911 Conversion from 912e Questions

[cason880]

Hey all,

I was unsure which section to post this in but I think there should be some knowledgeable people here. I have a 1976 Porsche 912e and I am currently swapping a 2.7 engine into it. I think I've ironed out a majority of the kinks but had a couple questions:

Do I need to convert the clutch release fork and guide tube to 915 with a 915 throwout bearing or can I use new 923/02 TO bearing and guide tube? Id like to use my 923 transmission and I have a 70-71 clutch disk, 915 pressure plate, and flywheel already. Just unsure if a new 923 guide tube and TO bearing would work instead of converting to 915 (which I'm also unsure whats involved beyond the fork)

Can I fully replace the CDI (which my car does not have currently) with a MSD 6AL? Do I need Pertronix Ignition or will the points be fine with MSD? Where would I wire the tachometer given that I dont have a CDI harness?

The only wiring to worry about changing is the 14 pin, the voltage regulator, the starter, and the distributor (which would come from the MSD); correct? Maybe the oil level sender as well but Im more meaning to run.

I already have the oil tank, oil pressure/temp/level gauges, external cooler, exhaust, and Im waiting on a Tach. Do I need to worry about much else apart from that (excluding little bolts/mounts/engine/etc).

These probably seem silly, but I am very new to Porsche's and just want to confirm before I spend the time/money.

[Dmitry at Pelican Parts]

Hello - our members will get back to you, but I would suggest searching the forum - the conversion topic has been addressed in quite a few threads. Just type in "912 conversion" into the search - some example thread links below:

How to convert a SWB 912 to a 911?

912 to 911 conversion

912 to 911 conversion

[Nditiz1]

While my car was not originally a 912E someone did convert it to one with all the correct parts. That said I never did get the correct answer about how to use the 923 with the 6 cyl eng so i just swapped both. Search my name in this forum for my conversion thread for some tips. I needed to add the whole oil setup tank, lines, cooler etc. I even cut the engine bar mounting bracket on the passenger for more room for the oil tank. Not sure if that was needed or i was saving weight. I can double check tomorrow. Anyway i converted to a 3.0 out of an 82. The tranny swap was easier than sourcing the correct info to mate the 923. Also the clutch pressure felt way better than the 923 setup. I even broke even getting ~3k for my 923.

[Bill Douglas]

912's are very popular.

the numbers may work out better if you sold it and bought a 911.

[bkreigsr]

Originally Posted by Dmitry at Pelican Parts

Hello - our members will get back to you, but I would suggest searching the forum - the conversion topic has been addressed in quite a few threads. Just type in "912 conversion" into the search - some example thread links below:
How to convert a SWB 912 to a 911?
912 to 911 conversion
http://forums.pelicanparts.com/porsche-912-technical-forum/650186-912-911-
conversion.html

Not so fast Dmitry.
None of those threads/links are relevant, as they do not deal with the 912 E --whole different set of parameters.
There is a world of difference between the 915 and the 923 trans and the related components, (and the 901 being discussed in the referenced threads.)
Bill K.

[ToySnakePMC]

Cason, I am not too far from you here in southern Wake County. I purchased a 912E with 3.0/915 swap already done. You’re welcome to visit and look over my car for answers. It’s currently on the lift with various projects under way!

PM and we can set up a call if desired.

[cason880]

Thank you to all who have answered or messaged me on this topic. Im hoping to finish the swap in the next couple of months and I would like to use this thread as a reference for others in the future. I do want to retain the 923 if at all possible. Ill add some pictures of my car and my 2.7 shortly.

Originally Posted by Dmitry at Pelican Parts

Hello - our members will get back to you, but I would suggest searching the forum - the conversion topic has been addressed in quite a few threads. Just type in "912 conversion" into the search - some example thread links below:

How to convert a SWB 912 to a 911?

912 to 911 conversion

912 to 911 conversion

Thanks for replying Dmitry. Trust me I have scoured the internet for references, unfortunately the 912e has some oddities that make it a bit different for the swap than the older 912. It should be easier overall, but the clutch with the 923 is confusing me. I will continue to look though.

Originally Posted by Nditiz1

While my car was not originally a 912E someone did convert it to one with all the correct parts. That said I never did get the correct answer about how to use the 923 with the 6 cyl eng so i just swapped both. Search my name in this forum for my conversion thread for some tips. I needed to add the whole oil setup tank, lines, cooler etc. I even cut the engine bar mounting bracket on the passenger for more room for the oil tank. Not sure if that was needed or i was saving weight. I can double check tomorrow. Anyway i converted to a 3.0 out of an 82. The tranny swap was easier than sourcing the correct info to mate the 923. Also the clutch pressure felt way better than the 923 setup. I even broke even getting ~3k for my 923.

Interesting, thanks for the notes! I have all the 915 clutch parts now, but my current research is indicating that 901 clutch setup may be better suited if I keep the 923. Im not sure yet, I think there are some hybrid options too. I think if I could get $3k for my 923 I may go your route too, haha.

Originally Posted by Bill Douglas

912's are very popular.

the numbers may work out better if you sold it and bought a 911.

I have thought about that alot recently. Im not sure my 912e would bring enough to fully justify it unfortunately. The longhoods seem to retain all the value and mine is admittedly rough around the edges. I only paid $16k a year or so ago so I doubt Id get more than that.

Originally Posted by bkreigsr

Not so fast Dmitry.
None of those threads/links are relevant, as they do not deal with the 912 E --whole different set of parameters.
There is a world of difference between the 915 and the 923 trans and the related components, (and the 901 being discussed in the referenced threads.)
Bill K.

Very true, Ive seen some 914 guys mount 2.7s to their 901s with a 65-69 clutch setup and Im curious if that would work for me since the 923 has the same mainshaft. But those are 215mm which may introduce slipping? Ive also contemplated converting the 923 to pull style since it looks similar.

Originally Posted by ToySnakePMC

Cason, I am not too far from you here in southern Wake County. I purchased a 912E with 3.0/915 swap already done. You’re welcome to visit and look over my car for answers. It’s currently on the lift with various projects under way!

PM and we can set up a call if desired.

Thanks so much for reaching out, Ill PM ya. Your car looks great, its awesome to see more 912es near me. My car is currently stored in Greensboro at the moment; I have a project Nissan that is occupying my garage currently haha. Hopefully Ill get to some cars and coffee or meets soon.

[ToySnakePMC]

Yes sir! Multi projects going on... You’re my kind of guy! Look forward to meeting you and seeing you motoring with 6 cyls under your foot. I’ve met some good air-cooled guys here in the Triangle. We try and do a monthly Saturday BBQ run that consists of fun local 2 lane roads. You’re going to have a blast with this car.

[Andy Somogyi]

The hard part will be the throw out bearing, it’s NLA, and a few criminal parts sellers have them for ransom at insane prices.

I’m planing on making a new clutch fork that will let you use a normal standard VW bus bearing that is like $25.

The 76 912 bearing is unique.

It’s not that hard to fab a new fork, going to turn a solid rod for the shaft part, and mill a billet fork. I originally was thinking about keeping the original shaft, but I don’t have a way to cut internal splines, so I’ll make a new shaft and pin the fork to it.


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[bkreigsr]

Originally Posted by Andy Somogyi

The hard part will be the throw out bearing, it’s NLA, and a few criminal parts sellers have them for ransom at insane prices.
I’m planing on making a new clutch fork that will let you use a normal standard VW bus bearing that is like $25.
The 76 912 bearing is unique.
It’s not that hard to fab a new fork, going to turn a solid rod for the shaft part, and mill a billet fork. I originally was thinking about keeping the original shaft, but I don’t have a way to cut internal splines, so I’ll make a new shaft and pin the fork to it.

Be aware that the input shaft of the 923 is a lot thinner that those of the 915.
Thinner = more likely to fail in a hard usage situation.
Bill K

[Andy Somogyi]

Originally Posted by bkreigsr

Be aware that the input shaft of the 923 is a lot thinner that those of the 915.

Thinner = more likely to fail in a hard usage situation.

Bill K

It is thinner yes, but not a lot. The 923 is same as the 901, with a 13/16” shaft, and the 915 is 7/8”. That’s about 7% smaller.

Yes, maximum torque goes as the cube of the diameter, so if you look up the material properties, it does have a fair bit more torque capacity. But I seriously doubt any streetable 2.7 would stress it too much.


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[carsinc]

Then 912E trans won't work with a 2.7 motor. trans Main shaft different.

[Nditiz1]

^This is not an accurate statement. It will work with the correct clutch and pressure plate package. That same package needs to be able to mate to the flywheel.

[carsinc]

I deffer to you if you could get it work. I couldn't.

[Andy Somogyi]

Originally Posted by carsinc

Then 912E trans won't work with a 2.7 motor. trans Main shaft different.

It will work fine, just need a 2.0 or 2.2 flywheel.

The 923 is a push clutch, needs the 2.0 or 2.2 clutch and pressure plate.


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[cason880]

Originally Posted by Nditiz1

^This is not an accurate statement. It will work with the correct clutch and pressure plate package. That same package needs to be able to mate to the flywheel.

Originally Posted by Andy Somogyi

It will work fine, just need a 2.0 or 2.2 flywheel.

The 923 is a push clutch, needs the 2.0 or 2.2 clutch and pressure plate.

Sent from my iPhone using Tapatalk Pro

I think Im starting to fill in my knowledge on the clutch setup. The 2.0/2.2 doesnt sound like a bad option, just a 215mm instead of a 225mm.

However, I am currently leaning towards converting the 923 to a pull clutch and running a 70/71 disk with a 915 pressure plate and flywheel. The only parts difference besides the bearing itself seems to be the release fork and the guide tube which are cheap enough (the clutch arm is a different P/N but it should work when its re-clocked to the pull side). Ill try to take pictures to update this.

[Andy Somogyi]

Originally Posted by cason880

I think Im starting to fill in my knowledge on the clutch setup. The 2.0/2.2 doesnt sound like a bad option, just a 215mm instead of a 225mm.



However, I am currently leaning towards converting the 923 to a pull clutch and running a 70/71 disk with a 915 pressure plate and flywheel. The only parts difference besides the bearing itself seems to be the release fork and the guide tube which are cheap enough (the clutch arm is a different P/N but it should work when its re-clocked to the pull side). Ill try to take pictures to update this.

The input shaft is different, that’s the big thing. The 923 has a 13/16 shaft, this fits the older style -6 and all -4 clutch disks. The pull style clutch needs a 7/8 shaft.

You can fit a 7/8 shaft in the 923 (case and everything else is the same), but that’s going to be a crazy expensive part.


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[cason880]

Originally Posted by Andy Somogyi

The input shaft is different, that’s the big thing. The 923 has a 13/16 shaft, this fits the older style -6 and all -4 clutch disks. The pull style clutch needs a 7/8 shaft.

You can fit a 7/8 shaft in the 923 (case and everything else is the same), but that’s going to be a crazy expensive part.


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Very true, I dont want to mess with the input shaft. Like you said expensive part, and I dont have nearly enough internal transmission experience to play with it.

But correct me if Im wrong, doesnt the 70-71 use the smaller input shaft and spline but with a 225mm disk? I think a combination of that year disk with a later pull pressure plate should work (assuming the release fork is converted)?

[Trackrash]

Originally Posted by cason880

I think Im starting to fill in my knowledge on the clutch setup. The 2.0/2.2 doesnt sound like a bad option, just a 215mm instead of a 225mm.

However, I am currently leaning towards converting the 923 to a pull clutch and running a 70/71 disk with a 915 pressure plate and flywheel. The only parts difference besides the bearing itself seems to be the release fork and the guide tube which are cheap enough (the clutch arm is a different P/N but it should work when its re-clocked to the pull side). Ill try to take pictures to update this.

Just to be clear. The '70-'71 uses the same pressure plate and flywheel as the 915 uses. I just replaced my 2,2 motor with a 3,0 and am still using the same pressure plate from my 2,2.

The disc is the same 225mm, HOWEVER, the '70-'71 disc is UNIQUE. It has the small spline for the 911/901 trans. Also different is the throwout bearing. The '70-'71 trans/clutch is a MICKY MOUSE reverse pull/push system that I would only use if you had a '70-'71 TRANS, since the release arm is unique to that trans, as is the cable and it's supports.

I can't imagine modifying a 923 to use the '70-'71 clutch release arm/ cable system. If someone has done it that way, I would be surprised.
Here is a good look clutch cable for 70-71 901


'70-'71 clutch release arm and pivot.

[cason880]

Originally Posted by Trackrash

Just to be clear. The '70-'71 uses the same pressure plate and flywheel as the 915 uses. I just replaced my 2,2 motor with a 3,0 and am still using the same pressure plate from my 2,2.

The disc is the same 225mm, HOWEVER, the '70-'71 disc is UNIQUE. It has the small spline for the 911/901 trans. Also different is the throwout bearing. The '70-'71 trans/clutch is a MICKY MOUSE reverse pull/push system that I would only use if you had a '70-'71 TRANS, since the release arm is unique to that trans, as is the cable and it's supports.

I can't imagine modifying a 923 to use the '70-'71 clutch release arm/ cable system. If someone has done it that way, I would be surprised.
Here is a good look clutch cable for 70-71 901


'70-'71 clutch release arm and pivot.

Thanks for replying Gordan, thats a lot of good insight and the link was very helpful. I do want to clarify that I dont intend to use the whole 70/71 release arm setup but instead an adaption of the '76 915 style with the 70/71 disk only. Here's the parts list Im going to experiment with:

'76 923/02 Transmission
'76 911 or 915 Clutch Release Fork (#1) (In place of the 912e fork)
'76 912e Clutch Release Arm (#7) (This will be reclocked from the push side to pull and the cable rerouted; The 911 uses #5 so it may need to be replaced)
'76 911 or 915 Throwout Bearing (#9)
'76 Bearing Guide Tube (#10)
'76 915 Pressure Plate
'70/71 Clutch Disk
'76 Flywheel

I am not certain yet this setup will work, but I pretty much have all the major parts except for the 70/71 disk and release fork to try it. I think when I have the transmission out of the car, it should be clear if this will work or not.