merchauser

not sure how many others out there feel the same, but I often wish I had a 6 speed in my car. For highway cruising,
one more gear would be nice.

wondering if anyone has put in a different 5th gear in their manuals, for an overdrive effect??

perhaps that "5th gear" does not even exist?

Darklands

You have the wrong car! The GT has the gearbox with the shortest final drive.
Final drive Ratio 2,78:1 A 928 S3 has 2,20:1

hacker-pschorr

+1
If you start a post to trade transmissions with any S4 5-speed you'll have a line around the block.

merchauser

happy with the GT, and don't spend a lot of time on the highway for long trips. but I would like to take a 12 hour
jaunt north this summer, and thinking one more gear, would make the trip a bit more pleasant.

is there a retrofit 5th gear?? more curious than ambitious.

GregBBRD

​​​​​​Not possible.

5th gear is direct drive to engine rpms....1 to 1 in all 928 five speeds.

The only way to change this is to change ring and pinion final drive ratio.

Rob Edwards

5th gear is part of the input shaft, so when you're in 5th, the input shaft is directly driving the pinion shaft, so there's not really any way to change the ratio. Only way to change would be to stick a different ring and pinion set in the box, but no one's going to be gutting a G28.55 box to turn it into a G28.13. If all you did was long distance highway driving, putting a 2.2 rear end in the car might be worth it. Might.

EDIT: Rats, gotta learn to type faster.

merchauser

OK

question answered; happy to stay with what I have! thanks.

GregBBRD

Important design "distinction" for those not well versed on the 928.

On 928 transaxles the input shaft is 5th gear, which is in a directly inline to the pinion shaft. When 5th gear is selected, it is directly coupled to the pinion shaft....thus 5th gear is always 1 to 1. Yes, 5th gear has a ratio, but it only affects the 1st-4th gears (and reverse.)

In most transaxles (911, 944, etc.) the input shaft is not directly coupled to the pinion shaft. Therefore, the 5th gear ratio can be infinitely altered by changing the tooth count on 5th (or 6th) gear.

merchauser

great information, and interesting that 911 cars give you options!

The Forgotten On

If all else fails you can stick in a Corvette transaxel and save your GT parts. Plenty of options there and it will get you a 6th gear.

GregBBRD

Or just buy a Corvette and not bastardize your 928....

merchauser

I like that idea, but I would not entertain the notion with the GT. better off to buy a more reasonable S4 with auto and convert.

better for me is to learn to be happy with what I have!!

The Forgotten On

That's why I said to save your GT parts. It's a completely reversible conversion in any 5 speed 928. Just get a donor sub frame from somewhere to have modified.

But I do agree with the sentiment. Be happy with what you have. I wish my 89 had another gear as cruising at ~3K at 80 mph make her very thirsty.

SwayBar

This is a perfect case where IF the 928 was so technically ahead of its time as everybody likes to parrot endlessly, why didn't they give the 928 a 6-speed transmission with an overdrive 6th gear? Now THAT would have been truly innovative!

Instead, because of pressure from the fuel crisis at the time, they elected to downsize the engine from 6.0L to 4.5L for better fuel economy. Whereas an overdrive 6-speed would've met fuel economy targets, as well as actually improving performance while not in 6th. What they chose to do was a complete lack of innovation.

One of the biggest dropped-***** in automotive history.

Rob Edwards

Was anyone building a 6 speed in 1974? I mean, besides Alfa Romeo for their 33 Stradale, and I doubt they were doing it for fuel economy.