4.10 gears...not what I expected.

[Hog]

Originally Posted by Bob Eyres

Semantics are important if you want your meaning to be clear.

I've never understood the semantics of the term "torque multiplication". I've seen it used, mostly, to describe the advantage the automatic transmission has, at launch, in the quarter mile. The torque converter allows enough slippage to let the engine come higher into it's power band before the car starts moving. So that you have more power available at launch. The automatic has other advantages, and disadvantages, but I don't see how torque is literally "multiplied" in any way. Semantics

Semantics in the actual number expressed as an ET being meaningless to me, while being a factor to you. In other words, I was willing to drop the subject of ET importance, based on semantics. Semantics being "the
meaning, or an interpretation of the meaning, of a word, sign, sentence, etc.: Let's not argue about semantics."
xxxxxxxxxxxxxxxxxx

The torque multiplication of a torque converter is in play whenever there is a greater force applied to the torque torque converter, as like you described during a standing start, but also down range and during upshifts.

Torque converters have an STR or K value. STR means Stall Torque Ratio. Usual STR's for stock GM TC's are 1.8. SO if you input 100 lb/ft you get 180 lb/ft applied to the input shaft.
The only time the STR is taken out of the equation when applying an acceleration force is when the Torque Converter Clutch is applied, then the engine torque is applied to the input shaft of the trans in a 1:1 ratio.

As I stated torque multiplication occurs in a standard clutch as well, while it is slipping. Not advisable in a conventional clutch, but it's advantages can be seen in a slipper clutch design. Whenever 2 friction materials are forced together yet move at differnt speeds, torque is multiplied. The difference in a TC is that instead of 2 friction materials, when have "fans" of different pitches driving and being driven by an incompressible fluid, in effect, performing the same torque multiplication that that a ZF-6 performs, except by using a fluid instead of mechanical gear contact and the amount of torque multiplication is controlled by blade design in the TC and gear tooth counts in the ZF-6.

Torque Multiplication occurs through a manual clutched trans as well, input 100 lb/ft into the input shaft of a ZF6 in 1st gear, and 266 lb/ft will be seen on the trans output shaft(assuming zero loss).

At least that the way I understand it, using my personal base of semantics.

xxxxxxx

Thanks X-Fire for the tire specs.

[WVZR-1]

For any calculations that require tire specifications you don't rely on "advertised" specifications or those of Tom, Joe, Jim or Bob. A very simple procedure that produces "correct" number to be used for calculations can be accomplished with a simple "square", chalk and a measuring tape.

Chalk the tire and the floor/asphalt at 6 o'clock using the square through the axle/hub center, then move the car "one tire rotation" and duplicate the chalk mark on the floor/asphalt, measure that dimension and you've a "rolling circumference" from which you can do any calculations you wish to accomplish accurately. Ideally the car should be at customary fuel load with the driver on board or his weight duplicated in the seat and at temperature. That's a "stretch" of course but it's real.

You've got what you know are good dimensions and no "Internet" lore or guesses from the multitudes.

All the references to 17", 18' and 19" are irrelative to most anything including brake packages. Caliper clearances are determined by the barrel specifications of a wheel not the tire mounting diameter.

The dimension mentioned for the 325/30R19 is center of rear axle to asphalt X 2 or asphalt to top of tire? It makes a difference. The rotation for circumference removes all doubt for "your car".

[Blue Flame Restorations]

If you can't feel a difference, something's not right. I loved my 4:10's.

[WVZR-1]

A friend asked me to evaluate a "calculator" and I don't generally use these calculators if it can be done with simple math but this one could be very interesting in rear gear, tire selection and just a better and simpler working knowledge of what is affected by which. If you have an accurate tach and speedometer, you can measure your tire circumference as I mentioned in a post a couple up (#122) and be better prepared to maybe buy a gear or select a tire size.

It won't make an argument for a light or heavy flywheel but you can easily see the RPM drops with the gear selections (the shift from 1 to 2, 2 to 3, 3 to 4 etc). I didn't check it first hand but with there being so many different "max power RPM" documentations this can be tweaked to each individual car. You can compare the axle ratios, various tire dimensions and maybe make a better choice in the selection of the rear gear or tire.

You just need to validate the MPH/RPM in the lower most portion and like I mentioned have an accurate tach and speedometer. I believe the link will open with the correct ZF ratios but I'll look again and you could confirm your self. I believe the ratio choices that I placed are correct for the Zf. I've read a couple different but these are what I believe I see most frequently.

I used the default tire Dominic mentioned and that's a 677.6 (by spec), he mentions 26.25 (666.750) so if he just substitutes that diameter then and modifies the RPM to what he feels his is then he should see pretty accurate #'s BUT he mentions also that his speedometer isn't accurate so the results would be skewed. If your speedometer is accurate and tach is also, these #'s should be quite reliable.

http://www.cargister.com/calculator-...l_ratio_teeths

The ratio for the ZF didn't transfer so here they are and you can do the input manually. 1st = 2.68, 2nd = 1.80, 3rd = 1.29, 4th = 1.0, 5th = .75, 6th = .5

I pasted the URL a couple times and it was complete but the URL won't paste here complete. How reliable? The numbers on paper that I checked RPM/MPH looked to be accurate IF the diameter is supplied correctly and not relying on the advertised tire specs and results using only the tire size.

End result is a graph showing RPM loss at each shift made at MAX power:

gear.png

MPH @ RPM for each gear like this:


Gear shift

Difference after shifting

RPM after shifting

from 1st Gear to 2nd Gear 2233 4567
from 2nd Gear to 3rd Gear 1927 4873
from 3rd Gear to 4th Gear 1529 5271
from 4th Gear to 5th Gear 1700 5100
from 5th Gear to 6th Gear 2267 4533


mph / RPM
1000 2000 3000 4000 5000 6000 6800
1st Gear 7.9 15.9 23.8 31.8 39.7 47.6 54
2nd Gear 11.8 23.6 35.5 47.3 59.1 70.9 80.4
3rd Gear 16.5 33 49.5 66 82.5 99 112.2
4th Gear 21.3 42.6 63.8 85.1 106.4 127.7 144.7
5th Gear 28.4 56.7 85.1 113.5 141.8 170.2 192.9
6th Gear 42.6 85.1 127.7 170.2 212.8 255.3 289.4

[XfireZ51]

BTW using my GPS for accurate MPH. when I compare that to speedo, speedo is about 3-4mph slower at 70+. I am sure there is "some" growth in the circumference of the tire due to heat and centripetal(sp?) force. Never could get that and centrifical force straight.

Also everyone, there is a way to mitigate the rpm drop from an aluminum flywheel within the calibration. Its a very crude version of Rev-Match utilizing what's called the Throttle Follower.

[Paul Workman]

Originally Posted by XfireZ51

*...Also everyone, there is a way to mitigate the rpm drop from an aluminum flywheel within the calibration. Its a very crude version of Rev-Match utilizing what's called the Throttle Follower.

I'm not clear what you mean by rpm drop, as it relates to an aluminum FW. I'll take an SWAG and say it relates to rpm loss between gears (I'm assuming??).

[XfireZ51]

Originally Posted by Paul Workman

I'm not clear what you mean by rpm drop, as it relates to an aluminum FW. I'll take an SWAG and say it relates to rpm loss between gears (I'm assuming??).

Yes.

[USAZR1]

Originally Posted by Hog

Lower gearing like 4.10's or 4.56's wont affect on the amount of rpm drop when upshifting. Transmission gearing is the only way to affect the rpm drop when shifting. This is where the terms, Close-Ratio and Wide ratio transmissions come into play, with the close ratio usually having less rpm drop during upshifts.

Trans gearing is not the only way to affect the rpm drop when upshifting. Don't you have to account for the overall gear ratio in each gear?

Overall gear ratios w/3.45 rear
1st: 2.68x3.45 = 9.25
2nd: 1.80x3.45 = 6.21
3rd: 1.29x3.45 = 4.45
4th: 1.00x3.45 = 3.45
5th: .75x3.45 = 2.59
6th: .50x3.45 = 1.725

Overall gear ratios w/4.10 rear
1st: 2.68x4.10 = 10.98
2nd: 1.80x4.10 = 7.38
3rd: 1.29x4.10 = 5.29
4th: 1.00x4.10 = 4.10
5th: .75x4.10 = 3.075
6th: .50x4.10 = 2.05

[WVZR-1]

That is what "Hog" is explaining and when he mentions wide or close, he's referring to various transmission builds where the ratios of the internal gears could be or were altered.

The most common early reference to wide and close were the GM/Muncie but you couldn't mix the two. It was either 2.52, 1.88, 1.46 & 1.0 OR 2.20, 1.64, 1.28 & 1.0

There are various manual transmissions where the internals can be mixed and matched. The ZF S6-40 is fixed with no internal options. Wide or close don't apply and shouldn't even be mentioned in a conversation where the ZF is mixed into the conversation.

If you would like to compare the Muncie wide & close use the link I provided and enter the appropriate numbers and it will display exactly what the RPM results of the two would be.

Clint - use my link and enter all of the information for the 3.45, now change that to 4.10 and you'll "see" the results and be able to more easily compare or sort your thoughts. Now if you would like change the tire sizing, you can see that difference also.

The friend ask me to evaluate it for him when using a transmission that is available with multiple internal combinations and I just thought it should make everything a bit easier to understand for everyone when they're considering rear axle ratios because it takes into account the "total drive ratio" right down to including the various tire possibilities. The graph and the MPH/RPM results make the one I linked a bit more understandable.

[PhillipsLT5]

Has been a interesting thread but my bottom line is almost redline in 4th at 1/4 mile & almost redline in 5th at 1 mile, perfect for me with 4.10's