Why would you put 4 gears on a turbo and 5 on a non turbo
 

I've always wondered why a 930 came with 4 gears and the same year non-turbos had 5? Doesn't make sense. I would think you would want more gears for racing and less gears for every day driving, not the other way round.

Ours go to 11.

The 915 transmission used on non-turbo 911s at that time was not strong enough to support the power/torque of the 930 -- the 4 speed 930 transmission was. The later g50 5 speed transmission used on 87 and newer non-turbo 911s (and 89 and newer turbos) is strong enough.

4 speed was stronger and you dont need as many gears when youve got all that torque

I'm with everyone else here, it's because the 4-speed was the only transmission Porsche had available at the time that could handle the 930's power and torque. The G50, which was available the last production year of the 930 was even more durable, and from what I was told by another enthusiast, can handle 1000 hp.

Like others have written, the 930 box is essentially a strengthened 915. But as the gears are physically larger, I'm told, they couldn't fit 5 gears inside the 930 box. Hence, just 4 fwd speeds. For marketing purposes Porsche claimed that the additional torque of the turbo motor was enough that 5 gears were not necessary.

During the development and early days of the 930, the master plan was to kill off the 911 in favor of the 928. Stuttgart did not wish to spend any extra money developing a separate 5-speed gearbox for the 930. So the 930 made-do with the strengthened 915 box. As the 80s continued, it became clear that the 911 would continue (a la the 964), so money was appropriated to develop the proper 5-speed G50-50 gearbox which was fitted to the last year of the 930, 1989.

The 930 transmission was developed after the 915 box. The 930 box is actually a double over drive. 3rd and 4th are both overdrive. Honestly, you don't need another gear although some have changed their 3rd gear ratio to make it a more even spread between 2nd and 4th.

The early 75 - 77 930 trannys were different than the later 3.3L turbo boxes. The G50-50 used in the 89 930s was not just a normal G50.

The 930 tranny has stronger internals than the 915 tranny. Also, the 930 tranny goes to 65 mph in 1st, 95 in 2nd, 120 in 3rd, not sure what 4th can do, but that's enough for me.

I would be interested to know what is the tallest 4-th gear anyone has put into the road going 4-Speed 930 Tranny?

I have a modified(internally strengthen 915 5-Speed) mated to an 86' 930 motor.

My 2 thru 5th gears sound pretty much exactly like the first 4 gears on the 930 4-speed:

Mine:

2nd to 70
3rd to 100
4th to 120
5th to 155(indicated)

I've seen 150+ in third:( having my old girl for 30 years I'd always heard the 930 Trans was made for 750. True or not I liked that old wives tale:)

Also interesting is that Ruf got around only being able to put 4 gears in the 930 transmission by adding a fifth gear on the nose cone outside the box (where reverse normally is I believe)

No quite - I've never gone this speed in mine, but according to the factory owner's manual, 4th gear on a 1987 930 is good for 167mph. And an additional interesting tidbit in there - they claim it is safe to downshift from 4th to 3rd at 130mph in 4th.

I'm assuming that they didn't want to confuse you with too many gears to choose........ while you were spinning off the road....as the boost kicked in...............

no, the 915 was not strong enough. but porsche could have built a strong 5 speed.
but these cars were not built as race cars. they were built for 150 on the autobahn.
1st and 2second are VERY fast gears. flooring it in 1st is actually rather "violent" and it is something i dont do. i am guessing putting in another gear and having closer ratio gears was something that just was not needed.

i can do 60mph in 1st gear. with it as fast as it is already, imagine 30-or 40 in 1 st. yes i would love the gear ratios after that if i was on a track or racing,

It was a lessons learned from the 1974 24 Hours of Le Mans and from the 917's previous to that. With the 917's, they had 5 speeds and 4 speeds. The 4 speeds would lose a couple seconds a lap of Le Mans, but was much stronger, so was more likely to finish the race.

Like the 915 and 930 gearboxes, the cases were very similar, but the differences were in the beefier internals, bigger gears, bigger bearings, bigger shafts. With everything bigger in the same sized case, you have to give up a gear.

Porsche underestimated the torque of the 2.1L turbo they ran in 1974. If they hadn't, they might have won Le Mans in 1974 with a 911. You'll notice that all 934's and 935's used a 4speed.

1974 24 Hours of Le Mans - Wikipedia, the free encyclopedia

Porsche used a 4 speed because they thought 4 speeds were adequate, both for the street and the track. They made the gears bigger and the whole gearbox was beefed up, but it still had to fit in the space available. When they changed the clutch in the later cars, they actually had to move the engine towards the rear, as there just wasn't any more room left at the front of the gearbox.

The 930 gearbox wasn't "just laying around" when the 930 was developed. If it had been, they would have used it on the Carrera turbo race cars, which used a 915-based box that wasn't strong enough to cope with the torque and was know to fail. They lost a 5th gear in one at Le Mans that cost them a good finish. No, it was developed just for the 930, with an eye to using it in the 930-based race cars down the road. Porsche had also previously found 4 gears adequate in their other turbocharged race cars.
Some of the speeds you guys are quoting arre a little off the mark. There were slight differences here and there but a 930 would do around 53, 93 135 and 160 (power limited, not gearing limited in 4th) in the four gears. US cars probably wouldn't pull past 155 in fourth, the 3 liter cars maybe did 153. I've seen tests where the redline observed was anything from 6,250 to 6,800, thus you sometimes see different speeds quoted. I used 6,700, which gives the speeds I listed above, give or take a mph...

A 930 really doesn't need 5 gears, in it's stock form. If you bias the power towards the higher revs and reduce the lag, then a 5 speed might be useful. I prefer a 4 speed.

JR

It took me a while to get used to the 4-speed, but it's perfect for the 930, I preferred the longer gearing for sure in that car especially when on full boost, think a 915 would be shifting too much

Less Gears = Less shifting = Less time off power and in racing its really all about being on the power as much as you can, isn't it?....

And why overcomplicate something that works just fine....

Regards
Dave

Ha! Perhaps, but this would have only been applicable to numbnutzzz drivers that were unable to successfully operate the throttle! :D

That's a good 1 Al :D

Well said, Dave. I've done a lot of racing in my time, and one of the main goals on track is to shift as little as possible.

LOL. Drove an 89 one time in anger. It has ten gears. Five off boost, five on boost. I would have done better with a two gear box.

I was real scared. Owner and I swapped cars. He smoked me in the twisties driving my 81. He tracks his other Porsche though, so way more skill.

You are not officially a numbnutzzz as Ronnie says unless you drive real fast like you have the skill when you don't. But, then, that would be most of us street only guys, even in the NA 911's. SmileWavy

Java dog pretty much nails it. The chassis was homologated, so they had to fit the gearbox in that space. It was done on the fly after 915's in the first 930 racecars started failing.

To this day the 930/962 gearsets are the widest gears Porsche ever made. Tallest I have ever seen is a .61. Not that much taller than the stock gear, but talk enough to break 220mph at LeMans with the higher redline of the racecars.

I don't know really what the final-drive ratio is on my 915 tranny, and that may be some of the difference on the top end. Of course, I gained another 500RPMS going to redline from the 3.0SC motor to the 3.3L turbo motor, which pushes the car(with additional stroke of 3.0 versus 3.2 crankshaft) from about 140 original top speed to 155(at redline).

That graph you speak of...is that past red-line where the line simply goes off the chart?

Can anyone provide a picture of their car at max speed in stock 3.3L with regards to the tach showing 6850RPM? or tell us at max RPM, what was indicated on speedo?

I still think my 2850 RPMS at 70MPH(in top gear) for me is too high.

I know all of you guys are right about the technical reasons for the 4 speed, but I always assumed philosophically the turbo was usually second priority for development and modernization. The 4 speed in 76 is fine but absurd in a 70k 1988 supercar.

The regular 911 had real efi starting with the 3.2s right. The turbo had CIS injection until 1994. It had been an archaic system for at least a decade by then.

In what way is the 4 speed absurd considering that it works so well with the Turbo power plant?

Good point about the continued CIS usage- I've often wondered the same thing.

The 4 speed worked better than a 5 speed would have, The basic nature of the car did not change, so why add an additional gear to make the spec sheet enthusiasts happy? I drove 4 speed 930s for over 25 years, stock and modified, US and ROW, and never once wished for another gear. The high first gear was nice, compared to the uselessly low first gear in a normal 911. 4th gear made for relaxed highway driving and there was enough torque that a downshift was never needed. Why add one more shift from 1st to 4th?

One of my Porsches now has a 6 speed. F'ing irritating, more often than not. It's not like the 6th gear is a real tall one. It's more like an older 5-speed 5th. Just one more shift, every time I run through the gears. It's not like I need the tighter splits for acceleration. It's got plenty of that.

In the early 1990's Porsche was cash-poor. You had a choice of a modified CIS turbo, or no turbo. Which one would you have preferred?

JR

all else being equal 5 speeds are better than 4. There are a lot of ways they could have approached a 5 speed in the 930s that would have been an improvement in my opinion.

A bit lower and closer 1-4 for example and keep the super tall top gear as 5th, would be my preference. everything is a compromise and the 4 speed is fine but it would have been great if it wouldn't have taken until 89 to improve.

My sentiments had nothing to do with the economic realities at Porsche. I'm glad they kept the turbo around, if keeping cis allowed them to do it, fine. It is an older and inferior system to what would have been state of the art at the time however.

Keep in mind I have owned my 930 for literally more than half my life, and turbo 911s are my favorite material items on the face of the planet. With those qualification, I am not sure the 4 speed does work that well with the 930. Or at least I think a 5 speed with well chosen ratios would be a huge improvement.

My 930 is completely stock and the combination of the super tall 1st and laggy power-plant make it a bit of a dog off the line

I disagree. Why anybody would want lower gears for first and second is beyond me. A stock 930 couldn't put all of it's power to the ground in first gear anyway, so a lower one would just have made that problem worse. An early one with 225 rear tires, or a modified later car could haze the tires in second when the boost came in, so why use a shorter gear that makes that problem worse? Once rolling, I never used 1st again.

Around town, I could easily skip 3rd. Just run it briefly into the boost in 2nd and drop it into 4th and cruise. I've got decades of seat time in normal 911s too and you'd have to drive the snot out of an SC or Carrera to keep up with a loafing-along 930.

You should have seen the gearing sometimes used in the 935.

JR

If you have an '84, it must be a ROW-spec car. Has it been federalized?

JR

So true! Not to disparage aschen's opinions on the matter , which he is entitled to, but you often hear people say that a 930 is a dog off the line or when puttering around town, and I always think, "say what"?

I also really like the 4 speed characteristics that you describe - really nice to make so few gear changes, even when just running errands around town, and there is so much engine torque available that even with low RPM all one has to do is press the accelerator down a couple-a-three millimeters and one is suddenly hauling much ass! :D

Sorta.....maybe

It has a the euro fuel system and exhaust, no air injection or cat. There was some half assed attempt to add a charcoal canister though. So it is basically stock euro power. It made a healthy 265 whp a few years ago.

You guys don't think a 930 is a dog off the line? I thought that is pretty much the defining characteristic of the car. Which car is better an 88 or an 89 930?

also not trying to be argumentative, but enjoy a bit of discussion.

What would be the finishing order for the following drag race from 0-25mph


1. 88 930
2. 89 930
3. 88 or 89 Carrera
4. 88 or 89 944 turbo (just for fun)

I suspect the results would be the reverse of the order listed, but I could be wrong

one more supporting piece of evidence for 5 speed superiority

Ruf spent big bux on a 5 speed 930 transmission

it was once a very popular upgrade to put a lower R&P, Ive been told the difference is like adding 100 hp, the problem of course is that 4th becomes a bit short for the freeway (so a higher fifth would be welcome).

My own opinion relating to this comment is that through today's lens, that comment makes sense but back in the day the idea of more gears was only just starting to catch on as a measure of value.

To that point more gears were more common on less powerful vehicles and was a sign that you had to work the gearbox to keep up with everyone else.

I think the typical consumer view was that bigger motors didn't need as many gears to keep up or get ahead.

Technical reasons aside, marketing in many motorcycle and car companies only started to cash in on the more gears idea mid 80s and later.

Aside from technical reasons, "Lots" of gears really didn't become a mainstream marketing tool for many years after

The loss of the air injection adds a little lag. You may also have non-standard ignition timing, as it's hard to find enough octane to run the thing with stock ROW specs and not have some detonation. At least 93 octane is needed and 94 is better.

Any Porsche is a slug off the line, compared to something like a Corvette. It's all a matter of degree. A 930 would lag a NA 911 for the first couple seconds but by the time the 911 driver was reaching for the shift lever, the 930 would be blasting past and that would be the end of that race.

I don't drive my cars like that, though. I don't care who's first off the line, or 2nd, or 3rd...

I'd pick an '88 930 over an '89 930 every time.

I'd pick an '83-'85 over any of them and ROW over US, every time.

JR

yeah they even had an add or something, that the car was so fast it didnt "need" a 5th gear. I think that is what I would classify as a marketing spin.

I believe the gentleman that said earlier that the racing cars were faster but less durable with 5 speeds was probably correct

Not that I agree with you but a Ruf BTR drives nothing like a stock 930. Then there's the issue of the extra gear and the problem that creates with a shifter based upon the stock part. One must be real careful in going from 1st to 2nd.

JR

Less durable, yes, but nobody said the 5 speed car was faster. The Carrera turbo (5 speed) was built to a different set of rules than the 934 and 935 (four speeds) so a comparison is impossible.

Porsche chose to use a 4 speed in the 917/30 and they had 5 speed boxes sitting on the shelf.

A 935 will run around 9.0/150 in the quarter mile with a fairly tall set of gears in a 4 speed box.

JR