3D printed lowering links

[scottm]

I wonder why on model S, when you swap tire sets over for the season, the TPMS detects the change and the calibration process always prompts you to select the diameter of wheels that are now on the car?

I'm told you don't need to do this on model X or model 3.

 

[sorka]

I wonder why on model S, when you swap tire sets over for the season, the TPMS detects the change and the calibration process always prompts you to select the diameter of wheels that are now on the car?

I'm told you don't need to do this on model X or model 3.

If there's a real purpose the only thing I can think of is that on 21" staggered rears which are wider, ARE taller than 19" by a half inch or so. It could also be that the sensor distance from the receiver requires calibration and that varies by 2" between the two sizes.

 

[sorka]

Doh, it's because the tire pressure warning threshold is different between the the 19s and 21s.

 

[sorka]

On standard height mine measure 29 1/4 in the front from the ground to the top of the fender with the tape measure vertical and crossing the center of the hub cap.

The rears measure 29.

The tech did a ride height calibration because he said the car was higher than others but the calibration did nothing.

 

[sorka]

So does anyone know how much height difference there is with each +2mm increment?

 

[Russell]

So does anyone know how much height difference there is with each +2mm increment?

10mm. Each mm increase in the link results about 5mm drop of the car.

 

[sorka]

Any word on if we should lubricate the ball joint on these and if so with what? Graphite? Any old grease? The white grease that goes on the plastic gears of my garage door opener?

 

[sorka]

Just another reference point. I installed 56 mm links on the front which resulted in exactly a 1" lowering, so about 25mm.

 

[The Duke]

Alignment specs change and do you align at the new "low" ride height?

 

[sorka]

Alignment specs change and do you align at the new "low" ride height?

Yes. Not just camber but even toe changes some when you change height.

As soon as I get my adjustable links from bbc speed machine, I'll lower the rear by 3/4" and go get my alignment done.

 

[sorka]

 

[scottm]

@sorka for those red links, have you cut away the felt fender liner a bit to clear the sensor arm when the ride height is adjusted to its fullest?

It looks like it might be contacting.

 

[sorka]

@sorka for those red links, have you cut away the felt fender liner a bit to clear the sensor arm when the ride height is adjusted to its fullest?

It looks like it might be contacting.

Yes, just enough so that it's not touching the felt. The link is actually forward of the felt and when there was contact, it was the flange of the nut behind the ball.

 

[sorka]

Just printed up a set of rears. PETG. No warpage or shrinkage and measured with my Mitutoyo.

But the balls are MUCH tighter in these than the fronts. They are the same size but the fronts have more give because they open up on the end and provide less resistance to being spayed apart.

I used a vice to press these in because I could not get them in by hand and they are quite stiff. I have not doubt over time they will loosen but I'm concerned they will stress the joint at the sensor where the flat plastic arms attach.

 

[sorka]

Putting on rear links.

It's possible to install a rear link with the sensor arm pivoted the wrong way.
If you do that the ride height will be terribly off.

Pay attention to which way the sensor arm is in relation to the link when you're talking the stock link off.
Install the new lowering link with that same angular relationship with the sensor arm.

Here pix of two ways of installing a rear link.
(A) is correct.
(B) is the wrong way.
When you're doing the job, you'll see the right way... follow that way.

View attachment 223264 View attachment 223265

So yea, I totally screwed this up even though I read the warning. The rear jacked up very high. I immediately removed the wheels and re-installed the links the right way and the height went back to normal.

Any word on if this causes any damage to have the suspension set so high up? Could I have bent anything.

So odd thing is, I printed 72mm at 1030% which puts the center of the holes at 74mm. Yet the rear lowers an entire inch from 29 to 28 which is where the front is with the 56mm links. I think I want the rear only lowered 1/2" to since I'm also using adustable upper arms to decrease negative camber which brings the toe out some as does lowering the car. The combination of both might exceed how much positive toe I can get rid of.

 

[sorka]

I think this thread is dead.

 

[sorka]

Well drat! I'm borked. It seemed fine last night but then I came out this morning and raised the car to normal from low and the rear shot up to 31" which was way way too high. I then lowered it back to low and it lowered but then a few seconds later the rear went from low back up to 31".

I re-installed the original links and same thing. Lowered but then raised back up to 31". So I took it drive around the block and got a "air suspension needs service". It completely deflated and the car is sitting so low. I suspect the original backwards install resulted in screwing up the calibration.

...or even worse, the sensor was moved to a position beyond it's mechanical limit although I don't think that happened.

 

[scottm]

The sensor brackets probably twisted. I don't think you're borked...

These are not that strong of a part and can be bent back into shape.

In fact, you can fine tune the ride height by careful bending. (Instead of using adjustable links!) This is actually how the service center returned one corner back to OE ride height, when I put OE links on the car.

I thought theyd just use software calibration tweaking to change height on one corner, but nope. He said he didnt need to do a recal, just a bend. He said this sometimes happens when doing alignments.

 

[scottm]

Just printed up a set of rears. PETG. No warpage or shrinkage and measured with my Mitutoyo.

But the balls are MUCH tighter in these than the fronts. They are the same size but the fronts have more give because they open up on the end and provide less resistance to being spayed apart.

I used a vice to press these in because I could not get them in by hand and they are quite stiff. I have not doubt over time they will loosen but I'm concerned they will stress the joint at the sensor where the flat plastic arms attach.

The rear links are tighter snap on because of design.

I do a few things to ease the fit:

Run a razor knife through the ball slits to make sure plastic is not bonded and will allow the ball socket to spread open

Pick out any plastic debris from the ball socket, even small threads

File the outside edge of the ball socket opening down a bit (fillet in CAD terms)

Wipe a dab of silicone lube around in the socket...

These things are enough to allow you to use good firm squeeze power of your thumb to snap them on..

If not, insert a broad flat tool into the space on either side of the ball in the link and twist it, this spreads the socket apart to help snap over the ball.

 

[sorka]

Putting on rear links.

It's possible to install a rear link with the sensor arm pivoted the wrong way.
If you do that the ride height will be terribly off.

Pay attention to which way the sensor arm is in relation to the link when you're talking the stock link off.
Install the new lowering link with that same angular relationship with the sensor arm.

Here pix of two ways of installing a rear link.
(A) is correct.
(B) is the wrong way.
When you're doing the job, you'll see the right way... follow that way.

View attachment 223264 View attachment 223265

OK, this is really strange. So they are on according to A right now which is wrong. I had it according to B the rear of the car shot all the way up to 32" inches. I *assumed* that I had it in the wrong position and just swapped according to A which turns out according to this post actually be the wrong way which almost immediately triggered the error.