A lot of older threads on the topic of marrying transaxles to V8s. I just finished rebuilding an LS1 and am looking to weigh current and cost effective options on the trans. G50s are out of my league but Boxter and Subaru variants sound efficient and reliable. Currently running a SBC 350 and 901 side shift.

For those of you who have had the experience of building them, or are building them now, what are your opinions, preferences, or realizations?

Planning for a street/track set up. Thank you for the help in advance.

To your point, it's about budget. I have an LS3 and I didn't want to worry about things breaking so I went with a Boxster S 6-speed (G86-20) as they've been proven to about 500 hp.
They can be found on ebay in the $2k range. You can get a stock shifter and cables for a couple hundred, last I looked.
Kennedy Engineering makes the adapter plate, flywheel and clutch. Or you can get the whole kit, including trans mounts from Renegade, but it's not cheap.

Best of luck with your decision.

Chris, is the proven to about 500 hp with V8s or flat sixes or? Curious as the later 981 GT4 6MT signed off on by Motorsport was limited to 310 lb-ft, which arrives at 4700+ rpm in that car. The gearing is pretty bad in a 981, too, with 2nd stretching to 84 mph and 3rd to 112 mph—so not too fun on a back road.

I've started to wonder about taking a 7MT from a 991 and flipping the ring gear as people do with 915 gearboxes, as the torque limit is higher. Next question is whether there's a way to delete 7th gear or lock it out like Porsche does on the GT4 Clubsport PDK, or just enjoy 9,000,000 miles per gallon.

Thank you. Did you rebuild the transaxle once you received it or run it as is?

Pete - I was only concerned about what to use with my V8. The LS3 in my car came out of Tony's (Cracker) 914 (also running a G86-20, though he does have an LSD) and was replaced with an LS7 that dyno'd at something like 530hp at the wheels. He tracks his car so regularly sees WOT and his trans is taking virtually all that power. To date, he hasn't had any gearbox issues. I think if you don't abuse it, it'll last, especially on the street.
For fun, here's Tony on track with the LS3 before I got it.
http://www.914world.com/bbs2/index.php?showtopic=271085

I got it via ebay, it had only 56k miles on it and the car it came from wasn't damaged at all anywhere in the back half. I've decided to give it a try as is. That said, I've only just gotten my car running. It was aligned and corner balanced two days ago and still needs some help with ITB and ECU tuning.
Give me a few weeks and I'll have a full road test report!

Tony's car is incredible, and I remember watching one of his Road Atlanta videos in a kind of awe. Looks like he's clean and smooth, FAST with mechanical symphathy. Perhaps Porsche's point about the GT4 6MT being at its torque limit already with the 2016 model has to do with their torture tests—which may be their way of anticipating certain…customers.

Down that road, I was in a Porsche shop years ago and a guy came walking in saying I owed him a transmission for his 993. Why, I asked? Because, apparently, I had said that his 993 had a strong transmission. He went on to say he had killed his transmission after some hard starts (5000 rpm and dumping the clutch). "Ah," I said. "I meant that transmission can probably withstand 24 hours of racing at a place like Daytona..." as I scratched my head and considered the fact that he had just gotten out of a Ford Lightning pickup.

"Strength," and "limit," can mean different things...and sounds like you'll be just fine.

I chose an LS6 with the renegade kit. super happy but I am not driving it yet as I started the build 2 months ago. lots of body work to do.

did I hear the 2nd gear in the boxster S tranny goes to 84mph? what is the top speed in 6th?

I'd have to dig into 986 gearing, but 981 gearing was a bit of a mess—to the point I wanted to have a shift knob made for my GT4 that said:

2-4-5
3-5-5

These figures for the 981 GT4 given match up with my experience:
1st = 46mph
2nd - 83mph
3rd = 118mph
4th = 150mph
6th = 183mph

The ratios were frustrating in the GT4, as there was no need to shift on the majority of backroads, and the GT4's shifter is one of the main attractions. They also seemed to really blunt its in-gear quickness 2-3-4. Meanwhile, 6th left you turning 3200-3600 between SF and LA where a 991 7MT drops the revs down to 2200, greatly increasing its comfort as well as its fuel range, while its 2-3-4 stack are really nice for a back road.

In a 914, the lack of a need to shift might be a bonus. Engine types matter, too.

I had a couple of 986 Boxsters, and preferred the 2.5 5MT gearbox to the 2.7 setup, as it was a bit shorter (in some ratios, I think) to make up for the 2.5's lesser torque. The 986 6MT was pretty nice on the street, iirc.

Supposedly, 987.1 6MT is:
1st = 30mph
2nd = 70mph
3rd = 99mph
6th = 172mph

EDIT: Found charts below, which may be helpful. The one on its own for "Boxster S: Transmission diagram" is for the 986 Boxster S 3.2

Wow that shifts nice (IMG:style_emoticons/default/drooley.gif)

Great info, I guess I got lucky buying the G86.20 6 speed. Not that I know a lot now but when I bought it I had no idea.

I have an 04 Boxster s 6 speed behind my LS2.

Used the Kennedy adapter package and the Renegade trans mount.

Not cheap but good quality parts.

If I recall I paid $1,400 for the trans.

Got a shifter & cables on ebay for ~$170.

Don't really use 1st as starting in 2nd seems perfect for the LS.

Shifts like a new car.

David

If money was no object..Xtrac transmission.

Guessing 10's of thousands of dollars.


https://www.youtube.com/watch?v=iG_9tbcpBbI

Looks to Pretty to put in the car.

Thanks David. Was your trans an ebay purchase? Did you rebuild before install? Also did you do the work yourself?

Same set up I'm starting with on my new 914 project. LS3 from Summit Racing, Boxster S 6 speed, along with KEP and Renegade/Hybrib products. This is my first post and I'm so happy that I found 914World.com........Roger, U.S. Army, stationed in Germany right now.

Thank you for your service and (IMG:style_emoticons/default/welcome.png)

Several mentions that the KEP adapter and Renegade mount are Pricey. Pricey is a relative term, how about a rounded dollar amount?

I have an LS1 and Boxster S. Go with Stuttgart Muscle for Adapters and Spec 2 clutch. I personally feel it is better quality than Kennedy or Renegade and for less money. Google the company.