Bit of a hypothetical question, but say if your RST was to have around 320bhp and was to have a new gearbox bulit by CTS, then would you keep the original final drive ratio, or change it?

I personally think it would be wise to change it to a slightly lower ratio, because...

a) You'll have loads of torque, so it may (slightly) eliminate some of the wheelspin in 1st/2nd and probablly 3rd gear.
b) You would be able to obtain higher top end speed

I havent got all the details at hand of the standard final drive ratio and the available final drive ratio's from cts when building the box, but would just be interested in peoples opinions.

I presume christian has a different final drive to achive his 168mph top speed run as I think the standard box is limited to about 153, but im not sure what his final drive ratio would be.

Opinions ?

 

i would 3.82 final drive not to my personal liking, i will be speaking to bernie about dropping to either 3.5 or 3.3 but it does all depend where peak power is, on most zvh for Instants going lower would help because peak power Achieved @ a low rpm but they have the torque to pull the gears.

 

I do have carefully considered ratio's. There are 2 sides to the coin.

Shorter ratio's will obviously make the car accelerate faster, but the power delivery could potentially smash the gearbox.

Alternatively, longer ratio's will make the car accelerate slower and in some ways be kinder to the gearbox. Although, the strain on the gearbox will be greater, so could just as easily strip gears.

If you go taller and get it wrong, the car will feel laggy and awful.

Also, don't expect to put a tall ratio in and just go and do 170mph.

I remember having Series 1 ratio's in mine and it was an absolute flying machine. But topped out before it went off the speedo. Now it goes off the speedo in 4th!!

 

I as just thinking that with that kind of power, it would be wise to choose a slightly taller final drive, but was just unsure of how you would go about deciding on an actual ratio so you get the most out of the potential of the power output.

 

What final drive ratio would you recommend for quarter-mile racing then? Bernie suggested to me either 4:1 or 4:26:1

 

What's the 3.3 ratio drive like on a zvh running 300 bhp or would you stick to standard final drive

 

IME Anything taller than the stock 3.82 feels horrible, I ran a 3.58 (IIRC) with 17" wheels and could do from 20mph to almost 120mph in 3rd, was like driving an auto!! I did have a theoretical top speed of 188mph though! lol

 

So would it be a better alrounder to stick with standard

 

u will need more power than that to pull a 3.3 final drive , stick to the 3.8 or if u want to gear it up put in a 3.5 , mine works really well with long gears

 

What car would u get tha 3.5 from

 

Personally i prefer a longer ratio box and i think once rolling they are actually quicker up to a point, ie the series 2s 3.82 vs the series 1 4.?? In a series 1 or xr3i you are always changing gear and its revving its tits off at 70/80mph whereas the Series 2 is relaxed at cruise and you dont need to keep changing.
Eg - an Xr3i or series 1 won't do a genuine 60mph in 2nd (standard rev limit applied)
whereas a series2 turbo or orion 1.6i will, as they have taller final drives.

In gear the shorter box maybe quicker but from say 50-100 there will be an extra gearchange so it ruins the advantage?

Karlos - was the 3.58 from a diesel?

Im tempted to try a longer final drive (maybe the 3.58) for an even more relaxed cruise (circa 2500rpm @ 70mph) and so i can use 2nd on roundabouts etc, as i currently use 3rd and its just at the point of spool up so 1/2 way round i hit boost and it upsets the car.

IMO with 300bhp i'd go for the taller gears as the torque and power will pull thru nicely, and the shorter ratios will just be wheelspinning and hitting limiter etc.

 

Sweet were can I get tha 3.58 from

 

true u are using all the power and torque instead of just spinnig up , i had a 3.5 bc and now im on a 3.4 in the mtx , think 3.5 is xr2 , tells in the haynes manualthe finial drives

 

Yeah as Stu says it's from an XR2 (not XR2i), I personally hated it but each to their own, I think the original S2 RST ratio's are spot on.

 

I had a 3.3 in my last one an was mental

 

Define "Mental"
I didnt realise an XR2 had such a long final drive...

 

Do not no y it went like that the chap at gear box said it was a 3.3 but was fast

 

I just want tha 3.3 again I think but Dow no what car the 3.3 gearbox it came out of

 

mk2 fiesta/ mk3 escort diesel i think and they mite be a different 6 bolt pattern on the diff aswel, cant remb

looked in to it a few years ago for mine but went for the 3.5 as gearing to 190+ on 16s @7.5k is more than enough

jamsport may still have the bits u need

 

Cheers I thought it was

 

Would it work better with the 3.3 with s1 gears on or s2

 

mine was a s1 box with 3.5 in it

 

I have both sets of gears s1 an s2 just got to find out if they are the same or dif an if there dif would like to no what wil work better on 3.3 final drive

 

I like the standard RST gearing, Im not sure what i have at the moment but its an IB5 from a 1.8 non turbo diesel van very close ratio's and its bloody annoying. Constantly changing gear, cant do 60 in 2nd (unless i raise the rev limit to nearly 7k)... A taller box will also load the engine up more and help spool up time in lower gears, I don't get max boost until 3rd gear as the load just isn't there, but that is 25psi in 3rd lol

Rob,

 

Rob u love abit of boost don't u... Im on a lowly 12-13psi , Car moves well as it is tho! I guess the stage 3 turbo helps!

I'd love to find an IB5 with the same (or at least similar) ratios to stock orion/rst. Or even with a little taller final drive!

 

tbh thats on a stage 2 t3... with a gt28 or stage 3 T3 my boost will be much lower, more like 20 probably.... That should be good for high 200's tho

The IB5 feels like a very positive improvement over all, and it didn't break when the car was on the road! But if I keep the escort I think an MTX75 swap is on the cards.

Rob,

 

S2 RS Turbo
1st 3.15
2nd 1.91
3rd 1.28
4th 0.95
5th 0.76
FD 3.82

1.8 Escorts Inc Estate
3.15
1.93
1.28
0.95
0.76
FD 3.82

1.3 Ka PAS (What I run)
3.15
1.93
1.28
0.95
0.76
FD 4.06

Non PAS has a FD of 3.59 making each gear a bit longer.

 

Cheers

 

so what everyones advise on a 3.3 final drive? on a 2.1 zvh stage 3 engine with cossi management pushing 300ish bhp

 

put a 3.5 in it

 

It's quite simple choosing what final drive you require.

Choose your realistic maximum top speed, wheel size and maximum engine rpm. From that work out your final drive required and choose the one thats nearest.

Our ERST top speed record with Oli's car was done on std gearing with 7600rpm limit for 174mph. Obviously if the engine did'nt rev as high we would have to have used a longer final drive.

Just do the maths and work it out, don't guess!

 

ok cheers just thought it mite get laggy with 3.3

 

Karl you seem to be making a passion ford come back recently, was having a good chat with your brother a while ago about his sunbeam, by chat I mean drool.

Im not so sure that choosing a final drive based around your maximum speed is the best way forward for a road car... probably a good starting point though. I would happily go for a car that cruised happily at 2500 rpm at around 60-70 if I was on the motorway a lot... clearly the car is never going to do 210mph though

 

Karlos - What shape escorts without pas, mk5 and 6 or just 5? Is that front starter aswell?

 

The PAS and NON PAS I was referring to are Ka box's mate (rear starter and hydraulic, but you can just take the gearset out if needed)....
Any MK5 Escort thats IB5 is front starter and cable IIRC.

 

Sorry m8, missed that
Nice 1 cheers!