Go Back   986 Forum - The Community for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical Chat

Post Reply
 
LinkBack Thread Tools Display Modes
Old 02-12-2015, 04:38 PM   #1
Registered User
 
Join Date: Feb 2015
Location: ontario
Posts: 5
5 vs 6 speed pros/cons

I know the 5 speed has a lower final drive ratio.
And I know the 5 speed is much lower cost initially

This is for my 914 project so very light car. Will have around 250 - 300 HP.

got_914? is offline   Reply With Quote
Old 02-12-2015, 04:57 PM   #2
Registered User
 
Join Date: Oct 2007
Location: Midwest
Posts: 1,746
6 speeds are known to have 2nd gear pop-out / synchro issues, also well known in the 996 series which uses the same transmission albeit inverted. Go with the 5 speed.
coreseller is offline   Reply With Quote
Old 02-12-2015, 05:14 PM   #3
Registered User
 
rdass623's Avatar
 
Join Date: Apr 2014
Location: new orleans
Posts: 249
six speeds have reverse in the wrong place on the shifter! all the years of muscle memory have confirmed that fact to me. allegedly the six speed is a more durable gearbox, but I have not had any problems with my 5 speed so that is an unconfirmed rumor as far as I am concerned.
__________________
2005 Porsche Boxster S, 2000 Porsche Boxster 2.7L Base, 2000 Mazda Miata LS Supercharged, 2010 Toyota Tacoma TRD Off Road
Previous Vehicles: 2005 Ford Mustang GT, 1986 Alfa Romeo Spider, 1971 Alfa Romeo GTV, 1999 Ford Mustang
1977 Toyota Celica GT
rdass623 is offline   Reply With Quote
Old 02-12-2015, 05:19 PM   #4
Registered User
 
tnoice's Avatar
 
Join Date: Nov 2008
Location: Champaign, IL
Posts: 355
6 Speed has one more speed than a 5, so more is always better.....right?
__________________
Lov'n my boxster!

2013 Lexus IS350awd
2007 Toyota FJ Cruiser
2004 Porsche Boxster S
tnoice is offline   Reply With Quote
Old 02-12-2015, 05:53 PM   #5
Registered User
 
Join Date: May 2014
Location: S.California
Posts: 2,027
The 6 speed driveshafts are at a rather steep angle compared to the 5 speed. So the boots wear .The 6 speed is a very expensive/difficult gearbox to repair.Just do a search and you will find mention of very expensive tools and massive force required.Not a great diy proposition.
In your case the gearing of the 6 speed is unhelpful unless you plan to remove tree stumps with 1st gear :-)?Your car will be so light/powerful,the 1st gear would be somewhat useless except for generating tire smoke.
Gelbster is offline   Reply With Quote
Old 02-13-2015, 06:38 AM   #6
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Southern ID
Posts: 3,701
Garage
300 hp may be too much for the lil 5spd which was only rated for 250 or so. It may survive with a good trans cooler. I do think the ratios are better for track work though.
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor-Ret.
Topless is offline   Reply With Quote
Old 02-13-2015, 06:56 AM   #7
1999 base
 
Meir's Avatar
 
Join Date: Dec 2011
Location: Coral Springs FL
Posts: 1,617
Garage
as a previous owner of a 01 boxster S with 75K miles 6 speed.
and a current owner of a 99 boxster base with 160K miles 5 speed
i'm telling you, go with the 5 speed. its a night and day difference.
Meir is offline   Reply With Quote
Old 02-14-2015, 09:37 AM   #8
Registered User
 
Join Date: Feb 2015
Location: Colorado
Posts: 62
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
Erik Johnson is offline   Reply With Quote
Old 02-14-2015, 12:55 PM   #9
Registered User
 
Join Date: May 2014
Location: S.California
Posts: 2,027
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
Gelbster is offline   Reply With Quote
Old 02-16-2015, 02:35 PM   #10
Registered User
 
Brad Roberts's Avatar
 
Join Date: Aug 2004
Location: Alta Loma, CA
Posts: 1,334
Run the 2.5 5sp. Want to upgrade later? Use the 987 BoxsterS 05-06 6sp. Shorter ratio's than the CaymanS 6 sp. I have multiple cars with 300-340hp through the stock 2.5 and 2.7 5sp transmissions. We can break them, but so can a 201hp 2.5. No need for coolers/etc. Cooling the trans does not stop the teeth from sheering off of 3rd gear
__________________
Engine Builds, Transmission Builds, Engine Conversions, Suspension Installs, Suspension Tuning, Driver Coaching, Data Acquisition, Video, SCCA/PCA/POC/NASA/GRAND AM/ALMS.
We have worked with amateur and professional drivers for over 26 years. In house machinist, In house fabrication. Our cars, our parts, our engines, our transmission's run nationwide at events every weekend. We work side by side with industry names developing parts.
Brad Roberts is offline   Reply With Quote
Old 10-12-2015, 04:00 AM   #11
edc
550 Anniversary
 
edc's Avatar
 
Join Date: Jul 2012
Location: Surrey, UK
Posts: 747
Garage
I have a 2004 986 S and want to investigate a lower final drive.

What are the ratios on the 2005/07 987S?

Brad - when you say use this box do you mean transplant the gear set or will the box just bolt up?
__________________
Current: 550 Spyder Anniversary- Carnewal exhaust - 100 cell cats - stainless manifolds - 4" underdrive pulley - poly gearbox mounts - rear lower alu brace - adjustable rear toe links
Sold: 986S - Zenith Blue - 18" Sport Classics - Black Zunsport grilles - Stainless silencer and manifolds - K&N panel - shortshift - M030 suspension - 75mm throttle body - custom 83mm intake - SmartTop - custom remap - MDS underdrive pulley
edc is offline   Reply With Quote
Old 10-12-2015, 05:08 AM   #12
Registered User
 
steved0x's Avatar
 
Join Date: Dec 2012
Location: FL
Posts: 4,143
Quote:
Originally Posted by tnoice View Post
6 Speed has one more speed than a 5, so more is always better.....right?
The 6 speed is "1" faster.


Last edited by steved0x; 10-12-2015 at 05:13 AM.
steved0x is offline   Reply With Quote
Old 10-12-2015, 05:13 AM   #13
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,369
Garage
What's the weight difference between the 5sp and the 6sp?
__________________
Rennzenn
Jfro@rennzenn.com
j.fro is offline   Reply With Quote
Old 10-12-2015, 05:23 AM   #14
Registered User
 
Join Date: Apr 2015
Location: Michigan
Posts: 114
Quote:
Originally Posted by rdass623 View Post
six speeds have reverse in the wrong place on the shifter! all the years of muscle memory have confirmed that fact to me. allegedly the six speed is a more durable gearbox, but I have not had any problems with my 5 speed so that is an unconfirmed rumor as far as I am concerned.
You have never driven an early 911.

You want to talk about a messed up shift pattern.

R 2 4
1 3 5
emore93 is offline   Reply With Quote
Old 10-12-2015, 09:27 AM   #15
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
Quote:
Originally Posted by j.fro View Post
What's the weight difference between the 5sp and the 6sp?
I think the 986 5-speed is about 50 lbs lighter than the 986 6 speed. the 987 unit is a bit in between the two. if I recall correctly from when I looked into it, the 986 and 987 6-speeds share the same slave cyls and hubs so are a relatively easy swap. the 986 5-speed is different. all have unique axles and shifter cable arrangements. you can use 5-speed axles with 6-speed hubs but will have less axle thread to nut on to. other than that, there are variations in the 986 5-speed gearing and flange dimensions over the years, and even more variation if you start looking at the interchangeable audi 012 units. the 987 boxster and cayman 6-speed also differ in gearing. also, I think that, in the case of these transmissions, mass is proportional to strength - the 986 6-speed is quite strong, the 987 unit less so, and the 5-speed is easiest to break. however, being lighter/smaller (shorter) they have better axle geometry than the 986 6-speed.
The Radium King is offline   Reply With Quote
Old 10-12-2015, 05:26 PM   #16
Porsche "Purist"
 
Paul's Avatar
 
Join Date: Aug 2003
Location: Wisconsin
Posts: 2,123
Garage
My 1998 3.6 has the original 2.5 5 speed, no issues, over 100K on the gearbox...
__________________
1998 Boxster with 7.8 DME, 2005 3.6 liter/325 hp, Variocam Plus, 996 Instrument panel
2001 Boxster original owner. I installed used motor at 89k.
1987 924S. 2002 996TT. PST-2
Owned and repaired Porsches since 1974. Porsche: It's not driving, it's therapy.
Paul is offline   Reply With Quote
Old 10-17-2015, 03:42 AM   #17
Registered User
 
Join Date: Oct 2015
Location: Cardiff, UK
Posts: 106
Quote:
Originally Posted by Erik Johnson View Post
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
Escy is offline   Reply With Quote
Old 10-17-2015, 04:55 AM   #18
still plays with cars...
 
BoxsterSteve's Avatar
 
Join Date: May 2011
Location: Baden, ON, Canada
Posts: 1,087
Garage
Quote:
Originally Posted by Escy View Post
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.
__________________
Six speed 2000 Boxster S
Arctic Silver on Metropol Blue | LN Dual Row IMSR | Arctic Silver console, spoiler frame & bumperettes | Crios mod | Technobrace | RoboTop module & modified convertible top relay for one-touch roof operation
BoxsterSteve is offline   Reply With Quote
Old 10-17-2015, 09:49 AM   #19
Registered User
 
Porsche9's Avatar
 
Join Date: Sep 2013
Location: Chandler, AZ
Posts: 1,796
Quote:
Originally Posted by BoxsterSteve View Post
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.
__________________
03 Carrera
02 Boxster S Guards Red, black interior with matching hardtop
89 Carrera 4
89 944 S2
78 911SC
Porsche9 is offline   Reply With Quote
Old 10-17-2015, 03:29 PM   #20
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,369
Garage
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.

__________________
Rennzenn
Jfro@rennzenn.com
j.fro is offline   Reply With Quote
Post Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 06:49 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page