Gearbos ratio

[Adam-o]

well I was wondering if it's possible to change just the final gear ratio to make the 5th gear longer. I know you can get "short" ones but does anyone make them longer?

 

[Hutchie]

you can always put 5th gear out of a diesel box in



i plan too, and you dont have to take gearbox out either, just take end cap off, carefull not to break the oil feed

 

[Danmalone1999]

I dont think you can replace individual gears on the JC5 to alter the ratios.

 

[172Ben]

why?

 

[Jonny1*2]

you can always put 5th gear out of a diesel box in



i plan too, and you dont have to take gearbox out either, just take end cap off, carefull not to break the oil feed

Would the diesel box stick straight on or just the gears?

 

[caister]

you can always put 5th gear out of a diesel box in



i plan too, and you dont have to take gearbox out either, just take end cap off, carefull not to break the oil feed

guide needed I think!!

 

[Adam-o]

yeah, could use one.

 

[latza]

i would also love this. im sick of high revving at 70

 

[Andrew Cooke]

I dont think you can replace individual gears on the JC5 to alter the ratios.

you can swap 5th, standard is 0.79, and you can certainly get a 0.74, so about 9% taller. I don't know for certain, but you can probably swap 5th without removing the gearbox.

 

[Ben_Stevo172]

Stevieh off here runs a dci gearbox on his turbo trophy, he told me it's good for 180mph+!!!

 

[f0xy]

Clio 1.9D box will do 193mph @ 7500rpm in 5th if you ever got there

 

[Andrew Cooke]

yeah, but diesel ratios are rubbish

 

[T.Trophy]

I actually find them more suited to large powered turbo conversions.

 

[Jonny1*2]

yeah, but diesel ratios are rubbish

how so, you not going to get more usable power lower down the revs?

Which box fits straight on steve?

 

[Hutchie]

how so, you not going to get more usable power lower down the revs?

Which box fits straight on steve?

iirc the jc series have the same mounting,

 

[shiftspark]

Mark Fish will fit a Laguna 5th to a box to improve motorway use.

 

[f0xy]

how so, you not going to get more usable power lower down the revs?

Which box fits straight on steve?

Mk2 boxes are interchangable between models if thats what you mean, same bolt/bellhousing pattern

 

[Danmalone1999]

why?

Because stan at ADP tried and couldnt do it. I think you can do 5th and thats it. So pretty pointess. I was under the impression the input shaft is one unit, except for 5th.

 

[Jonny1*2]

Mk2 boxes are interchangable between models if thats what you mean, same bolt/bellhousing pattern

sounds too sensible for renault that Anyone fitted this box then?

 

[f0xy]

Which, the 1.9D box or the Mk2 1.5D box? Matteh has ran the 1.9D for quite some time on his 172 engine now

 

[Jonny1*2]

presume you mean mk1 1.9 box? No I mean the DCI box from the mk2. I'm suprised more people haven't swapped as diesel boxs are suppose to be stronger.

 

[T.Trophy]

I'm running a jc5 128 gearbox from a dci 80 and it's been spot on.

It suits the characteristics of big power torquey turbo conversions, plus they tend not to of had such a hard life unlike most 1*2 gearboxes.

 

[Jonny1*2]

what's the ratios like in comparision then?

 

[stan*]

Because stan at ADP tried and couldnt do it. I think you can do 5th and thats it. So pretty pointess. I was under the impression the input shaft is one unit, except for 5th.

I said you can only change 5th, the rest are fixed as it's a one piece integrated input shaft.

 

[T.Trophy]

what's the ratios like in comparision then?

There alot longer to be honest.

1st is similar for both

2nd is slightly longer

3rd is good for 100mph +

4th is pretty much the same as original 5th

5th is god for 180+

Whilst they seem extreme for a clio when written down like above, if you consider I'm running 267bhp and 262lb/ft with quite a broad power band you'll see how it gives you alot more flexibility. Rather than constantly changing gear.

You'll probaly find a few 5 speed 300+ bhp cars that will be capable of hitting similar speeds per gear.

 

[Jonny1*2]

by longer I presume you mean that you can get more speed in the gear before changing? I suppose for track work though the box needs to have shorted gears?

Do you use the diff that comes with the box? Presume the DS are originals too?

 

[T.Trophy]

by longer I presume you mean that you can get more speed in the gear before changing? I suppose for track work though the box needs to have shorted gears?

Do you use the diff that comes with the box? Presume the DS are originals too?

Yes mate, for track work you need a gear box that suits your power band, high revving N/A throttlebodied and cammed engines tend to have a narrow band at the top of the rev range, so longer ratios would drop you outside of the power band on gear changes, where as turbo cars tend to have a broad spread of torque/power so you can use longer ratios and cover a larger spread of speed.

For example in mine with the torque I can drop as low as 10mph in second and then hit 140mph in fourth where as in a a highly strung N/A with a stock box you may have to drop to first to get decent pull from 15mph and will obviously have to be in fifth to hit 140mph.

The drive shafts are 182's coupled to a stock box/diff.

 

[Andrew Cooke]

I actually find them more suited to large powered turbo conversions.

ahh, but that's because you have a small turbo, run something that will make large power and the rev drop 1-2 will kill you. Same thing for the guys running big cams.

 

[Jonny1*2]

Yes mate, for track work you need a gear box that suits your power band, high revving N/A throttlebodied and cammed engines tend to have a narrow band at the top of the rev range, so longer ratios would drop you outside of the power band on gear changes, where as turbo cars tend to have a broad spread of torque/power so you can use longer ratios and cover a larger spread of speed.

For example in mine with the torque I can drop as low as 10mph in second and then hit 140mph in fourth where as in a a highly strung N/A with a stock box you may have to drop to first to get decent pull from 15mph and will obviously have to be in fifth to hit 140mph.

The drive shafts are 182's coupled to a stock box/diff.

Yeah thoughts so. Interesting though. If only there was a better box suited for high reving engines. Only option is to change final drive really.

 

[Danmalone1999]

I said you can only change 5th, the rest are fixed as it's a one piece integrated input shaft.

Thats is exactly what i just said isnt it? Stan tried it. Could only do 5th. solid input shaft. So didnt bother.

No?

 

[stan*]

Yeah but have you seen my 4pots? They are close ratio 4pots.

 

[T.Trophy]

ahh, but that's because you have a small turbo, run something that will make large power and the rev drop 1-2 will kill you. Same thing for the guys running big cams.

I guess we'll find out in the next couple of months when I fit my new turbo set up.

 

[Danmalone1999]

Yeah but have you seen my 4pots? They are close ratio 4pots.

Close ratio alcons
Grifter diff
Armarni race suit
blackberry at the ready to monitor property portfolio
Leaky gearbox
Slicks (hair, not tyres)

 

[kevin.s]

its funny how renault made all the boxes interchangable yet all the driver shafts are compleatly different for each and every model. ill never understand the french.

 

[_WILL_]

Sorry to drag up an old thread, but how bigger job would it be to just swap 5th for a dci one? I am thinking it would help with the commute and when I'm having fun on b-roads i don't usually use 5th anyway!

 

[Lynchy172]

Stick the jc5 002 out of the old turbo diesel renault 19 they have tapered bearings just like the 172 box and well able i had them in my 172 and clio 16v was able to get 150 mph no bother in the clio16v and ran out road at 156 in the 172!!

 

[superbenji88]

any gear boxes with short ratio's for on the track?

 

[Jonny1*2]

any gear boxes with short ratio's for on the track?

You want to change final drive really ben. Get a quaiffe in there with modded crown nice and cheap

 

[_WILL_]

Stick the jc5 002 out of the old turbo diesel renault 19 they have tapered bearings just like the 172 box and well able i had them in my 172 and clio 16v was able to get 150 mph no bother in the clio16v and ran out road at 156 in the 172!!

How are the rest of the ratios tho? I want to keep the 1st 5 the same and just change 5th for sitting on the motorway?

 

[superbenji88]

You want to change final drive really ben. Get a quaiffe in there with modded crown nice and cheap

The winking is making me think its not nice and cheap...