transmission rebuilt! - 986 Forum

j.fro · 03-29-2011, 05:08 PM

My trans had had the 2nd gear pop-out issue for the past couple of years, and this winter I finally decided to pull the trans and have it redone. Along with the rebuild, there were a few other things on my wish list. I had read that Gbox was making a detent that solves the pop-out issue, so that went in. I also wanted to swap the open diff for a torque-biasing unit from Guard Transmission, put in a LW flywheel, and replace the clutch with a sprung Spec stage 3+.
Holy cow, what a difference! Every shift is smooth, and I can feel the trans securely clicking into the gear through the shifter. The LW flywheel allows the engine to spin up much faster...but dropping down to neutral or taking off from a stop requires more attention. I've noticed the TBD just a bit during street driving; I've got a feeling it will be more a a benefit in autocrossing.

pompous · 03-29-2011, 06:01 PM

Nice!! Did you pull the trans yourself? Any tips?

Cloudsurfer · 03-29-2011, 11:25 PM

I had my gearbox freshened (though not by G-Box) when I had it out, and am also running a Guard LSD, which, with ~400HP on tap, is of enormous advantage. Push the car a bit, and you'll certainly feel it at work.

Why did you decide on a Stage 3 clutch? I have a 12:8:1 compression 3.8 (which lives on race fuel) and I'm only running a Stage 2 SPEC.

landrovered · 03-30-2011, 06:42 AM

I am going to redo my gearbox this year and put in a sprung clutch, I am tired of the clacking from a single mass flywheel and a solid clutch. It is amazing how much faster the rpms come up and also go down during shifts.

I have had to learn to keep my foot on the accelerator on shifts to rev match more smoothly.

Glad to hear about the Gbox detent, my second gear does not pop out but the synchro is definitely on the way out.

BTW: Spec recommended a stage three clutch to me as well with a 3.6 motor and 986 gearbox.

Cloudsurfer · 03-30-2011, 01:44 PM

Quote:

Originally Posted by landrovered

I am going to redo my gearbox this year and put in a sprung clutch, I am tired of the clacking from a single mass flywheel and a solid clutch. It is amazing how much faster the rpms come up and also go down during shifts.

I have had to learn to keep my foot on the accelerator on shifts to rev match more smoothly.

Glad to hear about the Gbox detent, my second gear does not pop out but the synchro is definitely on the way out.

BTW: Spec recommended a stage three clutch to me as well with a 3.6 motor and 986 gearbox.

I had several lengthy discussions with SPEC regarding my build, and was assured that Stage 2 would be more than adequate. Looking at the specs on Stage 2 vs Stage 3, the Stage 2 is good for 405 lb/ft of torque, while the Stage 3 is good for 508 lb/ft. Even putting down ~400hp, my motor doesn't even make 330 lb/ft of torque, so why would I need anymore than a clutch rated for 405? A stock 3.6 doesn't even make 300 lb/ft, so why do you feel the need for a clutch rated for over 500?

My clutch has NEVER slipped.

j.fro · 03-30-2011, 02:12 PM

I chose the Stage 3 Plus after a lengthy conversation with Spec about my car and how I use it. It is primarily an autocross car. Funny, I purchased my Spec through, I think, Vivid racing, and the price was better than what Spec themselves offered. As well, I think the Stage 3 Plus was cheaper than the Stage 2. When they sent the clutch, the unit I originally received was solid, and I had to send it back in exchange for the sprung unit. Even with the sprung clutch, I've got lots of chatter.

FYI, the job was long, but not particularly difficult. I did it in my garage with the car on jack stands. Record all of the bolts' locations! Holy cow, Porsche uses a lot of different fasteners for what appear to be similar uses. I used an Aasco FW, which includes FW bolts, which fortunately are not torque-to-yield. Simple red loctite + 60 lb/ft and you're good to go. I bled the clutch slave cylinder before hooking it back up to the trans, and now engagement is pretty high. I think I will re-bleed with he hope that engagement becomes more towards the middle of the pedal's travel. The Gbox detent was $100 and it's probably the best bang for the buck. I'm using a Schnell Short shifter that's seen over 100K through 2 different cars, but now it feels more precise than a new stock shifter in a stock trans.

Cloudsurfer · 03-30-2011, 04:32 PM

My sprung Stage 2 on an Aasco flywheel has only a minor amount of chatter, easily hidden by the exhaust. Unfortunately, the AP Racing clutch on my M3 chatters like nobody's business.

Pulling gearboxes and engines on these cars isn't quite as easy as it is on a 996 (which is worlds more work than pulling an air cooler), but I'll yank a Porsche gearbox or engine out LONG before I will on a BMW.