Are there any easy choices for upgrading the 4 speed in a 930?

[onboost]

Originally Posted by ficke

In the 930 transmission they only have two shafts, an input and an out put, there is no third lay shaft. The out put shaft on the Ruf 5-speed is longer than the 930 transmission and the 1st gear is hung on the end of it like in a 901 Porsche box ( I am sure where Ruf got the idea) hence the dog leg shift pattern. Then Ruf uses 935 gears to get the spacing they want.
Since the out put shaft has the Pinion gear it would be very expensive to change the R&P on a Ruf 5-speed.
Ruf 5-speeds were great because Porsche did not have a 5-speed at the time that could take the power of the 930, but in today's world we have access to the G50. I would recommend using a shortened bell housing G50 and regulate the Ruf to the stop gap, interesting, historical, classic category and not a good answer for people who want bang for buck and versatility.
I have a Ruf 5-speed in my car.

Ficke, thanks for the pics and the detailed description.

Your assessment is correct regarding the internals of the 930 trans.... and based on your comments, and from what I can see of the Ruf trans, the big difference remains the tail cover, and as you described, the lengthened output shaft, placement of/additional gears, and a few other details.

Yes, a nice stop-gap for the time and probably still a viable retro-fit/option at present with a properly priced/reverse engineered kit.

While the G50 is a nice upgrade, the level of work, cost, etc.. required for an install is not for everyone. Based on the items described above, if this were available in kit form to the 930 owner, it would be little more than a thorough trans rebuild.

Originally Posted by gumba

I would talk to Wevo. If there is enough interest he might, at least come up with some cost estimate to see if it's worth it to pursue. He's just finishing up a 5 speed conversion for the 356.

Bingo! My thoughts exactly.. from what I can see, and what I understand from my time with these cars.. is that Ruf didn't recreate the wheel, or the cog in this case.. he merely expanded on the theme taking a page from the 901. However, during the time line when Ruf did this.. ohhhh, it was like a black art with feats of machine shop magic! Not so much anymore with CAD and other 3-D types of machining and manufacturing.. we've come a long way with technology and manufacturing since the
80's.

[zcoker]

Originally Posted by kenikh

Guard still makes an R&P, but it isn't the 8:39 listed above. It is 8:41, so even shorter. Here's a ratio comparison:

9:38 4.22
8.39 4.875
8:41 5.125

Sounds too short for regular highway work.

It's not too short with 17" rims. I drove mine all the way from Alabama to Florida with no issues whatsoever. Around town it is absolutely perfect. But....when you are on the gas and nail it, man, you better hold on for dear life with the 8:41. It will rip you apart, literally. 4th will blast like first gear deep into the 100mph range in a fraction of a second. My 8:41 R&P is a factory stamped Porsche part, so I presume Porsche offered it at one time as an upgrade. I don't know if they still do.

[totle]

I did a G50/01 upgrade last year.
Shortened the bell housing, so That I could use my torsion bars.
Modified the transmission mount so a did not have to weld new mount to the chassis.
Can switch back to 930 transmission any time if I want to.

A great upgrade over the 930 transmission.

[kenikh]

Just found a great deal on an old stock 8:41. Will let you know how it goes after I find an LSD and install them both.

[Tom F2]

Originally Posted by kenikh

Just found a great deal on an old stock 8:41. Will let you know how it goes after I find an LSD and install them both.

Kenik, you might want to do some research before going with the 8:41. I put an Andial 8:39 in my car, which you can read about here: 8:39 ring/pinion - good or bad? - Page 4 - Rennlist Discussion Forums

Andial told me that they did not sell the 8:41s, because they are noisy. A search on Rennlist and Pelican might lead you to think the same.

BTW, ignore what I said on Rennlist about SC-spec cams. I now think that they are wrong for a Turbo for the street. I will be restoring the original 930 cams in my car.

[kenikh]

^ I've heard similar. Figured it was worth a shot. Matt Monson at one point told me that a noisy ring gear can be managed somewhat with meticulous setup and friction coating. That was a generic statement so unsure if it applies to this this of RnP.

[spuggy]

Albins make a taller (10:31) R&P for the G50 - CMS carry it; I considered it.. It was $3000 US at the time, Factory G50 gearsets are $900 per gear (1st involves re-welding the shaft as well).

Last I looked, core, non-broken G50/50's were reputed to be $10K - if you could find one. Good luck with that, they didn't make many, and most are either in the original car or already in an Ultima or GT40 rep...

I think you have to figure a used transmission with any mileage as "suitable for rebuild", especially for high-power applications. The G50/01 with 100K I used ate about $3000 worth of factory wear parts (bearings, bushes, seals, synchros etc) before it got anything trick - and it came out of a great-driving car (shop I bought the box from had been looking after it for 10 years) that got hit in traffic.

After the tall 5th I had in the 915, stock 911 G50 5th was also WAAAY too buzzy on the freeway.

[Mocker]

Resurrecting this thread, as there is a Ruf 5-speed up in the "911 Used Parts" forum: Genuine RUF 5-speed BTR BOX

I noticed that the Ruf 5-speed has a short bell housing, like on the early 3.0 Turbos, which would shorten the wheelbase of the car, wouldn't it? I presume that was so the longer "nose" of the transaxle (where Ruf stuck the extra 1st gear) would still sit at the proper location to attach to the shift linkage.

Full disclosure: I have a Ruf 5-speed in my car, installed by the PO, and I'm always trying to learn more about it. I never noticed the short bell housing before today, thus my inquiry.

[ficke]

Originally Posted by Mocker

Resurrecting this thread, as there is a Ruf 5-speed up in the "911 Used Parts" forum: Genuine RUF 5-speed BTR BOX

I noticed that the Ruf 5-speed has a short bell housing, like on the early 3.0 Turbos, which would shorten the wheelbase of the car, wouldn't it? I presume that was so the longer "nose" of the transaxle (where Ruf stuck the extra 1st gear) would still sit at the proper location to attach to the shift linkage.

Full disclosure: I have a Ruf 5-speed in my car, installed by the PO, and I'm always trying to learn more about it. I never noticed the short bell housing before today, thus my inquiry.

In 1978 Porsche went to that rubber center fat clutch disk to cut down on vibration/chatter, to make room for this fat clutch disk Porsche made the bell housing larger and moved the engine back, nothing to do with the wheel base.
Ruf took advantage of that space to make a 5-speed out of a 4-speed transmission just like Porsche did with the 901 box, same dogleg pattern.
The clutch cable is longer on the Ruf 5-speed than the 930 clutch cable since the transmission is moved back.

[Mocker]

Thanks, Ficke, yes, I need to think front-to-back and I had it backwards--the engine sits further back on the 3.3L cars, but the axles are in the same spot.

But as I think through this, I don't see how Ruf's longer nose (housing the 1st gear) didn't push the whole transaxle back.

Here's the Ruf box from page one of this thread:


And here's a short bell housing 930 box:


As you can see, the dimensions of the housing are all the same, except for the nose. AND, the front transmission mount hasn't moved. I'm still confused (no surprise there!), but it sure looks to me like that longer nose would have to push the axles further back on the Ruf box.

[quattrorunner]

The front part (bellhousing) is short. Later 930 is 1.1' longer to cover the thick rubber disk

[Mocker]

^ Yes, we know the engine sits further back on the later Turbos because of the longer bellhousing. We're all straight on that.

But look at the nose of both above, and where the tranny mounts are on both, and tell me the axles aren't pushed back on the Ruf box. That's what I'm trying to get my head around.

Do the Ruf boxes use a modified transmission mount that pushes the gearbox forward? If so, wouldn't that require modifying the tunnel--unlikely, since that would open a big can of worms.

[quattrorunner]

Actually ya that’s a good question. The nose section on the ruf looks longer that the 1.1” additional size of the bell housing. And the long nose bellhousing 930 box hits the torsion tube when the standard mounts are left alone. That is this voodoo magic?

[Jim2]

I'd suspect ruf used the center section from a G50 torsion bar tube to deal with the extra length.

[ficke]

Originally Posted by Jim2

I'd suspect ruf used the center section from a G50 torsion bar tube to deal with the extra length.

NO, it fits in a unmodified 930

[Jim2]

Ahh I see.

[ficke]

Originally Posted by Mocker

Thanks, Ficke, yes, I need to think front-to-back and I had it backwards--the engine sits further back on the 3.3L cars, but the axles are in the same spot.
But as I think through this, I don't see how Ruf's longer nose (housing the 1st gear) didn't push the whole transaxle back. It did move the whole trans mission back with the engine

Here's the Ruf box from page one of this thread: That is my picture I took of my transmission from my 78 930 with my 68 911S in the back ground.



And here's a short bell housing 930 box:


As you can see, the dimensions of the housing are all the same, except for the nose. AND, the front transmission mount hasn't moved. I'm still confused (no surprise there!), but it sure looks to me like that longer nose would have to push the axles further back on the Ruf box. It does of course and the axles are at more of an angle

In the 68 and earlier cars the axles went straight out to the stub axles.
On the 69-77 cars the axles were angled back for the new location of the stub axles to make the longer wheel base.
Making axles angle to connect up is not a new thing or taboo for Porsche.

[voitureltd]

Of course on the 78 ( different than on the 77 and prior 930) onward the motor was moved to the rear to compensate the longer bell housing. so could get a little room but not enough for the longer tail section. I have a 77 930 with the 930 4 speed into a 5 speed done by Andial. Can't see RUF embossed on the longer tail or investigated what else was changed as the 77 motor was not moved rearward until 78 so it would require a different installation than a RUF 5 spd going into a 78 or newer. Also not sure it is a RUF conversion as others have mentioned that the ability to convert was in practice before RUF. Also nice to know it may have 935 2-5th. I should investigate it up in the air against a stock 930 to find out more. I have owned it for close to 20 years and should know more about it. I talked to Dieter @ Andial about other things about the car a few years after I bought it but at the time did not get into the trans situation.

[Mocker]

Thanks, Ficke, that's the second time today you've set me straight! Of course, the rear trailing arms locate the hubs and wheels and determine the car's wheelbase. I guess it's not a huge deal if the stub axles sit at a slight angle. I'm going to investigate this on my own car and see what kind of angle we're talking here.

And, for the record, the Ruf 5-speed is a really solid piece of equipment.

[lite75]

Ruf box uses the stock 78 and up mounts and moves the axles towards the back. The shortened clutch housing makes up for the longer nose cone. Will not work in a 77 or earlier chassis.