close ratios for AE86 - XXX @ Alvin

[Acoustic]

Hi guys, especially Alvin, because this came out of my mind after seeing you drive, the way you full throttle through the curves and corners, Seeing how your engine rev up.

1st lets decide on the final drive. Since it's the ultimate deciding factor. Always work from end to head. I don't know what you're using, but my guess is 4.3 only. Cause 3rd at near 8k rpm is nearly 140 km/h :) hehehe I think

Anyway, one other thing for me to keep in mind is to design a 5 speed close ratio for you, because I seriously think that's all you'll need to recover the lost of acceleration against the DC5.

Now 4.778 FD is popular, but 4.556 can also be made easily using 41 teeth ring mated to 9 teeth pinion.

It's definitely better than the 4.3 and doesn't loose that much top speed compared to 4.778



Keeping this in mind and setting 5th gear as 1:1

with 4.556 the top speed is 190km/h at 8k rpm using 195/50R15 circumference

with 4.778 it drops to 181 km/h


You can recover the lost of top speed by changing to 60 series equavalent, which makes it

with 4.556 => 200

with 4.778 => 191

So, choose these as you wish.


4.778 comes from 43 teeth ring mated to 9 teeth pinion.



So, now to decide the 5 speed ratios. Using 4.556 as reference for maximum torque / acceleration, compromising top speed to a limit of 191 - instead of 181 using 4.778


1st column T50 TRD close ratio type #1
2nd column max km/h at above input rpm
3rd column Shift up gear and the rpm will drop to
4th column Lost of rpm

2.347 81 5316 2684
1.733 109 5729 2271
1.379 138 5972 2028
1.144 166 6293 1707
1.000 190 8000 0

This design looks promising, but 1st gear acceleration will be completely shit. You can consider not to use it and use the original instead.


The standard T50 ratio are just not relistic for track.

3.587 56 4300 3700
2.022 99 5221 2779
1.384 145 5511 2489
1.000 201 6568 1432
0.861 233 8000 0


revs drop too much :(

OK, lets see what you say :) May be we can sit down and talk later.

 

[TE27levin]

sorry just to share u about this..

""
2.347 81 5316 2684
1.733 109 5729 2271
1.379 138 5972 2028
1.144 166 6293 1707
1.000 190 8000 0

This design looks promising, but 1st gear acceleration will be completely shit. You can consider not to use it and use the original instead.
""

the first gear will launch very well if u had good torque. launch it at high rpm, will push u move all the way to red line with less wheel spin. extra torque will be taken in gearbox u wont take too much wheel spin.

one vtec sifu told me, they are using 3.0XX(forgot the ratio) 1st gear in drag will pull about 1/2car faster then a 3.1XX(1st gear).

i using 3.9 final gear with 215/50/16 wheel plus stock T50 gear box, launching i can pull 4G93T to 1car, but when going to 3rd gear will not so good.

 

[Acoustic]

yes, that's a high possibility, it's something which I do not have experience with :(

however it will be very useful for turn 1 and 2, after that can immediately go 2nd, and everyone can imagine the speed after that :)

 

[3SGE]

B) Hello...newbie here...how to choose a suitable final gear for a car??? B)

 

[wllim5]

Normally to choose a suitable gear ratio is according to the car engine performance then according to the tracks may also be driver driving style.

TE27,
That is a good launching. But don't forget the stress on the clutch and the transmission.

Anyway. Good tech article.

 

[Acoustic]

the launch is not important, that 1st gear at 8k rpm can give 81 km/h top speed is very good for corner 1 & 2, after that explode out of corner 2 into 3 using 2nd gear :)

Since the ratios are closer, he'll be able to reach the top speed faster than before, which is import.

i.e. last time reach 100 meters mark 180, now perhaps before 200 meters mark already 190 - something like that

 

[TE27levin]

when going to race, everyone should already have good clutch or else they wont go for TRD gear box. haha
clutch sliping should not a issue, cos we not going to drifting with that gear ratio. most power will go on ground and it can move ur car to 80km/h then going to 2nd gear. the problem we facing on launching was speedo meter going to 60km/h but ur car speed actually will go to 30-40km/h, the momentum is not there but u still need switch to 2nd gear and it start to cause ur tail swing cos ur car is not moving to that speed yet. it also will bring more stress to ur clutch cos 2nd gear ratio was small and it also able to break ur gearbox or shaft if u have a good grip tires.
with 8000rpm of torque kicking into 2nd gear.

 

[QiW]

waaaaaaaaaaa ... i am totally lost laaa ... heheheheehe ... :)

 

[XXX]

me also laaa...Chin, I think this one must sit down and talk to Ah Choy as I not very technical one but this is something we have been thinking about but dunno how to go about it as we are no rocket scientist :lol: . When, where to meet I bring AC along.

 

[3SGE]

Originally posted by wllim5@Nov 9 2004, 07:20
Normally to choose a suitable gear ratio is according to the car engine performance then according to the tracks may also be driver driving style.

B) Thankz B)

 

[madmax]

anybody know where i can get a trd#1 close ratio gear box.? what is the market price on one of these? thanks

 

[4agze]

-_- ain't my topic, dont know what sifoo toking... :)

 

[Acoustic]

Hi Alvin

Yes, we need to meet and talk seriously. Because I just set the TRD close ratio type #1 and the 4.778 final in "Live for Speed" Dam kau good :)

Accelerator, cornering etc.....

Tell you what ......... actually I know how to make the close ratio. But I need to buy allot of other RWD gearbox from various different models and open and take their gears.....

This is tedious, and not too expensive.

The other alternative is to go to gear box overhaul shop and tell them what gear teeth we need etc.

So, when free? tonight?

Today my working schdule

10:30 office KLCC
11:30 to go putrajaya
12:30 reach start work talk kok site supervision & inspection
14:30 finish lunch
15:30 come back KL
16:30 reach KL

ponteng :) ????

NO lah, see customer this and that :( haih....

at night free :)

 

[BH9]

you guys are so good with all the calculations...so advance@terror.

may i join? :)

 

[QiW]

2 + 2 = 5 .. rite guys ????? :)

alamaks !!!!! my maths FAIL laaa !!!! :( :( :(

 

[demuire]

Erm... What about this gear ratios (the Palmside NZ ratios):

1st 2.63
2nd 1.89
3rd 1.34
4th 1
5th 0.861

Final drive 4.77

Going on this gearset, at 7000RPM (which is where I shift because my power drops off quite sharply after that), top speed at each gear:

1st 60.7
2nd 84.5
3rd 119.2
4th 159.8
5th 185.6

Which I think is adequate for most track work. 1st and 2nd gears are still very useable, and every gear is quite close to each other. Approx 2000RPM drop per gear change. Graphing it out, it only looks like there's a slightly bigger gap for 4th gear.

Alternatively, I had a friend who was running a TE37 as a rally car, and he was running these gears:

1st 2.44
2nd 1.66
3rd 1.24
4th 1
5th 0.861

Final drive 5.125

Very similar in gearing, but slightly closer. Similar top speeds in all gears apart from 4th and 5th which are a bit slower, at 148.7 and 172.7 respectively.

 

[Acoustic]

wah 5.125 FD :) - wha like this cannot sleep already ........

Those close ratios are also find, except I don't like the 4th and 5th. I think if we're going to spend the $$$ shoud at least get 5th as 1:1

are we able to buy those ratios ??? 1, 2, 3 and FD ???

Actually, if you can help us find a 9 teeth pinion gear of a 6.7" ring diff would be very very nice already ........ since we have lots of 43 teeth and 41 teeth ring

43 / 9 = 4.778

41 / 9 = 4.556

both are equally good and street able :)

 

[yolk]

wahahahahah use gear ratio like this definately no need to even think of throwing away the speedcut <_< :lol:

 

[Acoustic]

exactly :)

 

[QiW]

its ok ... my car cannot reach speed cut anyways ... hahahahahaaha .. :lol: