Re: 4.10 gears...not what I expected.
 

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.

Re: 4.10 gears...not what I expected.
 

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".

Re: 4.10 gears...not what I expected.
 

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

Re: 4.10 gears...not what I expected.
 

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:

Attachment 3583

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

Re: 4.10 gears...not what I expected.
 

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.

Re: 4.10 gears...not what I expected.
 

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??).

Re: 4.10 gears...not what I expected.
 

Yes.

Re: 4.10 gears...not what I expected.
 

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

Re: 4.10 gears...not what I expected.
 

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.

Re: 4.10 gears...not what I expected.
 

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

Re: 4.10 gears...not what I expected.
 

Injecting other transmissions into this particular thread is for the most part irrelevant since ZF's and rear gearing are what we're discussing,I thought.

A statement was made that the rpm drop between gears would be the same with either a 3.45 or 4.10 gearset. That is simply false and I can't believe no one else even commented on it.

Just trying to keep misinformation off the site. No gearset is perfect. Both rear ratios are very versatile.

Re: 4.10 gears...not what I expected.
 

So long as the shift is made at the same RPM the RPM loss is the same. The MPH changes but the RPM differential is the same.

Re: 4.10 gears...not what I expected.
 

No,it isn't. Take two ZR-1's,one with 3.45's and one w/4.10's,both same tire diameter. Shift both cars into high gear at 80mph. Both cars will drop the same rpm? No,they will not.
At any given speed or gear selected,the 4.10 rear will be spinning the engine faster. Why is that so hard to understand?

Re: 4.10 gears...not what I expected.
 

You're NOW entering a MPH shift into the "mix" - the thread I thought and you mentioned again a couple of times was referenced RPM and if the shift is at the same RPM regardless of the gear the RPM differential remains the same but MPH changes at the RPM being discussed as the result. Tire diameter and axle ratio affect MPH but the RPM drop/spread isn't affected.

The engine and transmission are directly related/connected BUT the rear axle and the tire dimensions skew the results to directly affect MPH.

In this post "ZRXMAX" was in error and "HOG" corrected it and mentioned the only way to alter:

http://zr1.net/forum/showpost.php?p=...&postcount=102

Re: 4.10 gears...not what I expected.
 

"What we have here,is a failure to communicate." :neutral:

(throwing up my arms) Ok Dave,you win! I give up.

Re: 4.10 gears...not what I expected.
 

Here is the scene with Paul Newman and Strother Martin and what the Captain actually said:

http://www.youtube.com/watch?v=1fuDDqU6n4o

One of the best movies ever

Re: 4.10 gears...not what I expected.
 

Clint - I'll leave you with this and if you do this read and still don't understand it's beyond "communication". You need to pay attention to R1 and R2 explanations and maybe it will make better sense to you. Limit your thoughts to "drive-shaft" revolutions which don't change until the axle ratio and tire diameter becomes involved.

http://wahiduddin.net/calc/calc_speed_rpm.htm

Unfortunately every time that axle ratios get involved the formula seems to relate to end MPH and the transmission only controls drive-shaft revolution. Use the calculator that I linked to and use any RPM and change only the rear axle ratio and it will be displayed in a graph and also print. There are several other calculators that do the same thing but don't display the results in an easily understood way to be compared.

If you use my linked calculator and keep the RPM involved at an even thousand it's much easier to compare the MPH effected by the axle ratio and tire dimension. Use 5000 or 6000 or 7000 RPM, change the tire dimension and change the axle ratio to as many variables as you like and I believe you'll see the RPM differential didn't change but MPH changed only in regard to axle ratio and wheel dimensions.

Re: 4.10 gears...not what I expected.
 

If you would like to see shifts at MPH results you can use this Bonneville Excel spreadsheet and fill in the appropriate information.

http://purplesagetradingpost.com/sum...%20Excel-1.xls

If there's anything speed related that might interest someone the complete read might be interesting. There are numerous calculators available that are quite interesting for nearly every possible drive combination. Cars bikes whatever!

http://purplesagetradingpost.com/sum...lle-Index.html

Re: 4.10 gears...not what I expected.
 

In an attempt for comprehension as the internet excises 75% of our communication ability. I dont mean to fan any flames here.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxx
You are referencing vehicle speed, when we were talking about engine rpm difference during an upshift.

If you have your 4.10 gear car, and I have my 3.45 rear gear car, in 1st gear you wring your LT5 to 7500rpm, and I wring my LT5 to 7500rpm, we both throw a powershift into 2nd gear. What are out tachometers reading? All else not mentioned in the above scenario equal, our tachs will read the same RPM once our ZF's are in 2nd gear.

RPM drop can only be changed with transmission gear ratio changes. Speed vs engine rpm can be changed via trann gear changes, rear end gear changes and tire diameter changes.

I have never heard "RPM drop" referred to in a fashion to which you have described. To calculate a shift RPM drop, you must 1st have a Before RPM and a Resultant RPM. Shifting a 3.45 vs 4.10 car into high gear at 80mph tells you nothing of rpm drop, but will surely give you the engine rpm of each car, or which, the 4.10 gear car would be revving higher, all else equal. But if you are shifting from 3rd gear to high gear in both cars, the rpm drop in BOTH the 3.45 and 4.10 gear car will be 100% the same.

Quote
At any given speed or gear selected,the 4.10 rear will be spinning the engine faster. Why is that so hard to understand?"

You are describing a difference in overall final drive ratio which combines trans ratios AND trans ratios. Of course the 4.10 geared car will rev higher- all else equal, but this relates to rpm at a speed, not rpm drop as it relates to trans gearing. Regardless of rear gearing, rpm drop during shifts will be 100% the same as trans ratios are the same-all else equal.

Re: 4.10 gears...not what I expected.
 

Similar duscussion on the Viper site
http://www.viperclub.org/howto/faqs/...-gear-swap.php

Re: 4.10 gears...not what I expected.
 

Whether you have 4.10s or 3:45s, if both cars shift at the same 7000rpm, isn't the rpm drop based on the trans? Closed v Wide ratio trans.

Re: 4.10 gears...not what I expected.
 

You can bet on it. The gear ratios in the trans remain the same w/o regard to what is on the other end of the drive shaft.

Re: 4.10 gears...not what I expected.
 

so I guess we're done w this discussion.

Re: 4.10 gears...not what I expected.
 

Are the guts of a Dana 44 the same across applications? I know the housings differ.
In other words, should a competent guy who does Dana 44 work for off road trucks and
Jeeps etc be able to work on a Corvette rear? Key word here is competent...
Contemplating a change to 4.10s.

Re: 4.10 gears...not what I expected.
 

Yes !

Re: 4.10 gears...not what I expected.
 

Really Doug?
I have a guy locally I trust a lot if you're looking for someone.

Re: 4.10 gears...not what I expected.
 

So, I just got my car back from Corey who installed 3.90's and I kind of see what you're talking about. I expected this hair on fire experience of having trouble keeping the front wheels on the ground and that's not what happened. However, after a week of driving it and breaking them in now I absolutely love them. It almost felt like the car was slower at first because I was carrying more speed into the 2nd and 3rd shift points and it was noticeable. I got there quicker but I wasn't going as fast. The real beauty of these things though is hitting 3rd gear. That, too me, is where you make up anything you feel you may have lost because this thing hauls the mail now in 3rd and 4th gear. The RPM's are staying right in the meat of the curve and it never ever lets up.

I'm wondering if your impression has changed any now that you've had it a month or so? Mine certainly did.

Re: 4.10 gears...not what I expected.
 

Smooth cars are fast cars

Re: 4.10 gears...not what I expected.
 

Dittos...

I too find the performance trade-offs interesting, as the advantages between the stock 3.45 vs. 4.10s goes back and forth, depending on what the immediate application is:

Ami's 91 ZR-1 "Turq Monster" with 4.10s has approx 5% more hp than my 3.45 "Phoenix" and the combination of rear gear and brute hp tops my car in the quarter, every time. From the seat of the pants, it is a thrill to drive on the street and on country roads. However, in longer contests, the differences are less obvious.

Case in point:

Bob Banks' ZR-1 and my motors are pretty close, power wise: both @ or near the 510 chp range. However, Bob has 4.10s and I have the stock 3.45s in the rear.

One example does not a trend make, but we ran side-by-side at the last 1/2 mile WANNAGOFAST event last June. What I observed I think might be pertinent to this discussion (my reason for sharing it):

We started from a soft dig: more or less even. However, by the 1/2 way point (quarter mile), Bob had 3 to 3-1/2 lengths on me. I suspect Bob was still in 4th at that point, and had to shift into 5th as I was just shifting into 4th. That is when the gap began to close, and was whittled down to 1-1/2 to 2 lengths at the finish.

In the end, Bob (4.10 gear) crossed the 1/2 mile trap at 138+ mph in 5th and the "Phoenix" with the 3.45s crossed at 144+mph, & still in 4th. However, in spite of gaining on him, he still beat me to the 1/2 mile finish! That initial lead afforded by the 4.10s was too much to overcome, in spite of a significant speed advantage the Phoenix had - at least at the 1/2 mile point.

So, I dunno... Now having opportunity to experience both ratios; 4.10s vs. 3.45s, the each have their place. I like the snap Ami's car has when passing on the highway - and the extra 20-30(?) ponies at the wheels is just the cherry on top. But, I also like that long hard pull my car has to 90ish mph in 2nd gear, following a 5-2 downshift from about 45-50 mph. The 3.45 ratio delivers more torque to the rear wheels (above 75 mph) than the 4.10s do in 3rd, in spite of the 5% hp advantage, and without the additional shift too boot.

So, depending on what or where one likes performance to kick in, moving to a 4.10 ratio might not be "the bee's knees". Having both to compare back and forth makes the distinction much clearer now, and I've cooled to the notion of 4.10s just a little, now that I have that and the 3.45 ratio to compare it with. Maybe 3.73s or 3.90s? And, (to the OP) so it goes....

Paul.

Re: 4.10 gears...not what I expected.
 

Paul what mph was the 'soft dig' from ? Rolling in 1st?

Re: 4.10 gears...not what I expected.
 

Paul,

Your results in the 1/2mile mimic how Lee and I ran with VERY similarly modded 92s several years ago at Byron. Lee got to the big end about .3-.4 quicker than me. His 1/8 trap was about 2 mph faster than mine, however I would gain on him in the second 1/8 (not enough to get around him) and our 1/4mile traps were virtually identical. Lee has 4.10s and I had the 3.45s

Re: 4.10 gears...not what I expected.
 

Hey David,

Yes, I definitely like them better than I did at first. It sounds like we had similar experiences relative to inflated expectations. Once I came to grips with the fact that I had simply expected too much, I began evaluating the mod more objectively. The car moves away from a stop easier and feels more "drivable" in almost all circumstances. I'm happy with them now. Glad you are too!

Re: 4.10 gears...not what I expected.
 

It was a standing start, but with slightly less aggressive rpm and clutch release than typical of a "balls to the walls" quarter mile "ET" contest. This was for top-end primarily: not ET per se'.

Re: 4.10 gears...not what I expected.
 

I thought you might be. It feels like the car went on about a 500 lb diet. Very froggy and eager to run.

Paul, I think with modded motors like ours the taller gears are fine. That's why I did 3.90's vs 4.10's. We have the power to pull those tall gears in 1st and 2nd. For the same reason if I added boost I would never do 3.90's or 4.10's. Don't need to. Shorter gears are a great equalizer when you are short on power. IMHO, the more power you have the less gear you need.

Re: 4.10 gears...not what I expected.
 

I installed 3.73s for mine and when power is transmitted through 19" wheels, acts like a 3.55. I would be tempted to try 3.90s

Re: 4.10 gears...not what I expected.
 

Dave, I have come to agree with much of your (and Dom's) opinion. I too am starting to lean toward the 3.90s as having favor between the 4.10 and 3.90 ratios. Fact is, I just LOVE that 2nd gear/90 mph roll-out...and the resulting look on a few ricer's and LS drivers' faces...priceless! :jawdrop:

Re: 4.10 gears...not what I expected.
 

Paul,

Just to clarify, I'd consider 3.90's due to the 19" wheels. That would get me to a real world ~3.73. A 4.10 gets me to 3.90s. Having a 3.73 would be a nice compromise gear but its nothing compelling. Not sure it would even be that noticeable. When I had the stock 3.45s, my real gear was about a 3.30.

Re: 4.10 gears...not what I expected.
 

Yep. In your case, Dom, the bigger wheels/diameter would affect the ratios us mortal Z drivers are discussing. It is very easy to factor for your app by d1/d2 x R1*

*where d1 is the distance your new (bigger) wheels cover in one revolution vs. d2 the distance the stock 17" wheel/tire size covers in one revolution, and R1 being the stock 3.45 ratio.

Re: 4.10 gears...not what I expected.
 

You constantly try to mess with the conversation. Your REAL GEAR is what ever the numerical numbers (ring gear/pinion) dictate. Your tire diameters alter your 'final drive' but you constantly fail to mention that. You mention 'real world' - real world is same as 'real gear' - it's the mathematical numbers of the gear set.

19" wheels don't have anything to do with ratio's either and you constantly mention that. There is absolutely no truth to the conversation of yours that I just quoted.

If you want to discuss final drive ratio mention the tire specifications, rear gear and people can maybe relate better.

You might try referring to the tire dimension change as effective ratio and mention the tire dimensions (real measured vs. advertised) and it could more easily be understood. I don't recall you mentioning the tire size but maybe just once, that's the real relevance for comparisons 15", 16" 17" or 20" wheels have no effect on any of it. It's the 'outer circle'.

Re: 4.10 gears...not what I expected.
 

This gear ratio discussion has my head (and tires) spinning!
R R R
;)