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Mk6 Si Ross

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can anyone explain to me the differences between the IB5 and the MTX75 fitted in the RS/XR???

 

These are the figures i don't get

 

IB5

5th gear 0.75:1

Final drive 3.82:1, 3.84:1, 4.06:1, 4.27:1 according to model

 

MTX75

5th Gear 0.85:1

Final drive 3.82:1, 3.84:1 according to model

 

which 5th gear has more pull and why???

 

also what is final drive??? why/how could it differ from model to model???

 

Overall idea is that my car has no 5th gear, its shite, can do 140mph in 4th and the same in 5th cos it just won't pull, so would changing to an MTX75 benefit me any???

 

Cheers :thumb:

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Sorry, don't have time to go into it in depth.

 

What you want is shorter overall gearing on your 5th gear......

 

I suggest a 1.6 box :cheers:

 

Avoids messing around with gearing your 1.8 one differently.

 

I've only ever known the MTX75 to have a higher overall gear than the IB5. If you want a strong box AND lower gearing than present, fit a MTX75 with a final drive that gives lower gearing than you currently have. :thumb:

 

Hope that makes sense! :eek:

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Sorry, don't have time to go into it in depth.

 

What you want is shorter overall gearing on your 5th gear......

 

I suggest a 1.6 box :cheers:

 

I understand that bit :D

 

 

I've only ever known the MTX75 to have a higher overall gear than the IB5. If you want a strong box AND lower gearing than present, fit a MTX75 with a final drive that gives lower gearing than you currently have. :thumb:

 

Hope that makes sense! :eek:

 

This bit i don't cos my post was about the fact i have no idea what 'final drive' is, how is it determined??? how can they be different on the same box??? ?(

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I've only ever known the MTX75 to have a higher overall gear than the IB5. If you want a strong box AND lower gearing than present, fit a MTX75 with a final drive that gives lower gearing than you currently have. :thumb:

 

Hope that makes sense! :eek:

 

This bit i don't cos my post was about the fact i have no idea what 'final drive' is, how is it determined??? how can they be different on the same box??? ?(

'Final drive' is an extra reduction gear after the driver selected gears.

 

So you select a gear, then the gearing goes through another cog before linking to the driveshafts.

 

The final drive cog is changable, which is why you have a selection of final drives given, depending on model. :thumb:

 

Has that helped? :)

 

EDIT: IB5 is a good gearbox and will take 200bhp all day long......

Edited by Ex-Finesse
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the mtx gearbox will give better top end and can take more tourque than the ib5 but just onsent last between gears as long as the ib5. the ib5 is better at bottem end when it comes to transmitting the power but carnt handle as much torque hense the fact all ford diesels have mtx75 and not ib5 (apart from new fiesta diesel beacuase there naf no power or tourque) hope you understand and sorry if a bit long
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Zetec_mad is right in the sense that MTX will give a higher top speed.... but only if you've got the torque for it, and as the car doesn't have that with its current gearing, an MTX box will make things worse! :O

 

Do some maths.......

 

Find out what your final drive is at the moment.

 

We then multiply that by 0.75 (fifth gear in your gearbox) to get the ratio of crank : wheel turns. It should come out very roughly around 3 turns of the crank to 1 turn of wheels.

 

Then you can work out theroretical top speeds. You can also find out what kind of difference you'd get if you changed the final drive.

 

Or you could just drop it round to Giles, get him to chuck a 1.6 box in and see if that does the trick! :D :roll:

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ex finesse is right bout putting a 1.6 gbox in i put a 1600 gbox in my 130ish bhp escort and it gets to 125mph like theres no tomorrow but thats bout it beacuse the engine then wont go on enimore so more tuning requiered becaust the 16 gbox will go some more just quickly looked it up in my ford masters training book and it says the 1600 gbox is good for just oa 200bhp and will give a top speed which is more than your speedo

 

i hope this is usefull to you

sorry its a bit long

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I've only ever known the MTX75 to have a higher overall gear than the IB5. If you want a strong box AND lower gearing than present, fit a MTX75 with a final drive that gives lower gearing than you currently have. :thumb:

 

Hope that makes sense! :eek:

 

This bit i don't cos my post was about the fact i have no idea what 'final drive' is, how is it determined??? how can they be different on the same box??? ?(

 

 

EDIT: IB5 is a good gearbox and will take 200bhp all day long......

 

it'd be under wayyyyy too much pressure at anything above 130bhp if ur sum1 who gives it any kinda serious abuse ;)

Edited by Mike C
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thought a 1.6 box would give me great speed round town but kill the top end??

You current gearing is too high. By lowering the gearing at the top end (1.6 box will do that) you will increase your top speed because the engine can rev higher.

 

Have you got a pic of your RR graphs?

 

As far as I remember, redline is 6900rpm?

 

You ideally want a top speed where the engine sits around 6600rpm I'd say :)

 

What was it revving on the way up to Donington Spares a few months ago?

 

And what does it rev at when you change into 5th at 140?

 

Sorry, loads of questions! :roll:

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