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Learning how to build Lotus Seven replicas...together!
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PostPosted: July 16, 2019, 10:01 am 
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Has anyone using jack's front suspension setup using anti roll bars. I like the way a Caterham does it with sleve attached to the upper control arm that the ARB simply sits on. Checkout Image
Graham


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PostPosted: July 17, 2019, 4:35 pm 
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It a lot like the old beetle swaybar attachment. Mcmaster sells the bar to bend. You make the rest. Lots of people have made or fitted swaybars on their locosts.

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PostPosted: July 18, 2019, 11:21 am 
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Miatav8,MstrASE,A&P,F wrote:
. . . . Mcmaster sells the bar to bend. You make the rest. . . . .


Any special material? I understood just about any steel will do, even mild steel tube or bar. Not so?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

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PostPosted: July 18, 2019, 11:46 am 
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Any steel will do, but some work better than others. I helped a friend make a rear ARB for his TR-4A. IIRC, we used 5/8" 4130 steel. After hot forming it, we had to send it to the heat-treat shop to have it "Normalized".

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PostPosted: July 18, 2019, 1:10 pm 
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Agreed. Nothing special about the grade of steel. Any steel should work. Just be sure to keep well away from the yield point.

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“Any suspension will work if you don’t let it.” - Colin Chapman

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PostPosted: July 19, 2019, 11:04 am 
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Lonnie-S wrote:
Miatav8,MstrASE,A&P,F wrote:
. . . . Mcmaster sells the bar to bend. You make the rest. . . . .


Any special material? I understood just about any steel will do, even mild steel tube or bar. Not so?

Cheers,

I was thinking 4140. Excerpt from here: viewtopic.php?f=38&t=19628&p=244551&hilit=swaybar#p244551

“As far as bar size, the stock miata bar would work well but you need extensions from the frame to reach the bushing locations. Just above and behind the lca shoud fit best. If you want to make your own, that can be locost too. A 4140 rod already hardened is about $50 for 3 feet, shorten to the outside rail width plus 2 inches each side, have a machine shop drill the ends for a 7/16 bolt, fit nylon tube to act as bushings and 1x3x4 aluminum pillow blocks to drill for 3/8 bolts, split in half, then bore to fit the bush od. Fab the ends from tube and 1/8 strip at 45 degrees to the bar.”

Of course, you could anneal the bar by heating to bend it then heat treat but my suggestion is more locost. You could also rework an oem bar though a lot of them these days are hollow and yards won’t resell them since they get tweaked so easy. I said I don’t care if it is bent a little because I will fix it but no dice.

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PostPosted: July 21, 2019, 9:29 am 
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Cars like a Vette will have hollow roll bars, but your average grocery getter will have a bar made from 1020-1025 matl. The bar is just locally heated at the bends for forming and is not heat treated. If you can find a stock bar that is close to the width, and are careful you can weld a multi hole attachment bracket for the linkage. I would look at stock rear bars first, since they are typically smaller dia. If making your own bar avoid tight bends when forming. Davew


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PostPosted: July 21, 2019, 4:00 pm 
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They have hollow bars on cheap cars too. I was referring to my experience with hollow bars on the mazda B platform (90s ford ZX2/ protege).

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PostPosted: July 27, 2019, 11:13 am 
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FastG wrote:
I like the way a Caterham does it with sleeve attached to the upper control arm that the ARB simply sits on.


The Caterham solution is basically a bodge - introduced when the original Colin Chapman design (which actually used the ARB as the front link of the 'wishbone') started to exhibit problems under braking, as tyres improved and grip increased.

Both the original Lotus and the Caterham solutions actually result in conflicted geometry, and only work because of the compliance in the rubber bushes.

They might look neat, but I'm not sure I'd choose them as a 'clean sheet' solution on a new design.


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PostPosted: July 27, 2019, 12:13 pm 
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Graham, it just occurred to me that this setup now puts a spring load on the upper ball joint, or whatever device you're using on the upper end of the upright. I don't remember your front setup. Some use a tie rod end which is not designed for axial loads.

Also, the same advice about putting the "joint" close to the ball joint applies as if it was the main coilover on the lower control arm. Probably not the same forces, but some.

Personally, I don't like the design. But it is simple, and I like simple.

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“Any suspension will work if you don’t let it.” - Colin Chapman

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