Converting long G50 into short g50

[Stein]

I want to fit a g50/52 into a `88 carrera with 3L turbo. As you can see in the last picture below it has longer differential House and of course the longer front mount. I have measured diff House to be approx 2.3cm longer

1. If I shorten the clutch House so it will fit 930 clutch. How much will this shorten the tranny? How much shorter is a 930 clutch.

2. I have seen the front mount be cut of so it become same length as short g50. How is the front modified so the early gearbox mounting will bolt on??

[Stein]

Here I am now
Made a jig from a short G50

placed on the long g50:

welded on new alu pieces so it fit the jig. Also shortened the shifter as I am going to use Hargett Precision shifter.


The transmission is ready to be machined.


I bought a light weight flywheel, `77 Kep stage 1 PP and std spring centered disc. Measured the difference between the 3.2 clutch and kep clutch to be approx 35mm. Both with a g50 T/O bearing. The difference between the starter ring gear is 25mm. I think the transmission will be shortened 25mm so the starter will fit correct.


The g50\52 will then be 2mm shorter than my g50/01 and I think that will be fine.

I have one Issue i need to solve: When i put my 930 flywheel, kep PP , spring disc and g50 T/O bearing together the center of the disc hits the t/o bearing. It's only 2-3mm left between the PP and disc.
Do I have wrong disc? (number on disc is: 184900183)

(I do not have a kep pp with g50 spring center. I did not know that exist before I already had bought one, but searching pelican it seems like it should work.)

[Dennis Kalma]

I've been playing around with this and have documented my experience at putting a 6 speed into an '89 Carrera....

Here is the thread, somewhere in there are my measurements.....

Dennis


Fitting 6 speed G50 to '89 Carrera

[Stein]

Yes, I have read your tread. Impressive project!
As I understand you used a Kep 930 PP and spring disc. The measure you got from the bottom of the flywheel to the top of the t/o bearing the same as mine. (69.5)

I can't understand why my disc touches the t/o bearing. I will imagine with a kep 930 pp modified with g50 spring center it will leave a little more space since the springs are flat straight and for the 930 they are slightly bent toward the disc...?

here are a few pictures:

[Dennis Kalma]

I used a stock 930 (as in Porsche) pressure plate and disc with a G50 throw out bearing...not sure about the KEP one, it could be different??

I am also planning on updating to the Patrick Motorsports flywheel as it has the notches for the EMS system built in and I so hate those little crankshaft pulley set ups....

Dennis

[juan ruiz]

Very good staff guys ! I was just looking at the G50/52 yesterday but at 7k looks more like a dream

[Stein]

Still trying to figure out what to do with my disc. I do not think using a kep pp with g50 center will solve my problem as it sees like the difference in the bent center only is approx 2mm and I will need at least 4mm. Is there a thinner disc to buy?

I compared the g50\01 to the g50/52 and the transmission/engine surface to the transmission/starter surface is 2-3mm more on the g50/52.
so I should add this when I will machine the case.

I can see the 6 speed and g50/52 is not similar. I have 117 from engine/trans surface to the starter surface. From your drawing from the 6speed you got 99.3.
But we are probably using different starters.

The g50/52 has shorter distance to the reinforced area. So if I machine more than 25mm I will take away the reinforced area... Would that be ok?


I don't need the transmission shorter than taking off 25mm so I could do that, but than I may need to space out the starter ring gear 2mm instead. Is there thicker ring gear available?? (i think I have seen it somewhere, but don't know if it was for 930.)
Reading your tread I also found out I need to machine bigger diameter inside the bell house for the ring gear. Down too the marker

[lite75]

Why do you want to shorten the clutch housing? That transmission will fit right in your chassis with just the short front housing you have. If your using the early pressure plate use a ring gear spacer and a long RS throwout bearing.

[Dennis Kalma]

Just checked to see what the measurement from the engine/trans to the face of the starter mount.....currently (after shortening) it is 89mm, which implies a full unmodified depth of about 118mm....comparable to yours.

The mounting ribs are definitely in a different location on the 6 speed, although I really did cut it as thin as I dared. I also note that you are using a ruler, just be careful as I have found that they are not all that accurate when it comes to measurements of this type. It seems like the tip can be out a millimetre or two and screw up your measurements. I have been using calipers and so forth and still feel my measurements are only good to about 1 mm.

Dennis

[lite75]

a g5001 and g5052 have the same clutch housing dimensions to the starter. When shortened for a pre 87 911 chassis, 29mm is taken from the housing and a shim is used at the starter. If your just wanting the early pp, flywheel to work and not worried about overall lenth take 25.75mm off and the housing and the starter should fit without a shim.

[Stein]

Originally Posted by lite75

Why do you want to shorten the clutch housing? That transmission will fit right in your chassis with just the short front housing you have. If your using the early pressure plate uSee a ring gear spacer and a long RS throwout bearing.

The larger differential g50/52 have makes the diff house approx 23mm longer + 2mm more from the starter surface too the engine/trans surface
picture of g50/52 diff house length

picture of g50/01 diff house length

The measures are not very accurate, but they indicate the difference

Here you can see the bell house different:
g50/52

g50/01


The numbers in your lates post are similar to what I have, but I need + 2mm to get the right starter distansce. It would really be perfect to machine 28mm. It would make better fit too the To bearing and the guide tube, but than all the reinforced area will disapear... I'm not so sure thats a good idea....??


Dennis: The ruler was just for the picture. I know if I machine 28mm it will only leave a thin lip of the reinforced area (0-1mm). 25mm would be as much as I dare if I need the reinforcment.... Maybe the 6 speed bell house and g50/52 are the same except the reinforcment. It seems like the amout you machined would work for me if it hadn't bin for the reinforment.... What starter do you use?

So my options are
1. 25mm. Don't think t/o bearing will enter the guide proporly when clutch is disengaged. need shim on ring gear.
2. 28mm. better fit too the t/o b. and starter. weaker body??

Would it be a problem with out the reinforced area? The engine would support the bell house regardless. Never heard of any problem with bell house other than parts coming loose and cracks it.

[Dennis Kalma]

I am using an aftermarket lightweight starter, uses a Denso motor....its measurements are the same as the stock starter (except for the weight and all).

Just FYI, the engine for my car will be a high compression 3.4 litre, 10.3:1....I some days worry if the after market starter has enough torque, but we will see. Worst case I have one of the early heavy duty Bosch starters that I can rebuild...

In terms of the reinforcing rib, I think you need some but not much, all it really does is stabilize the rim of the bell housing as the strength appears to be in the cylindrical shape. You might be able to go into the rib so that its OD matches the OD of the mating part on the engine. Might give you your 28 mm...

Just a thought

Dennis

[Stein]

Originally Posted by Dennis Kalma

I am using an aftermarket lightweight starter, uses a Denso motor....its measurements are the same as the stock starter (except for the weight and all).

Stock for the 6 speed? I don't know if all the starters are similar for all the G50's.
I have starter for 74-89. Don't know if it's the same starter for the 89->.
But since the diameter for the ring gear is not so deep for the bell house in the g50/52 i would think that the ring gear is closer too the engine and needs a deeper starter...???
Pelican has listed one part number for 74-89 and a different part number for 90-98

Regarding the reinforcing rib i will do some more testing and thinking before I decide what to do, but it would certainly be the easiest Way to go for 28mm....

It's just typical that the transmission I choose should be different from others

Thanks all for your help so far!

[Dennis Kalma]

Originally Posted by Stein

Stock for the 6 speed? I don't know if all the starters are similar for all the G50's.
I have starter for 74-89. Don't know if it's the same starter for the 89->.
But since the diameter for the ring gear is not so deep for the bell house in the g50/52 i would think that the ring gear is closer too the engine and needs a deeper starter...???
Pelican has listed one part number for 74-89 and a different part number for 90-98

Regarding the reinforcing rib i will do some more testing and thinking before I decide what to do, but it would certainly be the easiest Way to go for 28mm....

It's just typical that the transmission I choose should be different from others

Thanks all for your help so far!

Not sure about all the variations, but I do know that this starter works insofar as engagement and spinning the engine goes. Before I did the chassis work I actually mocked up the whole thing...engine case with crankshaft in it, flywheel/PP/ring gear etc and the transmission of course. Hooked up a battery and gave it a whole bunch of spin time. It turned over very nicely, looked like the starter pinion was engaging right where it was supposed to...all was well.

Not surprised actually as the aftermarket starter was meant as a bolt in for the Porsche part and I **think** they are all the same, but I could readily be wrong....at least up to the early '89's which is all I am concerned about anyway.

Glad to help and share, as long as everyone realizes that we are both totally insane...

Dennis

[lite75]

That extra 2mm must be additional depth needed for the dual mass flywheel started in 91. Sounds to me the 28mm is right on track.

[Stein]

The front mount with shortened shifter:

Clutch house shortened 28mm

shortened axle

Had to drill a hole for the axelerator "pin"

Had to remove the end of the disc. The g5052 had thicker axle and the disc didn't move over the part that is not splined. Other g50 i have has a thinner axle and the disc would slide over when shortening..

the transmission mounted

And the shifter I`m going to use.


I`m waiting on a KEP Prssure plate with G50 center. hope that will fit with my disc and TO bearing.
Also need to make speedometer pickup. I thought I would place a sensor on one of the driveshafts and make a pick up.....

[sprbxr]

Nice.

I am having a problem trying to find the correct parts for my short G50/52 conversion. The problem is it was done before my ownership and the clutch/flywheel/TO bearing are all missing. Any of you guys know which oem flywheel, PP, TO bearing, clutch disc to use?

[Stein]

I am using a 930 flywheel, early 930 '77 PP from KEP with G50 springs and a std 930 spring disc.
The disc still hits the TO bearing barely but I will lath 0.5-1mm away from the disc center hub where it hits T.O.B and I think it will be fine.

there might be other disc's that will fit better and I would be most greatful for tips for other opportunities... I think disc with a solid center would fit but I don't know how this will be to drive...

I don't know what engine you have or how much your g50 is shortened but if you need flywheel sensors the single mas flywheels might fit with spring disc and a matching PP. but then you will need a short TOB. I belive the TOB for the single mas flywheel are longer to compensate the shorter flywheel....
You need someone to confirm this setup.... Anyone know the lenght difference on dual / singe mas setup??

[sptjohn]

Wow ! This is a very nice project...

Any update on this one ?

[Britain Smith]

Nice work. I would dump the shifter and go with a WEVO unit.

-Britain