3500S diff ratio

who when working out a gear ratio decides on a figure that best serves the car in question depending on power, weight, carrying capacity, etc
Good question...
I'd say the 'etc' is quite powerful in certain markets. In the USA 1/4 mile figures sell, in the 70's Japanese motorcycles were geared for 1/4 and 1/2 mile figures. Hence they sold but didn't go round corners....
For a race circuit car, again it's the stopwatch that governs the gear ratios used.
For a motorway cruiser, I suppose mpg, max torque around cruising speed to give max acceleration for those overtakes.

Why would you need to limit the amount of times the same teeth come together
Even when everything appears to be perfect, there are still imperfections. Impurities in the metal, oil, clearances etc. If the same teeth keep meshing, the worst clearance starts to wear and that wear get worse and on it goes; but only on those teeth. If you pick the gears to 'spread' the load, the wear is spread over all the gear teeth and therefore the gear set should wear slower

how do you work out when the same set will come together on a 3.08.3333333 : 1 gear set ?
I think your asking how long before the same teeth mesh again?

Number of Turns = Lowest Common Multiple of the gears / Number of teeth on the gear your turning.
12 driving 37 : Needs the 12 turned 12 * 37 / 12 = 37 times.

For the 928 with a ratio of 12:33 Take the prime factors of 12 ( 3 and 4) and 33 (3 and 11), the 3 is shared, so:
The 12 needs turned 3x11x4 = 11 turns.
Proof, 12 turned 11 times = 132 teeth & 33 turned 4 times = 132 teeth

You can see in these calculations why a prime number is useful. As a prime number has no prime factors other than itself and 1.

I bet people like these don't get out much, but it is beyond clever.
They let me out when I'm good.
“Any sufficiently advanced technology is indistinguishable from magic.” ;)
I remember spending a day or two looking at gears at university many years ago. Fascinating field and it's no wonder there are companies that make nothing but gears and gearboxes. Remember even F1 teams buy in their gears, they too think it is just magic.

What is the MPH/1000 rpm using a LT77 in a P6. Well, you see, although I've changed the gearbox to a LT77, but also the diff to a Jag and the tyre diameter....... All I know and keep reminding my other half is the speedo reads well under the road speed.:oops:
 
Magic !
For interest, what gears are in the Jag diff ?
What is the current tyre size ?
Is it LSD ?
Why the choice you made ?
Are you primarily running on loose, or metalled surfaces ?
Have you done any 0 - 60 times with the gears you have ?
 
For interest, what gears are in the Jag diff ?
What is the current tyre size ?
Is it LSD ?
Why the choice you made ?
Are you primarily running on loose, or metalled surfaces ?
Have you done any 0 - 60 times with the gears you have ?

Gears? Not sure on the gears, but ratio of 3.54:1, which the internet tells me uses 46:13 gears. There's another prime number.
1678917465125.png

Tyres? Hankook Optimo 4S 205/65R15

LSD? Yes, 4HU LSD PowerLoc, prelaoded to 65ft.lbs See Tightening the LSD
1678916713265.png

Choice? Because when I was about 16yo, I found a Playboy which the editorial section was photos of custom hot rods and their use of the Jaguar IRS. Ever since that I wanted a Jag IRS, not the only thing I wanted in that mag ;). I had always fancied building a trike around one, but then I learned the racing P6 used one.... that was my choice made.

The car was built for all surfaces, but mostly sealed surfaces. The primary need was a LSD for 360s around a cone. The deDion always gave remarkable grip, even on a loose surface. But the Salisbury type diif will always win when on a surface with areas of low grip. E.g. One tyre on wet leafs, the other on dry tarmac.

Performance figures? No timings at all, other than it revs out in top, just the stopwatch around tests. I must get round to doing some performance figures.
 
Guys, I have a "loose" diff that needs fixing. I'm in Australia and was advised to enquire about a Diff repair kit? Anybody know where I might find one of those?
 
It's a bit of a drive but Difftrans spares in Penrith is where I get my diff work done. They'll be able to work out whats loose and fix it. If not there is a guy in Queenbeyan who used to work on Flynn's cars that could probably source a replacement. Also Winns used to have some NOS gear sets at reasonable prices
 
Mike - does your msg mean they have done a P6 diff for you, and it was satisfactory? Mine is looser than I like.....
 
They've done several p6 diffs for me over the years. All good

Actually they are in South Windsor...next town north.
 
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