Gear Ratio

[HanJackaL]

Hi Guys,
Can you guys explain to me in detail what is the meaning of Gear Ratio please? What exactly does it do and what is FD ? What is FD 4.4 and 4.9 mean? What does the numbers and decimals represent ?

How come some similar cars can drag longer in gear 1 than another car of same make ?

If someone choose to make his car drag longer at Gear 1, will his car be faster at pick up than another similar make car ?

For example,Car 1 can drag till 80 Km/H at gear 1 and Car 2 can drag till 60 KM/H at gear 1...Does that mean that car 1 is faster than Car 2 ? Or does it take the same time to reach 80 KM/H for both cars, just that Car 1 can stay at Gear 1 till 80 KM/H ?

Very confused ! Please explain !
Thanks my friends !

 

[basahboy]

Hi Guys,
Can you guys explain to me in detail what is the meaning of Gear Ratio please? What exactly does it do and what is FD ? What is FD 4.4 and 4.9 mean? What does the numbers and decimals represent ?

How come some similar cars can drag longer in gear 1 than another car of same make ?

If someone choose to make his car drag longer at Gear 1, will his car be faster at pick up than another similar make car ?

For example,Car 1 can drag till 80 Km/H at gear 1 and Car 2 can drag till 60 KM/H at gear 1...Does that mean that car 1 is faster than Car 2 ? Or does it take the same time to reach 80 KM/H for both cars, just that Car 1 can stay at Gear 1 till 80 KM/H ?

Very confused ! Please explain !
Thanks my friends !

The connection between Gear Ratios (GR) and the Final Drive (FD) can be summed up as Absolute Gear Ratio (AGR). In layman terms, if your AGR is higher, you have better torque at the same rpm. For comparison purposes, most would compare a rpm on a 1:1 basis at each gear.

I have made some calculations comparing B18CR and B18C gear ratios with & without FD of 4.925 and ATS 345 with & without...you have to made your own deduction as to whether it is applicable to you should you want to drag or track racing...those two are NOT synonymous..

to summ it up:
1. For drag purposes, a FD of 4.925 and above is a big advantage at 1 or 2nd gear i.e. for instantaneous pick up (0 to 60ft)...
2. For track purposes, a 1st and 2nd gear is relatively unheard of due to the apex, hairpins, etc. so most of the time , it would be shifting between 3rd to 4th and in which you would want to maintain at high rev...this is where the close ratios work best...
3. Pls take note that when combining b18c FD of 4.4 with ATS 345...you must change the 2nd GR to B18CR GR at 2.105 because having a second GR at 1.900 and combining it with ATS 345 would do unjustice to your engine i.e. too close...

enjoy...

 

[hattech-v]

oit basah.. now doing thesis on transmission science ke? ekekekke

 

[HanafyEG]

wah..good review of ratios..i also need to know about this..hehe

 

[HanJackaL]

The connection between Gear Ratios (GR) and the Final Drive (FD) can be summed up as Absolute Gear Ratio (AGR). In layman terms, if your AGR is higher, you have better torque at the same rpm. For comparison purposes, most would compare a rpm on a 1:1 basis at each gear.

I have made some calculations comparing B18CR and B18C gear ratios with & without FD of 4.925 and ATS 345 with & without...you have to made your own deduction as to whether it is applicable to you should you want to drag or track racing...those two are NOT synonymous..

to summ it up:
1. For drag purposes, a FD of 4.925 and above is a big advantage at 1 or 2nd gear i.e. for instantaneous pick up (0 to 60ft)...
2. For track purposes, a 1st and 2nd gear is relatively unheard of due to the apex, hairpins, etc. so most of the time , it would be shifting between 3rd to 4th and in which you would want to maintain at high rev...this is where the close ratios work best...
3. Pls take note that when combining b18c FD of 4.4 with ATS 345...you must change the 2nd GR to B18CR GR at 2.105 because having a second GR at 1.900 and combining it with ATS 345 would do unjustice to your engine i.e. too close...

enjoy...

THanks for the reply bro. However,how do i know what gear ratio and final drive my car is at ? And how do i get the AGR ? Gear Ratio + FD ? What exactly does Final drive mean ? And what exactly does ATS mean ? What is FD 4.925 and ATS 345 mean ?

Thanks again !

 

[basahboy]

oit basah.. now doing thesis on transmission science ke? ekekekke

If only my Proton boss knows what i am doing during office hours...shhhhhhh...hehehe...time to test the cars....

 

[hattech-v]

test what car? for what? hehe