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PostPosted: May 1, 2009, 9:34 pm 
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I should have 20 feet of 4130 next week to do the a-arms, FINALLY! I went with 7/8" in a .058 wall thickness. it is .50 lbs per foot, so I think it is a good compromise between strength and weight. Pics as soon as I get it cut up and welded!

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PostPosted: May 3, 2009, 3:02 am 
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Location: Dallas Texas
Just a thought for building adjusters. We use them on the racecar. I ll try and explain it I know a diagram would be better.
Swift racecars (I have DB2) use a piece of tubing with a cap on the end. The male rod end fits through a hole in the cap. The rod end lock nut is used as normal on the bearing side. The trick is on the inside of the tube. An internal (allen) barrel nut is made to fit inside the tube snug fit (about .01 smaller). Its long enough to have enough threads for the rod end or whatever you choose to use and the allen for the adjustment. The cap tube is welded to the arm. Obviously this would not work if the arm is straight to the pick up point. You wouldn t be able to get the allen in to adjust
Adjustment is simple. Undue the tension on the lock nut, stick the appropriate allen in the barrel nut and rotate. Rotate locknut to lock back in place. Gives you infinite adjustment.

Rod end, nut, cap tube on arm, barrell nut.

On the race cars the backside where you stick your allen wrench they are cut on an angle and we use safety wire to secure.

I hope that makes sense. I don t have access to the car at the moment or I would take pictures. I think Carrol Smith mentioned this method in one of his books. I have seen several different racecars with this set up. I ve seen variations on this but the idea is to not have to rotate the the rod end (or other similar component) but rotate the internal nut instead.
Jay
locost in planning.

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PostPosted: May 3, 2009, 10:54 pm 
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Thanks Jay - a picture sure would help...

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PostPosted: May 4, 2009, 9:04 pm 
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RandyBMC wrote:
Thanks Jay - a picture sure would help...


I tried to post the drawing without success. I m not sure how to resize to fit. I sent you a PM with my email. I ll send it that way if you want.
This is a shot of the rear suspension on the DB2. The outer lower link at the upright is the one I am trying to describe. Its used most of the suspension arms for adjustability. The front uses it at the lower ball joint for the camber and caster adjustments. Its a rigid setup with the nut inside of the tube. These cars weigh 1300 pounds (ballasted) and will produce 2 gs in the corners.
http://www.race-cars.com/carsold/swift/ ... 6019lc.htm
This one isnt my car. The only picture on the web I could find.
As soon as I can get access to the car I ll take a few better pictures.
Jay

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PostPosted: May 5, 2009, 1:00 pm 
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I see what you are talking about in that picture, but can't see how they did it. My email is randy@webbmotorsports.com - thanks!

Randy

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PostPosted: May 6, 2009, 1:00 am 
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Email sent with drawing. My apologies. One of these days I need to learn about posting pictures.

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PostPosted: May 6, 2009, 6:03 am 
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Location: snow city - it's wet!
I love the DB2. I had a chance to play with one on VIR (full course) and loved it. I seem to always want more power though, lol.

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PostPosted: May 14, 2009, 8:30 pm 
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After looking at several builds and Westfields, I think I know how I am going to try to do my lower rear arms. I am going to see how cutting off the factory arm ends (where it meets the upright) and using them. That solves the rotation issue I was worried about that CMC uses, and the length of the factory bolt issue if I were to use metric rod ends. I'll post tomorrow when I start the cutting process. This is all subject to change!

Randy

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PostPosted: May 15, 2009, 11:26 pm 
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The a-arm surgery went well! It took some time with the cut off wheel and angle grinder, but I am happy with the results, and now I won't have to worry about binding (even if it is just in my mind), spacers, or using a non-OEM upright bolt. I have to fly for the next four days, but I plan on getting to the rear suspension as soon as I return. I am so happy to be making progress again!


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PostPosted: May 16, 2009, 10:45 am 
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What do you plan to do for the bushings when welding? Push them out before or replace them after?

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PostPosted: May 16, 2009, 11:09 am 
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I was planning on using the delrin bushings from iscracing.net. I haven't replaced them in a Miata - it looks like it may be a bit of a bear. I assume they will press out with a hydraulic press.

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PostPosted: May 20, 2009, 8:34 pm 
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I located the upright and the a-arm upper and lower mounts. I fabbed the a-arms out of pvc tubing, and it all looks pretty good right now. I have to take some pictures.

I also had to tile my lower floor bathroom today, so I managed not to get either project done today.

On mounting the a-arm, I asked a couple questions in a few places. If the heims are mounted with the bolt oriented vertically instead of horizontally, is there still an issue with alignment changes requiring different size spacers on either side of the heim?

Also, if I decide to slot the upper upright mount on the a-arm, do you think I would have an issue with the arm moving once the bolt is tightened? I have used similar mountings with swaybars, and once the are torqued, the bolt doesn't move in the slide adjustment. It seems a simple way to adjust rear camber.

Thanks!
Randy

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PostPosted: May 20, 2009, 9:37 pm 
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I wouldn't worry too much about welding with existing bushing in place BUT they will smoke up. When I worked at Quickor Suspension years ago, bushing removal de rigueur was with a torch to melt/burn them out so we could clean the sleeves and slide the poly bushings back in. That way, no damage to the sleeve. Watch it, very dirty, wear your worst through away clothes. Matter of fact, do it at your neighbor's house :-)
Mike Bynum


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PostPosted: June 2, 2009, 11:36 pm 
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Of course as soon as I posted this I found my post from some time ago...

viewtopic.php?f=5&t=2160



RandyBMC wrote:
Like this:

Image



Don't know if you got this figured out but this drawing of the front suspension of a Reynard Formula Ford/Continental might help.

http://www.gnegy.com/reynard/pubs/84_front_suspension.pdf

Item 35 is the barrel nut and is threaded on the inside. On the Reynard the end of the barrel nut was a hex head, about 3/4". I slides into the lower wishbone then the rod end (37) and jam nut (36) goes into the barrel nut.

It's a wonderful thing that I intend to use some day if I ever get to the point of building one of these things.


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PostPosted: August 27, 2009, 11:41 pm 
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Well guys, I have had to post a "for sale" on my project. It isn't because I have lost motivation, or because I have gotten frustrated, it is my life! I am having to move, sell my house (and my workshop), lose my job, and maybe move overseas. It is just too much. I have posted an ad in the for sale section.

I fully plan on building one - once I have any sort of stability! Maybe I will build the single-seater I saw Chris Gibbs writing a book to build... I can dream!

If anyone has any questions, or if I can still help anyone in the community, please let me know.

Randy

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