icsmike

I cant get a fast answer by searching so I wondered if anyone had the answer off the top of there head. Whats the rear gears in a 86.5?

Jim bailey - 928 International

it is 2.20 to 1 or 15 : 33

icsmike

Thanks Jim. So how does this compare when someone says "three seventy three's" and "411's" or something along the lines of this. What does each of the numbers represent?

Jim bailey - 928 International

for every revolution of the rear wheel your engine turns 2.20 times with a 4.11 rear end the engine turns 4.11 for each revolution.....So your 2.20 gives you a 225 MPH or so theoretical top speed IF you had a 4.11 your top speed would be just about 1/2 that and driving 80 mph gets old really really fast !

icsmike

Schooled. Thanks.

Cliff Ruckstuhl

I have a question along this line, living where driving the car like it was ment to be driven will get me cuffed and stuffed. Is it possible to change the rear end gears in the auto to get better low end speed. Having a car that can go 170 and ever getting the chance to do it other then a track is usless to me. If it were possible to change the gears so the car would have a top end of say 145 or even a 100 mph but got there very very fast would be more of a benfit to me. Has this ever been explored?

Cliff 87 S4 Auto

icsmike

Yeah that would be nice.

Jim bailey - 928 International

When Kibort sees this thread it will all get very complicated Euro cars ,all early cars and GT GTS 5 speed got a 2.70 + - final drive a few 3.09 custom ring and pinions were made and trust me on this one you would NOT like a car that redlined at 100 MPH because at 80 MPH highway cruise the engine would be spinning at 5,000 RPM or so !

Rick Carter

Vilhuer

Everyone who are running with all cylinders wants longer top gear in GT and GTS. Engine runs way too much on 80 mph highway cruising speed.

Cliff Ruckstuhl

I see that on the 100 top speed and I think that running 80 with this set up would be pulling maybe 4-5K rpm and this is will not work. But what if we had gearing for low end speed for the first 3 gears? Right now if I want, I can hold second gear till 65 mph and a little more. If we had low end gears for aggresive driving for 1-3 and then 4 th gear would be like an over drive gear for high way driving. Has this ever come up before?

Cliff 87 S4 Auto

Vilhuer

Changing ring and pinion is somewhat cost efficient. Changing three gears gets expensive quickly unless suitable parts are easily available.

mark kibort

Jim, I'll be brief !

3.11:1 or 3.83:1 usually applies to common aftermarket ratios for american cars or some foreign cars like BMWs as determining their final drive ratio.

the gear spacing between gears is what you REALLY need to look at , as well as the total ratio, that is made up of a transmission gear ratio x a final drive ratio.

generally, if you really want to discuss this with someone, determine the speed in each gear at redline. you can have the same speeds in each gear as many other cars, with our 928s with a 2.2:1 rear end ratio. As Jim has mentioned, sometimes changing the rear end to a 3.09 (for example on a 928 with a stock 2.2) just buys you a superlow 1st gear (i like to call it a "sub-1st" gear) and the all the other gears remain the same, right up to the point where you find out you dont have a 5th gear any more! (the new 5th is like the old 4th was with the 2.2, i.e being 3.09 vs a 4th gear normally being 3.2:1)

Hope that clears up some of the confusion.
MK