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Negative Camber in the Rear and Expensive Tires
- Thread starter lolachampcar
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- Driving Dynamics Model S
dennis
Model S Plaid
How close are these bushings to the OEM ones from Tesla? Will they be like the stiffer ones in all of the P+ links?
IIRC, when @lolachampcar was investigating doing modified links the manufacturer of the Tesla OEM bushings was unwilling to sell them to him.
SUPRKAR
Member
For those who need the bolts I will try to order some old style from Tesla, if unavailable fromTesla we will have to source some.
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We have not yet purchased the Plus toelink to see what we are working with but discussions with BBC have been about stiffer bushings. When we get furthur along I will let everyone know
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We have not yet purchased the Plus toelink to see what we are working with but discussions with BBC have been about stiffer bushings. When we get furthur along I will let everyone know
I was concerned with staying as close to the Tesla design as possible with my links so I bought sacrificial Tesla links to salvage the bushings. It sounds like these links are bespoke allowing the use of different bushings. BMW sells bushings separate from link assemblies and would be one (of many I suspect) sources for bushings. Do beware of polyurethane bushings which are common in the aftermarket as they can wear very quickly and actually squeak under high loading. I thought about designing in PE bushings but thought better of it after some research into the current state of street car suspension.
Agreed. I took an hour to read through this thread and need another go just to get conversational on tire camber.
I have a p85 with 21" tires and I am on my fourth set at 25k miles. The ones I just replaced had the same inside tread wear. Do I need to have an alignment shop reduce the camber as much as possible until these new links become available?
I have a p85 with 21" tires and I am on my fourth set at 25k miles. The ones I just replaced had the same inside tread wear. Do I need to have an alignment shop reduce the camber as much as possible until these new links become available?
Rear camber is non-adjustable. You should have rear toe checked. Many cars turn out to have toe-out instead of the specified toe-in. Toe-out creates the rapid wear on the innermost part of the tire.
The rear camber is (in my opinion) not ideal, but a tire with plenty of tread everywhere and then showing cords on the inside shoulder is a toe issue. The camber will create an "even uneven" wear. Meaning the outer groove has more left than the inner groove, but the wear increases evenly as you go towards the inner part of the tire.
Hope that makes sense?
Gws,
I'm in WPB and can put you together with my alignment guy if you like. Near zero toe in the rear (just a tad of toe in) along with Tesla's "camber bolts" biased to the least amount of camber may do the trick for you. PSS are also a less expensive better value/performance option and there is always rotating across the rear of the car to use all the tire. I hope these options help and do not hesitate to drop me a note if I can help.
Bill
I'm in WPB and can put you together with my alignment guy if you like. Near zero toe in the rear (just a tad of toe in) along with Tesla's "camber bolts" biased to the least amount of camber may do the trick for you. PSS are also a less expensive better value/performance option and there is always rotating across the rear of the car to use all the tire. I hope these options help and do not hesitate to drop me a note if I can help.
Bill
Gwstephens,
You received a most generous offer from lolachampcar. I do hope you jump at this opportunity.
Fact #1 he will net you $1,000s in reduced tire replacement costs
Fact #2 he has been instrumental in helping me achieve 40K (currently at 30K) from my original 21 Conti's
Fact #3 If Jerome flew him out to Fremont for the day and implemented his suggestions, EVERY tire wear issue would slowly die from this forum
Fact #4 he is the unequivocal suspension maven on this forum PERIOD!
Good-luck
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smorgasbord
Active Member
It's interesting reading about optimal camber on Model S. Some of us Roadster owners have been playing around with various alignment settings (some in preparation for Laguna Seca ReFuel today). Not surprisingly, the consensus for Roadster is the same as the Lotus Elise - run between a half and a full degree of negative camber in the front and between 1.75 and 2.5 degrees of negative camber in the rear. Those who drive highways straight up and down should go for less camber, but those who drive twisty roads are happier with more.
For racing/autocrossing, many Elise owners lower their cars and that affects camber. Now, many Model S's have the adjustable ride height. What I am surprised about, however, is that Model S's adjustable ride height also affects camber. Doesn't that strike anyone else as lame? Yeah, it's a natural effect, but for the road changing the ride height if often dong the exact opposite of what you want.
If you lower your Model S because you're going fast on the highway and want better aerodynamics, then the last thing you want is increased negative camber. That's because you're probably going straight. If you're on a twisty mountain road, you might increase the ride height some to get some additional ground clearance on switchbacks or other road elevation changes. But, its the curves where you'd want more negative camber. So, it's all backwards.
What was Tesla thinking here? Is this the result of track testing, where the track is flat or has slightly banked turns and so is not real world? Could it be something they simply overlooked, or didn't have time to get to? What happens with other ride height adjustable cars (not trucks)?
For racing/autocrossing, many Elise owners lower their cars and that affects camber. Now, many Model S's have the adjustable ride height. What I am surprised about, however, is that Model S's adjustable ride height also affects camber. Doesn't that strike anyone else as lame? Yeah, it's a natural effect, but for the road changing the ride height if often dong the exact opposite of what you want.
If you lower your Model S because you're going fast on the highway and want better aerodynamics, then the last thing you want is increased negative camber. That's because you're probably going straight. If you're on a twisty mountain road, you might increase the ride height some to get some additional ground clearance on switchbacks or other road elevation changes. But, its the curves where you'd want more negative camber. So, it's all backwards.
What was Tesla thinking here? Is this the result of track testing, where the track is flat or has slightly banked turns and so is not real world? Could it be something they simply overlooked, or didn't have time to get to? What happens with other ride height adjustable cars (not trucks)?
It's a simple result of good basic suspension design. All good suspension designs have a bit of dynamic camber so that as as the body rolls into a turn and compresses the outside wheels, you increase the amount of negative camber to keep the tires flatter on the road which increases grip.
Yeah, it's a compromise when you have an adjustable height suspension, but in a straight line tire wear should be minimal anyway as long as your toe settings are correct.
smorgasbord
Active Member
While a good point that incorrect toe is the alignment spec that causes the worst tire wear, perhaps I wasn't being clear in that I would have thought that Tesla would have thought outside the box and designed Model S such that the adjustable ride height would not affect things like camber. Maybe no-body else does this, but that doesn't mean it couldn't/shouldn't be done.
BTW, does anyone know how much camber changes between each of the different height settings? An owner with an accurate digital level should be able to find out in under 15 minutes.
You need to design in camber gain into your suspension. Without it you would get positive camber on the outside wheel in a turn due to body roll which would be dangerous (wheel looses grip and car spins out of control).
12 mm (1/2") changes camber about 0.4 degrees.
Agreed, but I'm guessing that:
1. There are so many other unconventional items that they went with a known suspension design to reduce development costs.
2. They needed to pass all the FMVSS rules and this suspension design is known to do that.
I would have liked inboard brakes which allow even greater suspension design flexibility and vastly reduced unsprung weight, as well as allow a much greater range of tire and wheel sizes.
What winds me up is that a coil spring MS sits higher, has less negative camber and passes FMVSS 126 for stability control.
The lower air suspended cars should perform better than the higher coil cars with exactly the same rear camber. Tesla chose to have but one rear geometry thus more rear negative camber then they need when they fit the air spring option. It is simply a matter of Tesla not having to have two different upper and toe links to support air versus coil.
In short, Cost and Complexity.
The lower air suspended cars should perform better than the higher coil cars with exactly the same rear camber. Tesla chose to have but one rear geometry thus more rear negative camber then they need when they fit the air spring option. It is simply a matter of Tesla not having to have two different upper and toe links to support air versus coil.
In short, Cost and Complexity.
smorgasbord
Active Member
My '66 Jag EType had those in the rear. Made replacing pads a bit of a pain and the rotors weren't ventilated so without exposure to air flow from the wheels, they overheated really easily.
My 1969 DS-21 had them in the front. They never overheated, and the pads were so enormous that there was still lots left at 120,000 miles, so I don't know how hard they would be to replace.
assuming you ever got around to needing to replace them.
I use brake dust as a measure of pad wear and MS is a champ when it comes to keeping its rims clean (in comparison to an ICE).
I use brake dust as a measure of pad wear and MS is a champ when it comes to keeping its rims clean (in comparison to an ICE).
smorgasbord
Active Member
You might have gotten away with that last century, but today's ceramic brake pads create dust that is both lighter in color and finer in particle size. So, the generated brake dust doesn't stick to the wheels as much, and what does stick is lighter in color and so typically less noticeable.
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My rears lasted between 18-20k (I need to check my records to see how long winters were on). I also swapped them across both out 6k miles ago (inside to outside). It's possible the rear right toe got knocked out when I caught part of a curb, it wasn't hard but gave me a couple of inches of rash on the wheel.
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