap. The end result is the same- you go faster, which almost always comes with a compromise to some extent. Whether or not 4.10's will wear out your T5 any faster than a stock ratio would is both arguable and negligable. I wouldn't worry about it.

The torque multiplication effect of gearing occurs on the OUTPUT side of the gears in question. If the engine's producing 300 lb-ft of torque at peak, that's all it can produce. With a 2.95 first gear, that get's turned into 885 lb-ft at the output shaft of the tranny into the driveshaft. With 2.73 gears that gets turned into 2416 lb-ft of torque at the rear axles. This is the twisting force the tires have to work with. Change the 2.73's to 4.10's and that becomes 3628 lb-ft -- when in first gear. Each time you shift the available twisting force available to the turn the tires at peak torque rpm gets reduced by the gearing in the tranny. So swapping rear gears doesn't do anything to impact torque input to the tranny. It does however impact how much torque the rear axles have to deal with, and how much torque gets put back into the chassis via the suspension arms. Shouldn't make any difference to the tranny other than turning it more quickly at a given speed. Same with the driveshaft (as others have said - this may introduce vibration that wasn't present at lower speeds). What does get used 'harder' are the rear axles, wheels/tires and suspension control arms that transmit reactive torques into the uni-body.

Just for the sake of argument, let me clarify my statement from the perspective of my driveshaft shop, who specialises in custom shafts in heavy commercial truck applications. You have two forces working against each other, the engine making torque to move the car and the weight of the car on the pavement fighting it. Everything after the combustion chamber is subject to stress, from the pistons to the tires. According to them, the lower the gearing in the semi, (the higher the torque multiplication) the more likely you are to spit out a driveshaft taking off with the same engine pulling the same weight load- and that's just their deptartment. If it's true in that area, then every other link between the power source and the point of resistance are equally subject to the same law. Putting slicks on a car can break axles just like a lower rear gear can, but they have also been known to split cranks, grenade clutches, and in my case- cause premature falure of universal joints; it isn't the rear that's trying to break 3500lbs of car free of gravity, it's the engine. Whether it has 300'# at it's disposal, or 380- put more power on the road (even if it's by not wasting power spinning tires) and it will work it's way back to the weakest link that much harder. From another angle: try taking off in 10th gear on a bicycle. You are the engine- assuming you are strong enough to (from a standing stop) immediately start pumping your legs the same speed in 10th as you could in 1st, it's still going to be a lot more work, and it'll be harder on you,and the pedals, crank, sprocket, chain, and the rear axle of the bike. And just like with lower gears in a car, you'd be going much faster at the same given RPM than with the higher gears (if nothing broke). I used to break chains on my mountain bike regularly, and it only ever happened when I was trying to climb a trail slowly in 5th when I should have been going that same speed only in 2nd. I never once broke an axle, bent a wheel, or damaged any other drivetrain part between the rear gearset and the path, but I sure broke a lot of chains that way and even stripped a three piece crank. A car is just a glorified bicycle. Try riding around in the top gears all the time, and if your strong enough you'll accellerate faster than starting in the bottom ones even though you aren't any stronger... and you'll hear and feel the whole bike crying for mercy. I don't think this is an argument I can win, I'm just not Michaels caliber when it comes to explaining myself- but anyone who ever rode a trail bike hard should know exactly what I'm trying to say.

I'll stand by my post above.

Here's another way to think about your bicycle chain-breaking analogy (I'm impressed by the way! All my bike work was over the road on the flatlands of Houston TX - we only downshifted for wind!). You broke the chain simply because you were capable of putting enough force into to it to do so - it was literally the weakest link in the drivetrain. The reason it didn't happen in 2nd, was that because of the torque multiplication available in that gear, you didn't have to pedal as hard (used less force) to move the bike. The chain didn't have to transmit as much force in 2nd. In 5th YOU had to supply the torque (instead of multiplying it at the rear gearset), and the extra force you supplied via leg power the chain couldn't cope with. In any event - your breaking it in 5th vs. 2nd would be the equivalent of breaking things with a 2.73 and not breaking them with a 4.10

With perfect traction - you'll find the weakpoints of the driveline for a given amount of transmission-multiplied engine torque. Could be shaft, tranny, ujoints, driveshaft, rear end. Once you've strengthened all that -- changing the rear gear should only result in more stress for the axles/rear wheels/tires/suspension components. At least that's how it looks to me.

Ok, read all these thoughts and I learned more after this post. If a bone stock 92 droptop with an AOD would swap gears, and if the car is used (NOT TO RACE) simply to cruise, but if puch came to shuff wanted quicker acceleration- which gears would you choose? sorry about getting off the original post.

I'd choose 3.73's for that application.

5.30's.

No, seriously, IMO 3.73's are the gest all around ratio. However, they can still be a bit jerky. If you want a smoother ride, 3.55's will still get up and go without being so inclined to snap your neck on every takeoff and gear change, or screw with your cruise control on the highway.

If gearing is messing with the smoothness of your cruise control, one option is to ditch the factory controller, and wire up the stock control switches to an aftermarket fully electronic control module. The newer solid-state units have all sorts of adjustability to allow altering how quickly the unit reacts to feedback from the speed sensors, etc.

Yeah, I know. I have enough wiring gremlins already, and don't care for cruise enough to go to the trouble. Thanks though. Generally speaking, the lower the gearing, the harder it is to maintain speed smoothly at higher R's (esp. highway) even with the CC off, as even slightly backing off the throttle can induce immediate reaction from the drivetrain. On the other hand, my brakes last forever

If your brakes last forever, then you're not using that fancy suspension hard enough -- in deep baby!