3.15 Diff Ratio for Bathurst

Dazz · 25 Feb 2005, 23:51 (Ref:1236240)

Finally a technically sensible decision from the rule makers.

This year the V8's will be running a 3.15 diff rato at Bathurst instead of the 3.25 ratio that has been used previously.

Hopefully the engines will now be spending a little less time banging against the rev limiter at the end of Mountain Straight (on a real hot lap) and Conrod Straight in particular.

James63 · 25 Feb 2005, 23:53 (Ref:1236242)

Will this mean slightly slower lap times?

Dazz · 25 Feb 2005, 23:54 (Ref:1236243)

Not necessarily.

twig · 26 Feb 2005, 01:21 (Ref:1236306)

I thought it may improve lap times...

Senna05 · 26 Feb 2005, 01:51 (Ref:1236313)

speed verus' acceleration required over the top. I think it might be ok, actually - the speed gained will far outweigh the acceleration lost.

00 XR8 · 26 Feb 2005, 02:05 (Ref:1236317)

Will we get 300 down Conrod?

William Dale Jr · 26 Feb 2005, 02:15 (Ref:1236319)

Without the gearbox ratios and tyre diameters in front of me (pity the old DJR site's gone, all the car specs haven't been put back up yet) I couldn't say for sure, but I would think they would. They'd certainly get closer to 300 than the 293 they were limited to with the 3.25:1.

D.R.T. · 26 Feb 2005, 03:27 (Ref:1236321)

What will Channel 10 commentators have to talk about at Bathurst this year, now ?

Raglanparade · 26 Feb 2005, 04:02 (Ref:1236327)

I think 302km/h will be the highest possible speed on conrod.

how fast would they go if they were allowed to choose there own ratios ?

Dazz · 26 Feb 2005, 06:27 (Ref:1236363)

the change from 3.25:1 to 3.15:1 will lift the speed at 7,500rpm from 292km/h to 302km/h.

I would think however that only the really big hp engines will be able to take any real advantage of the ratio change and go quicker down Conrod than what they have gone before.

It will be interesting to see though with a good run out of Forests Elbow and possibly a tow who will post the fastest speed down Conrod.

The SBR/888/Larkham cars would be the ones to watch I would think.

Gaz170 · 26 Feb 2005, 06:33 (Ref:1236365)

Be interesting to see what it does across the top.

Dazz · 26 Feb 2005, 07:58 (Ref:1236393)

Probably won't make much of a difference really becasue you're not really hard up against the rev limiter in any spots save for across Skyline hitting the limiter in 4th on a really hot lap.

When you look at it, it makes only about a 10km/h difference at 7,500rpm in 6th gear, so in the intermediate gears in the middle rev ranges between say 5,000rpm and 6,000rpm you're really only taking a few km/h difference for the new ratio over the old.

It would be great to see a proper rpm vs speed vs track position trace comparing the old ratio with the new though to see exactly what difference it will make.

**Tim Falce** · 26 Feb 2005, 08:22 (Ref:1236405)

Apart from watching these races on TV now and again I nothing of the tech regs for these cars. Would they be allowed to cahnge gearbox ratios to compensate for the change in diff?

Dazz · 26 Feb 2005, 08:51 (Ref:1236419)

No, gearbox ratio's are the same no matter what track and are never changed.

The rules specify which diff ratio is to be used for each and every round.

**Tim Falce** · 26 Feb 2005, 09:00 (Ref:1236422)

Quote:

Originally Posted by Dazz

No, gearbox ratio's are the same no matter what track and are never changed.

The rules specify which diff ratio is to be used for each and every round.

Thanks for the reply Dazz

mmciau · 26 Feb 2005, 09:14 (Ref:1236429)

Hooray,
The discussions held on this forum on 2004 were not pointless.

Now it may be possible to see the very good drivers extend the margins on Conrod by not getting " rev-limited".

Mike

**GTRMagic** · 26 Feb 2005, 09:18 (Ref:1236431)

Quote:

Originally Posted by mmciau

Hooray,
The discussions held on this forum on 2004 were not pointless.

Now it may be possible to see the very good drivers extend the margins on Conrod by not getting " rev-limited".

Mike

WOW!!

You mean the Kelvinmonster and his band of merry narks read this forum and take some ideas and implement them?

Coolness!

alfasud · 26 Feb 2005, 09:28 (Ref:1236439)

Quote:

Originally Posted by Dazz

Probably won't make much of a difference really becasue you're not really hard up against the rev limiter in any spots save for across Skyline hitting the limiter in 4th on a really hot lap.

When you look at it, it makes only about a 10km/h difference at 7,500rpm in 6th gear, so in the intermediate gears in the middle rev ranges between say 5,000rpm and 6,000rpm you're really only taking a few km/h difference for the new ratio over the old.

It would be great to see a proper rpm vs speed vs track position trace comparing the old ratio with the new though to see exactly what difference it will make.

Or another way to look at it, is the places you'd previously use 6500rpm, you now use 6350rpm for the same track speed.... or use a lower gear for longer.

Good decision... in a class with so many artificial restrictions, they didn't need to keep an artificial rev limited top speed on conrod too.

paydirt · 27 Feb 2005, 08:38 (Ref:1237034)

Will the new final-drive ratio be optional, or compulsory?

**GTRMagic** · 27 Feb 2005, 08:54 (Ref:1237049)

Compulsory according to the 2005 regs

The 3.25:1 centre wont go to waste though... the Pukekohe ratio has also changed to this new one...

Raglanparade · 27 Feb 2005, 10:40 (Ref:1237109)

Woudlnt Sandown be on that Ratio too ??

Lowndesfan6 · 27 Feb 2005, 10:49 (Ref:1237122)

Doubt is Jason, it probably only warrants it if they get up to 270kph +, Sandown is shy of that mark.

**GTRMagic** · 27 Feb 2005, 11:11 (Ref:1237138)

From the 2005 regs:

3.7:1 - Adelaide Parklands, Albert Park, Mallala, Oran Park, Wakefield Park, Winton
3.5:1 - Barbagallo, Eastern Creek, Hidden Valley, Queensland Raceway, Sandown, Surfers Paradise, Symmons Plains,
3.25:1 - Phillip Island, Pukekohe
3.15:1 - Bathurst
Unknown - China

So if you wanted to get your knickers in a twist, the Kelvinmonster's TEGATechnicalTitans have actually INCREASED teams' costs by forcing them to buy a new diff centre/crown wheel combination to be used at no other circuit....

mmciau · 27 Feb 2005, 19:43 (Ref:1237459)

So if you wanted to get your knickers in a twist, the Kelvinmonster's TEGATechnicalTitans have actually INCREASED teams' costs by forcing them to buy a new diff centre/crown wheel combination to be used at no other circuit.... :rolleyes

No, from the two available ratios, the selection for Bathurst should be an option/voluntary.

This "sameness" is control to the nth degree and it adds to the "boredom" of cars having shift points and gear selection at the same point lap after lap after lap!

Mike

Dazz · 27 Feb 2005, 20:12 (Ref:1237490)

I don't know about a cost issue really.

I'm sure teams probably install a new crown wheel and pinion for Bathurst anyway and the ratio they put in makes no difference cost wise.

Anyone know for sure how many km's they they do on a set of diff gears?

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