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    First time mini rail builders
    #1
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    Howdy all.

    Me and my Dad have started building a pair of mini rails. *We are from Canada and started going down to Oregon and the dunes there when I was 8. *Since then we have built a number of different types of buggies ranging from V6 powered to good old fashioned Volkswagen air cooled. *A few years ago now we met up with Ryan of El Toro sand cars (Actually before he was in the business and was still driving his first mini rail from Short Sand Cars). *He took us for a ride in his rail and we instantly knew what kind of sand rails we wanted. *It has taken us a number of years to come to the point of building with me in mechanical engineering school and my dad busy with other projects, but we have finally started. *The two sand rails are going to be powered by a 1000cc GSXR and a 1000 Yamaha for my dad and me respectively. *We started building over our Christmas break and have now welded together the main parts of two identical frames. *We are now trying to finalize our front and rear suspension designs and our rear axle. *So far we have hours of time invested and are having lots of fun.

    Anyways most things are going quite well, but I did have a few questions to ask you. *I thought of putting them in their respective form topics, but I thought this might be slightly neater for all of you website admin.

    So question #1:
    On the front we are planning on buying a sets of 10" air shocks. *I have been looking around and it seems that Fox and King shocks are the two options for these types of shocks. *I have had plenty of Fox shocks on motorcycles and snowmobiles and feel that I know they should be reliable and well built. *However, on the dune I have seen a lot of people running King Shocks. *Why is this? *What are the positives of King shocks over Fox Shocks. *I have read that King Shocks are rebuildable with no special tools. *Is this not true for Fox air shocks?

    #2:
    We have been trying to figure out a good option for our center carrier for our rear end. *I was trying to figure out a good way of getting some splines and couplers for back there and then to machine my own bearing mounts and everything. *Is there a cheep way of getting splined couplings? *Or what do you guys recommend for transmitting the 160Hp these things are going to be putting out. *I did some simple calculations and found that you would need a keyway well over 3inches long. *I have also read some of the 3000 page bitch about the guy that sells $750 FNR's but found that document no help (haha).

    #3:
    When setting up your suspension how much bump steer is acceptable. *I am having a problem with running the tie rods in between the suspension rails where I get no bump steer. *Although it works in SolidWorks to run the tie rod through the shock, frame or suspension arm, my dad has told me that in the real non engineer world this doesn't work. *I have it set up such that over the course of the travel it steers a total of 1-1/4degrees per wheel. *Is this to much? *What are the usual limits that you experienced fabricators allow?

    Well I think that is what I have to ask for now. *Thanks for reading and responding.

    Grant
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    Re: First time mini rail builders
    #2
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    Here are a few images from my SolidWorks file. *Hope they show you a bit what we are doing. *Note the change in toe as the suspension goes between full release and full compression. *Also give me any ideas you might have on my camber angles. *I read pretty much everything on suspension geometry in the forums before coming up with this
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    Re: First time mini rail builders
    #3
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    Re: First time mini rail builders
    #4
    Junior Member
    Join Date
    Nov 2006
    Location
    Mission B.C. Canada
    Posts
    29
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    Hi Grant. welcome to the site. with your Cad talents i'm sure you'll make a great job of your minis. Just wait till all the experienced guys get a view of what your doing, the real advice starts then. Was curious what part of Canada you are in, BC per chance? Anyways, keep the thread flowing with pictures and updates.
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    Re: First time mini rail builders
    #5
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    Hello Minibugger,

    Yes we are from BC as I see you are too. *I am currently living in Vancouver going to UBC, while my dad lives in Keremeos. *Anyways its good to hear from another Canuck who is crazy enough to be into a sport you have to travel a minimum of 8 hours to ('').
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    Re: First time mini rail builders
    #6
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    do (somehow that do deleted at the end of my sentence above.
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    Re: First time mini rail builders
    #7
    Admin Gene's Avatar
    Join Date
    Dec 2005
    Location
    Soyo, Angola Africa
    Posts
    6,715
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    Hi Grant,
    Ryan and the El Toro gang are a great group of duners and I look forward to you and your dad meeting up with us at the Oregon coast.

    Choosing between Fox or King is subjective. Both are adjustible and rebuildable. One may cost more and that probably influences purchase as much as what your buddy runs on his rig.

    Rear carrier parts are readily available from [url=http://www.shortsandcars.com/feature-product.htm:3rbwj8ia]Short Sand Cars[/url:3rbwj8ia] and others. Other members will chime in on building components and the good and bad of various options.

    Bump steer should be minimal, mine is 1/8 inch through 20 inches travel. Not sure how that converts to degrees. Before reinventing my car it had enormous bump steer and was one of the driving forces for me to radically change my car.

    Your "view from top" pic shows the rack mounting location to be inward to the point where it sits under the A-arm inner pivot point. I take it that this is what your dad is commenting as not real world. My rack is forward of th epivot point and the tie rods run paralell to the A-arms. I've attached two photos to show what I'm talking about. After I put it back together I can get better pictures if needed.

    It looks like you have good camber change and I think your ride height looks good at this point. One comment about shock mounting location will play out when you build the suspension. The comment is to get your shock angle close to 90* at full compression. I'm sure you've read up on that based on your post.

    Keep up the good work!
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    Re: First time mini rail builders
    #8
    Junior Member
    Join Date
    Nov 2006
    Location
    Mission B.C. Canada
    Posts
    29
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    Hi Grant . Good luck on your studies. I work in the Maple Ridge area and our fab shop has a complete machine shop, mandrel bender, laser cutting and powder coating capabilities so if you ever need a hand with anything, let me know.
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    Re: First time mini rail builders
    #9
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    Gene

    Thanks for your reply. *I have been looking at buying fox shocks off ebay through Down south motorsports. *He also had King shocks for $11 more per pair so I was just trying to fish for opinions. *

    So my bump steer with my current setup would be about 1/4" with my 22" tires, but with a set of 28" tires it would go up to 3/8". *When you look at it that way its probably a bit more than to much. *The current configuration of the steering all does work with no Tie Rod interference, its just that it has to much bump steer. *I was having problem with the tie rods hitting everything when I was trying to run them behind the spindles between the A-Arms.

    On the shocks, I have been trying to get them closer to 90deg but I have just been having trouble with if I move them in any further at the bottom it jacks the amount of travel I am getting. *I already have 18" of travel with short arms in comparison with other 18" travel rigs, and it just gets crazy with larger angles. *But I'm still working on it.

    Thanks for you input!

    Grant
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    Re: First time mini rail builders
    #10
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    Hi everybody.

    I have finalized the front suspension I believe. *What I did to get rid of some of my bumpsteer is I moved the center of my spindle down on the king pin shaft (I hope that makes sense) and moved the top shock mounts up. *By doing this I decreased how far my suspension goes downat full release, and increased the height it goes to at full compresion, while keeping the same ride hieght and full compression clearence. This has decreased the amount of camber change I have to go through as my suspension is not going to as extreme angles. *Now with less camber change I have much less bumpsteer. *Between 1/16 and 1/8 per side. *I also painted up the frame in solidworks to make it look way more dope, and added a concept (Far from actual design) back end. *I will attach pictures. *Hope you guys like it.

    Grant
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