jtabraham

Hi,
I have a MY00 UK Turbo which is currently undergoing TD05FE, pump, reg,headers, front mount, avc-r and apexi pfc.
From what I understand my gearbox will be near its limit.
I do not want to go down the 6sp route.
Would I benefit from a V5 or V6 Sti box, and would I have to change my diffs etc.....
All help much appreciated.
Thanks
Jt

scoobyDAZZA

i was gonna ask the same question

ive heard the standard 5-speed 99/00 is only good for around 300 ft/lb torque
there a couple of people on here running 500 bhp on the same box as us but obviously rebuilt using special parts and they say the 5sp is better than the 6
sorry i cant help you but i'll certainly be keeping my eye on this thread

Nezz10

Your gearbox should be fine unless you abuse it. I have been running a higher spec than you for a couple of years and my MY00 UK box is still going strong. OK maybe the syncros are a little worn on first and fourth but thats down to me and not the power.

Some people gearboxes have stripped with less than 300ft/lbs but others have been running well over that with out problems (touch wood!)

Unless you have a problem with the gearbox I wouldnt bother changing it yet, when you have a bigger turbo and more boost then maybe consider it if you have spare cash.

A fully fitted 6 speed will cost £2K from API, an STi 5 or 6 box (about £500 + fitting) is stronger than the UK but will have different ratios, you would have to find a matching rear diff I believe. Speak to any of the engine builders or the like from here and they can give professional advise.

Nezz.

Aztec Performance Ltd

iTrader: (234)

How many miles you done on your gearbox and on what spec?

Many drag/launches?


Bob

scoobyDAZZA

well i got off the rollers earlier and recorded 338.5 bhp and 325 lbs/ft torque

on hearing that uk boxes dont last long 300+ torque im definitly now gonna look at my options....

david - any advice
dazza1802@aol.com

jtabraham

bob's
My car has done 85,000mls, upto now it has only had enthusiastic road use, but I am entering scooby shootout and will be dragging it abit this year. The car is no longer my normal car, its just for fun.
I am still abit unsure of the gearbox issues.
Was it you that posted a 12.4 at the pod. On a UK box?

harvey

iTrader: (48)

The STi 5 or 6 box is probably the strongest O/E five speed so you could start looking out for one now in advance of needing it.
The STi 5 and 6 have 4.44 diffs and 1.0 :1 dropper. So you need the 4.44 rear diff from the same car.
Your box MAY have, )check it out yourself against the VIN plate to be sure), 3.9 front diff and 3.545 rear diff with 1.1:1 dropper.
I would not change the box until/unless it broke.

jtabraham

Cheers Harvey.
How much different are the ratios?
Are they still a good match to the UKs lower rev limit?

RON

Harvey,
I have a my00 turbo, with a few mods on the way which mean i will need a stronger box, I am buying an STI5/6 box from J Banks, with apparently a 3.9 front diff so that it will match the UK rear diff, this is all new to me, can you advise wether this is correct.

Not wishing to doubt what John has told me, just double checking.

Cheers.

Ron.

harvey

iTrader: (48)

The STi ratios are good but you go to 4.44 diffs from 3.9s so you are reving higher for the same road speed. On two cars I am using STi boxes/ratios which I like and 4.11 diffs.
I can work you out exact figures if you want but when comparing them, please remember that your speedo and rev counter are NOT accurate.

jtabraham

Hi Harvey,
Is it OK to call you this week, to discuss further?
Julian

harvey

iTrader: (48)

Ron: The 3.9 diff ratio is quite tall with the STi box which means that your top gear acceleration will be a bit blunted. I ran 3.9s when I was around 500 bhp and swapped onto 4.11s. I may go back onto 3.9s at 600bhp.
The UK car has a 3.545 rear with a 1.1:1 dropper. A 3.9 front in a Jap box with a 1.0:1 dropper MUST have a 3.9 rear diff.

harvey

iTrader: (48)

No probs. If I am tied up I will tell you and you can ring back.
I will work out the ratios and geared speeds and post on here.
Just be patient until I get time.

jtabraham

Thanks
Julian

RON

Thanks Harvey, so if the 1.1;1 dropper was also in the jap box, would that make it an ok match??

I'll have to get better with these things if i'm gonna do 'the project!!'

Cheers.

andy97

iTrader: (1)

Is anybody using a different gearset like PPG or Quaife in an original 5 speed housing?

Are there real benefits by using these gearsets in the terms of being able to handle alot more power/ torque?

I assume that the downside being noisy to use as an everyday car.

Andy

harvey

iTrader: (48)

All Jap boxes are 1.0:1. I suppose you could use a UK transfer case to convert the 3.545 to 3.9. I have never done this so I do not know if it physically fits and it would be better to run a Jap transfer box 1.0:1 with the same diff ratio front and rear.

The following are STi 6 ratios and geared speeds assuming 215 x 40 x 17 tyres. For OE 205 x 50 x 16 ADD 2% as these are actually taller.

......Gear Ratio ......3.9 diff.........4.11 diff...........4.44 diff
1.....3.166............. 5.56.............5.27................4.88 mph / 1000 rpm
2.....1.882............. 9.35.............8.87................8.21
3.....1.296.............13.57............12.88.... ..........11.92
4..... .972..............18.10............17.17.......... ....15.9
5.......738..............23.83............22.62... ...........20.94

I hope this helps you.

stockcar

as long as you match the centre and front diffs then you can basically 'mix and match' to get what you need, within reason.......................

if its a UK car and you run a JDM box then use the Uk front ratio and centre diff to match your original rear....................

the alternative is to run a complete JDM "set" and install the matching box and diffs................

alyn

john banks

Ron, Pavlo changed the 1:1 transfer gear to 1.1:1 to go with UK OEM 3.545 rear diff, and installed a 3.9 front diff to match. So the speedo is correct (as correct as OEM anyway) and the road speeds on 215/40R17 are as follows: (UK 5 speed with same tyre size in brackets, 4th & 5th are identical)

1st: 5.7 mph (5.2)
2nd: 9.6 mph (9.3)
3rd: 14.0 mph (13.3)
4th: 18.7 mph
5th: 24.6 mph

I had similar gearing to this on a 5 speed with 2.5 and 20G and it was the best engine-gearbox match I've come across on a 2.5, my terminal speed on the 1/4 dropped by about 4 mph when I switched to 6 speed because of the extra gearchange - it was mental with 4 gearchanges in 8 seconds. 2.5 with 7000 or just above rev limit suits longer gearing than a high revving 2.0. 6 speed options (apart from Forester which I haven't tried) are too short for the 2.5, especially with a low lag turbo setup.

Top gear acceleration in 5th with c.24-25mph/1000RPM with 2.5 and a 20G is hilarious. If you are at 3000 RPM or approx 74 mph, there is no real lag on putting the foot down, the boost gauge just swings round to full boost almost immediately, this is 500 RPM past the point where the turbo will reach 1 bar of boost. It is nicely geared for economy, refinement, and accelerates well on this engine/turbo/box combo.

RON

Thanks for that John, like I said i was in no way doubting/questioning what you'd said, it just needed clearing up in my head, the gearing sounds perfect for what i have in mind.

I'll be in touch..

Ron.

john banks

No problem at all, I think it will be a nice set of ratios. I use Delta Dash road dyno as my calculator, lets you play with lots of setups, you can use the demo version from the Ecutek site.

harvey

iTrader: (48)

Ron: The mph/1000 rpm for an STi 5/6 box with 3.9 diffs and either 215 x 40 x 17 T1-R or F1 GSD 3s is exactly as I have stated. It is now clear that the UK 1.1:1 transfer box can be used to retain the 3.545 rear diff, ie it becomes 3.9 with the 1.1 conversion. In particular 5th is 23.83 mph/1000rpm.
Having considerable experience of this gearing in two different vehicles I have settled on 4.11 diffs. Motorway cruising is not manic as it would be with 4.44s but it is not too tall as it would be with 3.9s. With more torque, the 3.9s become more viable and I would expect a 2.5 generally to produce more torque than a 2 litre.
Are you putting it in a 2litre or 2.5?

stockcar

Harvey, we built Dion's 2.5 with a v6 drivetrain converted to 3.9 ratios.......... personally think the overall spread of torque/gearing works very well although not tried this set-up on a 2.0.................#

alyn

john banks

What diameters are you using Harvey for 215/40R17 and 205/50R16?

Subaru quote MY00 UK 5th gear at 24.88 mph/1000 RPM and 205/50R16, which has the same 5th gear and final ratios as Ron's gearbox.

Toyo quote 612 and 606 mm respectively for 205/50R16 and 215/40R17. So with 215/40R17 Ron's gearing would be 606/612*24.88 = 24.6 mph/1000 RPM. Which happens to be identical to Delta Dash and markedly different from your figures.

Alternatively, 606mm * Pi / 0.738 / 3.9 * 60 / 1.609 = 24.6 to 24.7mph/1000 RPM.

To get 23.83mph/1000 RPM you would have 23.83/Pi*0.738*3.9/60*1.609 = 585mm or 21mm less than Toyo quote for a 215/40R17.

We have a 3.5% discrepancy which is more than just messing with a few significant figures.

harvey

iTrader: (48)

Tyre diameters are not satisfactory for accurate gearing calculations. The figure you need is the actaual rolling circumference. take your car to an empty super market car park and accurately measure 15 or 20 exact revolutions along a white line and measure it with an engineering tape measure. For F1s and Toyo T1-R you will find this is 1838-1840mm depending on the state of wear.
From memory the Goodyear NCTs 205 x 50 x 16 are 1878mm. Againa physical measurement.
KPH = tyre circumference in meters x 60 x RPM/1000 x gear ratio x diff ratio.
= 1.838x60x1000/1000x.7381x3.9
=38.31kph
=23.94mph.

john banks

I see what you mean Harvey. How realistic is the loading on the tyre when measured in a car park compared to being in 5th gear though? Clearly using the diameter is not realistic either though from your measurements, but correcting for speed/load/temperature/pressure/vehicle weight could be tricky? Are most car manufacturers quoting gearing information based on tyre diameter, gear ratio and final drive as Subaru are?

It probably doesn't matter for Ron since he will have the same 4th and 5th gear ratios he had to start with which work well on his 2.5/20G.

Aztec Performance Ltd

iTrader: (234)

How much of that was in a 'tuned' state?

Yes 12.4 was on uk box (full weight uk car, with 3/4full tank, cd player, cds etc etc) at the pod, with room for improvement.

Bob

jtabraham

Hi Bob, The car has always had the ppp, but it has been running about 260bhp and over 260 lb/ft torque for over 35,000 miles.
Just needed a bit more power!
Julian

ps. Congrats on the results.
Are you running the shootout?

Aztec Performance Ltd

iTrader: (234)

How many mls on your current state of tune?

Thanks. Wont be going to SSO as its too far and expensive.

Bob

Aztec Performance Ltd

iTrader: (234)

Sorry ignore the bit about miles etc. Was directed at Nezz10 earlier in the thread and has been mixed up since.

Bob