Transmission, Automatic

Auto -> Manual Transmission Swap

Auto -> Manual Transmission Swap

Recently completed an auto-to-manual swap on my 85. Most difficult part was cutting the firewall and adding the master cylinder mount. Everything else was just bolt-in. I got all the parts from Mark at 928 Int'l (714-632-9288). He supplied me a close-ratio, limited slip trans with 2.75 final drive ratio, freshly rebuilt, as well as all the associated bit and pieces. They were very helpful and supportive, and the job went very smoothly. This completely changed the character of the car, waking up the performance and feel of driving it. It knocked nearly a full second off the 0-60 time, even with me babying the launch. I would highly recommend the swap, if you are attached to your particular car, as I am. Cost will depend on how many new parts versus used parts, model year, etc.. You will have to talk to Mark about that. My conversion cost me about $3,000 doing a lot of the work myself. It could cost quite a bit more if you have it done at a shop.


I thought I'd pass on some info on this conversion. I do not normally recomend it as it is usually cheaper to sell your AT car and buy a 5sp but sometimes there are other reason in this decision. We have helped 5 people do this conversion and all were very happy they did it. Most were done by the owners themselves and it was not terribly difficult but it is a little time consuming. The cost will very depending on the parts used. You can spend as little as $750 for a used 1979 transmission or more than $2,500 for something rebuilt like a 1989 GT with LSD. You will also need to change the following;
bell housing (on some years)
torque tube
rear cross member
brake pedal
shift lever and trim

You will need to add the following:
clutch kit
intermediate plate
short shaft
guide tube
pilot bearing
clutch arm
pivot bushing
clutch slave
clutch master
clutch lines
shift coupler
forward ball socket
shift rods

You will also need to modify your firewall to install the clutch master.

As you can see from the long list of parts it can get expensive. Having done this 5 times now we have a pretty good handle on doing this. Would I do it on my own car? Probably not but I have been tempted to do so when I've come across a very nice AT car.

By the way, I just bought a 1993 GTS 5speed this week and I did have to look a lot longer to find a 5sp.
Have fun.

Mark Anderson
928 International

A conversion if done by a shop costs $9 to $10K. That would include the parts and a rebuilt transmission. I am not sure who I would trust with this other than DEVEK as there are some subtleties involved. You might contact DEVEK - they have done them before but would be a bit north of my figure and probably try to talk you out of it. Tell them I sent you - - speak to Susan or Marc. They will also be able to advise you as to the best bang for the buck for track performance.

Now I am just getting ready to do this to my 86 and have been collecting some information that may help steer you in the right direction.

1. The 79 will not work as a donor car as you will be missing the flywheel. Only a flywheel from an 85 or 86 will work.

2. The transmission from 85 up was a different trans and had better syncros for smoother shifting - that is the good news. The bad news is that it had a higher final drive ratio of 2.2 to help the top end and increase mileage for energy conscious buyers and to lower the gas guzzler surcharge.

3. The '79 trans will bolt up and give you a better drive ratio, but is going to be clunky and probably does not have a limited slip differential. This can be added from later models if you can find one but you are talking more bucks.

4. Now for some more bad news. The automatic cars were not set up for a clutch master. This means that the firewall will have to be modified to bolt on the clutch master. Well you say no big deal, but you have not looked at where the master is located. It is almost as though Porsche designed the car as an automatic and as an after thought added the clutch master. It is down under the brake booster and put in at an angle. The alignment is critical - get it wrong and you will not be able to keep clutch masters in the car. If you had done one of these jobs you would know that this is not something you want to do after each track day. To convert the car you have to cut the part out of the firewall of the donor car and weld it into the conversion car. I am working on a template and adapter to do this but it is still down my list of projects a ways.

5. With the transmission be sure to get the rear cross member. The one from the automatic will not work. Of course this implies that you have to pull the rear suspension as well - right. Probably time to check the brakes, shocks and emergency brake bands.

6. You are probably looking at $2500-3000 in new and rebuilt parts without having the trans rebuilt. For sure you want to use a new clutch master and the hoses that go with it. You can probably cheat on the clutch and torque tube, but I wouldn't. I would do new motor mounts while you are in there and of course new transmission mounts.

7. A rebuilt transmission can be got from German Transaxle Exchange in Oregon for $375 plus parts. They say it runs about a $1000 for the whole job and they give a two year guarantee - although I do not think that covers track conditions.

8. The center console will have to be modified for the shifter as will the hole where the shifter comes through.

9. The two disk clutch is a bit tricky to adjust.

Other than that it is pretty much a bolt up. DEVEK estimated 40+ hours for the work - but they are professionals and have done the job before. I am allowing about 100 hours for mine. Remember also with a donor car you have to allow for the time to take the parts out as well. The auto torque tube is worth a few hundred and Jim at 928 is short of them so will probably buy it from you. The transmission if good being a four speed is worth $500 to $700 if you find the right buyer - but you have to wait for someone to need one. So you might be able to recover about a $1000 on the old parts.

That is pretty much all I can help you with - good luck.

If you decide not to do the job I would be interested in the donor car.

Dan Brindle

Stage one of the auto to 5 speed conversion is complete. Clutch pedal installed. Whole sad story can be found at:

I had heard horror stories about how difficult it was to get the pedal and bracket mounted on the automatic. This actually turned out to be a fairly simple and straight forward job. Maybe it seemed easy because I have been in wiring hell for the past month or so. Total time start to finish including scavenging parts from the donor car was under five hours. This could be cut to an hour and half if the bracket can be obtained without scavenging the donor. Now that I have the template made probably cut the time by an hour. It is easier if the dash is out and the car is up on the lift by a couple of feet.

Now back to the installation of memory mirrors and seats.


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