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weight transfer from body roll is pretty much zero. yes, there is some. but even at like 10 degrees of roll the CG moves an inch or two, maybe. What is actually effected by changes to the suspension is the rate of weight transfer. slower weight transfer means the tire is loaded more gradually and grip better. This is why softer suspension works better. have you ever drawn a free body diagram? I would suggest trying it and then explaining to me how the suspension has anything to do with it. Here, I made one. F= Hcg * g / wb/2 where F= weight transfer from cornering g= cornering force Hcg = height of center of gravity wb/2 = 1/2 track width I did leave a couple things out but it gets the idea across jamal fucked around with this message at 09:56 on Apr 20, 2012 |
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Apr 20, 2012 07:17
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e: from that NASIOC thread: hood scoop delete. Lol, is this somehow cheaper/easier than trading/swapping for an NA hood?jamal posted:A certain car going around a corner at x lateral gs will transfer y lbs of weight to the outside of the car. It has absolutely gently caress all to do with springs or swaybars or anything suspension related. Let me say that again, and in bold: making your suspension softer or stiffer DOES NOT change the amount of weight transfer. Maybe I'm confusing some terms here, but these two parts seem to be contradictory. Did you mean degree of rate of weight transfer in the 2nd part? The phrase "heavily loaded" probably coincides with what some people take to mean weight transfer -- the extra force pushing down on a tire. quote:Notice how I said the tire with more load loses grip first? That's because the coefficient of friction of a tire in reality is not proportional to load. If it was, more normal force would equal more grip and chassis dynamics would be exactly the opposite of how they actually are. In high school physics, cf is constant. If that is roughly the case for rolling rubber on road, then I'd think grip would still be correlated or proportional to load. Take the classic hot hatch scenario. You trail brake into a corner. The front end digs in and gets grip; the rear end tips up and loses grip. Sometimes the inside rear tire even lifts, which would be zero grip. So in this specific case, I don't see how the tire with more load loses grip first. kimbo305 fucked around with this message at 07:57 on Apr 20, 2012 |
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Apr 20, 2012 07:53
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sorry, by proportion of weight transfer I mean front to rear proportion. so for a given cornering force there is a total y weight transfer. That total weight transfer will get divided between the front and rear depending on the suspension setup and car. Obviously when you get the proportions right you end up with more grip (and more total weight transfer). But, like I said, the total weight transfer is a function of cornering force, not suspension stiffness. In high school physics, yes cf is constant. for a real tire on a real road it is not. How it actually works is ridiculously complicated and even after reading engineering textbooks and journal articles and stuff I still don't completely get it. But simply put, when a car is going around a corner, of the outside two tires, the one with the most load will lose traction first. jamal fucked around with this message at 09:38 on Apr 20, 2012 |
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Apr 20, 2012 08:53
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jamal posted:But simply put, when a car is going around a corner, of the outside two tires, the one with the most load will lose traction first. I dunno -- I just don't see that in my hot hatch trail brake example. If the rear of the car starts to slide out -- did the outside rear tire really momentarily have more load on it than the front? You'd think just before it broke loose, the tire would have been almost tipping forward off the ground.
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Apr 20, 2012 10:03
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jamal posted:But simply put, when a car is going around a corner, of the outside two tires, the one with the most load will lose traction first. Is the load youre referring to vertical load supplied by the suspension or twisting load provided by the engine. If twisting then yes, obviously. If vertical with the two outside tires receiving equal twisting amounts (50/50 Power split F-R) I don't think this is the case. EDIT: Or are you talking about sliding in turns in which case your force trying to break traction is the momentum of the car and the twisting supplied by the engine and your tire is resisting this not with the Cf forward but with what it is side to side and to a lesser extent forward? Lord Gaga fucked around with this message at 15:18 on Apr 20, 2012 |
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Apr 20, 2012 15:09
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Awwww poo poo, CT and Jamal are fighting again  kimbo305 posted:In high school physics, cf is constant. If that is roughly the case for rolling rubber on road, then I'd think grip would still be correlated or proportional to load. Take the classic hot hatch scenario. You trail brake into a corner. The front end digs in and gets grip; the rear end tips up and loses grip. Sometimes the inside rear tire even lifts, which would be zero grip. So in this specific case, I don't see how the tire with more load loses grip first. Maybe I'm reading this incorrectly, but I don't think you're accounting for the weight transfer and the inherent nature/weight balance of said hot hatch. Also - I think in Jamal's example, he's talking about lateral load forces in losing grip, where as in lifting the rear inside tire in your example, is a different type of force (weight transfer, in conjunction with damping forces lifting the tire).
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Apr 20, 2012 18:50
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Hate to interrupt, but what kind of grease should I use to grease brake caliper slide pins?
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Apr 20, 2012 19:04
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by that logic, big front heavy cars like the chevy impala and ford taurus would have a reputation for dangerous handling and the porsche 911 would be an understeering machine. what I am talking about is a car going around a corner at a constant speed. so the only forces we are concerned about is the lateral and vertical force on the tire. There's no braking or acceleration going on which does change things.
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Apr 20, 2012 19:40
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When you said that you would run swaybars of equivalent thickness front and rear, am I correct in reading into that that the springs themselves compensate for the weight distribution? I seem to remember that on the springs I've fitted to my WRX the spring rate in the front is somewhat higher than that of the rear. Right now I'm having a problem where the car feels sort of weird going over bumps in a corner; the front end lifts up slowly and the rear end bangs up and down, making the car feel like it's 'dead' in the back - there's no transition or subtlety, like the springs aren't being allowed to work. It's hard to explain precisely. I think I've just set my dampers up too high (I cranked the rear ones up at the last autocross event of the year to compensate for what ended up being a thrown axle). Seat Safety Switch fucked around with this message at 23:43 on Apr 20, 2012 |
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Apr 20, 2012 20:05
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ssjonizuka posted:Awwww poo poo, CT and Jamal are fighting again  Swaybars are the most contentious topic in this thread. Every time they're mentioned this happens.
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Apr 20, 2012 21:38
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I absolutely love Jamal and CT. Their posts are the only time I ever learn anything. I'm not sure what I learn, but drat it, I learn something, even if I end up more confused. Seriously, don't stop guys, you both are awesome.
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Apr 21, 2012 00:12
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My belts were squealing when I start up cold. I went ahead and changed them, but the problem persisted. I walked out around to check it out and the power steering pulley was seized causing the belt to squeal and smoke! The fluid looks good, and once I turn the wheel a couple of times it comes loose and doesn't do it again until next time start up. I didn't take it apart and look at it yet because it's hot and getting dark. Is it likely I'll be able to rectify this with some lube, or am I looking at a new pulley and/or power steering pump?
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Apr 21, 2012 00:35
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Slow is Fast posted:I absolutely love Jamal and CT. Their posts are the only time I ever learn anything. I'm not sure what I learn, but drat it, I learn something, even if I end up more confused. I am agreeing with this 100%. I usually lurk here but the amount of knowledge you guys share is fantastic, and you're so cool about it. Jamal has been fantastic to do business with as well.
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Apr 21, 2012 03:16
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Splinter posted:Hate to interrupt, but what kind of grease should I use to grease brake caliper slide pins? Short answer: use disc brake grease for disc brakes. Purpose-made brake grease only; normal lithium-thickened greases won't handle the heat and/or will degrade the rubber boot. NuclearFusi0n fucked around with this message at 04:43 on Apr 21, 2012 |
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Apr 21, 2012 04:35
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e. sheeit think I figured it out
kylej fucked around with this message at 04:16 on Apr 22, 2012 |
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Apr 22, 2012 01:27
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I just got back from a track day after installing a bunch of suspension parts. Now I need more power, as my stock 02 wrx didn't have enough poop with a passenger to get much speed going. I rode in the instructors sti for a session. When I got back into my car, I thought it was broken because my foot was on the floor and I wasn't going much faster. Parts I managed to put on that are putting jamals kids through college Koni sports Whiteline alk Whiteline com-c strut mounts Kartboy sway end link, front (luckily the ALK comes with some new bolts for the subframe as I had to chop off one of the old links. One subframe bolt was recycled into the sway bar link) Kartboy rear subframe lock bolts (these went in half way and then I broke the captured nut in the frame. Basically now they make rattles. Woo) Other stuff Sti springs brake pads, rotors, dot 4 fluid Had some semi-local place weld up a big crack in one of my wheels All of this ended up taking 2 weeks to get done, and I finished at 9pm last night. Just enough time to bed in the pads and make sure nothing was going to fall off. Things for the install that I could have done better: New dust boots and bump stops, the rear dust boots are sort of zip tied in Gotten a tap for those stupid lock bolts. Also not tried to install them last night at 730 Paid attention to the direction arrows on the tires so I didn't have to swap like 6 times to get it right If I had more time I could have installed the other bushing on the control arm. Now I have to take the ALK all off to do it (note: probably will never do it) Should have bought new bolts for the brake calipers, the ones that mount the caliper to the hub. Mine were starting to rust in the middle. Will have to get new ones when I get the fancy calipers (which I want because they are red) Things that went well that might help others: I needed a 24mm open end for the control arm bolts. Luckily I had one, and its my biggest one. You can do the rear struts without spring compressors, but you need them to do the fronts. Had to buy those yesterday too, as they were out at the loan place. If you cut the struts at the recommended height you don't need longer bolts to suck them in. Next on the list: Get a new rad, I smell coolant every once in a while, plus I don't want the original one to explode somewhere Install all the ebay downpipe, uppipe, maybe swear and take it off because its cheap ebay stuff. Whatever I am saving money. Get a tune, hopefully All of this will hopefully be finished before the night of the next track day. Im happy with myself so now you guys get to hear it too.
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Apr 22, 2012 03:44
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I only had to get longer bolts for the Konis since I cut the least amount possible off so I could measure the exact amount to remove. Turned out they'd fit without recutting if I grabbed a longer bolt and sucked them down. 
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Apr 22, 2012 05:17
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For those who recall my last post, I was looking at Foresters. I found one, looked at it, and I like it. This is the car: http://edmonton.kijiji.ca/c-cars-vehicles-cars-trucks-2005-Subaru-Forester-2-5-XS-Wagon-Wagon-W0QQAdIdZ369556535 The only thing I found in my test drive was that when I was going about 20km/hr, I could hear a sound that sounds a bit like a vibration but it rises and falls about every two or three seconds. There was no feedback in the wheel or by touching the shift knob, and above and below 20km/hr there was no sound at all. It rode, accelerated, and braked fine at all speeds. Any ideas? I'm having it inspected before I commit.
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Apr 22, 2012 05:29
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my friends at GST have a new color scheme for the L, along with a rear mounted radiator, a bigger turbo, and a couple other changes for this year. They were even nice enough to put my stickers on the car
jamal fucked around with this message at 07:01 on Apr 22, 2012 |
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Apr 22, 2012 05:57
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Can you even call that a subaru anymore?
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Apr 22, 2012 06:50
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nm posted:Can you even call that a subaru anymore? mmhmm just not an L
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Apr 22, 2012 09:58
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 This is how all of you envision yourselves, isn't it? 
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Apr 22, 2012 13:51
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Slow is Fast posted:Go to your local autozone or whatever parts store. Have them pull the code for free. Tell us the code and we'll tell you what to buy and how much it should cost. gently caress dealerships. Hey thanks a lot, I did this and got the part way cheaper. The place will install it for 90, I looked it up online and I could maybe do it, but I don't have any tools so I guess I will pay that. Still saved like 200 bucks. The part was a Bosch 15537 Oxygen Sensor, OE Type Fitment I got it for 200 at Autozone. I didn't even think to check Amazon until after I got back, it is 100 bucks there so I am going to see if I can take it back, but if not no big deal I still saved like 200 bucks off buying through the repair place. And too defend the place I was at, they told me upfront that they could only sell it for 400 but I could go to the store and get it much cheaper and they would still install it. I (sort of) know a guy who works there and he was upfront about it. I actually have another stupid question. I had a Yakama rack on my car but I hated having the "feet" stuck in my door and the drat thing scratched my paint up so I got rid of it. Is it possible to put a permanent roof rack installed and about how much does that cost? I really like my car but I absolutely need a roof rack by the summer for my hobbies* and if I can only go Yakama/Thule style I might just sell it and get an SUV or something. Unfortunately, the car is now 7 years old so it is a little late to sink a bunch of money into an improvement like that, although this car would probably last me 10 more years the way I drive (like an old lady). *Surfing kayaking and hopefully windsurfing soon, mountain biking also but I can easily throw that in the back with my seat down, only sucks if I want to go with a friend Ribsauce fucked around with this message at 16:00 on Apr 22, 2012 |
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Apr 22, 2012 15:55
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Welp, got a tear in my inlet My buddy recommended replacing the fuel rails and putting in phenolic spacers while the manifold is off. Your thoughts jamal?
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Apr 22, 2012 18:06
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i would just get a perrin inlet so you don't have to take off the manifold and not bother with that stuff. no reason to replace fuel rails until like 500hp.
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Apr 22, 2012 18:15
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Ribsauce posted:Hey thanks a lot, I did this and got the part way cheaper. The place will install it for 90, I looked it up online and I could maybe do it, but I don't have any tools so I guess I will pay that. Still saved like 200 bucks. The part was a Bosch 15537 Oxygen Sensor, OE Type Fitment Order one from Amazon. Put it in the Autozone box. Return to Autozone. $100 in your pocket. Tell them you didn't feel like doing it yourself, so you brought it to the dealer to fix.
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Apr 22, 2012 19:11
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kylej posted:Welp, got a tear in my inlet This just recently happened to me as well. Got the perrin installed and all is well (aside from it needing the tune tweaked as there was also a leak in the BOV gasket, both leaks likely have been there for a very long time... before the last tune touch up I had.) If you have an MBC, you might need to turn it down a bit if you adjusted it at all. I was hitting my fuel cut from going over the boost target in 2nd gear.
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Apr 22, 2012 21:36
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Sockington posted:
This coloring book owns.
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Apr 22, 2012 21:46
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Kageneko posted:My belts were squealing when I start up cold. I went ahead and changed them, but the problem persisted. I walked out around to check it out and the power steering pulley was seized causing the belt to squeal and smoke! So I went out there yesterday to take a look, but none of the symptoms happened again. Drove it around, everything was fine. Worked great today too. I guess I'll just see if it comes back.
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Apr 22, 2012 23:12
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My brother is looking for a new (used) car and he's considering an 02 Legacy L wagon with 131k miles and a 5-speed. Any particular things I should tell him to look at or be aware of?
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Apr 23, 2012 04:24
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Opensourcepirate posted:My brother is looking for a new (used) car and he's considering an 02 Legacy L wagon with 131k miles and a 5-speed. Any particular things I should tell him to look at or be aware of?
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Apr 23, 2012 04:27
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So what should he know about them? Just that there's a decent chance he'll need to get one done? How much should he expect to pay at a private shop?
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Apr 23, 2012 04:38
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Most early 2.5L naturally aspirated Subarus are prone to have head gasket failures; on an '02 Legacy L that will be an external head gasket failure. Over time you're going to get sludging from coolant mixing with oil, usually resulting in a spun bearing. Overheating from poor cooling and oil starvation are more likely, however. If you get on it early enough it's pretty easy to swap both head gaskets (remember, two heads on a 4-cylinder Subaru engine). Once the head gaskets are swapped for newer multilayer steel (MLS) head gaskets, the problem is vastly unlikely to re-occur and you're ready to go on your way to 300k+ miles. Early symptoms should be oil leaking from the head gaskets and a coolant leak from one or both head gaskets. Not all cars will have head gasket failures, but you have to be pretty religious about oil and coolant changes to keep it in check. Putting new MLS head gaskets on a 2.5L is not a super expensive repair but it's definitely up there enough that most late-90s Subarus I see in junkyards are there from head gasket failures at high mileage. According to this thread, it should cost $1500-1800. You might opt to roll in other expensive services (timing belt, etc) to reduce the labour cost on those, but it's probably not a huge deal. You can probably do it yourself for much cheaper. Of course, if the car has been running this long there's a good chance the PO has taken it in for the various recalls for this issue or has had it done already. Make sure to ask and see documentation of both gaskets getting swapped, or knock the price down to budget for what will probably be the job. A Subaru dealership during the pre-purchase inspection should definitely know to look for it. Seat Safety Switch fucked around with this message at 04:51 on Apr 23, 2012 |
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Apr 23, 2012 04:48
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Thanks for the reply. I passed it on to my brother.
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Apr 23, 2012 04:53
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No problem. Don't let that scare you off; they're excellent cars that are super tough and have pretty good value for the money. It's a disappointing weak spot that has added a bunch of really good deals to the market.
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Apr 23, 2012 05:00
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Opensourcepirate posted:My brother is looking for a new (used) car and he's considering an 02 Legacy L wagon with 131k miles and a 5-speed. Any particular things I should tell him to look at or be aware of? Tell him to make sure he sees the maintenance records. Maintenance intervals can be found here: https://www.cars101.com/subaru/subaru_maintenance.html The timing belt is the most important bit. It's nice if they replace the water pump too.
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Apr 23, 2012 05:24
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quote:I absolutely love Jamal and CT. Their posts are the only time I ever learn anything. I'm not sure what I learn, but drat it, I learn something, even if I end up more confused. I dunno why this made me laugh but it did. jamal posted:slower weight transfer means the tire is loaded more gradually and grip better. Holy poo poo, no. FAST transfer is what you want and soft suspension gives you that kind of transfer to dig those wheels in as godawful hard as possible(*) (*) Depending on your surface. Tarmac, yes you want a more gradual transfer and I wouldnt run soft. On looser surfaces violent and vicious works best. Gradual will have you sailing past the corner - on tarmac I give the brakes a squeeze. On dirt I hammer the pedal as hard as possible. Interestingly a bunch of guys and I who like to argue and debate cars - and have been doing this a long time - had a read of this thread last weekend and we sat down to argue the topic over while brainstorming an idea, especially on the still controvesial idea of removing the front bar on the STI. And..... I'll actually answer Jamal's challenge in the next day or two because this poo poo is interesting as hell and what works on paper doesnt work in real life. Which actually hosed me around on the STI, took me a year to figure out how to tune it's suspension
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Apr 23, 2012 07:32
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Cat Terrist posted:And..... I'll actually answer Jamal's challenge in the next day or two because this poo poo is interesting as hell and what works on paper doesnt work in real life. Jamal defined weight transfer as the extra force over the outside tires in a steady state turn of a constant radius. I honestly think most of us had a much more handwavy definition, most of which would involve change over time. That last bit is probably what causes the most problems between track driving and rally driving. Rally surfaces are a lot more varied than asphault tracks, and I wonder if even the most advanced suspension and tire models can adequately model the behavior of a highly deformable, loose material interacting with the tires. As you (CT) discussed way back, picking the right dampers has everything in the world with making the car drive the way you want. And I bet that factor you're selecting for (damping rate or damping curve) figures largely into your mental model of "weight transfer." And thus is at definitional odds with that steady state definition above.
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Apr 23, 2012 07:57
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the rate and distribution of weight transfer is the important thing. the same total amount happens for a given cornering force regardless of the suspension setup. When you are going around a corner at a certain speed the only way to change the amount of weight tranfer is to change the track, the height of the center of gravity, or the weight of the car. Period. This is a concept that needs to be understood before we can go any farther, and I'm not saying much else about this stuff until we are all in agreement. and CT, please cite your sources. Mine include Puhn, Milliken, and Zuijdijk jamal fucked around with this message at 08:13 on Apr 23, 2012 |
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Apr 23, 2012 07:58
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Slow is Fast posted:I absolutely love Jamal and CT. Their posts are the only time I ever learn anything. I'm not sure what I learn, but drat it, I learn something, even if I end up more confused. SpellEdge posted:I am agreeing with this 100%. I usually lurk here but the amount of knowledge you guys share is fantastic, and you're so cool about it. Jamal has been fantastic to do business with as well. blindjoe posted:I just got back from a track day after installing a bunch of suspension parts. Now I need more power, as my stock 02 wrx didn't have enough poop with a passenger to get much speed going. I rode in the instructors sti for a session. When I got back into my car, I thought it was broken because my foot was on the floor and I wasn't going much faster. thanks guys I am happy that you are all happy and this is why I am here.
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Apr 23, 2012 08:01
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