Best Clutch For Street Use

[Daviboy]

Hi guys,
I was out today and must admit to dumping the clutch at higher than normal revs today. As I did lots of slip even up into second gear, this followed by that acrid burning smell belching out the tunnel in front of the parking brake. As I was about 6 miles from home I kind of panicked as I thought it may just quit on me right there. Long story short it did not, I managed to baby her home. Now I dont know if the car is still on the original clutch (she has 149,000 miles on her) but the smell I got was decidely rubbery in origin, though at first I was spinning the rear wheels. Anyway I just want the learned opinion as to what the best clutch is for street driving dont want anything expensive just a bit bulletproof. I just spent over $400 on a new alternator and this is the last thing I need....

[James Brown]

Understand, Davy, that could very well be t he original one in the car. They last a long time if not ABUSED!! And it could be the rubber center one. Doubt that is what you smelled, sounds like you just put your foot in it with the clutch not all the way out (read "slipped it like a 16 year old does").
Anyway, the stock Sachs clutch is the gold standard for replacement. You can just change the clutch plate but why, 150k miles is a good time to change everything (clutch plate, pressure plate, TO bearing, sleeve, and check the rest of the parts for wear. You can buy parts ala cart (one piece at a time) I'm sure the clutch will last a few more months if you operate it in "normal" mode.

[Oh Haha]

I have the Sachs Sport clutch and it works great.

In your case,there really is no valid reason to NOT replace all of the parts and have the flywheel at least checked over and machined if necessary.

You have to pull the engine/trans anyway so do it right the first time.

[Daviboy]

Yeah James Brown there was a bit of the 16 year old going on. I really hope the clutch will hold up as I dont want to drop the motor and tranny right now. I am in the middles of selling my house and about to build a new one so dont really have the time or space right now for that.

[DanielDudley]

Check youe cable adjustment, and adjust it so the clutch engages closer to the floor.

Other people will have different opinions, but I think you should not be doing high RPM clutch dumps or powershifts. You have lots of traction there, and not a lot to take up driveline shock. The clutch might have been doing you a favor by sacrificing itself. If you drive a 28 year old car like a beater, it is going to become a beater, and then it will become beat to death.

If you think a clutch is expensive, try a tranny or an engine.

[cashflyer]

Pelican Parts - Product Information: 915-116-911-00-M38

[dshepp806]

Rubber centered for the street.....quieter.

[Grady Clay]

Davy,

For comfortable street use, Porsche started using a much heavier flywheel and pressure plate with the 911SC. This increase in rotational inertia makes taking off from a stop much easier. The engine also idles better and helps to not stall when below normal idle, as when you take off without giving additional throttle.

This is done with a flywheel with additional metal around the perimeter. The pressure plate has a cast steel housing and a steel moving friction piece.

This combination makes for a very pleasant street car. It doesn’t change top speed and has only small effect at highway speeds.

It has a slight negative effect on acceleration in 1st and second gears (less so as you go up through the gears). It also reduces your ability to shift very fast (something you shouldn’t be doing with a 915 anyway).

Critical is a clutch disc that is full-circle friction material (not ‘pads’). The two pieces of friction material must have springs in between. This allows progressive engagement of the clutch without ‘judder’.

Even if a rubber-center disc is quieter, I would go with the reliability of the spring-center version.

I would replace ALL the clutch parts, including flywheel. You may be able to machine the original flywheel and remain in dimensional spec but it will be heat-hardened and probably heat checked. A new steel flywheel will have the proper metal characteristics to work best possible.

Even when machined in spec, the clutch fork now operates at a less advantageous angle.

When replacing your clutch, use the opportunity to replace the fork & cable, rebuild the pedal assembly, replace other associated parts and adjust everything correctly. When replacing the fork, also replace and lube the shaft bushings. A new ‘omega’ spring might be in order.

You want this new clutch to last another 150K. That is possible if you don’t do ‘jackrabbit’ starts slipping the clutch.


If you want to build a track-only 911, go the other direction and have everything as light as possible.

Best,
Grady

[Forza]

+1 for Grady's recommendation to replace everything at the same time, and definitely do not refurbish the current flywheel. It's a Porshe 911: Any apparent short cuts are false economy.

As for which new clutch to choose, that depends on whether you're willing to adapt to driving the car the way Porsche intended or to change the car to suit your, ahem, heavy-footed driving style. Either Sachs OEM (street) or Sachs Power (street & autocross) would be the most reasonable choices on an otherwise stock SC. But even the Sachs Power has its limits in this regard (slipping, burnouts, etc). Oh, and don't waste your time on a rubber-centered clutch; that debate was settled by Porsche during the original production run of your SC starting in 1981. Given yours is an '82, it should not have a rubber-centered one unless fitted by a previous owner.

[don gilbert]

PMS forged flywheel for 3.0SC . Out of a 1500.00 doller kit, yours for 200.00

[efhughes3]

Why were you dumping the clutch? Talk about diminishing returns! I've burned my share of rubber in my life, but figured out early on that these cars aren't made for hole shots. I ran a couple of stoplights yesterday with a hot semi-tube framed VW yesterday. I made sure an disengaged my clutch fully BEFORE I mashed it. That is the only way to get off the line efficiently in a 911.

BTW, the VW got its front wheels off the ground a few inches both times and was pretty damned fast. I don't normally do the stoplight thing....but it was another air-cooled flat engine. 6 cylinders did turn out to be better than 4 both times.

[RRD]

KEP (Kennedy Engineered Performance)

Their clutch ass'y is great.

[Daviboy]

Guys thanks for the input. But I would like to point out that I do not make this a habit and resent being told that I drive my car like a beater or that my driving style is heavy footed. I drive my 911 with the utmost care normally and respect the 27 year old components. I have sourced a sachs power clutch kit locally and will be replacing with that. Again thanks for the advise

[rnln]

wheels include?

Originally Posted by don gilbert

PMS flywheel for 3.0SC . Out of a 1500.00 doller kit, yours for 200.00

[Oh Haha]

I did the same thing when I first got my 911 except that my issue was powershifting into 2nd. Yep, it wasn't long before the synchros gave up. That was an expensive lesson.

[dshepp806]

I withdraw my rubber-centered suggestion, knowing it's a 915 (and, of course the fact that Grady suggested spring-centered). On my '89, I went with rubber (factory) due to noise reduction. Driven correctly, they will last, too.

I've heard a spring-centered in a friend's 88 and it was FAR louder than a rubber-centered one. In fact, my bud had them take it out due to noise. (Surely a personal decision).

You'd not go wrong with Sir Grady's recco's...

Doyle

[efhughes3]

Originally Posted by Daviboy

Guys thanks for the input. But I would like to point out that I do not make this a habit and resent being told that I drive my car like a beater or that my driving style is heavy footed. I drive my 911 with the utmost care normally and respect the 27 year old components. I have sourced a sachs power clutch kit locally and will be replacing with that. Again thanks for the advise

Not sure what there is to resent? You made the statement up front that you dumped the clutch. I asked why. I've not seen anyone here "telling" you that you "drive your car like a beater". The question was worth asking, as fairly regularly, posters come on here and talk about drag racing and wonder how they can improve 1/4 mile times.

[Grady Clay]

Doyle,

I hope I didn’t come off as saying ‘my way is the only way’. It isn’t.

I am looking at the original poster’s criteria. Most appropriate for normal street use. He proudly added that the clutch survived 150k mi.

My admonition for the spring-center disc is from many owners’ poor experience with the rubber-center part. It may very well be that the current generation of rubber-center discs have improved rubber technology.

The issue with rubber-center discs has been rubber failure due to age, heat, environment and stressed to the angular limit of the clutch hub. If the disc would simply fail in some noticeable way, that would be just fine. You periodically simply replace only the disc.

The subtle (and expensive) issue is, while the clutch appears to function correctly, the rubber tends to shred into very little pieces and get between the friction surfaces. This causes some ‘drag’ when you attempt to release the clutch. It is as if the clutch is adjusted where it doesn’t completely release. The pieces can also exit the friction surfaces due to centrifugal forces. This makes the ‘drag’ inconsistent: the classic at the shop “Well it was doing it a few minutes ago.”

Part of the diagnosis is to peer up into the little drain notch in the bell housing and reach up on top of the transmission (near the top openings to the bell housing) to find shredded rubber pieces.

The insidious problem with the ‘drag’ is it accelerates wear on the transmission syncros and ultimately damages the engagement dogs and sliding sleeves. We all know how expensive that can be.


Yes, a spring-center disc is noisier, particularly with age. The hub fit to the disc can gain clearance over many miles. More noticeable is the fit of the springs between the hub and disc assembly. When unloaded, they can seriously rattle.

So:
What to do?

For quietest operation, use a rubber-center disc. Replace the disc periodically. How often? Some research may give you an idea. For transmission longevity, I would err on the conservative side.

With a spring-center disc, all new parts, reasonable driving and some luck, there is no reason the clutch won’t last another 150K mi. I see no reason for anything other than stock OEM parts. In fact, heftier ‘sport’ parts may tolerate higher power and short-term abuse better but may have a shorter life and less 'comfort' in normal, careful operation. Will there be some noise? Sure but I suspect the engine, transmission and other will be somewhat ‘looser’ pushing 300K mi.

Best,
Grady

[don gilbert]

wheels include?


no, but i cant believe no one is jumping on the flywheel, brand new, never used.

[Forza]

Originally Posted by Daviboy

Guys thanks for the input. But I would like to point out that I do not make this a habit and resent being told that I drive my car like a beater or that my driving style is heavy footed. I drive my 911 with the utmost care normally and respect the 27 year old components. I have sourced a sachs power clutch kit locally and will be replacing with that. Again thanks for the advise

Hey, we all--myself definitely included--have done things behind the wheel or in our garages that we immediately regret! Thinking back, I'm afraid to think about the times I've turned an otherwise routine wrenching job into a mini-nightmare. Obviously, given your current clutch's longevity, you know how to look after your components. Sounds like you had a momentary lapse of reason followed by the inevitable, "Oh, $#%! ... Noooo!" We've all been there--that's an important part of why this forum even exists. As for your dilemma, I suppose dealing with whatever mechanical consequences will be penance enough, without having to endure additional wisecracks from the likes of me....

Anyway, let us know how the Power clutch works out after the smoke's cleared!