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Please Enlighten Me on Alignment

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Hi All,

I'm a new owner and am learning about my Roadster. I have done quite a few searches, but please bear with me on some of my questions. I know it is common knowledge that these Roadsters understeer quite a bit. I'm looking to see what I can do to alleviate that as much as I can. I'm looking to increase the tire size up front and dial in some more negative camber and max out the caster. Here's my plan and my questions...

- Put the rear 17x7.5 wheels up front with 205/40-17 tires. The stock 175's seem to be over worked. Actually, the 175 Yoko's are "pretty wide" for their nominal size...they actually seem to measure out to comparable 195/50's. So, I don't think putting new 195/50 (as opposed to the 175/55) will gain a whole lot. I am test fitting the rears now and so far so good.

- How can I increase the negative camber and max out the caster? I've read it is done with shims, but when I took off the front wheel, it did not seem obvious. I am a big advocate of DIY alignments with strings and measurements...worked good for me on my old 308. I would max out the caster first (as the only real drawback to that is heavier steering) and then dial in the negative camber balancing between understeer and tire wear.

- Why is there so much negative camber in the rear? IIRC, excessive rear negative camber provides good mechanical grip, up until you lose the grip, then it not a gradual transition (or was that excessive toe, can't remember).

- I am going to do the mods up front first and if there is still understeer, then maybe take some negative camber out of the rears. This may seem like going backwards, but I think having a more neutral handling car would be more fun, than ultimate grip on both ends but with understeer.

LMK what you all think...

Henry
 
FWIW I do occasional track days and drive outs with 'Caymen fwends' ;-)

I mostly dialled out understeer on the adjustable suspension by setting the front sway bar (anti roll bar) to max soft and rear sway bar to medium (I know, generally softening the front is counter-intuitive but does reduce understeer). This is more than recommended by Tesla/Lotus (see buletin below) . Also I set the front shock absorbers (1 soft to 10 hard) to 1 at the front and 3 at the rear (softer than recommended, but roads where I live are poor - so this avoids skipping). There was a whole discussion on these settings way down on TMC ..

I recommend a deep dive as there is plenty of useful stuff from early owners, including several threads on shimminh to tweak camber caster etc .. see picture below for shim locations 15, 16 25 & 26. On my to-do list is the have these re-checked and play with tweaks for personal preferences . Although the Roadster has steering pretty close the Elise/Exige with good feel - a recent drive in a friends new Caymen 718 (this uses the new electric 911 turbo rack), had fabulous high gearing, with surprisingly good feel (the advantage of electric rack over earlier hydraulic versions) . So now on my 'to do' list is to try a faster rack (as the extra weight is only at parking speeds which I can live with). See posts by @wiztecy a missed TMC roadster contributor and innovator - please come back wiztecy !!

I use the sport tyre set up: Front 195/50 R16, Rear 225/45 R17 on Front 6J x 16 and Rear 7.5J x 17 (but with more progressive dunlop tyres, as I prefer a bit of drift rather than max grip and more sudden 'let go' on the yoki's - but I get that other folk may differ on this).

Whilst I commend your innovative idea of using rear wheels at the front, I tend to follow the Lotus Elise and especially the Exige set-up forums. Lotus are THE steering and handling meisters ! ... I've had many happy track hours in 60's Elans and 2000's Elises :) So I trust the 'beckers' (lotus handling gurus).

Interested in all opinions on Roadster Handling, please share - the dream of an electric Elise brought me to Tesla.


EU settings.JPG
Roadster Parts Manual - Front Suspension (including Hubs) - 2.png
 
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Fantastic! Thanks Mark...just the kind of stuff I was looking for. I'll have to digest this over the w/e.

Couple questions...

- my 1.5 doesn't have adjustable suspension, right? I don't recall seeing any adjustable anti-sway bars or adjustable coilovers.
- Are Sector 111 V2 arms still available...thought they went out of business?
 
Fantastic! Thanks Mark...just the kind of stuff I was looking for. I'll have to digest this over the w/e.

Couple questions...

- my 1.5 doesn't have adjustable suspension, right? I don't recall seeing any adjustable anti-sway bars or adjustable coilovers.
- Are Sector 111 V2 arms still available...thought they went out of business?
Sector111 is now InoKinetics and their balljoints are the bomb! I've had them in my Roadster for a few years now and love them. Also avoids the need replace the entire control arm, which is super expensive.
 
Again, thanks Mark & Phil.

Any thoughts on reducing the rear negative camber and making up for it with a wider tire?

Problem is, by reducing the negative camber, the top of the tire would protrude out further, and a wider rear would also come out further (depending on offset), and then this could create a clearance issue. Doesn't look like there is a way to bring the bottom control arm in to do the same thing...

Any thoughts?
 
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Hey guys,

I did indeed put the rears on the front with 205/40s. The extra width provides much better grip in the front. The rears mount up on front w/o any issues, but I did put on 8mm spacers (along with longer lug bolts) so that all the additional 1.5" of extra width did not go in towards the center of the car...also made the outer edge come out flush with the fenders.

I have been able to do some spirited drives these past few weeks and definitely reduced understeer. But, as I was doing some of that "spirited" driving, I came into a left hand sweeper and stomped on the brakes and WHOA...not a lot happened. Not a lot of slowing at least. Now I'm going to have to look into some better pads. I know there is a whole thread on this, but does anyone know if there is a consensus on what pads to go with?

I'll post up some pics when I get a chance.

Thanks,

Henry
 
I decided also to change the rotors. Very happy with the result. Titanium Dave on this forum might still have a set available.
Thanks Marius...I'll try the pads first and if not satisfactory, then move on to the rotors.

Did you do a "Tire learning" session? I'm guessing the odd tire size might have triggered the traction control system to cut the regenerative breaking.
No "tire learning session" needed. The overall dia. of the tires are near identical. The rear wheels on front with the 205/40 are the exact same as the OEM setup...23.5" dia. The rears are 0.2" smaller at 24.7" dia. No traction control or regenerative issues at all.