LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently March 26, 2019, 6:34 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Double-Dip Suspension
PostPosted: January 13, 2007, 2:35 am 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2946
Location: Oregon, usually
This is a concept for allowing a shallow shock angle and lower shock attachment close to the wheel on the lower control arm. Since it's wordy, I put the full description and photos up on the Kinetic Vehicles site.

The page is at http://www.kineticvehicles.com/dds.html

For now the page is only accessible from outside the web site so you'll have to use the address above; no use searching for it in the menues on the site.

Here's an overview photo. Imagine the shock fastened securely (as in bolted, not taped) to the pushrod; as the wheel comes up, the shock is pushed up at the bottom and pushed down at the top.


Attachments:
ddsFrontQuarter.jpg
ddsFrontQuarter.jpg [ 44.49 KiB | Viewed 5621 times ]

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com
Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 13, 2007, 12:40 pm 
Offline
Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
Posts: 5940
Location: SoCal
My buddy came up with this design in the 1970s, plus it's been on various cars since then. It serves a good purpose, allowing a good shock ratio with respect to wheel motion. It's a great idea, just not new.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 13, 2007, 2:37 pm 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2946
Location: Oregon, usually
KB58 wrote:
It's a great idea, just not new.

That's a relief, I was afraid I was going to have to patent it. :-)

My site refers to West Racing Cars, which uses this system with great success--they're not Locost, but they're the go-to company if you want to win in D Sports Racing. If there are pix of your buddy's car from the 1970s, I'd love to put one on our dds page, to further illustrate the system's rich history.

I can't think of a single invention which has debuted on a Locost. If I implied this was new on an absolute level, I apologise. Frankly, I wish I knew what other people call it, the "double dip" name came from another Locoster on another forum, and I'd rather go with standard nomenclature.

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 13, 2007, 4:07 pm 
Offline
Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
Posts: 5940
Location: SoCal
To be fair, I don't know of my buddy was the original "inventor" either. He said he'd never seen it before he came up with it, but it very likely showed up in the 1800's somewhere, like on a steam engine or something.

I had never heard it called "double-dip" before.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 13, 2007, 8:09 pm 
Offline
User avatar

Joined: October 11, 2006, 4:49 pm
Posts: 600
Jack

i am interested in your lower a-arm design. what is the sizing and type of rectangular tubing. i wil be using the miata lower balljoint and your design looks more rigid and relatively easier to fabricate than my own.

due to packaging constraints and interfereance with other components my lower arm will look almost identical to yours, but i did not think of using a long peice of rectangular tubing. clever, simpler,cheaper, easier to fabricate and higher in beam strenght, compared to my design

apparently rod ends are not permitted to be used on vehicles in BC, canada, my front lower attach point will be a bushing, i was hoping to use a poly graphite version of the triumph's. however that bushing approx 1 7/16 long. would it be frowned upon to cut the back of the inboard rectangular section at 30 degree or so angle and cap it off, to taper the section width down to roughly 1inch so that a triumph bushing can be used. or would it be wiser to make a sleeve slightly wider than the rectangular tube and make a bushing from nylon.

points, counter points, anyone.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 13, 2007, 11:17 pm 
Offline
User avatar

Joined: January 3, 2007, 12:49 pm
Posts: 197
Location: Lanark Highlands, ON
airframefixer wrote:
apparently rod ends are not permitted to be used on vehicles in BC, canada, my front lower attach point will be a bushing, i was hoping to use a poly graphite version of the triumph's. however that bushing approx 1 7/16 long. would it be frowned upon to cut the back of the inboard rectangular section at 30 degree or so angle and cap it off, to taper the section width down to roughly 1inch so that a triumph bushing can be used. or would it be wiser to make a sleeve slightly wider than the rectangular tube and make a bushing from nylon.

points, counter points, anyone.


Can you make the mount so that you can retrofit rod ends later?

It is a fairly common suspension joint on aftermarket 4x4 suspensions. Just trolling bc4x4.com should make that apparent. IIRC Breeze Industries on the mainland even makes a steering kit for Suzukis that uses rod ends as an option. When I ordered mine way back when I spec'ed TREs though...

Get past the certification process with regular bushes and then retrofit what you want.

Alternatively, any production cars out there that use something "middle of the road" that may meet your compliance requirement and still pass BC road regs?

Just some thoughts on a different vector from your query.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 14, 2007, 2:09 am 
Image
Square Tube - Bushing End Design
http://www.stockcarproducts.com/susp12.htm


Top
  
Reply with quote  
 Post subject:
PostPosted: January 14, 2007, 2:31 am 
You might want to double-check on the allowance for rod ends in BC - my understanding is that the rules changed to allow them here a few years ago, after much cajoling by the SVBA (http://www.sva.bc.ca/) B.C. Specialty Vehicle Builders Association....

I'm using rod ends in my rear suspensions, but also using Triumph bushings - I'm of the opinion that the ride would suffer if the entire suspension was done with rod ends (especially on BC roads!), and it might be a handful. That having been said, I understand some guys are successfully getting their vehicles passed in BC with all rod ends in their suspensions (although I haven't seen any myself)....


Top
  
Reply with quote  
 Post subject:
PostPosted: January 14, 2007, 7:50 am 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6009
Neat design Jack.

zetec7 wrote:
You might want to double-check on the allowance for rod ends in BC


If necessary, one could argue that Ford Aspires and Festivas have a spherical joint in the lower control arms. The swaybar also acts as a strut rod which lightens things up a bit. The sphere is rubber. The swaybar is the rod, the joint is threadless, and a large washer prevents separation of worn parts. I think separation is the #1 issue on single-shear joints. IMHO, using a standard rod end in single-shear on suspension and steering without a safety washer should be prevented.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: January 14, 2007, 5:39 pm 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2946
Location: Oregon, usually
airframefixer wrote:
i am interested in your lower a-arm design. what is the sizing and type of rectangular tubing <snip> simpler,cheaper, easier to fabricate and higher in beam strenght...


It's 2-1/2" by 1" by .065" HREW mild steel, no torque strength to speak of and I haven't calculated (or tested) the beam strength 'cause I mount the lower shoch/pushrod bracket so close to the end that beam strength isn't an issue for this application. But for tensile and compressive strength it's good bang for the buck--lighter and less parasite drag than a round tube of equal strength.

But its best feature is it fits a Miata ball joint so nicely. Just file/sand/gring the sharp edges of the ball joint base a bit so it'll fit into the curves of the tubing corners (did that make sense? I'll put up a photo when I get home) and you'll need a .100" spacer between the inner end of the ball joint base and the inside of the tube. The recess for the top of the ball joint is a 2-1/4" semicircle (that's the hole saw size; it's a 1-1/8" radius of you're cutting it on a CNC mill or a laser) and it's easy to make by cutting the 2-1/4" hole in the middle of a tube and then cutting the tube in half to make two control arms.

For the chassis end, cut a 2-3/8" length (a little under, actually--measure the tube you're using since there is some slight varience from mill run to mill run) of 7/8" square mild steel rod, and then tap it through one side for the 1/2" rod end. File/sand/dremel a small rounded groove on that bit of bar (as needed to relieve for the weld line that's inside the tube from its forming at the mill) slide it into the tube and weld in place. You'll probably have to taper the ends slightly with a flapwheel or angle grinder; what I aimed for was a snug slip fit--don't make it a force fit or it'll put unnecessary loads on the tubing.

I'll put up some drawings of the top and bottom reinforcing plates also.

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com


Top
 Profile  
Reply with quote  
PostPosted: January 15, 2007, 12:26 am 
Offline
User avatar

Joined: September 10, 2006, 11:29 pm
Posts: 380
JackMcCornack wrote:
This is a concept for allowing a shallow shock angle and lower shock attachment close to the wheel on the lower control arm...


That double-action suspension is also used on Stohr D-Sports Racers.


Top
 Profile  
Reply with quote  
PostPosted: January 15, 2007, 1:43 am 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2946
Location: Oregon, usually
modernbeat wrote:
That double-action suspension is also used on Stohr D-Sports Racers.

Right you are. I mentioned that on the page I linked to, and hopefully West's successes will give the concept some credibility. They're called West Racing Cars now, that may be the source of the confusion.

I've made the page accessable from inside the Kinetic Vehicles site, now you can go to the <Sage advice> page from anywhere on the site and find a link to <Double-dip suspension> near the bottom of the page.

Can anyone tell me the proper name for this suspension?

airframefixer, here's those drawings. They're actually toolpath checks, I'm a thousand miles from my shop (and my desktop computer) and this is all I have on my laptop. The tool simulator leaves a graphic trace but it's a pretty crude bitmap--it's mostly a quick test to see if the tool is going to crash into walls while it's running. For scaling, the arm is 2-1/2" long and the circles (in the part they're circles, though in this tracing they look like bullet holes) where the rear arm bolts in are 3/8" in diameter. The big hole (I forgot the size) in the bottom plate is for the ball joint mount.


Attachments:
LCAPlates.jpg
LCAPlates.jpg [ 4.86 KiB | Viewed 5369 times ]

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com
Top
 Profile  
Reply with quote  
PostPosted: February 18, 2011, 3:10 pm 
Offline

Joined: June 27, 2006, 2:52 pm
Posts: 331
jack, you didnt reproduce the image in its entirety... gotto practice what you preach... haha


Top
 Profile  
Reply with quote  
PostPosted: February 18, 2011, 3:34 pm 
Offline
User avatar

Joined: February 8, 2011, 4:43 am
Posts: 96
Location: Saint Cloud, Florida
Jack,
What are the "pros" again, or did I miss it? I can think of one con right away. You would be relying on only one mounting point for the UCA as opposed to the normally 2 points. Judging by the welds I've seen 'round some of the build threads, I'd think, in this case, more would be better.


Top
 Profile  
Reply with quote  
PostPosted: February 18, 2011, 4:17 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7579
Location: Massachusetts
The UCA is not shown in this picture. This is just a change to the mounts of the coilover unit. The leverage is doubling the motion of the coilover by squeezing it at both ends, so to speak.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY