2001 Saturn SL1 Mod Thread

[stefanv]

Originally Posted by oldtamiyaphile

You can try this (in someone else's car of course). Sit on a hill, hold the car on the clutch at idle. Increase RPM. The car doesn't move because regardless of RPM, you're only transferring the same number of newtons.

Yes, you're transferring the same number of Newtons (force), but you're expending more power while producing those Newtons (thus, less efficiently). That extra power has to go somewhere. Since it isn't going into making the car move, it is going into removing material from the clutch and making it hotter.

Slip time and RPM is what wears out a clutch. It's just like if I'm sanding a piece of wood. If I apply the same amount of force, but sand faster, I will remove wood faster. If this weren't the case, power sanders would be pointless, since you could just make one firm but slow pass with a piece of sandpaper and achieve the same result.

[oldtamiyaphile]

Originally Posted by stefanv

Yes, you're transferring the same number of Newtons (force), but you're expending more power while producing those Newtons (thus, less efficiently). That extra power has to go somewhere. Since it isn't going into making the car move, it is going into removing material from the clutch and making it hotter.

The extra power has to go somewhere, but it doesn't have to go into the clutch disc. Just like revving in neutral, the energy goes into spinning the flywheel.

If revving with the clutch dragging created more friction, the car would move. You cannot create more heat in the clutch disc without more friction, and more friction would cause the the car to move, especially as friction comes first, heat is generated from friction.

My Ford has a hand crank handle. How much power can I exert with my arms? Tiny amount of power.

An electric starter takes 80A - cranking a hot engine takes 1 second. That's ~80mah.

Moreover, if a bump start caused the same wear as a 2000rpm start, you would experience the same change in motion. I don't feel a thing as my clutch spinning at ~2000rpm just kisses my flywheel accelerating my engine to the ~90rpm required for it to fire up. Once it fires, I rev match and I'm off.

I'm a semi-pro wood worker, and I think there are a lot of flaws with the sander analogy. When I first built my workshop, I did a feature beam running the whole width of the shop. I started hand sanding the whole thing - then switched to the belt sander - it was barely any faster, just less tiring since the motor was doing the work. The ~2kg weight of the sander means it's exerting more force than I could on a similar sized sanding float and still be able to push it across the surface. The speed of the belt ejects saw dust- hand sanding means regular stopping as your sand paper rides on it's own layer or saw dust reducing it's cutting power. Finally of course, a power tool doesn't stop/start at the end of it's stroke- which costs time.

Yes, I can take off more wood than a sander with just one heavy stroke, I can use a jack plane. I can also use a file/ rasp to take of a lot of material in a single stroke, using lots of pressure, or I can use less pressure and and go back and forth and do less work.

An example of a hand tool moving slower, having to stop and change direction and yet doing the same amount of work:

https://www.youtube.com/watch?v=y5xtr25oSq4

Power tools are just for lazy people.

[Stubby79]

Originally Posted by oldtamiyaphile

Power tools are just for lazy people.

I love power tools! If the job doesn't involve using some form of powered tool/equipment, I'm not interested.

This lazy person is one of the most productive at work.

[stefanv]

Originally Posted by oldtamiyaphile

If revving with the clutch dragging created more friction, the car would move. You cannot create more heat in the clutch disc without more friction, and more friction would cause the the car to move, especially as friction comes first, heat is generated from friction.

Heat is not generated by friction alone, it is generated by friction times speed-squared. So if I have a 2000 RPM difference in speed of the clutch plates, there will be more heat generated in the clutch than if I had only an 800 RPM difference (6.25 times as much in fact). Consider two rubber blocks against each other, and you try to move one relative to the other, and you can't because the friction is too high. Lots of friction, but no relative speed, so no heat at all.

[stefanv]

I haven't done any more significant mods, but have cleaned up a few things.

The first was a partial redo of the grill block and air dam extension. Last year, one grill block was shattered when I hit a cat in the winter, and the air dam extensions got broken a few times. The ABS plastic I used gets brittle in the winter, but I decided I'd stick with that for the grill blocks, as that was really an unusual impact, but find something more flexible for the air dams.

What I ended up doing was buying a black RubberMaid rectangular waste can (about 26" high), and cutting the air dam pieces out of one face of that. I was really impressed with the material, as it is quite thick (about 1/8"), very flexible, yet holds its shape when curved. I was really surprised how flexible the material was once cut out of the can, as the can itself is quite rigid. It's all in the shape.

To replace the grill block, I unscrewed the old patched-up one, and discovered that several of my mounting brackets had become dislodged by the feline collision. I had to reattach most of the ones on one side, and two on the opposite side. I also discovered that there was more damage to the car itself, in that the grill diffuser was broken in a few places. I patched it up with cable ties and a few screws, although in hindsight, I could have removed it since it serves no purpose when the grill is blocked.



Recall from my earlier posts that I had removed the factory radio and replaced it with an amplifier, hidden away behind my tablet display. I had some electrical noise issues, most of which were solved with a BHF (big honkin filter), but a few remained. The most annoying was that the HVAC blower motor sometimes produced crackling noises in the speaker, especially at low fan speed. I made a pair of capacitor-diode filters, one for the blower, and one for the fuel pump (whose whine I could also hear). I installed these across the power and ground lines to each motor.

These are the filters, each consisting of a 100nF capacitor and a 1N4001 diode, soldered to a small board, and enclosed in heatshrink:



They were attached using crimp-on splices, to the blower motor ...



... and fuel pump motor wires:



The blower one completely cured that problem, although the pump whine persists. Maybe it's not the fuel pump after all? (It only occurs when driving at low speeds, and cycles on and off.)

One last improvement was that I finally got around to making a bezel to better integrate the tablet into the instrument panel. It is made from a thin sheet of plastic, painted with matte black Krylon Fusion spray paint:



The bezel is cut to fit exactly into the radio opening (which is about 1/10" bigger than the tablet horizontally, and about 1/4" vertically). I left notches in the bezel to allow access to the tablet buttons (using a flat plastic stick) on the left, and to pry the tablet out from the right. I used a Sharpie to colour the exposed areas of the tablet black.



The bezel is attached to the tablet with double sided tape.

[teoman]

Nice work on the tablet!

[Pyre99]

Nice work!

[stefanv]

Since my car is a Saturn, I though I'd post this photo I took a few nights ago. A different kind of Saturn photo I guess, but then the Saturn was always advertised as "a different kind of car":



That image was assembled from a group of 9 images shot one second apart, aligned and then median stacked. Camera: Canon SX20IS.

[arcosine]

I stick my tablet right in front of the gauge cluster, so I can navigate and drive at the same time, sc1. I don't have the electrical noise, I do have some ignition noise and have wrapped the PCM and cables in aluminum tape shielding.

[stefanv]

Originally Posted by arcosine

I stick my tablet right in front of the gauge cluster, so I can navigate and drive at the same time, sc1. I don't have the electrical noise, I do have some ignition noise and have wrapped the PCM and cables in aluminum tape shielding.

The electrical noise isn't coming from my tablet. It's coming from the rest of the car and being picked up by my homebrew audio system. I.e., it's my audio system that is the problem, not the fact that I'm using a tablet. The big honking filter took care of most of it.