Fitting 6 speed G50 to '89 Carrera

[Dennis Kalma]

I have my new project car, an 89 Carrera in good shape, minus engine and transmission. Idea is to rebuild the 930/03 engine I have, fit a G50 (standard in the car) and live happily ever after restoration. i would love to fit a 6 speed G50, but from the pictures I have seen, 6th gear fits in the nose housing of the transmission which **may** not fit in the '89 chassis. I have heard that it would take as shortening of the clutch housing and some modifications to the torsion tube for things to fit. Anyone out there ever done this conversion or have insight as to what is required? Thanks

[Wil Ferch]

Another refugee from Rennlist....

Welcome aboard Dennis....I'm sure someone will chime in here....

Wil

[Bill Verburg]

I posted this in the other thread as well
6 spd t/p

Long story short, lots of cutting of chassis components, tube frame, some fabrication and you're good to go.

[Eric Coffey]

Originally posted by Bill Verburg
I posted this in the other thread as well
6 spd t/p

Long story short, lots of cutting of chassis components, tube frame, some fabrication and you're good to go.

I've always been curious about this as well.

Bill-

The car in that link states it originally came with a 915, so it had to be a pre-`87 chassis. So, even if you wanted to put a 5-speed G50 in a 915-equipped car, you would need to cut the T-tube, and do some fabrication work. However, I am not sure the same work is required to put a 6-speed G50 (993) gearbox in a 5-speed G50 (`87+) chassis??

Inquiring minds.....

[Bill Verburg]

There are several strategies that have been used to fit a G50 in a t-bar car

• move the engine back
• use the short bellhousing version of the G50
• shorten the trans main shaft
• install a G50 t-bar tube
• various combos of all of the above

I used to have a pic of all 3 of the trans, 915,G50, G50/21 laying next to each other. But I can only find the G50/21, it's much longer than the others.

[Dennis Kalma]

I have heard that fitting a G50 in a car which originally had a 915 is a pain on both ends of the spinal cord, but the question is how much effort to put a 6 speed G50 into a car that had a 5 speed G50 originally. The picture of the 6 speed sure looks long, but then again....

[89turbocabmike]

Dennis, I just looked under my G50 car and took some quick measurements. From the part line shown in the photo, the G50 5spd nose cone housing is 4" not including the actual shift rod. There is an additional 2" space between the front of the housing and body. Looks very possible, though I'm not familiar with the structural integrity of that area. Looks like you could cut the sheet metal and rebox it in to fit the new tranny. As far as the transmission mount is concerned, I wonder if it would mount at the second arrow? Looks to be about the right spot.

[Dennis Kalma]

Thanks for taking the measurement, an interesting measurement would be to find the distance from the hole in the big rubber mount at the front (nose) end and the centre line of the drive flanges on both the 5 speed and 6 speed. If I believe the diagrams I have in various books, I think it will be the same on both transmissions.....then the question would be whether the 2"of clearance you measured is enough for the additional housing.....question is the 2" clearance between the rubber mount and the chassis or between the top of the nose piece on your 5 speed and the chassis?

[89turbocabmike]

Dennis, here is a poor quality pic of my tranny when I had it out for a clutch job. I hadn't thought about it but perhaps the '89 turbo G50 is mounted different than the NA G50, though I don't think so. As you can see there is no front rubber mount on mine, and the measurements I gave earlier are based on this.

[Dennis Kalma]

Wow...didn't realize they were that different, obviously my diagrams are waaaaay out to lunch! I suspect that the '89 Euro cars were not all that much different....

The front of the transmission looks very similar, guessing from proportions, it seems to be very similar. The nose piece is really different though, not sure if it would even come close to fitting, definitely that large rubber donut would need to go somewhere.

Have to think some more about how to get the two side by side and see what is different in terms of dimensions. Hmmm....much to think about......

[Dennis Kalma]

Took a bit of time this afternoon and scanned in the cross sections (out of Frere's book) of the 5 speed and 6 speed G50 transmissions and overlaid them in Photoshop.

Given that one is prepared to remove the rear mounting lug (the big doughnut on the nose of the transmission) and the associated aluminium casting, looks like the difference in length of the two transmissions is about 63mm +/- 2mm or so (about 2 1/2 inches). I wonder if there is enough room in the '89 for this extra length...Turbocabmike measured about 2 inches clearance?

Only worry would be the flattened torsion tube...any insight from anyone? I think that the changeover to the G50 resulted in a flattened torsion tube with nothing in teh section at that point, seems like a bit more denting to clear a 6 speed ought to be do-able.

Other thought is to shorten the bell housing in the same manner as people have done to fit a G50 into the pre-87 cars....all it would need would be an inch or so to give plenty of clearance.

BTW, thanks to all who have responded, this is great stuff!!

[masraum]

Wow, this is cool, get this going and done so we have the numbers from some one who has done it. Seems like a great swap if not too hard. How much extra will the 6 spd weigh, I wonder.

[dean]

I would think that you shouldn't dent the TT. And when you shorten a G50 the most you loose is maybe 1.25". So I would think you would have to move the motor as well. I know I had to move the motor .75" to the rear with my G50 conversion
Dean

[Dennis Kalma]

Tend to agree that denting the TT is not a great idea, I was thinking more about clearance bumps and so forth.

If the numbers in the recent posts are correct, then things should fit without moving the engine. Given that there is 2 inches space with the 5 speed, and we gain another 1.25 from the shortened bell housing, and we need 2 1/2...let me see, we'd have about 3/4 inch space between the nose of the 6 speed transmission and the TT....should be enough? I think?

In terms of weight, according to the various documents I have, the 6 speed is actually very similar in weight to the 5 speed. Porsche apparently put it on a diet when the added the 6th speed, thinning the castings in spots to make up for the weight gain. ....so it ought to be fine.

I have emailed Patrick Motorsports about shortening the bell housing, anyone else do this kind of work (at reasonable rates??)

[Porschekid962]

Very interesting, would be nice if it could go right in with a shortened bellhousing. Does anyone have pics of a 6spd in an early (915) car?

[dean]

Bobby Hart at Califonia Motorsports does a nice job shortening the housing. Sam Shaila (sp) at Proteknik (again sp) in TX shortened mine. Patrick was double the price and twice the attitude of the above. Are you going to take the tranny apart or have them do it?
Dean

[Dennis Kalma]

OK, next step in the process. G50 6 speed is supposed to be shipped this Thursday, got a good price for a '97 6 speed, 27,000 miles. Now the fun starts.

First step is to get the thing fitted to my engine, move it up to the chassis and confirm that I need to find ~63mm of room somewhere to fit this thing in. According to what I have been hearing, I can take at least 28 mm off of the bell housing, there is ~50mm between the nose of the transmission and the TT, and an option of ~15 mm movement of the engine mount. We shall see.

I am also wondering about which flywheel to use. I gather the G50 uses the same 240 mm clutch as the Turbo w. 930 transmission. I will be using an aftermarket engine management system, so retaining the Motronic reference and speed sensors is not an issue, although within the bell housing is the right place to put the EMS sensors. Figure a Turbo flywheel is somewhere in the works, but then again, does everyone with a G50 use that fancy dual mass flywheel/clutch all the time or does anyone change it out for a "normal" flywheel and clutch?

Anyway, the musing continue....

Dennis

[dean]

With my shortened G50 I use an early 930 flywheel. I have an early 930 motor though. If you shorten the G50 I think you get rid of the dual mass crap. I just bought a KEP stage 1 PP with a G50 diaphram for my car. You might want to call KEP to check out your options. They are good to deal with.

[Dennis Kalma]

Sounds sensible, fits the picture as far as I see it, plus every thing I read suggests that the 5 and 6 speed G50's are the same pretty well, just the length is different.

BTW, who is KEP? Don't know them.....

Does Pelican sell these parts as well (like to support them if I can)

Dennis

[john walker's workshop]

Kennedy Engineered Products. www.kennedyeng.com

[pjv911]

Here is a picture of mine that was shortened by Patrick . The bell and mainshaft were shortened . This is a 1989 carrera G50 5spd . Its going into a 69` chassis . Im also using coilovers so the torsion tube is expendable . Supposedly its a direct fit without modifying the TT . I hope to be putting the car together soon .

Kurt Williams



Here is a picture showin a 901 - 911 - 915 - G50

[john walker's workshop]

please post a closeup pic of the shortened mainshaft.

[pjv911]

Here you go .

Kurt Williams



And for good measure

[Dennis Kalma]

Great stuff, thanks for the pictures, it is shortened exactly where I thought it would need to be (right at the stiffening rib).
A few questions for the assembled multitude...

1. Do you know how much was taken off (in terms of length)? I have heard it is 28mm, but in my case, I may need more as the 6 speed is 63 mm longer.

2. I assume you are going to use a 930 flywheel and clutch assembly to go with your transmission? Any fitting issues or problems. The dual mass flywheel was intended to reduce gear rattle at low rpm....notice any bad stuff with a G50 and a 930 clutch assembly? If there is no difference, one may question why Porsche did it in the first place!

3. I assume the starter is stock Porsche and it utilizes the stock ring gear location?

Thanks

Dennis

[pjv911]

Dennis , to be honest with you I bout 3 different clutch setups ($$$) and 2 flywheels . The starter I will be using (I think) is a 1989 964 type that I ordered from my local parts supplier . I have yet to put anything together . The most expensive setup I bought was a C2 turbo Cup clutch kit which came with a lightened flywheel . Thats the one I was told will fit correctely . Im sure I will find something wrong resulting in more $$$ . I had a hell of a time finding new (9) flywheel bolts for the lightened flywheel . The standard duel mass flywheel used longer versions . Thats just how it goes when your reengineering a car. I can also tell you that once shortened you cannot use a dual mass anymore . But then why would you want to anyways .

Kurt Williams

[dean]

Originally posted by Dennis Kalma
1. Do you know how much was taken off (in terms of length)? I have heard it is 28mm, but in my case, I may need more as the 6 speed is 63 mm longer.

I think how much comes off is determined by what clutch you want to run.

2. I assume you are going to use a 930 flywheel and clutch assembly to go with your transmission? Any fitting issues or problems. The dual mass flywheel was intended to reduce gear rattle at low rpm....notice any bad stuff with a G50 and a 930 clutch assembly? If there is no difference, one may question why Porsche did it in the first place!

I don't think I have heard a dual mass setup so I can't compare. I don't find the noise bad now. I did wonder what it was at first but I got used to the rattle very quickly.

3. I assume the starter is stock Porsche and it utilizes the stock ring gear location?

I am using the stock SC starter with a stock looking ring gear from KEP

Thanks

Dennis

[Speedster94]

hallo
Inside the Nose cone is the 6. and reverse Gears , so you have to go with the original nose .
When you use a g50 (964 ) instead of a 950 you can use the 950 Nose and shorten the shifter .
Withe the G50/20 or 21 you can not do this because of the Gears in the Nosecone .
So the clearing of the Tube is not the only thing you have to watch but the Shifter also .If you put the gearboxes side by side you will see what i mean .
Very interesting Projekt , i hope you have you are succesfull.
harald

[CBRacerX]

Good Luck! Figure it out so the rest of us have it "easy".

Chris

[RoninLB]

why would anyone want a 6 speed?

[Milu]

Why?

Because after an hour at 5500 in 5th the engine noise gets to you.

[RoninLB]

Originally posted by Milu
Why?

Because after an hour at 5500 in 5th the engine noise gets to you.

just curious.. so it's for a big top end speed.. thx

[Milu]

That's why I'd want it. Others may want a wider choice of ratios.

[CBRacerX]

I've got two cars with the same engine, 993 with six speed and 911 with 5 speed and 993 transplant. I find myself looking for the "extra" gear all the time in the 911. Love to be able to upgrade it.

Chris

[Dennis Kalma]

There is no "real" reason why I want a 6 speed, any more than there is a "real" need for a 911 in the first place.

I want it as I plan to build a 3.4 litre, TEC 3 managed engine with about ~270 hp, so a broader range of gears is "nice", plus I want to tour with the car, and even in my current 5 speed, 3400 rpm on the highway is too high for a number of reasons. 6 speeds offer low highway cruising with good gear spreads for the fun part. I too find myself reaching for another gear....plus, getting the '89 tub without transmission gave me the opportunity.

In terms of technical work, there is the need to trim the bell housing similar to the Patrick Motorsports work on the G50 5 speed. I will also need to trim the nose housing (with the 5th and 6th gears in it) to remove the rubber doughnut mounting system, and will need to trim the shifter rod housing to something shorter. Bets on that is that is effectively a tube with a seal. When I check out the cross-sectional diagrams I have, it appears there is a sealing arrangement on the tip of the shifter rod casting, I am hoping to relocate that after trimming the housing to an appropriate length.

In terms of information I would be delighted to have:

1. Documentation for G50 rebuilds, ideally for a 1997 993 (my particular transmission). Don't want anyone to do anything illegal, but I would love to be able to borrow a set for a bit...

2. Transmission dimensions from a G50 5 speed as fitted to a 87-89 911 Carrera. Relevant dimensions, at this moment, are the total transmission length from bell housing to engine mating surface to the end of the casting that supports the shifter rod. Also be curious as to the dimension from the bell housing mating surface to the nose casting that covers the gear assembly.

3. A measurement off a G50 87-89 911 Carrera for the maximum space between the transmission and the torsion tube/inner body structure. I have heard that it is around 2", which would be great, but confirmation would be nice to get.

I can then validate how much needs to come off prior to starting machining....

Thanks to all

Dennis

[CBRacerX]

Dennis,
I can get you the measurements you need, but it might be more than a week before I can do so. I'l check the thread before I start, as it is likely someone else will have taken care of you. Here is a 87-89 G-50 as installed in my 87.

[CBRacerX]

BTW, perhaps you could shorten the shifter link in the car (tunnel) instead of on transmission? It might be easier to clearance the pan (if needed) than machine the nose of the trans in the shifter rod area.

Just a thought.

Chris

[Slider79SC]

Here are some pics of a 6 speed install in a pre 89. Granted, to do this they needed to switch to coil-overs in the rear but that is not a bad thing.....

[Dennis Kalma]

Did the 6 speed in the pictures have the bell housing shortened? It looks pretty tight....also did they trim away the front transmission support system (doughnut)?

Dennis

[BeauBlues]

Just curious, how fast can those 6 speed G50's get up to?

[Speedster94]

hallo
Than you can use the section before the seat from a 964 ,
in a 964 or 993 the Topspeed is a little over 300 KM/h .But the aerodynamic is better . in a G-model i would guess about 290 km/h with a normal 3.6 .
Harald