Audi Swap - 986 Forum - The Community for Porsche Boxster & Cayman Owners

KenDFW · 04-10-2015, 06:48 AM

Hello 986forum

! I'm Ken. Here is a picture thread of a audi transmission swap I performed a while back.

Find yourself a donor. I found an audi a4 5speed manual transmission. Quattro will not work. Some VW passats will work too. S model boxsters can utilize a 5 speed transmission - but require a lot of modification, e.g. axle flanges, mounting hardware. There are forum members with 3.4 996 engines and 97-99 5 speeds. The swap I performed is practically a direct bolt up for 97-04 2.5s & 2.7s. It can be done with S models, or 3.4 etc.

Drain oil from old transmission, remove axle flanges- they are not compatible with 2.5/2.7 axles. But- interestingly audi flanges should be the same as S model chasis axles.

Remove Boxster transmission.

With boxster transmission removed, switch out axle flanges and swap all hardware between the transmissions.

Putting the Porsche flange in the Audi transmission.

Re-assemble

note: If you do not have M12x1.5x70mm (999-072-008-09) 'G' bolt location picture, it would be recommended to order and install
http://www.pelicanparts.com/techarticles/Boxster_Tech/37-TRANS-Drop/images_small/Pic4.jpg The boxster transmission has a stud in the case, whereas the audi does not. G bolt did not come with my car.

Total cost: $200
Results: Shorter, more aggressive gearing. First gear takes off like a bat from hell. Highway cruising in 5th is slightly more efficient compared to G86/01 5spd Boxster transmission.

Ratios:
Final Gear Drive 3.889
1st 3.778
2nd 2.176
3rd 1.429
4th 1.029
5th .838
(Similar ratios to G86/00 97-99 boxster, albeit shorter)

RPM Chart: (calculated with 255/40/17 tires)

Hope you guys enjoyed.

Feel free to give me your feedback and questions.

jotoole · 04-10-2015, 07:06 AM

why i pay a mechanic.

KenDFW · 04-10-2015, 07:17 AM

Labor of love.

Felt very satisfying turning the key, and rowing through the gears.

healthservices · 04-10-2015, 08:42 AM

Cool beans!

I'll have to try this the next time!

Have any more pictures of the two transmissions?

Any other things have to be swapped between the two transmisions ?

Valve bodies, connectors etc.

No codes plug and play?

KenDFW · 04-10-2015, 03:15 PM

Quote:

Originally Posted by healthservices

Cool beans!

I'll have to try this the next time!

Have any more pictures of the two transmissions?

Any other things have to be swapped between the two transmisions ?

Valve bodies, connectors etc.

No codes plug and play?

Once you see the transmissions side by side, it is very self explanatory as to what needs to be swapped. The one thing you have to is the axle shafts. The gear shifting hardware is external and is held on by bolts. It takes 5 minutes to unbolt and move over.

No codes.

If you have a tiptronic though, no dice.

healthservices · 04-10-2015, 08:55 AM

Trying to visualize the boxster trans, what is that hole on top of the audi trans? Make me want to go out and find one just to see the differences if any

Porsche9 · 04-10-2015, 11:46 AM

Nice work! Curious if there is a Audi 6 speed that would work.

KenDFW · 04-10-2015, 03:19 PM

Quote:

Originally Posted by healthservices

Trying to visualize the boxster trans, what is that hole on top of the audi trans? Make me want to go out and find one just to see the differences if any

The hole on the top is the speed sensor IIRC. I went and took the boxster's and stuck it in. I remember side by the side transmissions were very similar.

healthservices · 04-10-2015, 03:40 PM

Hai was thinking a tip trans. Lol this is still cool though. Thanks

NewArt · 04-10-2015, 05:56 PM

Cool thread Ken Thanks!

thstone · 04-10-2015, 08:31 PM

Quote:

Originally Posted by KenDFW

note: If you do not have M12x1.5x70mm (999-072-008-09) 'G' bolt location picture, it would be recommended to order and install
http://www.pelicanparts.com/techarticles/Boxster_Tech/37-TRANS-Drop/images_small/Pic4.jpg The boxster transmission has a stud in the case, whereas the audi does not. G bolt did not come with my car.

It is fairly common for one or more of the transmission bolts not to be re-installed if the trans has been out of the car previously. Many of the Boxster Spec racing cars are running fine with only 4-6 bolts rather than all 8. My car has 5.

I'm not saying that this is a "best practice", so don't run out to the garage and start removing transmission bolts. I'm just saying that this happens so don't be entirely surprised if you find that your car has less than all 8.

The Radium King · 04-11-2015, 01:31 AM

question - do you have confirmation that the audi flanges will work with a 6-speed axle (proper diameter, M10 fasteners, etc.)? thanks, trk.

CraigM · 04-11-2015, 07:38 AM

Absolutely awesome.

I've always wished the gears were shorter - and now there's an affordable way!

KenDFW · 04-12-2015, 06:14 PM

Quote:

Originally Posted by The Radium King

question - do you have confirmation that the audi flanges will work with a 6-speed axle (proper diameter, M10 fasteners, etc.)? thanks, trk.

Hi Radium King! I have the old audi axles in my garage along with the oem bolts.

Boxster 2.5/2.7 uses 8mm bolts (That's why I had to swap axles)

So the Boxster S uses 10x50mm bolts
The 1.8 A4 FWD axle bolts are 10x48mm 12mm triple square head bolts

So- the bolts will work and screw in.

I can take measurements of the axles. If the audi axle pattern will work with the Boxster S cv joint pattern, then this will get interesting. There are 6 holes, and the bolts will thread.

It wouldn't surprise me as Porsche and Audi share some parts!

The Radium King · 04-12-2015, 11:57 PM

cool. i ask because the torsen (similar to quaif) automatic torque biasing rear differential from a v8 audi will go into an audi 012 5-speed with just a bit of machining. apparently easily found at wreckers. the issue is that the diff will only accept audi axle flanges. apparently this is an issue for the 944 guys (they have an audi 016 in the back of their cars) put perhaps because they use 8mm axle bolts as well. otherwise a $200 solution to the $2000 limited slip issue.

Lobo1186 · 04-13-2015, 08:01 AM

Quote:

Originally Posted by KenDFW

Boxster 2.5/2.7 uses 8mm bolts (That's why I had to swap axles)

so which axles did you use? The 2.7 axles do not bolt up to this transmission?

KenDFW · 04-13-2015, 10:47 AM

Quote:

Originally Posted by Lobo1186

so which axles did you use? The 2.7 axles do not bolt up to this transmission?

I used the 2.7 axles for the swap. The Audi transmission flange uses 10mm bolts, whereas 2.7 use 8mm. You can see in the pictures, I pulled out a flange.

beater986 · 12-28-2020, 02:28 AM

Quote:

Originally Posted by KenDFW

Hi Radium King! I have the old audi axles in my garage along with the oem bolts.

Boxster 2.5/2.7 uses 8mm bolts (That's why I had to swap axles)

So the Boxster S uses 10x50mm bolts
The 1.8 A4 FWD axle bolts are 10x48mm 12mm triple square head bolts

So- the bolts will work and screw in.

I can take measurements of the axles. If the audi axle pattern will work with the Boxster S cv joint pattern, then this will get interesting. There are 6 holes, and the bolts will thread.

It wouldn't surprise me as Porsche and Audi share some parts!

Drudging up an old thread here. Did we ever determine if the audi axle and pattern matches the 986S?

PaulDash · 04-11-2015, 07:37 AM

Okay, so besides the gear ratios, any other advantages to doing the swap? Durability? Weight?

healthservices · 04-11-2015, 11:51 AM

Quote:

Originally Posted by PaulDash

Okay, so besides the gear ratios, any other advantages to doing the swap? Durability? Weight?

cost savings, try finding any Porsche at a "pick a part" junk yard or any self serve yard for that matter

Most places when they hear Porsche... there is the added "Porsche Tax" LOL

typical 5 speed transmission for a Boxster is north of 1k