930 4 speed

s_morrison57 · 03-19-2009, 03:59 PM

ok we had the post on the G 50 trans what about some feed back on the 930 4 sp. trans , I assume it was for the extra turbo HP , when was it used , when the turbo's came out ? why the switch in 89 to the G 50 , had to be because it was a better trans and 1 more gear to boot , never see a 930 4 speed trans rebuilt thread , mine seams tired from fist to second 2 to 3 is cool , 3 to 4 like wise is it showing signs of wear , going to do the swepco trans oil this weekend and hope it gets a little better than it is now , thought and coments please , are they a tough rebuild? car shows 60,000 miles but i suspect that to be some what jaded as I got the car with a screwy speedo and odometer
Finn

Kirk911SC · 03-19-2009, 04:16 PM

Check this thread out. I've had it bookmarked for when/if I need to rebuild mine.

930 transmission overhaul

esotoracing · 03-19-2009, 05:28 PM

Does somebody still sell the 5th gear conversion for the 930 fourspeed ?? Is that any good ?? I know Ruf sold it years back

equality72521 · 03-19-2009, 06:37 PM

Quote:

Originally Posted by esotoracing

Does somebody still sell the 5th gear conversion for the 930 fourspeed ?? Is that any good ?? I know Ruf sold it years back

+1, I'd love to get a fifth gear. 4 gears sucks in the tight twisties of NKY.

jwasbury · 03-19-2009, 07:48 PM

Quote:

Originally Posted by equality72521

+1, I'd love to get a fifth gear. 4 gears sucks in the tight twisties of NKY.

Really? I just leave mine in 2nd for tight twisties...its perfect, no need to shift.

equality72521 · 03-19-2009, 07:49 PM

Quote:

Originally Posted by jwasbury

Really? I just leave mine in 2nd for tight twisties...its perfect, no need to shift.

Not when you're doing tight switchbacks. I come out of them chugging.

jwasbury · 03-19-2009, 07:54 PM

Quote:

Originally Posted by Kirk911SC

Check this thread out. I've had it bookmarked for when/if I need to rebuild mine.

930 transmission overhaul

That same poster's trans seized up on him sometime shortly after the rebuild. There were some more recent posts from him as he has it apart again and is trying to understand what went wrong. Anyway, I think the 930 trans is very similar to the 915, so many people DIY them. I don't currently have the stomach for that, so I opened the checkbook and had mine done...it blew up within 500mi and the shop redid it. I am glad it wasn't my work that grenaded because I might have given up after that. Its been good now for a few thousand miles and shifts perfectly. Love it.

jwasbury · 03-19-2009, 07:55 PM

Quote:

Originally Posted by equality72521

Not when you're doing tight switchbacks. I come out of them chugging.

1st gear then...

equality72521 · 03-19-2009, 07:56 PM

Quote:

Originally Posted by jwasbury

1st gear then...

That's where I need something between 1st and 2nd ;-)

RarlyL8 · RarlyL8's Garage

You need a 915

911st · 03-19-2009, 09:12 PM

Brian,

Please bring my up to speed on how much HP you think we can put through a 915 and what we need to know?

How about for 20 minute DEs and TT's.

What mods are necessary. Just a clutch, stronger side plate???

Some times I fantasize about turboing my 85 3.2 w LSD?

I have no issue with going easy on first or pulling boost back in first.

Thanks in advance.

RarlyL8 · RarlyL8's Garage

Keith,
It is better info if I just tell where the weak spots are. I've been using the 915 behind a 325 ft/lb 930 engine for nearly a decade. The only issue was not at DE events but when I took it to the drag strip. I got into wheel hop on the concrete launch pad and damaged the carrier bearing before I could get off the throttle. THAT is the quickest way to kill a 915.
Heat is an issue at DE events in the summertime. I now have an oil cooler to install on the tranny but have not done so yet.
Torque is an issue when you get much past 325 ft/lb the life will shorten.
To protect the 915:
- Wevo bearing plate (holds R&P during shock)
- Wevo side cover (takes more shock than standard)
- Posi unit (spreads shock to both bearings instead of side plate.
- Oil cooler (for DE keeps heat down)

The G50 is a great tranny; wish I had one. Much stronger than the 915.

equality72521 · 03-20-2009, 07:20 AM

How would a G50 from a NA car hold up?

911st · 03-20-2009, 07:27 AM

Brian,

Dose the trans need to come out for those mods?

About HP limitations.

In my lowly uneducated mind, TQ is a measurement of power made with each stroke, HP is total force.

I guess TQ is important as that deals with how much of a hammering force that is transmitted with each combustion cycle.

If I do this, I could manage boost and thus TQ to stay at about 325#. That could be 309rwhp at 5000rpm, 371rwhp @ 6000, and 402rwhp @ 6500.

Thanks again.

beepbeep · 03-20-2009, 09:04 AM

930 can be considered an overbuilt 915 with one gear less. Thus it's mechanically undestructable but still suffers from 915-esque synch wear problems.

There are builds with 600-700Nm transported trough 930 transmission without problems.

RarlyL8 · RarlyL8's Garage

I would think a G50 would live forever in front of any normally aspirated 911 engine or CIS 930 engine. The main difference in the G50 series (G50/XX) is the gearing.

Torque is the issue with a turbo engine. My engine puts out more torque than HP and is at peak torque ~3000rpm.
If you have a turbo that hits hard it will hammer the side cover. Mine busts the tires loose at the same 3000rpm. So a modern "soft" turbo will help the 915.
Torque and HP = heat. Long pulls with high HP will heat up the tranny pretty fast.

Reaper930 · 03-20-2009, 09:18 AM

Quote:

Originally Posted by beepbeep

930 can be considered an overbuilt 915 with one gear less. Thus it's mechanically undestructable but still suffers from 915-esque synch wear problems.

There are builds with 600-700Nm transported trough 930 transmission without problems.

Yup...fresh 930 unit for me and a quaife diff. w/ 80% lockup. The problem on the 4 speed isn't the tall gearing, its the lack of hp to make them feel shorter

equality72521 · 03-20-2009, 09:49 AM

Quote:

Originally Posted by Reaper930

Yup...fresh 930 unit for me and a quaife diff. w/ 80% lockup. The problem on the 4 speed isn't the tall gearing, its the lack of hp to make them feel shorter

I like your thinking.

cajun · cajun's Garage

Quote:

Originally Posted by beepbeep

930 can be considered an overbuilt 915 with one gear less. Thus it's mechanically undestructable but still suffers from 915-esque synch wear problems.

There are builds with 600-700Nm transported trough 930 transmission without problems.

Been doing some research, and it seems that the 930 tranny can hold upwards of 700hp...

I am glad that what you stated is in line with what I have found...

beepbeep · 03-20-2009, 02:23 PM

Quote:

Originally Posted by cajun

Been doing some research, and it seems that the 930 tranny can hold upwards of 700hp...

I am glad that what you stated is in line with what I have found...

Well to be correct, it can hold to 1000hp or be destroyed by 10hp. It doesn't really care about HP, it's limited by torque and thermic losses.

So depending on revs that max torque is developed, its power capability will vary. But for typical 7000 RPM turbocharged range, it's probably OK for upwards 700hp with oil cooling.