4.10 gears...not what I expected.

[USAZR1]

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.

[WVZR-1]

Originally Posted by USAZR1

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.

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.

[USAZR1]

Originally Posted by WVZR-1

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.

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?

[WVZR-1]

Originally Posted by USAZR1

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?

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

[USAZR1]

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

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

[Jagdpanzer]

Originally Posted by USAZR1

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

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

[WVZR-1]

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.

[WVZR-1]

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

[Hog]

Originally Posted by USAZR1

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?

In an attempt for comprehension as the internet excises 75% of our communication ability. I dont mean to fan any flames here.
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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.

[Jagdpanzer]

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