DougM

It came from a car that the PO said was running and shifting strong until an electrical fire. When I drained the fluid, it was a little brown from the lower drain plug but was not full of metal shavings. When I get it removed, I will remove the top cover and inspect the gears.

Ispeed

In a 4.7 euro I would go for the 2.64 even though I am normally a fan of the 2.20. The 4.7 seems to like to rev more than a 5L.

Cheburator

I cannot believe we are even discussing this. The Euro S and S2 came with 2.72 from the factory. The lame excuse for a transaxle that is the 2.2 was never offered outside of the US. Fit the 2.64 and enjoy the take offs in your car. Fuel economy, schmeconomy. If you drive a 928 and want economy, park it and buy a Prius or a Volt...

Vilhuer

Its not $$$ saving in fuel bill why I want to have GTS box with 2.20 diff and gearset. Only reason to get it is engine rpm at motorway speed. 1st and 2nd gear gearing is really close to same as in all other 928 boxes so acceleration on small gears is very close to same. 2.20 box is like 6sp manual without 5th gear. 6sp box would be ideal but factory screwed that project up during GTS development.

mark kibort

that is an ignorant description of the gears. give me two race cars one with a 2.2 vs a 2.64 and ill find tracks that will favor either. its the final ratios you care about. forget about the "2.2". thats 5th and thats only for fuel economy on street driving and speed record runs with 400+ hp.
plus, no lsd, he is going to be burning rubber using 2nd gear for his "take offs "


yes, in fact, if you look at the corvette 6 speed, the s4 with the 2.2 matches up pretty close in most gears you actually use.

remember gearing doesnt buy you HP , closer gears can . : )

GlenL

...turn it back into torque.

mark kibort

rear wheel torque and Hp at speed, can be used interchangeably.

hacker-pschorr

I'm trading out a 2.73 and a 2.75 in my two cars for 2:20's.

If stock 928's had ever come with real horsepower, they would all have 2:20's.

The only downside I'm not looking forward to is the wider gear spacing of the 2:20 boxes.

For future reference, no, I'm not selling any gearboxes.

dprantl

I really would like to switch to the 2.2 in my car as well. However, there is some information out there suggesting that the GT transmission is stronger that the earlier 5-speeds. I would also have to deal with PSD defeat/removal, which is not something I look forward to. So I have just learned to live with the crazy high RPMs (for a 5.0 liter V8) on the highway for now.

Dan
'91 928GT S/C 475hp/460lb.ft

Cheburator

Funny how my 7-speed E61 M5 (that's the Estate version of the V10 M5) turns pretty much the same rpm in 7th at 80mph as my GT... 2.73 is ideal... And yes, both the GT and the GTS boxes are stronger than the 2.2 or 2.64 boxes. The GTS box is the strongest Porsche ever fitted into one.

I also notice thread deviation - there is a lot of "what if and buts". The fact of the matter is the OP asked about fitting a 2.64 or a 2.2 on a standard car. As such, any discussion along the lines if bigger power or GTS boxes is irrelevant The fact is, for a standard car, if you wanna go fast, you would want a 2.64 diff over a 2.2 ones. I am sure Kibbort would suggest that even 1.1 would be enough, but that has been covered before thus I would not go into it.

blown 87

Yea, you take them out, put them away and will never, ever find them again.

mark kibort

The only wider gear spacing is really only from 4th to 5th. it acts like a true overdrive, which is really kind of good.

mark kibort

clearly , you are missing the point. and yes, it has been covered before.

GTS or GT rpms are "optimal" at 80mph. hardly. the car gets much better gas mileage with the rpm down near 2500rpm at 80mph.

so, what would a 1:1 get you?? well, look at the gear ratios. what does a 1:1 give you? maybe i would only use 1st through 3rd for racing. (obviosly, i know you are joking) BUT, the point you are missing is that its the final ratios you care about. the 2:2 and the 2.75 all have only near 10% differnet ratios, even though the difference in the final drive is near 20% so, besides 5th and we dont use 5th in races generally , the trade offs of the two boxes is kind of subtle.

do yourself a favor, since it seems you clearly dont understand, just look at redline in each gear as far as MPH. then, make your decision of what gear box you want for street or track. on the track, it will depend on HP and the track. funny, a 2.2 for my hp is the perfect gear box for laguna (most optimization of HP-seconds possible at near 400rwhp. ) its true for a HP range of 250 to 400hp. after which you start to need a 2.75, and for less you could have an advantage of a 2.75. you see, gearing *(given that the gear spacin is the same) is optimized by the the speed ranges you will spend most of the time at for ANY application.

Now, if you disagree with what i have said above, i and others would love to hear how a 2.2 is a bad ratioed gear box. love to know that me running 1:36 at laguna with 372rwhp could be still improved by using a 2.75 gear box while shifting 2-3 times more per lap in to non optimal HP range RPM levels.

also, what I have said above is exactly what race teams do to optimize their gear ratios. many times, they only change the rear ends, not just to match top speed, but to match the optimization of HP used throughout a lap. when consideriing this for our cars, it may be a 2.2 it maybe a 2.64 it maybe a 2.75. you have to use your head to figure out what is best, not condem one over the other without basis.

Funny, I just had this discussion with a racer buddy who did the higher numerical ratio in his 400rwhp 5 liter M5. I drove it, yep, it did burn rubber in 1st gear mcuh easier. but the discussion went on to talk about, what speed ranges would now be optimal. is it 40 to 80mph or 50 to 100mph? for example. THIS wiill dictate the gear box that is best, not just a change to a 2.75 vs a 2.2 .
(sorry to beat the dead horse here)
mk

928mac

Until my tach starts going whacky, you can get an idea of the speed vs RPM

In this short video.
http://s103.photobucket.com/albums/m...t=MVI_1595.mp4


Red lights are Cat fire sensor which is disconnected (no cats)
and my LSD which stays on if I roast the tires, till I cycle the key.

ShawnSmith

I'm baffled by the love of ultra low gearing for the 928. At least for my car, it's at the limit of traction as I take off in 2nd gear on the 2.20 rear end. If I kick it to 1st gear I'm already having to carefully apply throttle to avoid endless wheelspin.

Going to 2.64 would make 1st gear even more useless, and give me what amounts to a 3 speed box.