Differentials For Landspeed racing.

[Dr Goggles]

Don't forget Doc that up to 200mph you can run V or Z rated road tyres, so you could experiment with different diameters (and widths) without having to spend a fortune on the Goodyear LSR tyres.

na, the profile is always way low....ultimately it saves us little......and beside , they look shit Dave...

2!! now that;s just being greedy.
Doc I'll distract him, you nick off with one..

Mate, You park out the front of his house and lay a big burn-out, while he's running out and shaking his fist at you I'll back the ute up and we'll have one each........

You flash bastard Cookey, two?....did you have a big win at Bingo?

[Cookey]

Goggs,
I have had them for years and always thought they came out of a 1949 Vauxhall Velox

[David Leikvold]

Doc, I forgot with my previous post that your car currently runs about .005" ground clearance anyway so any reduction in tyre diameter, front or rear, would be impossible. So then I though move the diff down in the chassis a bit but that just opens up a whole can of worms so I think the idea of stealing Cookie's beautiful quick change has considerable merit . Speaking of low profile tyres, I always have to laugh at the people with 4x4s who put 22" chrome alloy wheels and 40 series tyres on and then realise after spending thousands of dollars that they suddenly can't actually drive off road anymore. Not that they ever did. And the car rides like a dray all of a sudden and little flat spots start mysteriously appear in the rim edges.
Cookie, what brand is that diff?

[nitro-nige]

I was watching top gear Australia the other day and they had one of the supercharged walkinshaw clubsports on. The Stig gave it a thrashing and came up with a lap time. Then they took the posser rims off and put small wheels with taller profile tyres on. Went 3 seconds faster (even beat the W427 mega dollar HSV)

[Cookey]

David,
The top pictured QC diff is a heavy duty Winters 10" Grand National with magnesium center and side bells and the bottom one which is in my street rod at present is a combination of Frankland Racing and Winters components and is also a 10" unit.

[vetteracer]

Hope this is not too far off the topic- although I am a salt virgin, have had plenty of experience in working out overall ratios. With the tremac 5 speed in the Targa Vette using a vette Dana 3.45 diff and Dunlop Formula-R 245/40ZR17 tyres the speeds in gear are as follows:
1ST 47 mph
2nd 78
3rd 115
4th 154
5th 237 mph (theory only!)
With a shift point of 7000 rpm, the revs on the upshift never drop below 4000 rpm, well inside the torque curve. 200 mph equates to 6000 rpm which should (I hope) on the 434 cid will be pumping out 500+ ft lbs torque. Had thought the Tremac which is rated @ 450 ft lbs would not be able to handle 550 ft lbs- maybe if I drive it very carefully?
QUERY-for David- my initial aim is to hit 200 mph. If I do say 200.1 mph on ZR rated tyres, am I banned from a subsequent run- or can the car run again, if kept below 200 mph?
Vetteracer P.S. Can someone with more brains/experience tell me if it matters that the overall ratio is gained through a tall diff and 1:1 ratio, or a low diff and o/d gearbox. My only direct knowledge is from racing a Mini Sports Sedan- straight cut gears chewed less hp than helical cut. PPS N-Nige- thanks for the gear ratio tip- it prompted the grey matter -bloody eggtimers disease!

[David Leikvold]

VR, I don't remember anything in the rule book that specified what the procedure would be if you ran over 200mph on your ZR Dunlops, someone else could probably do a better job of answering that one. If you haven't already done so, download the rule book and see what you can find. Sorry I can't give you a definitive answer.

[vetteracer]

Maybe my ignorance of the salt and excitement at the prospect of running is getting in the way again- perhaps a more sensible approach is to build the car for 200+ but to treat the first year as a shakedown for car and driver, and aim to run at 175- with anything over that, a bonus.
Vetteracer

[Rob]

G'day VR,

Don't forget that your first runs are license passes and as such, speed limited.

The first to 125mph, the second 150, the third 175 with chute pull, the fourth 200, the fifth 250 and the last 300, from there you're open.

Each pass must be approved by the powers that be before you progress to the next or you would need to repeat it.

Before all that, your vehicle and personal safety gear must pass scrutineering.

Cheers,
Rob

Edit: Pays to scroll for one more page, I missed the 250 and 300 passes in the original post

[Dr Goggles]

Doc, I forgot with my previous post that your car currently runs about .005" ground clearance anyway so any reduction in tyre diameter, front or rear, would be impossible.

We can go to 26" rears without getting too close, the floor tapers up toward the rear.

So then I though move the diff down in the chassis a bit but that just opens up a whole can of worms so I think the idea of stealing Cookie's beautiful quick change has considerable merit

We can change the rear housing with a little heavy engineering, which is on the cards, and moving it down in relation to the frame is possible...

.

Speaking of low profile tyres, I always have to laugh at the people with 4x4s who put 22" chrome alloy wheels and 40 series tyres on and then realise after spending thousands of dollars that they suddenly can't actually drive off road anymore. Not that they ever did. And the car rides like a dray all of a sudden and little flat spots start mysteriously appear in the rim edges.

they belong on forklifts those tyres, and there's something I really don't like about HUGE wheels.,..

[momec]

Doctoor
I only run a 9 inch because it reminds me of home and more so because the abundance of ratios.
Otherwise l'd run an 8 inch anyday, suck much less power.
Good luck on your hunt.

BTW building a high perf alloytech for a speedway guy at the moment. High dollar thing with latest Motec and all the fruit. Will consult when shes done, maybe a cheap recipe.

Chris