987 6mt in 986 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

NickB · 06-11-2021, 07:48 AM

Can anyone help with a definitive parts list to get a 987 6mt from a cayman into a base (2.5) 986 5mt. From reading/searching around looks like:

1. Both mounts
2. Clutch and pressure plate
3. Shifter
4. Shift cables
5. Both axles - Do the axles require the S wheel carriers - I understand that a 986 6mt would - couldn’t find any info about 987 boxes though.

Not worried about exhaust brackets at this time.

Thanks in advance

itsnotanova · 06-13-2021, 04:32 AM

You don't need the shifter but the 987 shifter is better. You will need to upgrade to the S rear uprights and brakes as the 6 speed has a larger CV joint. I believe You'll also need to make axles using the 986 outer Cv and shaft with a 987 inner cv

NickB · 06-14-2021, 04:03 PM

Great info thanks! One last question - cross checking the p/n compatibility for flywheels looks like using a 987 clutch disc and pressure plate may work with the 2.5 flywheel - is that correct?

itsnotanova · 06-14-2021, 04:50 PM

Quote:

Originally Posted by NickB

Great info thanks! One last question - cross checking the p/n compatibility for flywheels looks like using a 987 clutch disc and pressure plate may work with the 2.5 flywheel - is that correct?

I think it will but don't quote me on that. Why are you using a 987 6 speed?

NickB · 06-15-2021, 05:46 AM

Quote:

Originally Posted by itsnotanova

I think it will but don't quote me on that. Why are you using a 987 6 speed?

Ok thanks, appreciate the help! Planning to use a 987 because our maths shows the ratios are a little better optimized for road racing, also had a really hard time finding a 986 6mt.

itsnotanova · 06-15-2021, 10:30 AM

Is this with a 2.5? There's lots of optional gear ratios with the 5 speed if you're only worried about gearing. That transmission came in a few different cars for many years. Even among the boxster there are 3 different transmissions with different gear ratios

NickB · 06-15-2021, 05:10 PM

Yes 2.5. We looked at options for VW/Audi 5 speed ratios. Couldn’t find any reports on how easy it would be to mix and match - but if there’s already a path would love to get more info. Lower 5th from the Audi/VW 02W (i think) helps paired with a 2.5 standard final, however really need a longer 2nd and 3rd from other Audi/VW transmissions though, goal is to maximize the output from a 2.5 between 45-130mph, so the plan is to use either aftermarket 3-6 ratios or a lower final in the 987 box. Similar options exist for 986 6mt however apparently unavailable at the moment. None of these are what one would call cheap though …

itsnotanova · 06-15-2021, 05:35 PM

Sounds like you've been doing your homework. I'm not sure which years or models can be used together. I would think the 986 2.5 and 2.7 5 speeds should interchange with no problem but the 987 5 speeds have larger synchros and might not work. I've heard that you can't buy any new 3 & 4 gears from porsche anymore either. Have you thought about playing with tire diameter? I went from a 26 inch tall tire to a 23 on my rallycross car and it was like night and day.

ike84 · 06-15-2021, 06:02 PM

I can tell you that on my 00 986 base 5 speed with the 2.7 (max powerband 4k - 6.2k rpm), first gear hits 40 just past 6k. Upshifting at 6-6.2k will keep you consistently in that powerband, and you will hit 150mph just past 6k in 5th gear. I know everyone poops on 5 speeds but Porsche mated this one beautifully to the 2.7.

Btw, the more widely known name of these 5speed is the 01a. The 997 6 speed, if I'm not mistaken, is a version of the 01x (I could be wrong about that but that's in my brain at the moment). There's a guy named Scott at advanced automotion that probably knows more about European manual transitions than anyone. He's a nice guy and will answer a bunch of questions by email.

Woody - talk about downsizing your tires! I'm strugglebussing hard right now with picking new wheels and need input from people who have done some "outside the box" changes.

Sent from my POCOPHONE F1 using Tapatalk

ike84 · 08-30-2021, 04:45 AM

Hey Nick, did you ever complete this project?

Sent from my SM-G970U1 using Tapatalk

Quadcammer · 08-30-2021, 07:31 AM

anybody thrown a 987 5 speed into a 986? I wonder if different cables and different axle flanges are necessary for this swap. My G86.01 is plugging along, but could fail at any time.

itsnotanova · 09-04-2021, 04:14 AM

Quote:

Originally Posted by Quadcammer

anybody thrown a 987 5 speed into a 986? I wonder if different cables and different axle flanges are necessary for this swap. My G86.01 is plugging along, but could fail at any time.

I have a good friend who has been using a 987 5 speed in his 3.4 race car for years now. From what I remember the 987 5 speed uses the same cables as the 986. I can't remember if it uses 8mm or 10 mm bolts for the axles. I'm thinking 10mm and you have to use the 2003/04 axles. The sychros on the 987 are larger but the the 986 and 987 5 speeds are basically the same. The 987 has an overall gear ratios similar to the 97-99 5 speeds.

ike84 · 09-04-2021, 05:30 PM

That's great info, thank you

Sent from my SM-G970U1 using Tapatalk

NickB · 01-08-2022, 11:58 AM

Quote:

Originally Posted by ike84

Hey Nick, did you ever complete this project?

Sent from my SM-G970U1 using Tapatalk

Yes, sorry for slow reply. Quite a big project all said and done.

ike84 · 01-08-2022, 03:25 PM

No worries, how'd it go? Was your original parts list accurate? Did you wind up changing out the carriers and uprights as well?

Sent from my SM-G970U1 using Tapatalk

NickB · 01-10-2022, 05:14 AM

Yes, did not need the shifter, the rest is accurate.

Used 986S wheel carriers with 986S axles but as expected the fit is not optimal on the left axle in particular. Wheel carrier change drove a change to S brakes/calipers all round. Not a lot of space behind the trans, so the exhaust will need to be custom or modified - we run basically straight pipes so not a huge deal for us to figure out.

I went around and refreshed the whole suspension / wheel bearings etc while it was all apart so in the end the project was quite large and certainly put up a fight, however the trans part wasn’t any harder than a regular clutch/flywheel job once the right parts were on hand.

Smallblock454 · 01-10-2022, 03:25 PM

Well that's about the hardware. But how about the electronic part and wiring harness? The 987 Cayman engine will definitely not run with the 986 2.5 ECU or BCU. Also the ABS / PSM ist completely different.

NickB · 01-11-2022, 04:38 AM

Quote:

Originally Posted by Smallblock454

Well that's about the hardware. But how about the electronic part and wiring harness? The 987 Cayman engine will definitely not run with the 986 2.5 ECU or BCU. Also the ABS / PSM ist completely different.

Only set out to swap trans… don’t know what it would take to add a cayman engine

Escy · 01-12-2022, 01:00 AM

What did you think about the increase in weight? The 6 speed is way heavier than a 5 speed, not a swap I'd have done on a n/a engine through choice.

NickB · 01-12-2022, 01:02 PM

Quote:

Originally Posted by Escy

What did you think about the increase in weight? The 6 speed is way heavier than a 5 speed, not a swap I'd have done on a n/a engine through choice.

We removed weight to accommodate the 6 speed, bigger brakes, bearings, axles etc. Ended up slightly less than the “before” weight with about a 1-2% shift to the rear.