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What does it mean when an AWD system is e.g. rear-biased? How does that work mechanically?
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Feb 26, 2023 04:32
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Safety Dance posted:What does it mean when an AWD system is e.g. rear-biased? How does that work mechanically? Imagine a regular longitudinal front engine rear-wheel drive setup but add a transfer case with a slip coupling to the front axle (i.e. viscous couper, etc). Or a mid/rear engine with the same sort of thing only originating from the rear of the vehicle. The "primary" drive axle is usually directly driven by the drivetrain (driveshaft out of the transmission) with no sort of slip coupling inbetween. For instance in the opposite case, my 2000 CR-V is a transverse-mount front engine with the front axle as the primary, but there's a transfer case with a driveshaft to the rear differential which has a hydraulic dual-pump system that engages and grabs power from the transfer case when the front wheels slip. https://www.awdwiki.com/en/honda/ This is just my $0.02, I'm not an engineer or anything, just been working on my own poo poo for 20 years. Beach Bum fucked around with this message at 05:08 on Feb 26, 2023 |
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Feb 26, 2023 05:02
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That makes sense! Thanks!
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Feb 26, 2023 05:31
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Safety Dance posted:What does it mean when an AWD system is e.g. rear-biased? How does that work mechanically? https://www.youtube.com/watch?v=EjYrHQ83mbM
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Feb 26, 2023 16:28
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On a lot of Haldex systems (generally what you find on mass market CUVs etc) there’s a maximum torque bias of 50% to the rear. The more torque you intend to put through a given component of the system the more robustly you have to build it. Generally these systems will fully disengage the rear differential until the system senses front wheel slip. There are different tunings and biases but 100/0 up to 50/50 seems to be the most common.
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Feb 26, 2023 16:55
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FWIW, the Nissan Rogue AWD variant lets you set how much power goes to the rear - from 0 to 50%, IIRC. That's assuming the transmission or rear diff doesn't blow up the first time you crank it to 50/50 Hadlock posted:Other than renting a warehouse and filling it with tires there's not much "economic moat" stopping someone from directly competing with tire rack so how you optimize the site/data is really your only leg up in a lot of cases. Wouldn't surprise me if they have like an entire data analytics team (of like 4-5 people) ordering duplicate pages like that to be built due to reading the modern equivalent of tea leaves Tire Rack was one of the largest (if not the largest) online tire retailers before Discount Tire bought them. Discount Tire is the largest tire retailer in the US (before accounting for Tire Rack), pretty sure they have more than 4-5 people working on it.
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Feb 26, 2023 17:12
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KYOON GRIFFEY JR posted:On a lot of Haldex systems (generally what you find on mass market CUVs etc) there’s a maximum torque bias of 50% to the rear. The more torque you intend to put through a given component of the system the more robustly you have to build it. I want to say that newer Hondas with the electronic clutch setup have an even lower limit on how much power can be sent to the rear, on the order of 10-20%. It's still (barely) enough to check the boxes most people want when they want AWD, while letting them make that entire rear drive setup have as little of a weight penalty as possible on the car the 99% of the time it's just dead weight. Two other tricks that haven't been mentioned yet with AWD/traction control - a good number of these vehicles will also use the brakes as part of this system. Instead of putting in an actual mechanically-locking / limited slip differential in the drive axle(s), the computer will monitor wheel speeds and if it sees one wheel spinning up, it will engage the brake caliper on just that wheel to send torque to the opposite wheel. And finally, with heavy/full electrification, all bets are off. A few hybrids have the gas engine drive one set of wheels while an electric motor drives the other, and I'm 99% certain every mass-market AWD EV just uses two (or more) drive motors with no mechanical links between them.
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Feb 26, 2023 17:44
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Dumb questions time again. 2016 Hyundai accent hatchback. It started squeaking over bumps. I took it out to make it squeak so I could try to isolate where the problem was and now it doesn't squeak anymore. Why might that sound suddenly go away? Did a bushing fully explode, did a dampener finally detonate, or is the squirrel/cat now rendered to jelly? Seems to ride fine.
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Feb 26, 2023 17:55
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IOwnCalculus posted:And finally, with heavy/full electrification, all bets are off. A few hybrids have the gas engine drive one set of wheels while an electric motor drives the other, and I'm 99% certain every mass-market AWD EV just uses two (or more) drive motors with no mechanical links between them. Can confirm this about Tesla. Single motor models are RWD, dual motor is AWD, triple motor is 1 motor up front with a diff, and a motor for each rear wheel.
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Feb 26, 2023 18:00
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knuthgrush posted:Dumb questions time again. 2016 Hyundai accent hatchback. It started squeaking over bumps. I took it out to make it squeak so I could try to isolate where the problem was and now it doesn't squeak anymore. Lots of rubber suspension bushings will squeak as they get old. This happens more/louder the colder it is outside. Was it warmer outside this time?
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Feb 26, 2023 18:01
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Motronic posted:Lots of rubber suspension bushings will squeak as they get old. This happens more/louder the colder it is outside. Was it warmer outside this time? Ah good point. It did warm up a bit. I'll get under there and just give everything a look just in case. Thanks.
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Feb 26, 2023 18:12
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Got a friend looking to buy an affordable* hybrid with a view to trading up to an EV in maybe 5 years. Any recommendations? Not really any car guys in our circle. *for a given value of "affordable", considering the market
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Feb 26, 2023 18:44
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the holy poopacy posted:Got a friend looking to buy an affordable* hybrid with a view to trading up to an EV in maybe 5 years. Any recommendations? Not really any car guys in our circle. This would be a good thread to check out. https://forums.somethingawful.com/showthread.php?threadid=3213538&pagenumber=1&perpage=40
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Feb 26, 2023 19:03
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Thanks!
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Feb 26, 2023 19:08
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Mozi posted:
Day 2 of Mazda ownership - it's OK to go 20 over, right? I hope it is. This thing is so much fun to drive.
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Feb 26, 2023 19:27
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IOwnCalculus posted:And finally, with heavy/full electrification, all bets are off. A few hybrids have the gas engine drive one set of wheels while an electric motor drives the other, and I'm 99% certain every mass-market AWD EV just uses two (or more) drive motors with no mechanical links between them. Yeah the last is the Prius AWD system which I think is useful up to 6 mph or something like that. So it'll do OK getting you unstuck or something but is not gonna help you get up a big hill much.
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Feb 26, 2023 19:48
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KYOON GRIFFEY JR posted:Yeah the last is the Prius AWD system which I think is useful up to 6 mph or something like that. So it'll do OK getting you unstuck or something but is not gonna help you get up a big hill much. I think it engages up to 40 or so. My uncle in north-as-gently caress Michigan has an AWD Prius and loves it, I’d not hesitate to recommend one.
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Feb 27, 2023 01:30
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the holy poopacy posted:Got a friend looking to buy an affordable* hybrid with a view to trading up to an EV in maybe 5 years. Any recommendations? Not really any car guys in our circle. Newest/lowest mileage Toyota hybrid that's within the budget
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Feb 27, 2023 01:51
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What kind of ticking time bomb is a 2007 ML350? My brother in law wants to get rid of his so he can keep his new tesla in the garage lol.
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Feb 27, 2023 02:21
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RIP Paul Walker posted:I think it engages up to 40 or so. My uncle in north-as-gently caress Michigan has an AWD Prius and loves it, I’d not hesitate to recommend one. It can engage a 7 hp motor up to 70km/h but in normal driving behavior it only engages up to 10 km/h. It's a good car, but there's essentially no reason to buy one over the 2WD one.
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Feb 27, 2023 02:36
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KYOON GRIFFEY JR posted:It can engage a 7 hp motor up to 70km/h but in normal driving behavior it only engages up to 10 km/h. It's a good car, but there's essentially no reason to buy one over the 2WD one. Is there a diagram for this? 7hp is like a wheelchair motor
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Feb 27, 2023 02:43
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tactlessbastard posted:What kind of ticking time bomb is a 2007 ML350? My brother in law wants to get rid of his so he can keep his new tesla in the garage lol. Depends, is he the original owner, and did he meticulously maintain it and have ALL the records with no deferred regular scheduled maintenance? If not don't bother
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Feb 27, 2023 02:44
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Hadlock posted:Is there a diagram for this? 7hp is like a wheelchair motor That's basically what it is. Here's a description from a C&D review. quote:The AWD-e system adds a stand-alone electric motor, packaged within the rear multilink suspension such that it does not intrude on the car's cabin or luggage compartment. The only connection between this compact, 7-hp motor and the standard 121-hp front-drive powertrain is electronic; there is no physical driveshaft. With our XLE test car weighing in at 3233 pounds, the system adds about 120 pounds. The extra mass and driveline mass also ding EPA fuel-economy estimates a bit, to 50 mpg combined versus the front-drive variant's 52 to 56 mpg (depending on trim level). So it's basically marketing bullshit, and it'll help you maybe get unstuck a little bit in certain situations. Review here if you wanna read it: https://www.caranddriver.com/reviews/a25475797/2019-toyota-prius-awd-e-drive/ edit: note that the new gen Prius will have a different system. KYOON GRIFFEY JR fucked around with this message at 02:58 on Feb 27, 2023 |
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Feb 27, 2023 02:53
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Applebees Appetizer posted:Depends, is he the original owner, and did he meticulously maintain it and have ALL the records with no deferred regular scheduled maintenance? Yes, he is a fastidious guy, all services done, and it has 180k.
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Feb 27, 2023 20:21
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KYOON GRIFFEY JR posted:That's basically what it is. Here's a description from a C&D review. Oh I was getting excited about a 7hp capable rear differential with like, a literal 7hp wheelchair motor attached to where the driveshaft would go. With an un-integrated rear differential that would make it interesting for go-kart swaps. Looks like it's more like a Tesla-style* integrated "transaxle"  I can only imagine what mental corporate gymnastics were required for this thing to come to fruition. Looks like it only has 7hp, but 40ft lbs torque (55nm) so I can see it being useful going up a steep driveway in the snow, pulling away from a red light on ice, or something. 40 ft lbs still isn't a lot, but as supplimental torque to the main engine... not terrible, maybe? My 2WD sedan got stuck in 3 inches of mud last year backing on to a main road, had to have a neighbor give us a tug. 40 ft lbs would have been more than enough to push us the six inches to victory. Not sure I'd pay for the feature or to maintain it though. Having delusional fantasies of dropping this rear axle in my Traction avant and add 50% more torque to the engine for driving around town. Looks like it would bolt up to the rear suspension with very little work. This rear axle will probably go in all sorts of hybrids like the corolla and camry Edit: looks like the rear diff has a 10.4:1 ratio? Sounds like a stump puller up to about 20mph *calling it similar to a Tesla is grossly overselling it, but whatever Hadlock fucked around with this message at 20:59 on Feb 27, 2023 |
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Feb 27, 2023 20:51
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Bay Area people who don’t want to put on chains to go to Tahoe with AWD and M+S tires. (I got a Subaru instead for this purpose)
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Feb 27, 2023 21:00
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Fornax Disaster posted:Power windows may require a relearn procedure after the battery is disconnected, if you have the owner’s manual it should be in there. Had a look online and this wasn't it sadly. It's only impacting the driver window too so not sure what's up. The other thing that's weird is that the rear windscreen wash spray thing makes a weird clunking sound in the roof of the car now when I use it. The spray is fine so I don't think it's a blockage, but it's definitely a new sound. I'm basically gonna have to take it back to the Ford center that serviced it and get them to take a look.
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Feb 27, 2023 21:42
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luminalflux posted:Bay Area people who don’t want to put on chains to go to Tahoe with AWD and M+S tires. It also drops assist over 40mph. It doesn't provide enough torque to push the car off a set of rollers. It's also using NiMH chemistry. It is 100% loving worthless as an awd-e add on. About the best thing it does is add some mass to the rear end of the car that makes it sliightly more easier to slide it around.
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Feb 27, 2023 21:50
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cursedshitbox posted:It also drops assist over 40mph. It doesn't provide enough torque to push the car off a set of rollers. It's also using NiMH chemistry. I have direct first-hand experience in an AWD Prius on snow tires going up a bigass snowy hilly curvy driveway in the counrty with zero issues. That same hill, a FWD Prius on the exact same snow tires could barely make it, and even then you had to really run at it. It's a worthless add-on for any sort of performance driving, but for folks who live in snowy-rear end places it seems to fill in the gap nicely. I'm also pretty sure the couple of times my FWD Hyundai running Michelin X-Ice3's got a little stuck in snow, a little AWD motor on the back would have gotten me just fine.
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Feb 27, 2023 22:41
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Adding "some" to "nothing" is infinity times better.
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Feb 27, 2023 23:27
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Problem statement - Brake lights on our beat up old Scout don't work. Question - Is it possible the brake lights activate off a brake pressure switch on the proportioning valve rather than the brake pedal switch in the cab? This seems crazy and not the way I'd do it but maybe it could make sense? The logical thing to do here is reinstall the brakes and see, but the parts won't be here for a week or so and I'd rather not waste time counting on that if there's something else at play. A mess of poorly sorted extra context: The truck has no rear brakes installed. The rear brake circuit ends at the rear axle's hard lines. The front brakes are in place. The brake lights have worked while the truck was in our possession, though it's been a while and we've messed with a lot of things since then (though nothing electrical, at least not intentionally). The brake light half of the dual element taillights are wired. I believe this to be sufficent but intend to wire the tail light portion tomorrow to rule that out. 4 way flashers work just fine and I believe they're eventually on the same electical circuit as the brake lights. Turn signals do NOT work front or rear, but that relay isn't clicking so I've put that aside for now. I'm not seeing where that's an issue but could be overlooking something. I have 12v everywhere I'd expect to right up to I think #56 and #57 in the bottom right of this diagram (the turn signal harness). I may go double check the exact location though. https://forums.ihpartsamerica.com/attachments/wiring-diagram-cab-and-dash-jpg.10982/ The "BRAKE" light on the dash is illuminated, telling me the truck knows there's no brake pressure when there should be. This leads me to think the truck is comparing the pedal switch to the pressue switch and illuminating when the two are out of sync, though this is significantly more smarts than I expected given what we're working with. The current state of the truck is best shown here if there's any value in anything to be found - https://forums.somethingawful.com/showthread.php?threadid=3983095&pagenumber=5 Thanks smart people!
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Feb 28, 2023 04:38
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I’ve got a buddy with an S14 Nissan Silvia with a MegaSquirt II on it. He has no idea what he’s doing and needs a base tune to like… idle. Please PM me if any of these words make sense to you.
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Feb 28, 2023 04:44
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WTFBEES posted:Problem statement - Brake lights on our beat up old Scout don't work. Yes. Pressure switches are a thing. There is even brake-banjo washers designed to work as a pressure switch. Valve block tapping for this? Unlikely unless it already has a dedicated port. Just make a couple flares and T it in with a block. Front preferably, especially if disc. Rear drums have a residual pressure valve built into the prop valve or the master itself. The 'brake' failure warning light is there to compare the two circuits. if there's a pressure differential, a small valve moves and the light will turn on. Your diagram kinda lacks in detail. Namely the pinout of the turn indicator switch, and the connectors for the lamps. A top down view of older systems with integrated stop/turn: With integrated stop/turn the brake switch is wired into the turn indicator switch. Left and Right stop/turn lamps are wired individually to the turn indicator switch. When activated, the turn indicator switch breaks the respective side's brake-switch-side contact to then make contact with the flasher relay. The flasher relay is powered from the ignition circuit of the fuse panel. Hazard switch with its own flasher relay is usually with its own dedicated L/R circuit contacts. Sometimes built into the turn signal switch piggy backing off of its contacts. Hazard circuit is always live. Brake lighting circuit default is live but wasn't always the case. Turn indicator, ignition only. It is possible to test with a couple of jumper wires. Bypass the flasher. Bypass the brake switch. Problem sounds like its in the turn indicator switch.
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Feb 28, 2023 05:04
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Dr. Lunchables posted:I’ve got a buddy with an S14 Nissan Silvia with a MegaSquirt II on it. He has no idea what he’s doing and needs a base tune to like… idle. Please PM me if any of these words make sense to you. If it's not running right with the sr20 base map he should turn on spark-wasting in case he's got the ignition order hosed up but the injector order correct. These maps are just available from the manufacturer and they're supposed to get you to the dyno basically.
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Feb 28, 2023 05:30
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WTFBEES posted:Problem statement - Brake lights on our beat up old Scout don't work. Why uh, why do you care about the brake lights working on a truck that you've disabled the rear brakes on? Surely you're not driving it in traffic, around other people? Are you?
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Feb 28, 2023 07:20
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spankmeister posted:Why uh, why do you care about the brake lights working on a truck that you've disabled the rear brakes on? Surely you're not driving it in traffic, around other people? Are you? because he's restoring his truck and this is one more thing that has to be fixed before it's drivable?
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Feb 28, 2023 07:43
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my sw20 is taking forever to start, once it starts it stumbles above 3k rpm when cold, once it's warm it stumbles below 3k rpm. i am thinking it either needa a tune-up or there's a fuel issue? e: once it's warmed up for the day it starts just fine from then on out, it's only when it sits overnight that it takes like 2 full minutes of turning over before it catches DEEP STATE PLOT fucked around with this message at 15:57 on Feb 28, 2023 |
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Feb 28, 2023 15:51
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cursedshitbox posted:Lots of good info Nice, appreciate all the info! I'm glad it's not just me that couldn't make sense of the black box of the turn signal switch. I'll go poke around with a jumper and report back. Raluek posted:because he's restoring his truck and this is one more thing that has to be fixed before it's drivable? This is correct. I have no intentions of operating a vehicle without rear brakes. The rear brakes are less disabled and better described as "completed removed and awaiting parts to make them function like new."
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Feb 28, 2023 16:21
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tactlessbastard posted:Yes, he is a fastidious guy, all services done, and it has 180k. Well then it would depend on the price, if he's giving you a great deal cuz you're family then grab it, if not maybe find something else that has better reliability at those kind of miles like a Lexus.
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Feb 28, 2023 16:51
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tactlessbastard posted:What kind of ticking time bomb is a 2007 ML350? My brother in law wants to get rid of his so he can keep his new tesla in the garage lol. A few model years of the ML350 are well regarded as tanks that will run forever, but sadly the 2007 is not one of them. 2010 seems to be the sweet spot according to the benzworld forum. This post says to avoid the 2006 to 2008 ML's https://www.benzworld.org/threads/w164-buying-advice.3098036/ I'd say it depends on the price, your ability to do any work on it yourself, tolerance for dealing with 16 year old german vehicles, and how long you planned on keeping it.
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Feb 28, 2023 17:00
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