Swapping gearboxes Q

Affiliate Joined: 13 Jan 2005 Posts: 219

Folks,

going to be putting an RSI lump into my car soon and i'm looking into gearboxes.

The lump will come with an RSI box but my 1.2 item is on far less milage (40k) - i know the 1.2 will fit but will it handle the power and what affect will it have ofnaccleration etc?

My 1.2 is a JB1 138

Your thoughts?

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

yeah, it will be fine strength wise, ratios will be less than ideal though.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

well thats not striclty true now is it neal.

What speeds are you currently pulling in each gear?

I know the ph1 19 1.4 energy box has ratios very close to 16V but the 1.4 c-type is much taller so would make the 16V lethargic.

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

I consider the 'ideal' ratios to be the ones Renault chose to go with the RSi engine. The 1.2's box won't have those same ratios, so in that sense, i still say it's 'less than ideal'

whether or not it's different enough to be at all bothered about is another story!

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

Well you consider wrong, they are adequate for general running about as are the 16v's. But theres other boxes in the range that can vastly alter the cars driving characteristics.

Affiliate Joined: 13 Jan 2005 Posts: 219

Well currently the 1.2 box (on the 1.2 engine and 6k limiter of course) flatout does;

1st - 25/30mph,
2nd - 50mph,
3rd - 65mph,
4th - 90mph,
5th - dunno...nae enough power to find out!

Obviously with the rsi it'd do the same but get there quicker but not sure if it'll get there before an rsi box if you get me...theres little info on them.

How do you know the box will be ok strength wise...is this a trial and error thing as AFAIK the JB1 box only got used up to an RT?

Level 4 User Joined: 03 Jun 2006 Posts: 83

Stick with the rsi gearbox,its what renault designed to mate to that engine.

Site Subscriber Joined: 11 Feb 2005 Posts: 2929

true, but they also made the 16v gearbox so weak that you can pop it without giving it that much abuse.

Thats why we like to put the jc5 box on.

sometimes standard isn't always best

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

again, not always true...mine has done 130K with much abuse!

Site Subscriber Joined: 11 Feb 2005 Posts: 2929

yea, tbh i've never popped a circlip either but neo has. lol several times so i believe.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

the box uses the same bearings and shafts as the JB3 but I have yet to hear a jb1 pop. I have run them with 17's and done burnouts and they are fine with mega miles. On the other hand pulling out of a parkign space has popped jb3's.

Those ratios are a bit short but they will make it ramp through the gears pretty quick keeping it in the power band as well.

As long as your not going down to glasgow everyday I would use the 1.2 box.

Affiliate Joined: 13 Jan 2005 Posts: 219

Excellent - thats what i was hoping to hear Chris! Smile

Should work out well...will be a bit quicker than a normal RSI plus i can redeem some of the costs by selling the JB3 onto a RSI/16v owner.

Thanks again! Smile

Level 4 User Joined: 18 Feb 2006 Posts: 86

didnt the later boxs on the phase 2 valver have a 50mm nut instead of the circlip

Retroholic Joined: 23 Dec 2005 Posts: 3315

wouldnt that be masive

FCS Event Manager Joined: 04 Jan 2005 Posts: 3680

Doc";p="98218 wrote:

yea, tbh i've never popped a circlip either but neo has. lol several times so i believe.

i have indeed Sad

but i can now change one out in less than 30 minutes lol

Mals has also popped the diff circlip on his cabby

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

dan_19_16v";p="98304 wrote:

didnt the later boxs on the phase 2 valver have a 50mm nut instead of the circlip

that holds the diff to the box and isn't a problem.

Its the sunwheel in the diff that pops which is th eother side.

Level 4 User Joined: 18 Feb 2006 Posts: 86

so if one of them goes is that bye bye gearbox or do u just lose drive, can u get in there and change it by takin the ns driveshaft out

FCS Event Manager Joined: 04 Jan 2005 Posts: 3680

in effect, its goodbye gearbox, once its popped, its gonna keep popping, thats my experience anyway.

It's easy to change out, takes me 30 mins to do one but like i said, once its popped, you will be a lucky bastard if it does not pop again.
I've seen several 19's in the scrappers where ppl have run welds to keep the circlip in, i was tempted to do that myself but it does not work.

If you can, invest in a JC5 box from the megane 2.0 16v coupe and drop that in.

Retroholic Joined: 23 Dec 2005 Posts: 3315

whats the ratios like the same or what??

Affiliate Joined: 28 Jan 2005 Posts: 360

I just happen to have the tech sheet for the Megane JC5-025 next to me:

1st - 11/37
2nd - 22/41
3rd - 28/37
4th - 34/45
5th - 39/32

FDR - 21/18

Good box but prone to the 5th gear syncro hub working loose due to a 20mm nut on the end of the shaft working loose. I've got a spare that's suffered this and is being rebuilt in a few months and will be kept as a spare for our 19 just in case as they seem to fetch about Â£200-250 on eGay and you can never find one when you need it! You can also use the gearboxes from the Clio RS but the speedo drive is an issue as the RS uses the ABS Signal to work out speed rather than a sender on the diff.

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

Mick, got any ratio details from the other JC5s, Laguna ones etc?