[trackday_prep] 205 2.1 16V Rallye Track Car

[harryskid 193]

A proper diff

[edbar 6]

Just out of interest Ash why are you changing diff? It didnt feel like it struggled with traction when I was in it, oh wouldn't the mi box make it longer geared? If thats the case I wouldn't do it! Good work!

[welshpug 1,622]

its a proper LSD, with that much grunt you'll highlight the shortfalls of an ATB quite easily (i.e spinning up an inside wheel if it lifts or has not enough traction)

 

also with that much grunt an Mi16 box will be just fine its not a stage rally car, so slightly longer gears work fine, though 1.9 gears are a little long.

 

this is a great spreadsheet you can use though, there is an error where the custom 2nd gear ratio result isn't correct but otherwise fantastic data.

 

http://www.mckeown-enterprises.co.uk/downloads/205ratiosGti6.xls

[edbar 6]

As I said after actually going in Ash's car it did not suffer with horrific traction issues and from experience of that it didnt seem to show any short falls of the ATB. I know exactly what the differance in diffs are as the tran x will lock and the atb doesnt so if you have it on two wheels alot or you snap shafts alot it is obviously going to be better. The question was for Ash's reason for changing from the ATB and considering the mi box over his 1.9 as the gearing seemed good also. I think only Ash should answer the question really.

[rallyeash 155]

im going to stick with the 1.9 box as i feel it suits the power.well and is a good match.

 

to be honest i don't get a massive amount of wheelspin when the tyres are hot and on track and wheelspin isnt really the reason im changing diff's. its more down to having more of an agrressive diff which should pull me through the bends abit harder.

 

we'll see what the difference is as im going to fit it this weekend...

[rallyeash 155]

interesting spreadsheet though welshpug! just saved it and will be handy...

[jonXS 30 1 Cars]

hey ash

how's it going?

 

did you ever send them wheel bolts off to me? if so ive not ever received them

 

jon

[edbar 6]

Ash, that seems fair comment. Fancy giving me a lift around combe on the 31st so I can feel the difference for myself. As mine is a budget track car I need to feel if the difference is large enough to warrant a change. Although I have other priorities on the car first.

[petert 550]

Surely you're not using a std 1900 gearbox with that nice engine? That would really dull the experience. Only a 1900/mi16 hybrid would suffice with your setup. Maybe a 4.06, but yuk with 3.62.

[welshpug 1,622]

not everyone wants to do 4k @ 70 mph Pete!

[petert 550]

But it's not a street car, is it?

[edbar 6]

Im with peter personally 4.1cwp would wake it up even more on track I love mine just have to suffer a bit on the road. It does go well even with the box as it is

[stu8v 68 1 Cars]

I've always had this dispute with my mate when I owned an Impreza.

 

Both similar power but mine was geared to 145 with his geared to 175mph

 

I always felt mine was more adjustable and frantic,

 

which for a track car, to me is more fun :) :)

[Spiky 37]

be interested to hear your views after the first track day with the diff,

 

i too run an ATB and the 1.9 box, and it feels fine to be honest, but would like to know what it would be like with a different diff

 

as for a shorter ratio box, IMO, thats a no no, even when i had TB's and a 1.6 box i could get 7000 in 5th at combe,

 

so these higher power cards need more gearing

 

edbar, you on track on the 31st?

Edited March 8, 2012 by Spiky

[petert 550]

as for a shorter ratio box, IMO, thats a no no, even when i had TB's and a 1.6 box i could get 7000 in 5th at combe,

 

So? Isn't that what's supposed to happen? With this spec engine you'd want to be hitting 7400-7500 in 5th towards the end of the main straight, where ever that is. I run a 4.75 with 1900 gear set in mine.

Edited March 8, 2012 by petert

[Spiky 37]

Why would he want to bounce off the limiter in 5th half way down the straight?

 

I know i don't

[edbar 6]

So? Isn't that what's supposed to happen? With this spec engine you'd want to be hitting 7400-7500 in 5th towards the end of the main straight, where ever that is. I run a 4.75 with 1900 gear set in mine.

 

Yes, just watch btcc footage and nearly all clip the limiter just before the braking point for the next turn. I think its just personal preference as to whether you want that to happen or not and quite a few don't.

 

Spiky im not on track but im going to come down and have the banter and pester you for a proper ride out ( Bring fuel this time ) round the track. I think my first outing will be rockingham sportscar circuit on the 14th april. Just got to get the cage in mine and we are away!

 

Just read your post spiky, halfway down the straight on the limiter is definatley not what you would want! Would yours do that with the charger then?

Edited March 9, 2012 by edbar

[Spiky 37]

i'm not joking, if put a 1.6 box on mine now, i would run out of revs with it, at most track days,

 

the 1.9 gives we a 150mph top speed,

 

and as i do tracks like bedford and donnington, a low top speed a is a no no.

 

i know race cars do, but thats becuase they are race cars and can afford to blow engines up

 

i may put fuel in it this time..lol

 

bring a cup of fuel with you..lol

[edbar 6]

Ok Steve We shall see how far we can get on a liter of fuel lol!

Was also going to make the point of race cars have the budget to rebuild after every event and most people dont.

You fancy rockingham steve?

[Spiky 37]

not thought about rockingham, as there dont seem to be many track days there,

 

not that i seen any how

 

where is it?

 

probably not on 14th as thats 2 trackdays in one month out of the same wage..lol

[edbar 6]

Shouldnt be much further for you than donny, its about the same distance for me. Im surprised you havent been already.

[rallyeash 155]

right, ive always liked the 1.9 box in my car, never found it too long or too short, for those that know combe im changing into 5th just before turning into folly at around 7400, then pulling uptowards avon rise in 5th. i wouldnt want a much shorter box as i'd definatly hit the limiter...

 

Wednesday night i went over to the rents and pulled the 1.9 box off, removed the quiafe and felt like the mi16 box i had was in better condition so decided to use the mi16 box and grind the various spots to make the Tran X diff fit. Last night i fitted the box back in the car with new driveshaft seals and cars ready to go again, just need to buy some proper gearbox oil which i'll pick up from merlins saturday so will take it for a spin the weekend with the new diff.

 

quite excited to see what difference its going to make

Edited March 9, 2012 by rallyeash

[welshpug 1,622]

NIck Charles's 220bhp+ 106 runs a 4.26 FD with standard MA sport cluster and a 7800 ish limiter, optimised for castle combe...

 

that gear ratio gives 125 @ 7k...

[Spiky 37]

where as if he took that car to donny or bedford would be bouncing off the limitter, and again this is a race car

 

 

we have track cars, so we need to comprmise, at least i do any how

[rallyeash 155]

yeah his ratio's are spot on for a combe only race car. im planning on doing Cadwell again this year, SPA and a few other circuits so want abit of flexability up top really.

 

i don't ever feel with around 230hp it struggles in any gear atall...