Final drive ratio

[sid131]

Whats the final drive ratio of standard 131 sport rear axle?

[mick131]

A 2000 final drive is listed in the Haynes manual as 3.9:1, same as the 1600. Not sure if the Sport's is different.

[Fiat 131 Abarth#2]

Whats the final drive ratio of standard 131 sport rear axle?

Hello sid131,

It is 10/39

Enzo

[wak131]

Different sources speak of 3.9 for the Sport/Racing.
Supermirafiori 2000/TC should have 3.58.

[sid131]

thanks lads so if the ratio is higher the quicker up through the gears & slower top speed & if the ratio is lower is the opposite? is this info correct?

[wak131]

thanks lads so if the ratio is higher the quicker up through the gears & slower top speed & if the ratio is lower is the opposite? is this info correct?

Exactly.

But if the engine is gonna be more revy or more rev?ed, you don?t mind a bit shorter final drive, it?s optimal for faster acceleration.

[sid131]

Thank you, my final drive will be 4.3:1 so she will be a bit quicker through the gears, (someday)

[wak131]

Yes, that will be quite quick through the gears:) Supposing you?ll be reving it at least to 6500 rpm for to let each gear shifted at least few seconds

I had a 3.9 diff in my standard 2.0 TC and it seemed quite short for normal driving. You could start moving just by letting the clutch go anyhow in 1st gear without any throttle. Nice in traffic jam, but it was reving too high when cruising at 120km/h.

[miro-1980]

Look at this ..


This shows it all...( or almost all  )



 Miro


I can send you a spreadsheet for the calculation ...

[sid131]

Hi Miro looks like 4.3:1 is a good choice (accidental because thats what the lsd axle is)

[wak131]

12-43 diff standard gearbox.JPG

Hi Miro, is the second picture really a 10/43 diff?
 I read the speed at about 6000 and it shows approximately the speed a 2.0TC with standard 3.58 diff should attain at given revs. So I thought it could be what the name of the picture says a 12/43 diff...?

Edit: Would you be so kind to send me the spreadsheet please?
I?d like to see how will a VX 3.42 diff change the gear spacing in my car in comparsion with 3.9 and 3.58 diffs.

[djape1977]

high or low diff ratio?

my lada is runing on 1.8l 111hp fiat 132 engine, 131ab gearbox and 4.3/1 lada diff.
compared to my mirafiori 1.6cl (86hp) and standard diff (3.9/1?):
lada is much quicker in acceleration although being around 100kg heavyer than 131 and running on 205/60/13 tyres. starting in 1st gear with a little bit of trottle, car is VERY quick, much more lively than any non modified car i've ever driven. great for jumping in between cars when changing lanes or on traffic lights. starting with no trottle at all, just on iddle (850rpm) is quite easy. great during rush hour traffic jam. if i rev it up to around 5.000rpm and just dump the clutch it easily smokes both rear wheels and leaves double marks behind for 20meters at least withouth LSD. top speed in 1st gear is around 40km/h.
131 on the other side is in my opinion quite lazy, needing to be revved up to at least 3.000rpm for a quick start. it starts puling strongly only over 3-3.5k rpm.

starting in 2nd gear im lada is same feeling as starting in 1st in my 131. 2.000rpm, easy on the clutch and off you go! full trottle and you're doing 70km/h in a blink and than its time for 3rd gear. if changing from 1st to 2nd on 6.000rpm with clutch just being dumped, it spins rear wheels again. drifting in 2nd gear on coarse dry tarmac withouth lsd is very easy, during a turn, 2nd gear 20km/h,  i just need to press the clutch, rev it up to 5.000rpm and dump the clutch. as long as i don't let it go below 3.000rpm it slides around.
3rd gear is good up to 110km/h, and has insane acceleration. when using engine for braking, if i shift down from 5th to 3rd at 100km/h and release the clutch as i would normally do on my 131, lada will lock up rear wheels for a moment.
4th is more or less useless. i ofthen shift from 3rd straight to 5th. i only use 4th gear if i want to make someone in an new expensive car blush.
5th gear is great. no need to shift down during overtaking except in extreme situations. pulls strongly at any rpm. from in 5th gear 30km/h to 170km/h acceleration is smooth. when given a full trottle at 120km/h (highway cruising speed and speed limit) it pulls so strong that most of my pals who had a "pleasure" to be driven in my lada asked if it was 3rd gear. feeling is as in 131 in 3rd when given full throttle at 70km/h and accelerating to 110, only in lada it goes onto 170.

from a perspective of a daily city driver and a working car:
last year lada made 22.000km 90% city driving. i'm a locksmith and it's a locksmiths working car. full boot of tools. fuel consumption is resonable.


upsides of a high rato diff?
GREAT acceleration
excelent elasticity. you don't need to change gears as ofthen if you're driving at resonable speeds.
strong engine braking.
when driving slowly you don't need more than 2.500rpm ever!
when towing something there's tons of power available.
uphil, flat, loaded or empty, its all the same...
0-100km/h - 9seconds and 100-170 km/h 15seconds

downsides:
sometimes too strong engine braking
too much revs for a long highway driving.

[miro-1980]

12-43 diff standard gearbox.JPG

Hi Miro, is the second picture really a 10/43 diff?
 I read the speed at about 6000 and it shows approximately the speed a 2.0TC with standard 3.58 diff should attain at given revs. So I thought it could be what the name of the picture says a 12/43 diff...?

Edit: Would you be so kind to send me the spreadsheet please?
I?d like to see how will a VX 3.42 diff change the gear spacing in my car in comparsion with 3.9 and 3.58 diffs.

Sorry it was 12:43  . I have corrected it !

Miro

PS:  spreadsheet sent by email ...

[wak131]

high or low diff ratio?

I have similar experiences when comparing my 2.0/TC with 1.6/CL both with the same 3.9 diff,
 except I?m not really leaving black marks on the road,  just snake traces in the snow
Btw, what is the peak torque figure for 1.8TC and what revs?

PS:? spreadsheet sent by email ...

Thanx Miro! Nice work.
edited the values for my car and it looks like that

[miro-1980]

Glad you liked it !

I have no idea about the 1800 - sorrry ,

 But,  put the "close ratio" gearbox ratios in and then see the difference !!

M