When pushing more HP - impact on drivetrain? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

mcgrews3 · 08-03-2021, 09:03 PM

For those running turbos and/or swaps - have you had any axle problems? Did you upgrade the drivetrain? Buzz on various forums is that boxsters axles can be weak as they were designed for ~250 HP. Thanks.

Qingdao · 08-04-2021, 08:38 AM

No problems as of yet.

Tires, driving style, and clutch do a lot to determine transmission longevity. Oh and the most important factor in transmissions... Luck.

ike84 · 08-05-2021, 05:29 PM

Depends on if you're talking the 5 or 6 speed tranny's. 5 speeds, aka 01a, are considered disposable items in euro racing and have a top power rating of somewhere 250-300 ftlbs depending on driving styles. 6 speeds are far more durable though. I've not heard of axle problems for either model but I've not into that much truthfully.

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Escy · 08-06-2021, 12:24 AM

My 5 speed took 400ft/lb

ike84 · 08-06-2021, 05:39 PM

Quote:

Originally Posted by Escy

My 5 speed took 400ft/lb

That impressive! How long did it last? And what type of driving? Did you have any clutch issues with that torque?

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Escy · 08-06-2021, 11:11 PM

Not that long before I upgraded to a 6 speed but I used the car hard, launches, etc and it had an LSD so was putting all the power down. My clutch was an Audi RS4 one (engine was an Audi S4 2.7 bi turbo)

Qingdao · 08-07-2021, 06:10 PM

Quote:

Originally Posted by Escy

Not that long before I upgraded to a 6 speed but I used the car hard, launches, etc and it had an LSD so was putting all the power down. My clutch was an Audi RS4 one (engine was an Audi S4 2.7 bi turbo)

I'm using an Audi A4 clutch on my 5 speed, too. No clutch, trans, or shaft issues thus far. Open diff and regular street tires. No nasty launches or hard shifts; that doesn't mean I don't give it the berries every now and again.

ike84 · 08-08-2021, 12:52 PM

Quote:

Originally Posted by Qingdao

I'm using an Audi A4 clutch on my 5 speed, too. No clutch, trans, or shaft issues thus far. Open diff and regular street tires. No nasty launches or hard shifts; that doesn't mean I don't give it the berries every now and again.

Aren't they the same clutch? If the a4 is a late 90s fwd version, thats the exact same tranny as the 5 speed.

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Qingdao · 08-08-2021, 04:40 PM

Quote:

Originally Posted by ike84

Aren't they the same clutch? If the a4 is a late 90s fwd version, thats the exact same tranny as the 5 speed.

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Its a LOT bigger. More contact area. The 5 speed boxster clutch is dual mass and that apparently means you get a lot less gripping surface.

ike84 · 08-08-2021, 07:00 PM

Quote:

Originally Posted by Qingdao

Its a LOT bigger. More contact area. The 5 speed boxster clutch is dual mass and that apparently means you get a lot less gripping surface.

I'm super confused here and also extremely interested. Our flywheels are dual mass, the clutch disk is single mass.

Do you have the PN for the clutch you're talking about? I would love to see it.

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Qingdao · 08-09-2021, 06:51 PM

Quote:

Originally Posted by ike84

I'm super confused here and also extremely interested. Our flywheels are dual mass, the clutch disk is single mass.

Do you have the PN for the clutch you're talking about? I would love to see it.

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Already tossed everything; so no pics..

The Audi clutch gripping surface has a smaller ID; but the same OD. The dual mass clutch has workings and weird stuff happening on the inside of the clutch so the ID is greater and the OD is the same. IDK what the weird duel mass trickery was; didn't take a hard look at it just went strait to the scrap yard. The dual mass clutch's band was about 3cm thick; I'd say the Audi disk is about 4 or 4.5 cm thick.

EDIT:

Damn I was close guessing their thickness... This guy is selling A4 clutches and has a side by side picture.

https://www.europeanpartssolution.com/porsche-986-987-boxster-cayman-5speed-upgraded-clutch-kit

ike84 · 08-09-2021, 07:03 PM

Quote:

Originally Posted by Qingdao

Already tossed everything; so no pics..

The Audi clutch gripping surface has a smaller ID; but the same OD. The dual mass clutch has workings and weird stuff happening on the inside of the clutch so the ID is greater and the OD is the same. IDK what the weird duel mass trickery was; didn't take a hard look at it just went strait to the scrap yard. The dual mass clutch's band was about 3cm thick; I'd say the Audi disk is about 4 or 4.5 cm thick.

That's really interesting. The only time I've heard of using a sprung clutch disk on these cars was with a single mass lightweight flywheel. This wasn't a popular update for many because that DMF serves as the engines harmonic balancer and deleting it may or may not cause crankshaft failure.

What'd you say killed your original m96 motor?

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Qingdao · 08-09-2021, 07:17 PM

Quote:

Originally Posted by ike84

That's really interesting. The only time I've heard of using a sprung clutch disk on these cars was with a single mass lightweight flywheel. This wasn't a popular update for many because that DMF serves as the engines harmonic balancer and deleting it may or may not cause crankshaft failure.

What'd you say killed your original m96 motor?

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IDK about killing your crank... Honestly if I was developing a car and the crankshaft was so fragile that it requires a special flywheel I wouldn't use that crankshaft. IMPO the M96 is a TERRIBLE engine, but thats just me

Don't know and kinda don't care about the original engine from my car; I don't hold the M96 engine in high regards LOL
I was told by the PO it was IMS failure, but the guy I bought the car from ate meth for breakfast like every day for 10 years. He saw the cash in my hand and got a big woody for that next crack rock. LOL

All my trash talking aside; my wife had an M96 powered boxster for a couple of years. No IMS, D chunking cylinders, no cracked cylinder walls, or cracked heads so IDK.

ike84 · 08-09-2021, 07:55 PM

I remembered that it wasn't you that fried the original motor, that's why I teased about it.

I don't think guys are talking about it much any more but a few years ago when far more racers were involved in the forum, there were a lot of debates about the single mass lightweight flywheel and sprung clutch disk. The harmonic balancing is just another weird thing about these motors. I'm with you, I feel more like the m96 was the result of cutting as many corners as possible. Or maybe they were just over confident in their engine design capabilities. Who knows.

Still interesting though your observations about the a4 clutch. Please share of you every stumble across that part number for comparison.

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PaulE · 08-11-2021, 02:27 PM

Here is a thread from a while back documenting an LS Swap into a Boxster S. My recollection is the half shafts weren't up to drag racing starts, but that they worked fine if he didn't dump the clutch at high rpms.

Qingdao · 08-11-2021, 05:57 PM

Quote:

Originally Posted by PaulE

Here is a thread from a while back documenting an LS Swap into a Boxster S. My recollection is the half shafts weren't up to drag racing starts, but that they worked fine if he didn't dump the clutch at high rpms.

I feel like CV angle has a lot to do with axle failure. I'm not 100% sure but I think I didn't move my trans as far back as the V8 guys do; which saves me from CV axle issues.