mickg Posted November 4, 2004 Posted November 4, 2004 Going up a snowy switchback, the rear tires lost traction, TRAC control brought the engine back to idle even though the throttle was floored, and back down the hill I went. I then disengaged the TRAC control, booted her back up the hill, and discovered that my '94 LS400 only has an open-center differential. One wheel lost traction and spun out, and back down I went again. I guess this is one of the ideosyncrasies of electronic traction control and attempting to control wheelspin by modulating the wheel brake calipers. I'll know next time to be very wary of snowy inclines, and realistically evaluate my chances of getting up them! Around town, the system works perfectly in preventing massive fishtails and 180's, particularly when my wife drives it. Great traction control for starting on snow, just self defeating on any form of slippery incline.
wwest Posted November 4, 2004 Posted November 4, 2004 Prior to VSC both rear brakes were applied simultaneously upon wheelspin. With VSC it only brakes the slipping wheel.
silvermate Posted November 4, 2004 Posted November 4, 2004 No POSI TRAC for LS the LS is horrible in snow......glad i don't live in colorado with this car... good luck, and be carefull
wwest Posted November 5, 2004 Posted November 5, 2004 No positrac.....NOT! For the Later LS models equipped with VSC the rear brakes are used differentially to simulate positraction/LSD. Much better than positraction or LSD. If you can learn to use the throttle with a light feathery touch!
1990LS400 Posted November 5, 2004 Posted November 5, 2004 the LS is horrible in snow......glad i don't live in colorado with this car... ← It all depends on which LS you have! We have had lots of rear wheel drive cars including three Volvos made in snowy Sweden, three Mercedes made in snowy Germany, and are on our second LS. We have also had lots of front wheel cars - one VW, four Hondas, our current Camry V6 with TRAC/ABS and four nearly new all season tires. I thought the 90 LS we had was pretty scary on snow covered roads even with four snow tires. However, our current 2000 LS with VSC and "snow" transmission mode (and with four Blizzak snow tires) is far and away the best winter car we have ever had and handles snow completely differently than the early LS. We "parked" the Camry last winter during the "big" 10 inch snow storm here since the LS performed so much better in the snow.
silvermate Posted November 5, 2004 Posted November 5, 2004 No positrac.....NOT! POSI is where both wheels spin at ALL times or "locked" i'm sure you know that. the LS 400 does NOT have continueuous locking differential MY 92 does not have POSI or trac control........nor is MY car worth a flip in the snow
wwest Posted November 5, 2004 Posted November 5, 2004 Both Positraction and LSD are designed to provide traction to the opposite side of the "axle" from a slipping wheel vs an open differential which by default routes all available (limited by) traction to the slipping wheel. Most modern day DSC, VSC, PSM, systems will have the very same result by applying moderate braking to the slipping wheel. But you're right in that LSD or positraction will allow you to spin both drive wheels whereas VSC, Toyota/Lexus, will quickly dethrottle the engine rather than overheat the brake rotors. With BMW's DSC, and Porsche's PSM, you caqn disable the dethrottle function in favor of allowing wheelspin but in BMW's case the virtual LSD will eventually be disabled to prevent brake overheating. Don't know about Porsche.
Em91 Posted November 5, 2004 Posted November 5, 2004 Hey guys. I have a 91 ls without the trac system. I got stuck last year in the snow and when asked which tire was spinning we noticed that both tires were spining. These cars do has limmited slip dont they?
Em91 Posted November 5, 2004 Posted November 5, 2004 Are you sure wwest? Then why do both my tires spin when you hit the gas when stuck in the snow?
wwest Posted November 6, 2004 Posted November 6, 2004 If the surface under both tires is slippery enough then both tires will spin with very little engine torque.
mickg Posted November 30, 2004 Author Posted November 30, 2004 If the surface under both tires is slippery enough then both tires will spin with very little engine torque. ← I went and bought studded snows for the rear, like I know I should have done in the first place. A vast improvement in ability to get going and to be able to stop again.
Thienn Posted November 30, 2004 Posted November 30, 2004 Take it easy on the throttle if the tires start to spin! You don't want to fry that expensive transmission...
daffy Posted December 1, 2004 Posted December 1, 2004 Hi, I use my 1991 Ls400 all year round and found that a good set of winter tires reduces that amount of trac lock usage. With all season tires, the traction control was working more than I wanted it to. Hugh difference with winter tires. First set were Blizzacks and now Nokian (studded from the factory). Both good tires. Studs gives me a little edge though... My two cents worth. Daffy
Lexusfreak Posted December 1, 2004 Posted December 1, 2004 You might want to consider getting 4 snows for your neck of the woods my friend. ;) Just a suggestion.....the back will have better traction, but if all seasons are still on the front, you won't be able to steer properly should you need to quick. All 4 tires should be the same for the best possible traction & safety.
bartkat Posted December 1, 2004 Posted December 1, 2004 If we get enough snow around here to stick, they just barricade and close the roads.
bartkat Posted December 1, 2004 Posted December 1, 2004 Ouch ← When I first moved here we had a foot of snow. I had a Pathfinder at the time. Only 3 people made it to work in the front office for 3 days. I, stupidly, was one of them.
daffy Posted December 2, 2004 Posted December 2, 2004 You might want to consider getting 4 snows for your neck of the woods my friend. ;) Just a suggestion.....the back will have better traction, but if all seasons are still on the front, you won't be able to steer properly should you need to quick. All 4 tires should be the same for the best possible traction & safety. ← Hi Lexusfreak, I said "set" of winter tires, I meant all four. I have them mounted on rims so I can switch them myself instead of depending on tire stores which are too busy that time of year. I would never recommend only two! So you are correct, 4 winter tires or four all season tires- never mixed! Thanks, for clearing that up. Daffy
Lexusfreak Posted December 2, 2004 Posted December 2, 2004 You might want to consider getting 4 snows for your neck of the woods my friend. ;) Just a suggestion.....the back will have better traction, but if all seasons are still on the front, you won't be able to steer properly should you need to quick. All 4 tires should be the same for the best possible traction & safety. ← Hi Lexusfreak, I said "set" of winter tires, I meant all four. I have them mounted on rims so I can switch them myself instead of depending on tire stores which are too busy that time of year. I would never recommend only two! So you are correct, 4 winter tires or four all season tires- never mixed! Thanks, for clearing that up. Daffy ← Sorry for the misunderstanding daffy B)
wwest Posted December 2, 2004 Posted December 2, 2004 On the early models there was two separate pumps, an ABS pumpmotor and a trac pumpmotor combination. If Trac activates too often and you are a reasonably conservative driver, one that "feathers" the throttle at the very first instance of wheelspin, you can simply unplug the fuse for the Trac pumpmotor assembly on the firewall in the corner of the driver's side (for non-UK). No more dethrottling nor delayed "un-dethrottling". But then you could also just unplug the connector to the servomotor that provides the dethrottling.
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