LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently March 29, 2024, 1:50 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 7 posts ] 
Author Message
PostPosted: March 21, 2018, 3:45 am 
Offline
User avatar

Joined: November 11, 2013, 4:47 am
Posts: 1617
Location: No. Nevada
Been working on getting the engine mounted in the Dio-Alfa but until the dry-sump system arrives I would like to get back on the rear suspension.

My plan has been to mostly recreate the original Alfa Three-Link, which I guess is not a true Three-Link as it uses a triangulated upper link instead of a Panhard rod.

For convenience and minor weight savings I'm wondering if there is any real penalty to having the lower trailing arms at a shallow angle rather than strait to the rear as seems to be standard?
Seems it might marginally help with limiting sideways movement, which is really the upper links job, but would it also cause any sort of binding or other issues?

I have to admit that suspension development is my personal weak link. :oops:

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: March 21, 2018, 8:24 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1879
Location: 4AGE in S.E. Michigan
Should not be an issue, as long as one or both ends of your control arms have rubber bushings. Several leaf spring suspension systems are designed with slight angles.
DaveW


Top
 Profile  
Reply with quote  
PostPosted: March 21, 2018, 8:38 am 
Offline
User avatar

Joined: December 17, 2010, 1:24 pm
Posts: 1580
Location: Gainesville, Mo.
If you're concerned, you can always mock it up in miniature. Get some turnbuckles, or something similar for your links.

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


Top
 Profile  
Reply with quote  
PostPosted: March 22, 2018, 2:45 am 
Offline
User avatar

Joined: November 11, 2013, 4:47 am
Posts: 1617
Location: No. Nevada
It "Seems" that 4" of vertical movement on an 18" arm should not be a real issue.
I think I can mock it up in CAD and see how much the arc wants to pull it inward.
Looks like about 20º angle, a little more than I had thought it would be.
Plan has been rod ends at the axle end and bushings at the frame end.

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: March 22, 2018, 3:16 am 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7652
Location: Massachusetts
The pivot could be aligned to be perpendicular with the chassis centerline? Then it would still be more of a trailing arm.

_________________
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: March 22, 2018, 3:20 am 
Offline
User avatar

Joined: November 11, 2013, 4:47 am
Posts: 1617
Location: No. Nevada
20º as viewed from the top.
Level or close to it from the side.

_________________
If I must be a one-man PC free zone, so be it!


Top
 Profile  
Reply with quote  
PostPosted: March 22, 2018, 11:35 am 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7652
Location: Massachusetts
Quote:
For convenience and minor weight savings I'm wondering if there is any real penalty to having the lower trailing arms at a shallow angle rather than strait to the rear as seems to be standard?
Seems it might marginally help with limiting sideways movement, which is really the upper links job, but would it also cause any sort of binding or other issues?


Quote:
I think I can mock it up in CAD and see how much the arc wants to pull it inward.


If the arm tries to pull it inward, it won't work at all because the axle can't move up for bumps, both sides would try to pull it inward. So it is fine to have the lower arms at an angle in top view, but the pivots at the front of the arm need to be mounted at an angle on the arm so the pivots are perpendicular to the car centerline. If you grabbed the trailing arm and rotated it in a full circle, that circle must line up with the car centerline.

So if you were using a bushing, you need to weld the trailing arm on to the bushing at an angle and the bolt of the bushing needs to be perpendicular to the car centerline.

Are you going to use a Panhard rod or use the upper link to keep the axle centered? You want the pivot of the centering link as low as possible. You can make one of the lower trailing arms into a wishbone so it does the centering. That was done on some of the Super 7s.

_________________
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  [ 7 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 18 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