gearbox options :)

[Chris P]

ive breifly researched, a RS5F31V gearbox. i hear it was a rare factory option in Jap and Euro markets. and was used with E15ET, CA & GA16DE motors.and bolted to EK10 March's. apperently the GA16DE has the same bell housing bolt pattern as CG, so can be fitted into K11?? is this true. so i could fit anything of a ga16 engine?? also any1 know of where id be able to source or build my own box. i oculd do it if i had the parts knowledge isnt an issue i am very interested in this RS5F31V gearbox though

Ratios of RS5F31V in K11
Gear Ratio
1st 2.938:1
2nd 2.095:1
3rd 1.538:1
4th 1.133:1
5th 0.810:1
Final 4.353:1

a relitivly close ratio box if im not mistaken ?? thanks in advance guys

 

[Low Rider]

As far as I am aware those were the March R ratios stated and the ratios for the K11 RS5F31V were closer to the stock ratios found in the CG13DE gearbox. You do however find some March ST's and K11's with the close ratio boxes fitted, perhaps they have been modified at some point, (I'm not really sure). Mulholland in Japan used to sell them until they got too rare. I cannot comment on anything regarding those variants available for the Pulsar, most of them are looking for longer ratio boxes though due to having more power and torque available.

It is possible to obtain a box but they are indeed challenging to find with those ratios and getting a box and shafts together is doubly hard. Having just done so myself you'll be looking at a fair bit of cash to get one landed in the UK. You'll also need to ensure you get shafts from a K11 and not an ST, as they are different and are required to engage the viscous coupling.

There are some people stating that you can use one shaft from a CVT gearbox to engage the viscous coupling but I have exhausted this information and found it to not be true, (shafts were very different).

It's also important to note that the internals from the RS5F31V are NOT compatible with those in the standard RS5F41A or 30A gearboxes, so you cannot mix and match things, (belllhousings are different and so is the gear cassette size), so you WILL need an RS5F31V variant and driveshafts.

 

[frank]

+1 on the cvt driveshaft myth (the N/S inboard c/v does,nt have the extended/doublespline tail).
the 41A type are slightly closer ratio, and with the 3.6 diff from a k10 would be my choice

 

[Low Rider]

Naff all difference between CG10 and CG13 box ratios in terms of separation, just lower overall ratios. 1st, 2nd & 3rd are practically the same spacing, 3rd, 4th and 5th are slightly closer together however.

Other than a dog box the RS5F31V is pretty hard to beat with the exception of the obvious drawback that motorway driving becomes a TOTAL pain!

If you're making power up in the rev range a CG13 box is hopeless, 100mph in 3rd is a joke on a track....

We'll have some comparative tests once the box is fitted so we can see what happens. Also we'll look into dumping flywheel weight, as we're still packing considerable weight compared to a lot of the 1/4mile bandits on here

 

[Stani1029]

I once had one of these but the bellhousing was shagged and we couldnt make the diff fit into another so it got binned

 

[Low Rider]

Hope it was a standard ratio one rather than a close ratio one. I know plenty of people after the gear packs and they're worth a pretty penny!

 

[Stani1029]

I couldnt possibly tell you, i got it free because the bellhousing damage. Took it to a local gearbox place who couldnt get a replacement or make it fit so gave up

 

[Chris P]

ah I see so what would the alternative be if I was perhaps to build my own using for example standard box and swap the internals could I achieve something similar.. ? just to clarify i have a 1.0L to soon be converted to 1.3 I just really want to build a close ratio box for when i end up converting to a 1.3 the plan is to build a road legal rally car, like I said previously i will be able to build a gear box seeing as it seems i dont stand a hope in hells chance of finding a RS5F31V how if at all possible could i build something with a similar out put by changing the shafts/ gears inside and using a different differential??? also I was to build my own box, has anybody had the same idea and not been able to do something (is there going to be some details that will be stupidlly complex) as you guessed im rather keen to do this and as frank said

+1 on the cvt driveshaft myth (the N/S inboard c/v does,nt have the extended/doublespline tail).
the 41A type are slightly closer ratio, and with the 3.6 diff from a k10 would be my choice

i have a 1.2 k10 gear box from my previous car so in short if i cant find one ill build my own and what would be the best bit to use thanks again guys much appreciated

 

[CliveBowles]

+1 on the cvt driveshaft myth (the N/S inboard c/v does,nt have the extended/doublespline tail).
the 41A type are slightly closer ratio, and with the 3.6 diff from a k10 would be my choice

Frank how do i know which gearbox i have? any exterior signs that would tell me which model gearbox i have? Thanks in advance!