A Fresh Perspective
11-14-2012, 10:39 PM
#46
Race Director
Thank you, and while we're talking about experience, I might as well comment on break-in. I remember when this argument raged in the letter columns of Popular Mechanix back in the fifties and the positions were the same. The positions and the people, who were just as inflexible then as now. It's a polarizing issue. For what it's worth then, here's my take after ... omigod, after 47 years as an engineer. (I could have done without that arithmetic tonight. Now stuff hurts. I may have to go take an Advil...
)
I was mostly in the space business with some aircraft work, and otherwise naval/military equipment. Never consumer products of any sort. And essentially everything we built in the space business was intended for single use. No chance to break in an Atlas booster. It either works the first time at full power or we have to break it ten thousand feet above the Pacific. Ditto satellites. And don't even think about Minuteman III.
You might suppose I'd scoff at break-in procedures. Well, with the finest machinists in the world creating our parts with tolerances down to spooky levels, the last step is worth noting. Assembly of parts that would move against each other always included hand lapping them. You put on a mild abrasive, put the parts together, and carefully mimic the motions expected in operational use. Sometimes they wouldn't go together at all. Tolerances so tight can mean two pieces on opposite ends of their tolerance range will not fit, so we had ... well, never mind. Too much detail.
Having lapped for a prescribed period, the compound is then washed off with an appropriate solvent, and a finer abrasive applied, ending with a polishing compound when we wanted them that well mated. (We often have specs to prevent them being too well mated. A phenomenon called vacuum welding must be avoided if the two materials in contact are susceptible to it.) Basically, for lack of gentle early operations, we substituted human manipulation to achieve break-in.
I'll stick with the book recommendation for my Porsche, adapted only slightly with some techniques I learned years ago.
Gary
)I was mostly in the space business with some aircraft work, and otherwise naval/military equipment. Never consumer products of any sort. And essentially everything we built in the space business was intended for single use. No chance to break in an Atlas booster. It either works the first time at full power or we have to break it ten thousand feet above the Pacific. Ditto satellites. And don't even think about Minuteman III.
You might suppose I'd scoff at break-in procedures. Well, with the finest machinists in the world creating our parts with tolerances down to spooky levels, the last step is worth noting. Assembly of parts that would move against each other always included hand lapping them. You put on a mild abrasive, put the parts together, and carefully mimic the motions expected in operational use. Sometimes they wouldn't go together at all. Tolerances so tight can mean two pieces on opposite ends of their tolerance range will not fit, so we had ... well, never mind. Too much detail.
Having lapped for a prescribed period, the compound is then washed off with an appropriate solvent, and a finer abrasive applied, ending with a polishing compound when we wanted them that well mated. (We often have specs to prevent them being too well mated. A phenomenon called vacuum welding must be avoided if the two materials in contact are susceptible to it.) Basically, for lack of gentle early operations, we substituted human manipulation to achieve break-in.
I'll stick with the book recommendation for my Porsche, adapted only slightly with some techniques I learned years ago.
Gary
11-15-2012, 12:09 PM
#49
Well I for one am certainly receptive to the idea of some sort of break-in being beneficial in the long run. And it matters a lot to me, being the kind of guy who keeps his cars a long time. Going on 15 years with my 79 SC, and if I can ever get my hands on a 991S they will have to bury me in it! (Of course I would never actually subject my car to such treatment!) In fact everything Gary said makes perfect sense to me. My 911SC motor was rebuilt some years ago. I definitely did follow a break-in procedure, and remember thinking while tooling around varying load and rev's that what I'm really doing is sort of a final parts polish. Only by power not by hand and with random little metal bits in place of engineered polishing compounds.
Maybe we should add those polishing compounds to the new motor oil, run it a while, replace oil with finer compound, run it, flush it, and only then drive it?
So happy to say my question got just what I was looking for, good info and reasons why we should in fact follow some sort of break-in process. Next question, Gary, "adapted only slightly with some techniques I learned years ago"? Please do tell!
Maybe we should add those polishing compounds to the new motor oil, run it a while, replace oil with finer compound, run it, flush it, and only then drive it?
So happy to say my question got just what I was looking for, good info and reasons why we should in fact follow some sort of break-in process. Next question, Gary, "adapted only slightly with some techniques I learned years ago"? Please do tell!
11-15-2012, 12:17 PM
#50
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11-15-2012, 01:54 PM
#51
Race Car
I had a 78 SC for 30 years and over 100k mi, and never had a bit of mechanical trouble with the engine or drive train. I likely prevented some by changing oil with the seasons, wiping metal filings off the oil plug), adding oil lines to the chain tensioners and getting rid of the rubber center clutch.
I broke it in at a two day Watkins Glen PCA DE, and three other such events in its first year. It had a manual transmission, so I guess that could be considered "hand lapped". PS it ran very well the first year and over the next 29. Probably still somewhere.
I broke it in at a two day Watkins Glen PCA DE, and three other such events in its first year. It had a manual transmission, so I guess that could be considered "hand lapped". PS it ran very well the first year and over the next 29. Probably still somewhere.
11-15-2012, 05:21 PM
#52
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- We're breaking in the whole car as a piece of equipment, not just the engine. The book version comes out: "No steady speeds. Keep it under 4000 rpm." but think about what that implies. With a seven-speed transmission, we have four or five gears available for most speeds we see in the U.S. Playing the variations on those gears at a constant speed is good for the transmission, whether it's manual or PDK. But changing the chosen speed is important for the rest of the driveline. The idea is to take each part of the car over its scales, I mean like those scales music students practice. We're keeping the power levels low, while we play chopsticks.
- Permit excursions occasionally. Take the engine briefly to higher rpm than your limit (4000 is ours) and to higher torque levels at the low rpm ranges. Not both until late in the break-in period. After the tires and brakes are broken in, take the chassis progressively closer to its limits in cornering and braking. Flex the car's muscles more as the break-in period proceeds.
- "Use the back of the gears" was the old term, meaning that gear sets have a driving face and an overrun face. You want to go into overrun pretty regularly. It used to be explained as sucking some oil up past the rings, and I suppose that might be a factor, but I still think of it as breaking in both 'sides' of the driveline. Because I don't rely on the "oil past the rings" justification, I try to do this in all the gears, not just the highway cruising choices like fourth and fifth.
- Explore the different things the vehicle is built to do. Have fun. High power levels is not everything a car is about, especially a sports car. In that earlier simile, we may be saving ourselves for marriage, but nobody says we can't fool around, right? Corner, brake, accelerate. Put stuff in, take it out: more and less payload. Top up and down, music, phone, nav system. Keep within your current bounds, but within those bounds ask the car to deliver what it is supposed to be able to deliver. That means the ancillary systems as well as the driveline. I know you've got four years to find out the g-meter doesn't work or the nav thinks Plymouth is in Great Britain, but why wait?
- As someone suggested (with cynical intent) in the 997 forum, it is important to break in your driving skills as well. Adapt them to this car. On track, I always have my students back off from their own limits to learn finesse in the skills they already possess. Most of mine seem to be advanced drivers so it frustrates them to go slow, but things like control transitions and subtle modulation are best learned well inside the 'envelope'. (Test pilot term. Don't fret the definition.) Use this period to learn the feel of your new car, how it differs from similar cars, and what it 'likes' and doesn't like. Learn how to fluently operate the ancillary systems during this honeymoon period while the chassis and driveline are not being pushed. Learn the personality of your car and you'll get along better when you both are pushing the corners of that envelope in later life.
Gary, off to fiddle around
11-15-2012, 05:48 PM
#54
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11-15-2012, 05:56 PM
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I'll try for interior pictures today.
Gary
11-15-2012, 11:38 PM
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Tough to do it justice in a low-resolution shot in low light, so I put them in a Picasa album for those seriously interested. Here's a low-res version of one of those:
and a flash photo in what can most charitably be described as a documentary style, right down to the dusty footprints of your aged correspondent:
That's what I get for letting a cripple get in my pretty new car...
Gary
and a flash photo in what can most charitably be described as a documentary style, right down to the dusty footprints of your aged correspondent:
That's what I get for letting a cripple get in my pretty new car...
Gary
11-16-2012, 12:08 AM
#57
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I took the tighter canyon road to a restaurant in Valencia and saw 1.01 g on the recording meter for right turns. And again, left turns were lower at only 0.87 g. Either it's characteristic of the road or I've developed a habit of not cornering as hard toward the driver's side. Odd if true. I'll check it on track. Learned how to use the sport chrono's chrono by the way. Not that it serves any purpose on public roads.
On the way home, the return canyon is more open and I saw only 0.98 to the right and 0.87 to the left again. Noticed that braking has reached 0.87g. Gotta get those brakes bedded in, you know.
Gary
11-16-2012, 12:22 AM
#58
Could it be that when in the right lane turning left you are always in the outside lane, and when turning right you are always in the inside lane causing a tighter turning radius and higher g force on average?
11-16-2012, 12:32 AM
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Entirely possible.It also could be that my back is a factor. I may be subconsciously bracing my arm against the door when turning right, but when turning left my back has to carry the load without that extra support and I pamper it. Since turns at the track are more to the left than the right (by 360° worth obviously), we'll see what results the g-meter shows on at the track Sunday.
I may just have to admit to getting... old.
Gary
