G50 conversion

dean · 03-06-2003, 06:07 PM

Here is what I have found out so far with my conversion. The shortened tranny does not fit with out moving the motor back. I am going to have to move the motor 3/4" back. I really didn't want to do that because of the turbo piping and all. The shift coupler needs to be lengthened a little. The shifter needs to be screwed with to make it shift smooth. I haven't figured that out yet.

alfizzo · 03-06-2003, 06:16 PM

dean,

i have a shorten g50. it to sits 3/4" back to far also. how does your clutch assembly fit in the bell housing does it bind at all? does your starter work properly? what do you mean by (The shifter needs to be screwed with to make it shift smooth)

franco

Bill Verburg · Bill Verburg's Garage

Sounds like you are going in the wrong direction w/ the engine. You want to move it forward like Jack is doing. That is also what most of the factory RSRs, 934s and 935s did with their engines(once they switched over to coilovers)

TimT · 03-06-2003, 06:27 PM

Like Bill said you are going the wrong way..

The way to get the G-50 to work is to cut the torsion tube. that way tranny fits etc. You will have to get rid of the rear torsion bars if you do this and get rear coilovers.

alfizzo · 03-06-2003, 06:33 PM

with the stock tranny mount the g50 in my 77 sit right up against my torsion tube. sure i could fab a new mount and cut the torsion tube. but i want to keep the torsion bars. either way its tricky.

Jack Olsen · 03-06-2003, 06:34 PM

Quote:

Originally posted by Bill Verburg
Sounds like you are going in the wrong direction w/ the engine. You want to move it forward like Jack is doing. That is also what most of the factory RSRs, 934s and 935s did with their engines(once they switched over to coilovers)

We got over an inch.

alfizzo · 03-06-2003, 06:44 PM

jack

your engine is sitting over an inch too far back with the g50 bolted in?

dean · 03-06-2003, 07:09 PM

Franco,
I haven't fit the clutch yet so I don't know. I also wanted to keep the torsion bars. I modifyed the rear mount and the tranny mount so far. The end of the tranny is right up against the torsion tube.

The shifter rod seems to bind if I screw down the shifter assembley to the OE holes. If I move the shift ass. a little forward the bind is less. So I don't know what is going on yet. I am building the headers right now so that is taking time.

alfizzo · 03-06-2003, 07:15 PM

did you cut that metal bracket in the tunnel under the shifter assembly? do you have a pressure plate?

Jack Olsen · 03-06-2003, 07:33 PM

Quote:

Originally posted by alfizzo
jack, your engine is sitting over an inch too far back with the g50 bolted in?

No. I have a 915. TRE Motorsports was able to cut into (and then reinforce) the torsion bar tubes to move my engine over an inch forward -- for better weight distribution. Of course, this meant modifying all the motor mounts, shortening the shift coupler and reconfiguring the rear sway bar mounts.

dean · 03-06-2003, 08:10 PM

Quote:

Originally posted by alfizzo
did you cut that metal bracket in the tunnel under the shifter assembly? do you have a pressure plate?

Yes I did cut the bracket. It is the shift rod that is binding. I think if I straighten the rod a C-hair that would do it.

I do have the PP. I bought a early 930 clutch setup with a G50 bearing. It is going to be a pain to modify the turbo inlet pipe with the motor moved back. I sort of wish that I knew that the tranny wouldn't fit before I started because I might have considered coilovers.

alfizzo · 03-07-2003, 04:38 AM

rear coil over are not that expensive. then just cut the tube. go to a welding shop and cut the mount and position it so the tranny mounts 3/4" foward. however i had problems with the clutch ass. binding. i had to get a pressure plate with g50 spring center from kennendy engineering. the throw out bearing fits perfect and the pp is rated for 650 ft. lbs. and my tranny bell housing was cut to short and the ring gear was hitting the bell hosing. i had to make a .25" spacer to compensate for the tranny being cut to short. i guy i know has a 87 turbo with a g50. and his bell housing is cut .10" to short. he eats 1 ring gear a year.

dean · 03-07-2003, 04:45 AM

What car did you put your G50 in? I like my torsion bars and didn't want to go with coilovers. I can do coilovers in the future if I want. Who cut your bellhousing? What clutch did you have when you were having problems?

alfizzo · 03-09-2003, 05:49 PM

77 911s. coil overs can always be added. i got my tranny from power haus II. i didnt have a problem with the clutch. it was the bell housing being to short. i just installed 28mm sanders torsion bars with rsr upside down mounted shocks. i have coils to help stiffin the rear up. but they are like helper springs like the 934. i can always take them in or out because the car is set to the torsion bars.

Mike the mechanic · 03-09-2003, 07:27 PM

Jack, you have coilovers? You mention you cut into the torsion tube... I am not exactly sure how far the torsion bars go towards the centre of the torsion tube, but I am wondering if maybe the torsion tube can be cut into slightly to avoid having to move the engine back?? As with Dean, I wasn't aware that the engine had to move back, and this would highly complicate my turbo piping. If my G50 hadn't already been shortened, I would have gone with the coilovers.

Jack Olsen · 03-09-2003, 07:48 PM

Yes, I have coil-overs now. Part of the reason we cut in was to remove the heavy piece that anchors both of the torsion bars inside the tube. Again, though, there was a lot of reinforcement done to make sure the chassis' strength wasn't compromised by the cuts. Even without torsion bars inside it, the tubes are an important structural component.

dean · 03-10-2003, 04:17 AM

Mike, I did a rough measure of the torsion bars already. According to my measurements the torsion bars almost touch in the center of the car. I was thinking that I could dent in the tube a little, but I can't. You might not have the same problem that I do. I heard that for different clutches you shorten the G50 more or less. Like if you use a 935 clutch you take more off. Did you get your tranny back together?

garrickl · garrickl's Garage

I feel for you guys and the problems you are encountering fitting the shortened G50 into your cars. I have a 1978 US version 930 and my shortened 1987 G50, done by Jimmy Privett, slips in like a glove with no relocation of the engine or original engine mounts. I am using the factory G50 tranny cradle with frame adaptor blocks that fit over the factory mounting holes that are tack welded to the frame .... allowing use of the original mounting holes if one wanted to reverse engineer back the original 4 speed. Privett got the adaptor blocks from Powerhaus and I purchased their custom lengthen shift rod coupler from them also. If you want photos of the adaptor blocks and custom shift rod coupler email me and I will send them to you. When Jimmy was shortening and rebuilding my transmission I had to provide him with my flywheel, ring gear and starter for fitment and clearance issues. I have only dry fitted the tranny into the car using a bare engine case since my motor is being rebuilt but everything went in without a problem so far. Have not installed the KEP Stage I clutch and pressure plate with G50 spring but it all looks like it will fit fine. I followed Lee Rice who had his shorten G50 done by Privett before mine was done and I am posting his install notes to me regarding the problems he encountered fitting the G50 into his earlier chasis:

"Because I have a "SC" chassis set up I had no room to spare. I had the engine/trans in-out-in-out 9 times to get clerance against the torsion bar and set the trans mount height just right. You have the longer 930 chassis, that should not be a factor.
I used a 3.0 liter "sport pressure plate, stock spring disc (6 springs). The throw out Bearing is a stock G-50."

Fortunately mine went in the first time without a problem. Neither Lee or I had to move the engine for the install. I had an identical spare 87 G50 available after I received my shortened G50 back. Using a micrometer I measured the amount of bell housing removed on my shortened G50 and it was 24mm. Hope this helps.

beepbeep · 04-24-2003, 12:11 AM

Yupp, later cars have thicker clutch-assy to accomodate rubber clutch and engine that sits further away in the back. You have to either convert to coilovers or shorten the tranny.

alfizzo · 04-24-2003, 04:21 AM

garrickl,

do you have a pic of the shift coupler? my shift coupler is hitting the top of the hole in the chassis. i was told to put some spacers between the tranny mounts and chassis so the coupler doesnt hit the top of the hole in the chassis. also my **** rod sits low on the floor of the chassis. i was thinking to cut off the foam so it can be at the same height as the shift coupler. i can take some pics of my problem.