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PostPosted: October 18, 2017, 2:22 am 
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Joined: August 12, 2011, 1:46 pm
Posts: 85
Hi all ,
I'm redoing my rear end now for fear of the mount breaking off .
The original Haynes rear end has horizontal A arms .
So now is a good time to add a few extra holes to the br*ckets to be able to dial in some anti squat .

The new design has br*ckets that cannot be removed or installed afterwards (basically a piece of plate with a hole for the tube to pass through).

Any advice on how much or is it at all necessary is welcomed .

Cheers


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PostPosted: October 18, 2017, 10:44 am 
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Joined: September 30, 2005, 1:28 am
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Location: Sunny-Okanagan, Canada, eh?!
Google 4-link anti squat setting, and look for the drag racing or off-road sites, they have a wealth of information.

For autocross, it is usually a good idea to have very little, if any, anti-squat, as it can negatively affect cornering for reasons I can't immediately remember. I think because it induces "jacking."

Having said that.....

My last suspension (not Locost) had the lower arm mounts adjustable such that they will always stay horizontal at whatever ride height I choose, and the upper arms were adjustable over a 5" or 6" span. I aimed for the instant center (intersection) of the arms to be at the front of the car.

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PostPosted: October 18, 2017, 11:08 am 
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Joined: August 12, 2011, 1:46 pm
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This is what I have drawn up .
Attachment:
assembly.jpg

Attachment:
closeup1.jpg

Attachment:
closeup2.jpg

Attachment:
closeup3.jpg


Should be pretty solid, so I'll have a tough time taking them out if necessary .
Now is the time to add any adjustability to things .
I was thinking of another set of holes on the front mounts to be able to tilt the arms .

P.S. The real question is will it help on the track ?


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PostPosted: October 18, 2017, 12:48 pm 
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The voice of reason
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Joined: January 10, 2008, 4:47 pm
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Location: Massachusetts
Quote:
I aimed for the instant center (intersection) of the arms to be at the front of the car.


This would be anti-dive on the front suspension but pro-squat and pro-lift on the rear suspension.

The way I look at this is understand the motion of the axle pin compared to the chassis as it rises and falls. If the motion of the axle pin is completely vertical with no fore and aft motion, it is neutral. If the axle pin moves a little bit forward or aft during it's vertical motion then it has some "anti" or "pro" tendency.

For example if the axle pin moved forward 1/4" at full squat that is saying the force of acceleration has also lifted the chassis forward by 1/4" as part of the work of accelerating.

I think your brackets don't need to completely wrap around the tube. 2 or 3 sides might be stronger because of less welding heat and damage going into the underlying tube. Also there should be a diagonal somewhere, at least on the bottom. In can be inside the box you are building or outside.

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PostPosted: October 18, 2017, 1:09 pm 
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Location: West Chicago,IL
If you plan on using Rod ends, a lot simpler and less expensive is Jack's Rod end mounts. That's what I used. If the br@ckets are located close to the end of the tube, it will get strength from the adjoining tube.

http://www.kineticvehicles.com/brackets.html#suspension
Attachment:
Kineticvehicles.JPG


If that doesn't work for you, try using something from https://www.aa-mfg.com/ . I'm sure they have something that you can use ready made.


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PostPosted: October 19, 2017, 12:22 pm 
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Joined: August 12, 2011, 1:46 pm
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Thanks for the links ! But I'm on a different continent, so Jack's stuff is out of the question .
There's plenty of places where I can have stuff laser cut and bent for a reasonable price .
After not a lot of searching I came to the conclusion that it's a serious topic to "master" a few days before actually building it .
I'll do it the Haynes way and continue to read up on this .
Which program would you suggest, vsusp or wishbone ?

Cheers from Bulgaria .


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PostPosted: October 20, 2017, 12:10 am 
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The voice of reason
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Joined: January 10, 2008, 4:47 pm
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Quote:
This would be anti-dive on the front suspension but pro-squat and pro-lift on the rear suspension.


I said this a couple of posts above and it's wrong, the other stuff I said is right. I don't understand talking about the instant centers of the suspension in side view. Instead of tilting the upper link you could tilt the lower link the opposite way and still have it intersect in about the same place but it would have the opposite effect.

you can measure how much the axle pin moves forward and aft while going up and down. If you then hold a board at that angle and push on the car with a ball bearing or even any ball - you can imagine most of the force pushes the car forwards or backwards. Since the board is tilted though, some of the force will push the car down or up - that's the anti squat or anti dive etc.

If you have a solid axle, the torque of the engine is a large and different effect. Similarly with outboard ( normal ) brakes.

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SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


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