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Learning how to build Lotus Seven replicas...together!
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PostPosted: August 23, 2017, 10:29 am 
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horizenjob wrote:
So where are we on the discussions we had a few years ago with cheapracer who claimed and then demonstrated with life size models that the links should not be parallel on a 4-link, but should instead converge slightly away from the axle?
I'd say that it generally seems to be a rather good solution to reducing/eliminating axle binding in one wheel bump and roll.

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PostPosted: August 23, 2017, 10:52 am 
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If brake torque reaction becomes problematic, you can always float the calipers and run a separate link that transmits brake torque to the chassis.

In this configuration brake torque can be harnessed to plant the tire by adjusting the bar angle.

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PostPosted: August 25, 2017, 7:36 pm 
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You have to keep an eye on wheel offset and caliper locating if you plan to use brake stays. FWD-style offsets bury the rotor inside the wheel, so you'd have to have a J-shaped stay.

The stays are *very* effective at eliminating brake hop on motorcycle rear wheels; I imagine they'd do just fine for cars as well.


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PostPosted: August 25, 2017, 8:56 pm 
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Jack, you know i have to ask this don't you!!!

does your car have a limp?

this is all very interesting but will using a limited slip center compared to an open axle change this and removing a bar on which side with an open axle may give different results.

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PostPosted: August 30, 2017, 12:05 am 
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Good point, for those with sufficient power to require differentials of some sort. At 32 horsepower, I think I could have one wheel drive a la 1F2R pedal trikes and I wouldn't feel much difference.

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PostPosted: October 21, 2017, 3:58 pm 
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My car has a three link and the diff is a toyota rwd diff. The PO welded some fairly thick angle iron across the width of the diff horizontal to the ground in an effort to reduce torque twist and flex. The three link pick up points that the PO used create unparalleled arms which do bind at the extreme range of travel.


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PostPosted: October 21, 2017, 11:19 pm 
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Surprised nobody has mentioned Alfa Giulietta (the 750 and 101 series, not the newest one). They used a 3 link system with 2 lower trailing arms and a triangle upper arm attached to the diff using a ball joint. Not a lot of HP going through but it worked quite well. Despite the excessive body roll these cars handled great partly due to the well located rear axle.

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PostPosted: October 22, 2017, 10:05 pm 
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Up to 2014 the Mustangs use a 3-link which works well. ~400ft/lbs on a 3600lb car. I've run one at autoX in Street class and it's very planted.

My Seven also has a 3-link (with ~280ft/lbs and NT01s) which so far works well, but need to finish dialing in the chassis to say for sure.

Cheers.

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PostPosted: October 22, 2017, 11:01 pm 
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Used a 3-link with panhard rod in a dirt track stock car. I wasn't the only one doing it. We all won some races.

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PostPosted: October 24, 2017, 2:32 pm 
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Were the three links parallel? Three with panhard seems a little much. But if it works Ynot


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PostPosted: October 24, 2017, 2:41 pm 
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Well, the two lower links were basically parallel to each other and the ground. The upper link ran from the top of the center center section downward to the frame giving quite a bit of anti-squat. This helped the rear end really dig-in while coming out of the corners. You must remember, this was for a dirt track. We spent more time sideways than anything else.

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PostPosted: October 24, 2017, 4:35 pm 
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Quote:
Were the three links parallel? Three with panhard seems a little much. But if it works Ynot


Three links doesn't mean one link is a triangle, could just be 3 simple radius rods.

I'm not sure about which models but at least some of the Sevens were 3 link. I sw one in a friends shop some time ago that had the third link on the bottom. The outer ends were at the back of the bottom chassis rail and the center went to a fitting welded or part of the rear diff. In that case you would not need a panhard bar obviously. If I remember right that would give a quite low roll center for a rigid axle so it seems like a good solution. Worth looking into.

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PostPosted: October 24, 2017, 10:33 pm 
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Marcus, you are correct in that my 3-link consisted of three simple radius rods, hence the need for the panhard rod.

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PostPosted: October 25, 2017, 4:50 am 
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This is the 3 link Alfa romeo used in the Guilietta series. "Worked great.

http://classicalfa.com/product_images/u ... rear1a.jpg

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PostPosted: October 25, 2017, 8:27 am 
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Does that "A" arm attach to the top of the center section?

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