Longer 5th for a 172 box

[Blackdavid]

Hello. I'm looking for some info as to what 5th gear i should use, for highway cruising.
Not for top speed since its a daily and just a fun road car.
More about reducing the highway revs for some mpg improvement, i usually just use the 1-4 gears anyways.
I don't know the code of my gearbox, since i can't seem to find the plaque where its stamped. Is there an engraved code on the casing itself?
Anyways, its a 2004 ph2 172.

 

[R3k1355]

The man you need help from is the forum gearbox expert.

@NorthloopCup, This man needs some length.

 

[NorthloopCup]

Hello. I'm looking for some info as to what 5th gear i should use, for highway cruising.
Not for top speed since its a daily and just a fun road car.
More about reducing the highway revs for some mpg improvement, i usually just use the 1-4 gears anyways.
I don't know the code of my gearbox, since i can't seem to find the plaque where its stamped. Is there an engraved code on the casing itself?
Anyways, its a 2004 ph2 172.

The gearbox you have is a jc5 130, and unfortunately the only way to get better mpg is to swap out the final drive for the ph1 172 item - gearbox code jc5 089.

There aren’t any options for 5th other than making it shorter which isn’t what you’re wanting.

 

[bashracing]

remember the the megane scenic 105 dci 5th you fitted to mine, that would work

 

[bashracing]

JC5-107 5th gear is what i had.



----------------------------------------


Clio 182
JC5- 130: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795
Final Drive: 4.067

Clio 172 phase 1
JC5-089: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795
Final Drive: 3.867

Clio 172 cup
JC5-129: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795
Final Drive: 4.067

-----------------------------------------

All other JC5 ratios
JC5 Renault Gearbox Ratios / Relations
JC5-014: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.794 Final Drive: 4.067
JC5-053: 1st: 3.363 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.821 Final Drive: 4.067
JC5-062: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795 Final Drive: 4.067
JC5-070: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.795 Final Drive: 4.067
JC5-072: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.733 F9Q 736 Engine
JC5-089: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795 Final Drive: 3.867
JC5-090: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.821 Final Drive: 3.867
JC5-100: 1st: 3.727 2nd: 2.048 3rd: 1.393 4th: 1.097 5th: 0.821 Final Drive: 3.867
JC5-103: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.733 F9Q 736 Engine
JC5-106: 1st: 3.727 2nd: 2.048 3rd: 1.393 4th: 1.097 5th: 0.892 Final Drive: 3.563
JC5-107: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.294 Megane 1.9dCi F9Q 105hp Gearbox
JC5-113: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.563 F9Q 732 Engine
JC5-108: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.821 Final Drive: 4.067
JC5-109: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.733
JC5-119: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.795 Final Drive: 4.067
JC5-120: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.867
JC5-125: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.867
JC5-126: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.563
JC5-128: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.294
JC5-129: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795 Final Drive: 4.067
JC5-130: 1st: 3.091 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.795 Final Drive: 4.067
JC5-131: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.821 Final Drive: 3.867
JC5-132: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.563
JC5-137: 1st: 3.364 2nd: 1.864 3rd: 1.321 4th: 1.029 5th: 0.821 Final Drive: 4.067
JC5-138: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.738 Final Drive: 3.294
JC5-140: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.294
JC5-144: 1st: 3.727 2nd: 2.048 3rd: 1.321 4th: 0.971 5th: 0.756 Final Drive: 3.294

 

[NorthloopCup]

remember the the megane scenic 105 dci 5th you fitted to mine, that would work

Ah yeah! Forgot about that! The biggest headache is getting one from Renault tbh.

 

[Darren S]

Hello. I'm looking for some info as to what 5th gear i should use, for highway cruising.
Not for top speed since its a daily and just a fun road car.
More about reducing the highway revs for some mpg improvement, i usually just use the 1-4 gears anyways.
I don't know the code of my gearbox, since i can't seem to find the plaque where its stamped. Is there an engraved code on the casing itself?
Anyways, its a 2004 ph2 172.

@NorthloopCup fitted the Ph.1 final drive to my gearbox when it had its rebuild. For me personally, I think it was worth the swap over and glad that I did it.

 

[Blackdavid]

Thanks for the replies.
So a diesel 5th wouldn't work?

 

[NorthloopCup]

Thanks for the replies.
So a diesel 5th wouldn't work?

Yes mate looks like it

 

[Blackdavid]

What are some compadible gearboxes that i should find? Asking more about the bolt pattern etc.
I'm also a VW fanboy, so the rule of thumb there is that 6 cylinder gboxes fit on any 6 cyl. So are 4 cyl boxes.
So might find some other gearbox with better gearing.

 

[Robbie Corbett]

What are some compadible gearboxes that i should find? Asking more about the bolt pattern etc.
I'm also a VW fanboy, so the rule of thumb there is that 6 cylinder gboxes fit on any 6 cyl. So are 4 cyl boxes.
So might find some other gearbox with better gearing.

Basically none. Someone did install a VW box at some point (wasn't you was it Northloop?) But it looked mega ball ache and you have to notch the chassis leg.

My 182 was always quite happy buzzing down the motorway at 40mpg but one of the first questions I asked on here was whether I could fit a longer 5th! So I know where you are coming from.

There were questions at the time about traction control not liking it and I just learned to ignore it 😂

 

[Robbie Corbett]

Yes mate looks like it

5th is under the little tin cover isn't it? So could potentially swap 5th without removing the box?

 

[Krarl]

dTi box also has a longer 5th iirc

JC5-087

 

[NorthloopCup]

5th is under the little tin cover isn't it? So could potentially swap 5th without removing the box?

Yes mate. But you need a puller to get the gear off.

 

[Blackdavid]

No traction control on mine, so no problem really.
What about the vw box? Have a couple of those, don't mind notching the leg. Are the bolt holes similiar?

Can't get better than 17mpg on mine.
Maybe if i'm really careful abiut my driving i can get about 20, but thats really not enjoying it. I'd be happy with 25 really, at least in 5th.

 

[Robbie Corbett]

No traction control on mine, so no problem really.
What about the vw box? Have a couple of those, don't mind notching the leg. Are the bolt holes similiar?

Can't get better than 17mpg on mine.
Maybe if i'm really careful abiut my driving i can get about 20, but thats really not enjoying it. I'd be happy with 25 really, at least in 5th.

Something is broken.

Mine was 30+ round town and 40+ on the motorway without trying. They are properly economical little things. When I first got mine it was doing mid 20's because the lambda was shagged and it was running very rich.

 

[Ol’ Tarby]

Yep definitely broken. 40+ is easily achievable in a 172. High 20s/low 30s running round town

 

[Blackdavid]

Okay, might have to do some digging then. Does this have a primary and secondary lambda?
Coluld it be the injectors are spraying wrong?
I'd like to upgrade the injectors anyways, and add a catch can somewhere. Might have a look around that.