4.10 gears...not what I expected.

[Schrade]

Originally Posted by Schrade

Just hung up with Psychic Hotline. They said heated discussion on the way yup...



This statement needs quantification, for starters...

And I think a more judicious use of the term "multiply torque" is in order.

[KILLSHOTS]

Originally Posted by Dynomite

You traded wheel spin for wheel torque........same horsepower. Your wheel spin dropped 18%...the guy you were racing just out ran you
18% more torque to the rear wheels at all engine rpm is a true statement. The wheel spin drop at all engine rpm was not mentioned

So, in reality, an identical car with 4.10 vs 3.45 gears does not necessarily accelerate quicker or harder...it actually accomplishes exactly the same thing, only requiring more engine RPM to do so? Honestly, not trying to be a smartazz here, just trying to understand. Has anybody ever timed a car to 60 or through the 1/4 before and after such a switch? I'd be interested to know because the car doesn't really "feel" any quicker. It definitely revs FASTER but doesn't feel quicker and most surprisingly, doesn't seem to spin the tires more easily. I was hoping to burn those masquerading-as-a-315 Sumitomos to the ground with one burnout!

I've gotten a little more used to it over the weekend and frankly, I sort of like the new "personality" of the car. The upper gears are more usable and the car moves away from a stop more easily, which is great. Again, this has to do with having unrealistic expections, more than anything else. Overall, I'm more surprised with the result than disappointed.

[mike100]

A chassis dyno won't take the gear ratio into account except that some gear selections may have more friction than others. Lets say your engine makes 300 lb/ft of torque and you run it through a 3.08 diff. The axle will see over 900 lb/ft of torque (and of course 3 times slower rpm for a conservation of energy). The chassis dyno won't read 900 lb/ft, it's a separate system with its own diameter and speed calculation. All you get is the engine torque minus the frictional losses (and whatever other fudge factors are in the mix for the dyno).

I always felt individual trans gearing would always be more useful than just the final drive, but that is not too practical in production transmissions. Take a look at the MT-82 trans in the new mustangs... 1st gear is nearly 4:1 and the 1:1 gear is actually 5th (not 4th). That's about 1/2 the reason those new Mustangs scoot so well in the 1/4. I wish the ZF had tighter ratios sometimes.

It is a time-to-distance mod, not so much a seat-of-the-pants mod. I'f I had the budget, I'd do 3.73's myself.

[PhillipsLT5]

.22 @ 1/4 mile, I like it

[Hog]

Stock gearing 3.45

385 lb/ft engine torque/2.66:1 1st gear ratio/3.45:1 rear gear'

385x 2.66x3.45=3533 lb/ft torque at the rear at the halfshafts

4.10 gearing
385 lb/ft torque/2.66:1 1st gear/4.10 ratio

385x2.66x4.10=4198 lb/ft @ the rear halfshafts.

4198/lb/ft3533lb/ft=18.84% increase in torque

We are measuring the actual torque or twist that is seen at the rear wheels, not calculating the torque of the engine.

There would be a measureable difference if before and after 1/4 mile runs were done.

I went from a 3.08 gear to a 4.10 gear and was unimpressed in gains in acceleration during WOT SOTP testing.

[PhillipsLT5]

SOPT = butt dyno

[zrwhat]

I recall when I went to 4:10's in my 91 ZR-1, I shaved .3 tenths off my quarter mile times and the fact that 6th gear could be used more often without downshifting was priceless, before that 6th gear was pretty much worthless unless you were going 70mph on a flat road.

I felt it was a worthwhile change and cheap $ to get there a little faster, I guess I'm one of the few that did notice a big difference with the gear change.

Gibby

[JFFerner]

It seems too much might not be enough, meaning the extra shift into fourth gear is offsetting any positive impact of torque multiplication when using the 4.10 ratio. Why not use a 3.73 ratio which will give a smaller torque multiplying advantage, but will keep you in third gear in the 7000 rpm range through the traps.
And so it goes....Jim

[KILLSHOTS]

So, I've had these new gears for a week now, and I am ready to amend my initial comments. Those comments, as I've said earlier, were based upon overly-inflated expectations that had gone unrealized. I also want to reiterate that I know Marc's "18% more torque" claim is 100% true. I NEVER doubted Marc and never wanted to give the impression that I doubted him and if I did that, I apologize to all, and especially Marc. My point was that I didn't FEEL 18% more torque, not that I thought it wasn't really there.

1) The car moves away from a stop much more easily and requires less slipping of the clutch. It gives the impression of a smaller, lighter car.

2) As Marc says, it does get to the "meat" of the power band more quickly, which is great.

3) The upper gears are definitely more useful.

To anyone considering this gear change, my advice would be to consider it more of a "driveability" upgrade than a "performance" upgrade. In my opinion, the overall character of the LT5 does seem to work a little better with the shorter gearing, which lends credence to the claim that the engineers originally designed this drivetrain with these gears in mind. Just don't expect the thing to take flight the first time you hammer it, like I did!

[Paul Workman]

Originally Posted by JFFerner

It seems too much might not be enough, meaning the extra shift into fourth gear is offsetting any positive impact of torque multiplication when using the 4.10 ratio. Why not use a 3.73 ratio which will give a smaller torque multiplying advantage, but will keep you in third gear in the 7000 rpm range through the traps.
And so it goes....Jim

Yeah... That's where hp elbows its way into the discussion. For example, I (and several others here in FBI country) are @ or above 500 hp. I go through the traps at 121 mph and just as my shift light comes on (at 7100 rpm). A 3.73 would require a shift to 4th before the traps.

However, a 3.73 may be correct for a stock motor. When mine was stock, I ran 112 mph in the traps at about 6600. A 3.73 might be a good stock motor ratio.

This echos back to what Lee says - that being power mods are what makes the big difference, at least in the ZR-1/ 1/4 mile performance.