T-uk

what is involved with fitting this when still wanting to use a standard UK rear diff?

I was planning to try and source a type UK 6speed but think the shorter JDM ratio may suit my car better on track. I know Skassa has fitted a type UK 6speed and prop without changing the rear diff , on his euro but would I also need a JDM rear diff?.

I am wanting to do this as cheaply as possible , by getting my own prop shortened and using as much from my current set-up as possible . the last thing I would want to do , is open up the gearbox to make it work with my standard rear diff.

Pavlo

uk 6 speed is actually quite close ratio as it is. i don't think it would be a problem on track at all

JDM would require matching 3.9 rear diff, rather than 3.545 that the UK has with it's 1.1:! drop gear.

You will also need linkage.

David wallis had just a box, got a linkage and got prop shaft shortened to suit. Same rear diff etc.

Paul

Denmark

iTrader: (2)

T-uk,

I don´t think you would want a shorter ratio ,then it is with the 6speed!

It´s short!!!!!

But it fit´s the TD05/06-20G perfectly.

This is about the speed in the gears

1rd gear/7000rpm 34mph
2rd gear/7000rpm 51mph
3rd gear/7000rpm 75mph
4rd gear/7000rpm 100mph
5rd gear/7000rpm 137mph
6rd gear/7000rpm the needle pointing straight down

The 6th gear has only been tested once,

Skassa

SPEN555

T-UK

Just FYI the UK and JDM 6 speeds have the same ratios gears 1 to 4, it is only 5th and sixth that are slightly shorter on the JDM.

Damian.

T-uk

thanks all,

sounds like I need to source a uk box then.

cheers

Denmark

iTrader: (2)

Is it really cheaper to get the oe propshaft made shorter,
instead of getting the propshaft from the same car as you get the gearbox from.

And yes the shiftlinkade is also needed.


Skassa

EMS

Damian,

Do you know the exact ratio´s for 5th and 6th gear? How about the final drive ratio, is it the same as in the UK version?

Mark.

Denmark

iTrader: (2)

Mark,
The finaldrive in the UK is 3,9:1 with the a reductiongear of 1,1:1
so the euro reardiff is 3,545

I do belive that the JDM gearbox has a 3,9:1 without reductiongear
So ,the reardiff is in the JDM 3,9

Skassa

Simon Lines

EU / UK STi
1st 3.636
2nd 2.375
3rd 1.762
4th 1.346
5th 0.971
6th 0.756
drop ratio 1.1
Front diff 3.900
Rear diff 3.545

JDM / Au STi
1st 3.636
2nd 2.375
3rd 1.762
4th 1.346
5th 1.062
6th 0.842
drop ratio 1.0
Front diff 3.900
Rear diff 3.900

Cheers

Simon

Denmark

iTrader: (2)

Great Simon,

I would just love to have the JDM ratio,

There is a big gab from 4th to 5th gear on the UK gearbox.

Skassa

T-uk

the JDM does sound better but I understand fitting the JDM rear diff leads to other changes at the rear , driveshafts , hubs and brakes. I do not know if my rear struts would fit then either.

I am now thinking of doing some 1/4 mile days next year , so possibly sticking with the UK classic box is best for this. I know andyf liked the longer ratio for them.

David_Wallis

its easy to get prop shortened.

SPEN555

What effect does the different drop ratios have UK vs JDM?

Damian.

EMS

Thanks Simon! Helpfull info.

The drop ratio of 1.1 means that the propshaft turns at the speed of the front differential divided by 1.1. Therefore a slightly longer rear diff ratio is used. Why not use the same as in the JDM car??????? Sometimes (often) I don't understand FHI!

Anybody know which Subaru model uses a 3.9/1 ratio with the R160 rear diff? (Is it the Forester S-Turbo?)

Mark.


[Edited by EMS - 12/12/2003 7:33:52 PM]

Andy.F

Early WRX RA has a 3.9 rear diff (and ultra low g/box ratios). If you find a DCCD version you will get yourself a plated 3.9

Edited to add - It's a 160 diff

Andy

[Edited by Andy.F - 12/12/2003 9:30:56 PM]

Pavlo

T-UK,

If you get JDM gearbox, R160 diff from P1 will have plated unit with 3.9 ratio AFAIK.

Also, 3.9 CWP can be fitted into existing diff, available from various nissans, I have a complete list of what diffs came on what (nissan) cars somewhere, soyou may be able to get one from a breakers.

Paul

David_Wallis

3.9 rear diff is in a sport.. remove cwp and mate with turbo lsd.

ustolemyname??stevieturbo

iTrader: (1)

You can use the prop from an auto box car.
Or as David says, get a CWP from a 2.0 sport model, which most are 3.9:1

Other than that and the linkage, its a simple bolt on job. Its also heavy.

To add.... I may have been mistaken about the P1 plated diffs...., but they do look completely different to a normal VC diff in an Impreza. Not actually sure what they are now ..

Also, an STI V3 RA AFAIK has an R180-3.9 which should make a good strong bolt on rear end.




[Edited by ustolemyname??stevieturbo - 12/14/2003 12:14:24 AM]

P20SPD

iTrader: (1)

Whats the top speed of the JDM one then? Can someone with more ability work it out for me please

Steven

Andy.F

Not sure your exact tyre diameter but based on 620mm
it will run 22.24 mph/1000 rpm in top

so thats
7000 = 156 mph
7500 = 167 mph
8000 = 178 mph

Andy

P20SPD

iTrader: (1)

tyres are 225/35 x 18 or 205/45 x 17

so for higher top speed a rev limit of 7000 the 6th gear out of the UK one would be better?

T-uk

steven,

iirc a JDM with 7k rev limit , will do around 153mph. it would be good if a JDM box,prop,linkage and P1 rear diff could be bolted straight into a UK classic but I have never been involved with diff swaps , so do not have a clue about which rear driveshafts etc are needed.

I am not so sure if a 6speed is the way forward now. the JDM sounds better suited in 5th and 6th after skassa's comment but I think for anyone doing 1/4's , the UK classic gearing is probably as good as it gets. I know andyf liked the UK gearing just not how weak the gears are do you know if david thinks he could pull away in second on the 1/4's to save a change? I can't see a 2litre doing this but perhaps a larger cc could.

there is a spare uk box here that I have been told I can use if mine lets go , so I may just do what you have done and use standard boxes until the money situation is a bit better. I think next year I will need to do a few 1/4 days and decide from there as perhaps the UK is the best all-rounder for 2litres. I am also needing another run in alang's car with it's shorter sti gearing.

the thing that contributed to this thread was when I was looking for a UK box for JB , I had been offered a JDM.

P20SPD

iTrader: (1)

Think he was going to try setting off in 2nd, but then his PS set fire.

Not tried setting off in 2nd on the road, guess we will have to.

Where did you find the jdm sti7 and how much.

Steven

ps i am still on my 2nd gearbox, which has done over 11000 miles since the last one went.

T-uk

steven,

YHM

(in about 20min the speed I type)

Denmark

iTrader: (2)

I will try to see if i can start i second ,but i don´t think it will be faster then a 0,15sec gearchange,from first to second,
but maybe it can.

Just how fast is the car going with the UK box at 7000rpm,
I had on the GermanAutobahn ,mine to 7050rpm in topgear,this is with 215/40-17 tires,so a bit lower gearing

Thanks,
Skassa

David_Wallis

I think it will pull off in second.. dont think it would gain much...

Its too damp and greasy to consider testing it in damp old leeds..

David

Andy.F

Skassa

You hooligan !! by my calcs that's a genuine 170.5 mph !! Adding the std speedo error of 10% that would be reading 187 mph

Andy

Denmark

iTrader: (2)

Andy LOL

The speedo is way of then

The needle was pointing straight down

Skassa

EMS

Do you still have all your side windows in the car?

Mark.

Denmark

iTrader: (2)

LOL

I did not check how much the windows were open ,but i could here the were wide open

I had a gps in the car and it showed 269km/t,it was still raising ,but slow

Skassa



[Edited by Denmark - 12/17/2003 10:45:54 AM]