16 replies to this topic

[76lxhatch]

The other thing to consider is the Gear Vendors unit only offers a small overdrive, the ratio is similar to what you'd get in a Jap 5 speed (0.78:1) whereas most V8 transmissions would have something closer to 0.7:1 at least. To me it seems a bit of a waste, a V8 will happily push a taller gear which gives better options for diff ratio while maintaining economy and cruising manners.

[dattoman]

6L80E ratios are usually

Gear ratios:

1  4.027

2  2.364

3  1.532

4  1.152

5  0.852

6  0.667

R  3.064
 

 

Now the thing to remember with this sort of box is there is no direct drive 1:1 like on normal boxes

So in effect you are always driving a planetary and therefore always have components turning and wearing

Also not as strong. However 80 series boxes are plenty beefy and strong for the most part

[Bernie]

Your 4L80 won't fit and the GV will hit on the crossover at the rear of the tunnel .If you are super keen you could cut it all out and fit  one in .4L 80 is very big and heavy .Wholesale automatics or PACT can do you a killer T700 and run a set of 3.25 gears .

But if you want one....

[76lxhatch]

I really want to find out firstly if it is going to even fit for Torana, secondly is like to find out ratio it gives for the 4th gear ( or 3 1/2 gear )

No not without significant modification, and as above the ratio is 0.78:1.

Also If anyone knows how to calculate what RPM at 100km by using wheel size,diff ratio, transmission ratio. Could you post a link on here please.

Just do the maths...
100km/h / 60 minutes = 1666.67m/min
/ rolling circumference (e.g. 205/70R14 tyre roughly 2.05m) = 813 wheel revolutions per min
x diff ratio (e.g. 3.45:1) = 2804rpm at driveshaft, which is engine RPM in top (1:1 gear)
x gear ratio (e.g. 0.78:1) = 2187rpm

[76lxhatch]

^ Both of those numbers can't be correct if the overdrive ratio is 0.78.

If they're 28" tall then they're approx 88" circumference (pi x diameter) which is 2.234m (25.4mm per inch), so...

100km/h / 60 minutes = 1666.67m/min
/ rolling circumference (2.234m) = 746 wheel revolutions per min
x diff ratio (4.11:1) = 3066rpm at driveshaft, which is engine RPM in top (1:1 gear)
x gear ratio (0.78:1) = 2391rpm

Note that calculating the circumference probably isn't the ideal method due to the way a tyre moves, especially a drag slick. Pump them up to a good pressure (to best simulate growth from higher turning speed) then simply mark a spot on the tyre and on the driveway or garage floor and see how far it goes along the ground in one revolution. You'll probably get a slightly smaller number than what I calculated above.

You're not going to fit a 28" tyre under a Torana without surgery either.

[V-SLR5000-P]

The calculators are OK with a manual gearbox where there is direct mechanical drive. A torque converter in a T400 is a fluid coupling (no lock up). You may have 10%-15% slip at 100kph and your engine revs will therefore increase.