[lolachampcar] Performance Upgrade Efforts

[lolachampcar]

I found the two OEM bushing suppliers. The composition is bespoke Tesla which means developing my own bushing to move forward. These are OEM suppliers so, unless I want to buy 100K of bushings there is really no way to work with them.

I've used Lord for aircraft motor mounts and they will work in much smaller numbers. However, I do not feel comfortable designing bushings that handle vibration, axial/radial damping and work as a bearing for suspension travel (angular movement).

Lastly, my back of the napkin analysis says buying the bits from Tesla should not be that bad. My reasoning is that kits are typically half labor and half parts. That puts the parts at roughly $3250 which is in the ball park of what a set of parts for a P85 cost today (upper arms, lower a-arms, torque links and toe links). It just makes more sense to buy the Tesla bits (and Tesla's engineering) and install them myself.

In short, I chickened out

 

[jcstp]

"chickened out" is putting it to harshly

Always good to know where the bushings came from! You never know when it will come in handy!

But it is also nice knowing Tesla gives good buck for the money!

Maybe one day Tesla can start a performance division that sells performance upgrades and accesories
bit like "mopar" "gm performance" & "ford racing"

maybe they can offer your upgrade too then!

 

[lolachampcar]

I have another path to pursue. I just looked at the accident pictures posted on another thread. I suspected MS' suspension was based on BMW and sure enough, the ripped off rear corner of the M5 looks very similar to MS' rear suspension. I'll call Turner Motorsport tomorrow and get some parts heading my way for comparison.

 

[lolachampcar]

I just pressed in the high angular misalignment ball bearings in a set of test upper links. The setup looks like it should work well. These bearings are commonly used in aircraft control surfaces to aid in aligning several hinge points along a large surface.

Last three pictures at the bottom. The bolt was used for reference to show how the bearing supports misalignment.
New Upper Rear Model S Suspension Arms

 

[lolachampcar]

I installed the ball bearing based upper control arms in my P85+ with near zero difference in feel from the rubber bushings. There may be a slight increase in noise but not much.

I did have an interesting issue at the alignment rack. I was unable to get the left wheel to toe out any more than 0.25 degrees in. In contrast, the right rear was toed out and was easily brought in to match the left. This gave me 0.25 plus 0.25 or 0.50 degrees of total rear toe. This is a bit more than I would like.

The increase rear toe had two affects. First, my car tended to hunt less on the highway or was less "busy" requiring less attention to steering to keep it going straight. Second, my range decreased.

I have an appointment with the alignment guy to shift the sub-frame and get me back within adjustment range for both the left and the right wheels. My target is 0.10 to 0.20 total rear toe at Standard height.

WRT the ball bearing upper arms not making that much difference, I suspect a vast majority of the P+ rear suspension stiffening could be accomplished simply by changing the lower a-arms. The outer joint is already a ball type so simply changing the inner rubber joints to the stiffer P+ specification would likely be sufficient to dramatically improve rear feel. I'd like to find someone in the WPB area willing to give the approach a try to test the theory. It would be a cost effective + upgrade as I think the a-arms are around $550 each.

 

[lolachampcar]

We loosened the four rear sub-frame nuts at the alignment shop today while the wheel sensors were attached. As soon as it dropped down just a tad with the last nut loosening the toe shifted over just the perfect amount to allow 0.05 degrees per wheel for a total of 0.10 degrees of rear toe in. It literally just fell into the right position and we tightened up the nuts and were on our way!

The slightly busy steering on the interstate has returned and my milage is back where I am used to it being (310 WHr/mile ish range). And there is 0.6 and 1.2 degrees of negative camber on the back for an average of 0.9 negative. Tire life will be just fine

 

[lolachampcar]

We just took delivery of my wife's S85 with coil spring suspension. After driving the car for a hundred miles I'm even more convinced that there is another upgrade path for MS. Specifically, I think a set of custom wound Eibach springs combined with + lower a-arms in the rear and camber adjusting upper links would be an awesome combination. The car could be lowered to the desired ride height and stiffened just a bit on spring rate and bushing compliance without introducing the head snatch associated with the big sway bars. Combine these mods with a lighter set of (20") rims and performance tires and I think you would have the best of all worlds.

I'm considering doing it with my wife's car. Any interest out there?

 

[mnx]

Sounds cool! Why isn't this thread in the Driving Dynamics Section?????

We just took delivery of my wife's S85 with coil spring suspension. After driving the car for a hundred miles I'm even more convinced that there is another upgrade path for MS. Specifically, I think a set of custom wound Eibach springs combined with + lower a-arms in the rear and camber adjusting upper links would be an awesome combination. The car could be lowered to the desired ride height and stiffened just a bit on spring rate and bushing compliance without introducing the head snatch associated with the big sway bars. Combine these mods with a lighter set of (20") rims and performance tires and I think you would have the best of all worlds.

I'm considering doing it with my wife's car. Any interest out there?

 

[lolachampcar]

mnx,
probably because I fouled up and put it in the wrong place.

 

[lolachampcar]

Pulled over from another thread-

The whole P85 to P85+ to S85 (coil spring) suspension thing is a huge can of worms. I thought for sure I would have concrete finite conclusions about the three different options but have found the situation is not so simple. For instance, I love the stiffer bushings in the rear as they removed a great deal of the squishiness that bothered me so much with my P85. However, I really dislike the head snap that comes from those thick sway bars. I then pick up my wife's coil spring car and find that it is as stiff as my + in bump but has all the looseness of the non-+ bushings. Some of that stiffness could be related to the newness of the dampers so I will need to get a few hundred more miles on the car to be certain but I'm really starting to scratch my head.

I love the support provided by the coil springs. I've always HATED MB air. Tesla's is much better than the MB system but I did not realize how its transient support was lacking until I drove my wife's S85. I am beginning to think the very best solution may be + lower a-arms, camber adjusting upper links (ball bearing like on my P85+ or using + bushings) and a set of custom Eibach progressive springs. My gut tells me this would provide that instant M5 like response without all the head tossing drama of the + package. it would also allow me to set a more reasonable ride height for the coil spring cars. Combine that with a light weight set of (20"?) rims with good quality tires and I think you would have a killer package.

The problem here is one of divorce. My wife is going to take a dim view of her car up on jack stands out at my hangar while I start ripping suspension bits off and trying things. I can hear it now.... "So you bought that expensive fancy handling package and now you want to experiment with my car?".... and she would be right. Perhaps I'll just order in some stock springs as a reference for some custom wound units along with the a-arms. If I can get it all in one place it will only take a day to swap everything over. I know I should not mess with her car but this will drive me nuts if I do not at least look into it.

My gut also tells me a coil S85 with four thousand in bits could be the absolute best driver's car value. Sure, it will get killed in a straight line by a P85 but otherwise will be the perfect balance of handling, feel and overall cost. Again, this is just my gut but my intuition has been very good to me in the past

 

[Blsteen]

That's a good tip on alignment. Now that I've passed the 1,000 mi. marke, I'll get it checked. Thanks for posting on your upgrades.

 

[Dreamin]

Any interest out there?

YES. Very interested.

The + lower a-arms are for the +'s stiffer bushings? And why only the rear?
I'm not a huge fan of progressive-rate springs... as the handling is not as predictable as linear springs - IMHO. But I do understand the benefits, so could easily be convinced.
And yes, camber adjustable upper links would be a must.

I worked with Ground Control on custom adjustable coil-overs for a previous car. The bad news is they are in NorCal, and I recently moved to SoCal. The good news is i'm now ~50 miles from Eibach.

Are you planning on working with Eibach for the springs? If so, I can certainly loan them my car - as long as it's for days/weeks not months. Maybe I can take my springs out and at least get the spring rate measured. I have a 60 - likely a different spring rate than an 85 (?).

I'd been trying to figure out (just) a new spring setup - as the coil-spring car sits too high and could use a bump in spring rate. But your idea is a more complete solution.

 

[simplesolar]

I always thought the coil spring model s I driven handled better than the ones equipped with air suspension. Why not order a set of coil overs and replace them on your p85+. I saw how it was done at the factory, should be relatively simple. Perhaps something like this with different dampening mode paired with one of their coilovers.

KW DDC coilover kits /// with electronic damping control /// KW automotive GmbH

 

[lolachampcar]

The + package only addresses bushings in the rear (lower a-arm, upper camber link, torque link and toe link so I am told).
I would think the best starting place for a spring would be the exact same design as currently on MS with an increase in spring rate to offset the amount lowered. I've done this in the past by getting (buying in the case of MS) a stock spring then combining that with corner weight information to calculate installed height. If a quick measurement on the car confirms the data, all can be provided to any competent spring winder with instructions on how much you want to shorten the installed height. The spring company will typically have a recommendation for an increase in rate. Eibach is but one of many good spring companies.

I'll do a bit of digging to get rough numbers on the springs and then an idea from a few spring companies if they might have anything close. If not, I'll see what the minimums are for having some wound.

As for the completeness of the approach, I'm just looking at the minimum number of changes needed to address sloppy compliance (bushings) and ride height. If those things can be addressed such that they dovetail well with a nice looking set of light weight rims and upper links to get the camber back to a reasonable number then I think the total solution will work well while not costing an arm and a leg. It is hard for me to imagine that such a simple approach would work so well on MS given the energy Tesla has put into the suspension. At the same time, the coil spring car performs well and just seems to need a few small tweaks to make it great.

SSolar,
I agree with you on the coil spring cars. My wife's handles nicely even on the 19" all season tires which is what got me heading down this path.
There are all kinds of things that can be done with different dampers, adjustable spring perches and the like. What I was hoping for was the least number of changes for the most benefit. This is why I was thinking an inexpensive set of springs, swapping out the lower a-arm for the + bushing one (because I was unable to locate just the bushings) and light weight wheels and tires. The upper link will need to be changed to get camber back to normal once the car has been lowered. Also, it will take some playing to determine how much the car should be lowered and yet still have it be a good now worries daily driver. The Standard ride height of the air suspended car would be a good place to start. I have lowering links on mine that take it down another 3/4" and have not had any issues (even with highway lowering to the Low position). Again, a little playing around should get some answers.

 

[lolachampcar]

I got some parts in today. The Continental air spring units are normal fare and it should be a straight forward process to change them to coil springs. To disassemble, you unscrew the top plug (o-ring'd), remove the strut shaft nut and tap the air spring unit up off the damper body. There is a simple clip ring and landing ring that carry all the spring loads.

 

[Gizmotoy]

So I guess your current plan is to revert the air suspension on your P85+ rather than tinker with the coil suspension on your wife's car? As someone with a standard suspension P85 on the way, color me sad. :crying: Maybe we can bribe your wife with something to resolve aforementioned divorce issue .

Still interested to see what you find, though!

 

[lolachampcar]

Nope, just converting the air pieces to something I can swap out on a S85 to try ideas.

 

[lolachampcar]

Back by popular demand

 

[Dreamin]

Nope, just converting the air pieces to something I can swap out on a S85 to try ideas.

Wonder if you can use the spring perch from the coil suspension shock... that way the same spring could be used on an air-suspension or coil-suspension car.

- - - Updated - - -

Back by popular demand

I'll take two. Where do I mail the check? :biggrin:

 

[lolachampcar]

Could you do me a favor and extract a bit of info while you're shooting pics of that suspension. Specifically, I'd like the unloaded and normal loaded length of the spring (I know, you can not get the free length without taking things apart), the wire diameter (and let me know if it changes) and the coil diameters tied to the number of coils with each diameter. This will help start the process of determining the spring rate. I was going to buy a front and rear from Tesla but why wait if we can start the process now.

WRT using the existing perches, I'm sure the tops will work but I would not think those bottoms would be located with a snap ring like the air dampers. Normally they just weld on those lower perches before they assemble the damper. How do they appear to be attached?