LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently March 28, 2024, 4:00 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 61 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next
Author Message
PostPosted: October 25, 2017, 5:07 pm 
Offline
User avatar

Joined: December 24, 2007, 5:11 am
Posts: 1307
Location: Seattle area
Mike,

Yes it does. Alfa has used this basic design on other models.

Cheers

_________________
Larry in Seattle


Top
 Profile  
Reply with quote  
PostPosted: October 25, 2017, 5:47 pm 
Offline
User avatar

Joined: December 17, 2010, 1:24 pm
Posts: 1580
Location: Gainesville, Mo.
OK! Seems like it would have an awfully high roll center, but Alfa's been in the game a long time so I guess they know what they're doing! :?

_________________
Mike - Read my story at http://twinlakesseven.blogspot.com/


Top
 Profile  
Reply with quote  
PostPosted: October 25, 2017, 10:04 pm 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 621
Location: White Rock, BC, Canada
If it helps anyone a more readily available rear axle already set up for 3-link (lower links, upper ctrl arm w/ balljoint) is from the Jeep Liberty. The upper arm is junk, but other than that I think they are a decent axle. Suzuki also used one but I don't remember what model. Probably has that goofy hub on it though.

Interesting point: Foxbody Mustang guys at autoX used to install a panhard bar and just remove one of the upper links. Because the suspension is so bad on them, most chassis companies offered a 3-link kit, and now seem to have settled on using torque-arms (I assume because they are easier to install).

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
PostPosted: October 26, 2017, 9:05 am 
Offline
User avatar

Joined: August 11, 2011, 12:38 pm
Posts: 271
Location: Akron, NY
Has anyone tried the rubber rod ends that Seals-it makes? Looks like you could use it as a replacement for one or two rod ends in the 4 link to eliminate binding and it would be a quick swap with a rod end and no fabrication of new links.

http://sealsit.com/product/sf88r-sealflex-rod-end-12-x-12-right-hand/


Top
 Profile  
Reply with quote  
PostPosted: October 26, 2017, 1:15 pm 
Offline
Toyotaphobe
User avatar

Joined: April 5, 2008, 2:25 am
Posts: 4829
Location: Fort Worth, Texas
That looks cool. No metal on metal contact so it should eliminate some of the noise plus it should be stiffer than a poly bushing.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


Top
 Profile  
Reply with quote  
PostPosted: October 26, 2017, 4:20 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7652
Location: Massachusetts
If it's soft enough to allow the required amount of rotation without the rotating on it's mounting bolt, it might be too soft to really accurately provide location. Maybe it would work, regular bushings certainly allow relative motion of the parts. So it's a bushing replacement with rod end adjustability, which I guess is what you guys are saying anyway! :rofl:

_________________
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  
PostPosted: October 26, 2017, 10:02 pm 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 621
Location: White Rock, BC, Canada
If that is just rubber bonded to the inner and outer sleeves, it's probably too stiff and has too little rotation before binding anyhow. You can use flexible bushing to get compliance, but that is what Ford did on the Foxbody Mustangs which resulted in very sketchy handling at speed. The bushings bind on large bumps which you don't notice at lower speeds, but at high speeds it usually results in the car swapping ends.

I know some racers have used rod ends similar to that to take a little bit of the shock loads out for launches etc.

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
PostPosted: October 27, 2017, 11:21 am 
Offline
User avatar

Joined: August 11, 2011, 12:38 pm
Posts: 271
Location: Akron, NY
My understanding is that the rubber rod ends are designed in such a way to allow the same articulation as a rod end while allowing some compliance. How much compliance is what I was wondering? Seams like if they allow as much articulation as a rod end they would be to soft to accurately locate the axle, but I also have not seen one in person.


Top
 Profile  
Reply with quote  
PostPosted: October 27, 2017, 1:05 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 3268
Location: Under the weather. (Seattle)
If anybody (manufacturer or otherwise) ever offers a half-way decent technical explanation of how (or even 'if') they manage to achieve a sufficient combination of rotation, misalignment, strength, and stiffness with that small amount of bonded rubber, I might give them a second thought...But until then, no thanks.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie


Top
 Profile  
Reply with quote  
PostPosted: October 27, 2017, 8:33 pm 
Offline

Joined: February 8, 2014, 10:47 pm
Posts: 781
Location: Cornelius OR
The big problem with a 3 link in a locost is packaging. Unless you ditch the passenger seat!

It would package easier if it was inverted (center link on the bottom) or a torque arm.
But then you give up the ability to offset the link to compensate for torque transfer picking up the RR.

_________________
Honey anyone?


Top
 Profile  
Reply with quote  
PostPosted: October 28, 2017, 8:52 pm 
Offline
User avatar

Joined: June 8, 2010, 8:02 pm
Posts: 621
Location: White Rock, BC, Canada
Bent Wrench wrote:
The big problem with a 3 link in a locost is packaging. Unless you ditch the passenger seat!

It would package easier if it was inverted (center link on the bottom) or a torque arm.
But then you give up the ability to offset the link to compensate for torque transfer picking up the RR.


In theory if you are running a 4-link w/ panhard, you can just remove one of the upper links.... Not sure I'd try that with the typical Locost setup. If you just run a 3-link w/ panhard the loss of space isn't too bad. Some elbow room lost is all. Can also aim the 3rd link rearward (not really viable on the locost though).

Driven5 wrote:
If anybody (manufacturer or otherwise) ever offers a half-way decent technical explanation of how (or even 'if') they manage to achieve a sufficient combination of rotation, misalignment, strength, and stiffness with that small amount of bonded rubber, I might give them a second thought...But until then, no thanks.


You could leave the inner or outer un-bonded so it can rotate (or bonded to a sleeve), then use the flex in the rubber for the sideways movement. Not much room for that and yeah, I doubt it.

_________________
Build log: viewtopic.php?t=9291


Top
 Profile  
Reply with quote  
PostPosted: October 29, 2017, 11:22 pm 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 3160
Location: Oregon, usually
C10CoryM wrote:
In theory if you are running a 4-link w/ panhard, you can just remove one of the upper links.... Not sure I'd try that with the typical Locost setup.
I tried it in practice, and it was fine...with low rolling resistance tires and 32 horsepower, so YMMV. But I felt a bit nervous, 'cause I no longer had a backup in event of a rear suspension component failure (which I had once; it was one of those "I figured you'd readjust it anyway, so I didn't tighten the jam nuts" things--what made it spooky was I couldn't feel any difference, I just saw a dangling trailing arm during a walk-around.

That Seals-It rubber rod end seems like a good backup, but then again, better maintenance would eliminate the need for a backup. Colin Chapman wouldn't do a backup suspension part, would he? Then again, he dealt with the four-link-and-panhard bind problem with chassis flex, so maybe we shouldn't emulate him on everything.

_________________
Locost builder and adventurer, and founder (but no longer owner) of Kinetic Vehicles


Top
 Profile  
Reply with quote  
PostPosted: October 30, 2017, 1:35 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7652
Location: Massachusetts
Quote:
Then again, he dealt with the four-link-and-panhard bind problem with chassis flex, so maybe we shouldn't emulate him on everything.


I'm embarressed I don't know enough Seven history, but can someone knowledgable on that comment here? The Seven I looked at most recently had a 3 link, the bottom link was a triangle with apexes at the back of the bottom frame rails and the bottom of the diff. Was this a modification by the owner for racing or were some built this way?

Does this require welding on the diff housing or could you build a sandwich plate under the diff cover?

With a nice truss design for the triangular link and good connections to the bottom rails this seems like an elegant and efficient solution. It seems one of the best places to feed loads into the frame. If we can find a good solution for the diff connection this is what I would like to see for a solid axle version of Car9.

_________________
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  
PostPosted: October 30, 2017, 2:12 pm 
Offline
User avatar

Joined: January 1, 2012, 12:44 pm
Posts: 588
Location: Boise, Idaho
Marcus,
This is the way that Series 2 and 3 Sevens were built. In a factory manual, it appears that the center diff bracket was bolted to the bottom of the housing but the ones I've seen/worked on were welded.

Ron


Top
 Profile  
Reply with quote  
PostPosted: October 30, 2017, 3:00 pm 
Offline
User avatar

Joined: January 1, 2012, 12:44 pm
Posts: 588
Location: Boise, Idaho
This lower "A" bar design was used in one of our GT2 cars when we were using a Ford 9" diff. It set a desirably low roll center. The lower "A" was actually two bars (one right and one left) with the center mounts right next to each other, which made adjustment easy.


You do not have the required permissions to view the files attached to this post.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 61 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 20 guests


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

Jump to:  
POWERED_BY