Struggling a bit with the standard 1600 gearbox on my 16V conversion, It may be that I'm just getting used to the AFH's lack of grunt at low revs but I'm becoming convinced the gearing is a bit leggy for the free revving nature of the AFH.

 

Bearing in mind this is a road car would the 1.3 (4.12) final drive be an improvement? 

 

Also there's a post or two about substituting 3rd and 4th from a Fabia 1.4 8V in an attempt to close the ratios up a bit, is this just substitution of standard parts or is a bit of engineering involved?  

 

Or frankly for all the difference it makes would just fitting a 1.3 box be a far simpler solution?

hi, i ran a bog standard 1300mpi gearbox on mine, to all intents and purposes they are the same as the 1.6 box except the final drive ratios are different. 4.11:1 versus 3.8:1 i found it to be quite irritating on a long drive if i'm honest, it always felt like i wanted to a gear higher, however going up hills was so much nicer with the 4.11:1 diff, it gives something like 15% more torque at the wheels.

personally i wouldnt bother swapping gears about, you'll just end up with a pile of broken gearboxes that you cant put back together

Looking at the overall 6N Polo 16V Ratios I think the 1300 gearbox is probably the better fit?

 

I appreciate the Polo final drive is close to the 1600 but unless I'm much mistaken countering that 5th gear is pretty close to 4th on the 1600.

 

6N Polo 16V Manual gearbox

5-Speed 085

Engine

1.4 ltr. - 74 kW

 

Final drive

62 : 16 = 3.875

 

1st gear

38 : 11 = 3.455

 

2nd gear

44 : 21 = 2.095

 

3rd gear

42 : 29 = 1.448

 

4th gear

45 : 41 = 1.098

 

5th gear

41 : 46 = 0.891

 

Reverse gear

44 : 13 = 3.384

 

Skoda Felcia ratios from the web (98-01)

 

1. 3.46
2. 1.96
3. 1.31
4. 0.98
5. 0.76

Final Drive 1600 - 3.83, 1300 - 4.12

After a bit more number crunching the 1.3 (4.12)  is still quite a big longer geared than the Polo box. 

 

To illustrate theoretical speed at 6750 revs in 5th on 185/60 x 14s something like:

• 132 on the Polo box,
• 145 on the 1300 box
• 156 on the 1600 box 

 

The 1.3 box is a step in the right direction, but any opinions on it being worth the hassle/expense of swapping (ie for a road car)? 

 

I hear what Tom is saying regarding motorway noise but according to my figures the 1.3 box only needs about 4600rpm at 100mph, so I'm not sure there's too much of an issue with that. 

Are you you've crunched the numbers right?

You could try smaller tyres. 185/60 14's are a bit taller than the standard Felicia 165/70 13. 185/55's would be closer. You could bung a set of standard Felicia wheels on and see what happens. I realise you want something wider for the grip but just to see how it feels in a straight line. I've got a set of standard wheels in my garage if you fancy a trip up to Southampton.

It's a lot easier than messing about with gearboxes.

Are you you've crunched the numbers right?

Well fairly approximate and a little bit out on the 1.3 but close I think?

 

The maths for 5th gear, 1300 4.12 diff:

 

Lets say 1000rpm at the engine,

 

5th gear 0.76:1, so input to final drive is 1000/0.76 = 1316rpm

 

and at wheels 1316/4.12 = 319rpm

 

Circumference of 185/60 x14 is 1.797m approx

 

and so engine 1000rpm equates to 319 x 1.797 metres/min =  573m/min = 34km/h or  21.25mph/1000rpm

 

so 6750 rpm equates to 143mph

 

 

and for 1600 3.83 diff:

 

1000 engine rpm = 1316/3.83 = 344rpm at the wheels

 

and mph/1000rpm = ((344 x 1.797) x 60/1000)*5/8 =  23.15mph/1000rpm

 

and 6750 rpm equates to 156mph 

 

and plugging the numbers for the Polo in:

 

(10000/.891)/3.875 x 1.797 x 60/1000 * 5/8 =  19.52mph/1000rpm and 132 at 6750 

 

(All assuming the ratios I've stated are correct of course).

You could try smaller tyres.....

Fair point and it would be a small step in the right direction but I have driven both my old 1300 and the current car pre conversion on standard and current wheels and I couldn't perceive the difference in gearing.

Putting standard wheels back on now is not an option as I have bigger brakes, but thanks for the offer.

Probably will look at 55 profile tyres if I see some at the right price or when replacing.

 

I found this which can be used to validate the figures...http://www.roversd1.nl/sd1web/wheelcalc.html

 

(as I was beginning to doubt myself)

Sorry, I hadn't thought about the bigger brakes. It just occurred to me as the tyres on my Citigo wheels are a fair bit bigger and it has taken a bit of an edge off the acceleration. I too was thinking of 185/55's at some point but as my wheels came with nearly new Bridgestones I'll be keeping them for some time.

Sorry, I hadn't thought about the bigger brakes. It just occurred to me as the tyres on my Citigo wheels are a fair bit bigger and it has taken a bit of an edge off the acceleration. I too was thinking of 185/55's at some point but as my wheels came with nearly new Bridgestones I'll be keeping them for some time.

CityGo? When was this little purchase made then?

No Lee, it's only the wheels from a Citigo not the whole car. Do try to keep up! See the Felicia appreciation thread.