5 vs 6 speed pros/cons

[Erik Johnson]

Hey there Guys,

I have quite a bit of experience with both of these gearboxes, so I can answer some of the questions that have come up here.

The 5 speed would certainly work well for you. It is geared pretty low, but then so is the 6 speed. It is however far less durable than the 6 speed.

It really depends on which of the 6 speeds you decide to use though. There are two of them to chose from. The 986.20 and the 987.20 one is out the Boxster S and the other is out of the Cayman S.

If it was my build, I would try to find a good low mile G86.20, do the detent mod on it and rebuild it prior to installation. It is a very strong gearbox, and with the detent mod done along with the rebuild, it will be very durable. You will want to make sure to take care of the 1st and 2nd gear as much as possible, but 3rd -6th are pretty strong, and can be beat on without fear of breaking them. I would also recommend a good differential. My personal favorite is the OS Giken, but there are several out there to choose from.

Feel free to give me a call if you have more questions, I would be happy to discuss the pluses and minuses of your choices out there.

Erik Johnson
(970) 344-7761 phone

[Gelbster]

Erik,
Thanks for giving your expert advice. The gearbox gets very little attention on the Forums. As the cars age, the gearbox issues will become more of an issue for Forum members. So your comments are useful and most welcome.
The cost of repair/rebuild for the 6 speed will also become more of an issue as the value of the cars declines but the cost of parts and labor increases.
So people will understandably try to do diy repairs . There have been very few diy gearbox repair threads here.
Transmission repair
Second gear problems on the six-speed gearbox - 986 Series (Boxster, Boxster S) - RennTech.org Forums
This was the best link- a long pdf of a complete 2nd gear repair and even a photo of the Kukko puller they used. but sadly it is now dead:
http://itguynetworks.com/articles/boxster/2002BoxsterSTransmissionRebuildDecember2011Revisio n3.pdf

[Escy]

Originally Posted by Erik Johnson

If it was my build, I would try to find a good low mile G86.20, do the detent mod on it and rebuild it prior to installation.

What's the detent mod and what's the reason for doing it? I'm planning on running 400+bhp on a G86.20

[BoxsterSteve]

Originally Posted by Escy

What's the detent mod and what's the reason for doing it? I'm planning on running 400+bhp on a G86.20

Here's what I have read. The modified detent allows the 2nd gear selector to engage a bit more deeply, reducing synchro damage and gear pop out.
I fit one to the transmission because of a minor crunch on the initial 1-2 up shift of the day before the gear lube warmed up. That was 2 years ago, and it hasn't recurred since.

[Porsche9]

Originally Posted by BoxsterSteve

Here's what I have read. The modified detent allows the 2nd gear selector to engage a bit more deeply, reducing synchro damage and gear pop out.
I fit one to the transmission because of a minor crunch on the initial 1-2 up shift of the day before the gear lube warmed up. That was 2 years ago, and it hasn't recurred since.

I installed the detention a few months back to address the same issue and it has not happened since.

[j.fro]

The 6sp trans has a 2nd gear pop-out issue. I had to rebuild mine at 142k. I did the G-box detent, I'm at 180k no issues.

[Gelbster]

The best source of advice and parts for this issue that I found was:
Erik Johnson
(970) 344-7761 phone