P85D (pre/post April) ride performance

[sorka]

Torsion bars can sometimes be hollow, reducing the spring rate of the "twist". But I've never heard of hollow sway bars, and agree 5-6 extra mm implies something really, really stiff.

That's an interesting point anyways. But yes, I've never handled a hollow sway bar and I've changed dozens back in my hotrodding tuning days which I'm really really glad I'm no longer doing.

I think in the case of my P85D, that reducing the diameter of the front sway bar by a few mm would make a big difference in the compliance without any other changes.

 

[3mp_kwh]

For those of us with P85s who would like to get our handling closer to the P85+, is there anything we can do short of paying Tesla the exorbitant price for a + retrofit?

Tesla policy would likely keep to "all, or none", for claimed safety reasons. Each version is a package. Sub-frame replacements are possible, with new arms, I think because that = the later P85 package. Ask for just bigger sways, and you may face $12k in firmer air spring units as well (the P85+). Sounds weird, but maybe a P85+ owner can buy sways, no questions asked. Your issue then becomes the install. I'd be sure to get the ball-jointed UL's, if you're happy with camber. ~$500.

I lowered my car and am prepared to be refused suspension/alignment service. It goes with the territory. Of the three snap-rings I had cut in the rear, I have to go up one (to the current front/back standard "SAS Low" height). I have a lift, air, and a spring compressor. So, 2hrs no biggie. On the P85D coil, the unique choice Tesla made to keep the front low, and back "high", I am realizing may have been done to minimize front wheel spin. Take the back down more, and it gets a tiny bit worse. I've been ~1/4" below "Low", back there.

On square 245 setups, I'd be curious if the SAS P85Ds also tend to front spin, a little bit? It's confusing, because if that steering wheel isn't dead straight, you're going to get it anyway.

 

[AWDtsla]

Hollow sway bars are common for weight reduction. The inside the bar does very little. It must be confirmed.

 

[3mp_kwh]

Hollow sway bars are common for weight reduction. The inside the bar does very little. It must be confirmed.

That's it. They forgot to hollow Sorka's out!

If true, I doubt they're using two different bars with the same outer diameter. A formula equates how much the inner diameter (ID) reduces the stiffness, compared to solid.

It is still useful to collect stats, and then maybe find an engineer who'll volunteer if there are any IDs.

 

[lolachampcar]

General observation - My PD has significantly less front bar than my P+ had. I have no idea what the diameters are nor if any are hollow. Lastly, race cars routinely use hollow bar elements for the torsional loads.

AR,
If I had a P and wanted to get to my ideal, I would likely change the rear lower a-arms if the car was a very early one (requires changing the motor cradle as well if memory serves) then change the front spring/damper units to PD. I would pass on any bar change. Just my opinion....

 

[sorka]

General observation - My PD has significantly less front bar than my P+ had. I have no idea what the diameters are nor if any are hollow. Lastly, race cars routinely use hollow bar elements for the torsional loads.

AR,
If I had a P and wanted to get to my ideal, I would likely change the rear lower a-arms if the car was a very early one (requires changing the motor cradle as well if memory serves) then change the front spring/damper units to PD. I would pass on any bar change. Just my opinion....

I'm just waiting for someone who thinks that they're Pre April Air P85D has a softer suspension to *please* go out and measure the diameter of their front sway bar. I strongly suspect we're going to find a mix of pre April Air P85Ds that have different diameter sway bars. 28mm is so thick that the left and front suspension height are practically tied together with very little independence.

 

[cassiri]

I am also curious how the ride heights vary and why between P85D and P85+'s. The loaner + I had was about an inch lower at the low setting than my PD. Funny enough it didn't seem to scrape as much as my car does.

 

[3mp_kwh]

I am also curious how the ride heights vary and why between P85D and P85+'s. The loaner + I had was about an inch lower at the low setting than my PD. Funny enough it didn't seem to scrape as much as my car does.

You mentioned you were "June" production. If Tesla wanted to keep the weight capacities the same, for luggage, passengers, etc., a post-April spring softening would have required a higher starting ride height. They could also be tweaking weight distribution, for traction.

You would have to soften a spring a lot, to need an extra inch.

 

[lolachampcar]

I was told once by Tesla that spring rate has not changed across the air springs (P, P+, PD). Apparently all the difference in perceived spring rate is due to damping.

 

[lolachampcar]

Late January 2015 delivery P85D
26mm front
21mm rear
both measurements were taken from the trailing run of the sway bars and assume the transverse portion of the bar is the same diameter. I'd have to throw it up on a lift to get access to the transverse torsional portion of the bar.

Has anyone looked to see if the AWD version of the front bar has the same length trailing section as the two wheel drive version?

 

[sorka]

Late January 2015 delivery P85D
26mm front
21mm rear
both measurements were taken from the trailing run of the sway bars and assume the transverse portion of the bar is the same diameter. I'd have to throw it up on a lift to get access to the transverse torsional portion of the bar.

Has anyone looked to see if the AWD version of the front bar has the same length trailing section as the two wheel drive version?

So that settles that. P85Ds prior to April had different diameter sway bars at different times. Perhaps even different compression and rebound damping values in the shocks.

Lola, what size wheels do you have? Do you have 21" wheels? Perhaps a stiffer sidewall resulted in a smaller sway bar set to compensate. We might need to multiple the chart to include wheel size. Also, just to confirm, you have air and not coils?

 

[lolachampcar]

Air and bought it with standard 19s as I was planning on using aftermarket wheels/tires

 

[sorka]

Air and bought it with standard 19s as I was planning on using aftermarket wheels/tires

Thanks. That finally proves Pre April P85Ds with Air and 19s have have had different sway bars. I guess I win the prize for having by far the stiffest sway bars ever put on a Tesla.

 

[linkster]

sorka

Might you be able to provide the p/n's of your bars and for your chart?

btw, I have found that hollow (anti) sway bars that I have used in the past have small drainage/vent holes on the tapered ends by the end links.

btw II, anyone that wants to get rid of their aweful :biggrin: head snatching 28 front and 22mm rear bars, please let me know.

 

[sorka]

sorka

Might you be able to provide the p/n's of your bars and for your chart?

btw, I have found that hollow (anti) sway bars that I have used in the past have small drainage/vent holes on the tapered ends by the end links.

btw II, anyone that wants to get rid of their aweful :biggrin: head snatching 28 front and 22mm rear bars, please let me know.

Me

 

[Cyclone]

btw II, anyone that wants to get rid of their aweful :biggrin: head snatching 28 front and 22mm rear bars, please let me know.

Me

Ok, who drives East or who drives West, or do you meet in Chicago or Cleveland?

 

[Andyw2100]

sorka

Might you be able to provide the p/n's of your bars and for your chart?

btw, I have found that hollow (anti) sway bars that I have used in the past have small drainage/vent holes on the tapered ends by the end links.

btw II, anyone that wants to get rid of their aweful :biggrin: head snatching 28 front and 22mm rear bars, please let me know.

Me

He wouldn't want yours, sorka. In his eyes, you're a "crybaby." I'm surprised he's talking to you at all.

I use a 14-30 nightly (54,000 miles) to charge the P85. I specifically installed a HPWC for great (no P85D crybabies/letter writers to Elon allowed) Telsla owners on Plugshare.

 

[lolachampcar]

why Andy???????

 

[Andyw2100]

why Andy???????

Why?

Why what?

Why inform sorka, whom I consider a friend, that someone who is corresponding with him in this thread has been insulting him behind his back?

Because that's what friends do.

 

[3mp_kwh]

FWIW, When I took my 24/20, the running lenth of the sway did, indeed, have the same diameter. So, I'd guess the trailing (after bends start?) sections mimic the rest.

Interesting piece, on hollow sways: http://www.whiteline.com.au/docs/.../Hollow vs Solid Swaybar.pdf

According to this, hollow and solid equivalents don't seem to be apart by too much. When tube walls get to 25% of total diameter, steel achieves 98% of the same strength as a solid bar. Take the wall down to 12.5% and you are still 90% of the equivalent solid. The pdf claimed it uncommon for hollow bars to go outside these wall thickness ratios. This would say that, if a 28mm Tesla sway is hollow, its solid counterpart would be 25.2-27.5mm thick. Because of the weight savings, my guess would be the front bars may indeed all be hollow.

Bar strength goes up in relation to diameter, by: https://www.google.com/search?biw=1...cW_KnM:;n--K_AiWyVvV3M:&imgrc=GsE80ZzicW_KnM:

Would suggest going from 24mm, to 28mm, is 85% more stiff, holding everything else constant. Down to 19mm-20mm, I think it becomes more common to go solid, but it doesn't appear there is a consistent break point.