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Interested in rear swaybar for Bolt?

60K views 236 replies 60 participants last post by  v-pilot 
#1 · (Edited)
This is a feeler for interest in rear swaybar adapters for the Bolt.

I plan to fund manufacturing of adapters that allow easy installation of a rear swaybar on the Bolt, such as the Cruze swaybar by Whiteline, as sold by EV-MODS and others. The adapters are dasto's design, as shown in another thread.

This should make the car feel considerably more nimble and willing to turn, for autocross or just fun use on twisty roads.

At this point I don't know what the price should be, but I'm guessing in the neighborhood of $75-100 for the adapters. I'm currently waiting for a prototype to be shipped to me, so this will most likely take several weeks to get to the point of taking orders and shipping.

I'm presently soliciting interest to get a sense of how many I should expect to order from a machinist.

Please reply here with a note indicating your interest in such an offering. As the project progresses I'll post availability and pre-payment price here.
 
#3 ·
This is designed to fit a specific swaybar to the Bolt EV. I have no idea and no way of finding out whether it fits any other cars and bars.
The adapters are the "plugs" that fit into the D-shaped hole in the lower rear suspension arms, with offset bolt-holes to accomodate the length of the Whiiteline Cruze bar.
 
#4 ·
At least I know who beat me to the bar. I was on vacation when he sent me an email and I responded to late.

I'm interested, but the cost is a bit high IMO. I'd measure up and make my own at that point. $50 is a reasonable price IMO though.
 
#5 · (Edited)
Feel free - I can't imagine valuing my time that cheaply - it would take quite a few hours to measure and machine a set of anything worth the time for this. I'd only price these because dasto already did the measurement and development and I can build on his work.
We'll see what the machine shop wants for stainless steel parts. Plain steel or alu is probably not a great choice, corrosion-wise.
 
#7 ·
"Has anyone beside EV-MODS driven with one to see if it makes a big enough difference to justify the extra weight?"

Ask dasto - he's another guy who autocrossed with it, aside from EV-MODS.

And I'm pretty sure that 6 or 7 pounds (around .2% of the Bolt's weight) is not going to make a measurable difference in anything.
 
#13 · (Edited)
I'm having serious second thoughts about making these for sale, due to liability concerns.
The GM engineers didn't exactly design the swing-arms to have a strong piece resisting motion near the center of the spring seat, thus there is some chance of damage occurring sometime down the line, leaving me legally liable in case of an accident caused by breakage. I have no way of analyzing the stresses involved or of testing to destruction, so there is some risk involved.
If I do sell them, I'm thinking that at a mimimum I'd want a signed release of liability from purchasers.
Anyway, I'm taking the prototype parts to a machinist tomorrow, and there is a chance they won't even take on the fabrication, as I have no engineering spec or drawings, and they would have to measure the pieces and hope that copies would fit in Bolts.
 
#15 · (Edited)
Unfortunately this isn't happening.
What with concerns about liability if I were to sell these, and the pricing I got from a machine shop I've worked with before, I'm going to just take the parts I bought from dasto, and have them powder-coated for anti-rust.
Sorry guys, but the pricing was way too high, and even if I ordered a dozen they would be over $450/pair for stainless and $300 for alu. One-off pricing was four times that.
(Obviously the machinist didn't want the job)
 
#16 ·
I had asked Datso via email to send me drawings of the parts, or if his person was willing to make me a set (remember we know each other, and race together). He didn't have dimensions. Are you willing to share the dimensions and save everyone else the time to do that at least?

We could have our own made up (in my case I'll make them at work) and at least get moving forward. I suspect there is only 20 or so folks that even want this anyway.

Appreciate you looking into it, but this is why I was upset I missed his email when I was on vacation, I knew this was going to be the difficult part.
 
#17 ·
I'll take a shot at measuring, but no promises on how accurate the off-center bolt-hole placement will be. Also, these were hand-filed to size, so the measured diameter of the top-hat part could be a little off. dasto said they were a hammer-in fit on the car.
 
#19 · (Edited)
OK - measurements for dasto's rear swaybar adapters. Click the image for full size.
26964

Sway bar requires four pieces: two flat disks and two top-hats. Note: the two top-hats are mirror images.
These measurements are from parts that were machined and then hand-filed down to size, so the dimensions are somewhat irregular. I'm told that these parts were a hammer-in fit on the Bolt.
The rightside-up top-hat has a line scribed across it (actually two in parallel, due to a cheap centering tool) to show position of the hole.

Disk diameter = 1.93" more or less
Disk hole diameter = .500"
Disk thickness = nominal .25"
Disk hole to O.D. of disk = .505" - intended to align with the hole in the top-hat

Top-hat brim thickness = .255
Top-hat brim diameter = nominal 2.00"
Top-hat height = one is 1.75", the other 1.72"
Top-hat crown height = 1.43"-1.47"
Top-hat crown diameter = 1.485 plus/minus .004
Top-hat chord to flat thru the crown = 1.375" nominal, varies due to hand filing
Top-hat hole diameter = .500
Top-hat hole to flat = .385"
Top-hat hole to outside of crown - shortest distance = .292"
Top-hat hole to outside of crown - long way across = .700 plus/minus .005

I believe that the assembly sequence from the top down is nylock nut, top-hat upside-down inserted thru top of spring-seat, then disk, bar-end, washer, with a 3.5"x .5" partial-thread grade-8 bolt up from the bottom. The bar should have the ends toward the back, but I'm not sure of the vertical orientation, as the bar-ends are tilted – I'd like to have as much ground clearance as possible.

I have yet to install these, so if I have tips or issues I'll post in a couple of weeks.
 
#20 ·
OK - measurements for dasto's rear swaybar adapters. Click the image for full size.

Top-hat chord to flat thru the crown = 1.375" nominal, varies due to hand filing
Top-hat hole to flat = .385"
Top-hat hole to outside of crown - shortest distance = .292"
Top-hat hole to outside of crown - long way across = .700 plus/minus .005
Thanks!

I believe I understand everything but these above measurements. I'm an engineer, but not a mechanical one... Here's a bad drawing to represent what I think I do understand. Any way you can fill in the blanks? **Note: Nothing to scale, this is drawn up in Google Slides!

26968
 
#21 · (Edited)
I'm not formally an engineer, although I do design and manufacture small parts, but I have no good way to locate the center of the hole relative to the rest of the piece. The last three of those were the only ways I could think of to describe its location.

  • The first of those is the length of a perpendicular centered on the flat, to the outside of the shaft (crown). It indirectly also defines the width of the flat. I didn't try to measure the width of the flat, because the edges needed to be somewhat rounded.
  • Second one is sticking the mike into the hole, and measuring the shortest distance from the hole to the flat.
  • Third is sticking the mike into the hole, and measuring the shortest distance to the outside of the shaft.
  • And finally the last of those is with the mike in the hole, measuring the longest distance from the hole to the outside of the shaft - the opposite direction from the third one.
While cleaning up the parts, I sanded a slight chamfer on the small end of the top-hat for insertion, and rounded the edges of the flat slightly for easier fit into the swing-arm.
The parts are in for powder-coating this week, so I hope to install the bar next week.
 
#22 ·
Thanks... I think I can follow that.

Ideally I would have just scanned the parts and created a point cloud and 3D printed some parts for fitment. Once I knew I had the fit correct I'd output on a CNC and from there could provide the path g-code for others to get parts made pretty easy.
 
#29 ·
After a bit of measuring my dimensions came out pretty close to One1whaoo. These adapters use a 9/16" x 3 1/2" bolt. You'll need to make 4 of them, 2 with the offset to one side and 2 to the other side. The set I made for myself look a bit more like One1whaoo where one side has a long D shaped barrel, but instead of just a flat disc, I added a little bit of the D shape to keep the disc properly located while torquing it up. Afterwards I figured it would make more sense from a manufacturing standpoint to make all the parts the same, aside from the offset hole. Alternatively, if you'd like to use the hardware that comes with the swaybar, just change the length of the D shaped barrel to be long on one side and thread it with a m14x1.5mm tap, and then drill 9/16" through the short side (1.375" and .125" barrel lengths respectively).
27361
 
#34 ·
Afterwards I figured it would make more sense from a manufacturing standpoint to make all the parts the same, aside from the offset hole.
View attachment 27361
Thanks... signed up for a Tinkercad account and made this up from your drawing.

27366


Going to 3D print these first and check I've got everything correct, but looks like it should be just fine.
 
#35 ·
Looks good. With the contact with the steel swing-arms, it would be good to have the pieces anodized To avoid corrosion.
Just as a comment, this swaybar won't make the car corner flat like a sporty Porsche - I did a couple of quick left-right-left-right quarter-turn-of the-wheel swings the other day, and some (considerably reduced) body roll still exists.
 
#36 ·
Understood... I personally know Datso and talked to him about what it did for him on the autocross course. He had the car at an event I was at so I got to see what it does as well with my own eyes.

The rear sway combined with the shocks and better spring rates will help alleviate the last little bit of roll I believe. I'd still like to find a solution to the front struts (to modify a set from a Cruze) and then I know what I can do with some modified BC Coilovers from a Cruze to revalve them and set things up the way I'd like for autocross or even the track.
 
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