C1j With Jc5..?

[raj]

How would fitting a jc5 gearbox to a c1j change its gearing? ie would i be changing gears more quickly?

how strong are these boxes compared to the jb3?

what other boxes fit the c1j without too much faffing about?

[SCHWARTZ]

volvo gearbox.:D

[Os8472]

volvo gearbox.:D


I thought the JC5 was a diesel box?

[SCHWARTZ]

i meant use a volvo gearbox like the ones on the 440 etc...

[Andrew Cooke]

I thought the JC5 was a diesel box?

not necessarily, it's a high torque box, so used with diesels and 2L engines

[Matt Cole]

not necessarily, it's a high torque box, so used with diesels and 2L engines

Higher torque than the gt box?

[R5TURBORON]

it will fit but think the ratios are different if its the williams box you want its a JC5 014 but the diesal box is also a jc5 but carnt remember the code

[GTphil]

I am going to be doing the very same thing shortly, a wise man once told me,

"172 has a 4.07 diff, compared with gtt's 3.73, so in other words you'll have to rev about 9% more.";)

The questions I have about this box are

Is the speedo pickup differant? ( I'm assuming it is)

Is the reverse light switch differant? (as above)

I'm also pressuming the only thing that I will have to do is move the starter dowle thingy to the same place as the GTT.

[Bigfoot]

you will have to go phase 1 172 gearbox as it still has the speedo pickup rather than using the wheel sensors. Speedo pickup is mechanical though so would need to look at getting different clocks in place.

[Andrew Cooke]

Higher torque than the gt box?

sure, why else did Renault go from the JB3 in the valver to the JC5 in the Williams

[Andrew Cooke]

I am going to be doing the very same thing shortly, a wise man once told me,

"172 has a 4.07 diff, compared with gtt's 3.73, so in other words you'll have to rev about 9% more.";)


he forgot to mention that 4th is also ~6% shorter, so make that 15%

[Andrew Cooke]

you will have to go phase 1 172 gearbox as it still has the speedo pickup rather than using the wheel sensors. Speedo pickup is mechanical though so would need to look at getting different clocks in place.

That's not strictly the case as my PH2 had a speed sensor too, as will cups, but they are 3 wire electrical sensors, so I still don't think they're compatible with GTT clocks.

Oh, and the phase 1 has a 3.89 final drive.

[GTphil]

he forgot to mention that 4th is also ~6% shorter, so make that 15%


So speedo will have to be sat nav! :wasntme:

You don't need a revrse light to pass an MOT! (yet:scared:)

15% is 900rmp revs higher for the same speed at 6k.

In other words say 90mph is 6k rpm in fourth with a gtt box, with a 172 box 90mph in fourth will be 6.9k rpm (all speeds/revs are just an example)

I'm pressuming that the rest of the gears it will just be 9% more revs?

The only reason I want to change is i'm sick of gtt boxes expiring on me!:mad:

[Andrew Cooke]

The only reason I want to change is i'm sick of gtt boxes expiring on me!:mad:

the reality is that the difference in reliability between a 172 box and a GTT box will be down to how it's been abused during it's life. A few years ago you could buy 172 boxes with 3K on them for about £150 since no-one wanted them, that isn't the case anymore, and it's more likely that any box you fit could do with a rebuild.

[Matt Cole]

sure, why else did Renault go from the JB3 in the valver to the JC5 in the Williams

Andy,

Do you have any info on the gearing materials/ case thickness / bearing types etc to suggest the williams boxes are indeed stronger? Not that im questioning your knowledge, its just that plenty of JC boxes go tits up as what the JB boxes do, mechanical sympathy or not. Knowing renault, the JC box could have been robbed from something else?

[Andrew Cooke]

The thing is Matt the JB3 is rated at something like 160lb.ft and the JC5 180lb.ft. not enough difference to get excited about either way, but enough that the 2L engines and diesels tip the JB over the edge.

I don't think the JC5 existed when the GTT was built.

I think you'll find bearings with balls in the JB, and cylinders in the JC, but it's a while since I looked.