Arachnid Build, ... or is it! (Highly Modified)

[Silvergrizz]

*** One question for those that have the Arachnid plans before I start welding, if I may;

In the picture below, ... I cannot seem to find any dimensions for the placement of the (4) 1.250" square tubing spacer upright parts #FM03-90 on parts # SB12-9045, are these just placed under the bushings?

Bill, I looked over my plans when I got home from work last night and it appears to me that the uprights are centered under the upper bushing brackets. I base this on the diagram on page 35. No measurements are given. Makes sense for strength to place them there.

 

[Bill CNC]

*** One question for those that have the Arachnid plans before I start welding, if I may;

In the picture below, ... I cannot seem to find any dimensions for the placement of the (4) 1.250" square tubing spacer upright parts #FM03-90 on parts # SB12-9045, are these just placed under the bushings?

Bill, I looked over my plans when I got home from work last night and it appears to me that the uprights are centered under the upper bushing brackets. I base this on the diagram on page 35. No measurements are given. Makes sense for strength to place them there.

Grizz,

I saw that also, ... but being a Prototype/Model Maker for many, many years, ... you cannot really trust a plan. If you look at that same picture, ... and it has the bushings shown to be welded to the rails, part # SB12-9045. It even notes in the plans to space the bushings the same as the measurement of the spindle.

However, ... If you look at page #60 at the center top photo, ... It shows NOTHING like it does on page #35. That picture clearly shows It being down a good .750" down from the top surface of part # SB12-9045. He has normal spindles on their so we will see.

This is why I asked. I thought as I am going to hit the half century soon, ... my eyes were willing to admit it before I was.

I guess I will find out today, ... as I have lot's of goodies showing up. I will have to check what the overall height of everything is once the spindles and rod ends are thrown into the mix.

Bill

 

[Bill CNC]

To the Arachnid Builders,

Just thought I would throw this out there, ...

Since I decided to make the Arachnid with IRS, ... I decided to make the rear A-arms out of 1.250" sq tubing. I will not need these extra parts that I machined from 1." stock to mate to the bushings, ... part# AA02-90N. These are the (8) pieces that are machined with a notch in them for mating to the A-arm bushings for the front end suspension on page # 46 of the plans.

I machined the notch on a mill with a 1" end mill cutter and I can supply pictures if you would like.

If anyone that is building an Arachnid want's them, ... maybe we can barter something for them. Better yet, ... they will be FREE (less actual shipping cost) to the person that can help me figure out and finalize all the parts I will need to figure out the ISR.

Now THAT'S a deal!

Pm me if your interested.

 

[Silvergrizz]

Grizz,

I saw that also, ... but being a Prototype/Model Maker for many, many years, ... you cannot really trust a plan. If you look at that same picture, ... and it has the bushings shown to be welded to the rails, part # SB12-9045. It even notes in the plans to space the bushings the same as the measurement of the spindle.

However, ... If you look at page #60 at the center top photo, ... It shows NOTHING like it does on page #35. That picture clearly shows It being down a good .750" down from the top surface of part # SB12-9045. He has normal spindles on their so we will see.


This is why I asked. I thought as I am going to hit the half century soon, ... my eyes were willing to admit it before I was.

I guess I will find out today, ... as I have lot's of goodies showing up. I will have to check what the overall height of everything is once the spindles and rod ends are thrown into the mix.

Bill

Bill, I measured my spindle, it is 2.45" and I also discovered not cut parallel.. I am out my league here, but if the double A arms are supposed to run parallel, then yes, the top mount would need to be lowered. Given that the riser block is 3" and the spindle is only 2.5, your assumption of a 3/4 inch drop of the top bracket seams correct. Also noticable on Page 65.
I must admit, I am starting to get confused, I thought your original question was in reference to the fore and aft placement of MF 03-90, not the positioning of the upper spindle bracket. Hang in there man, we'll get this all figured out. I just cut the front suspension pieces today, but not the a-arm pieces. You are ahead me on this part.

 

[Bill CNC]

Well I guess we will know soon enough. I tac-welded everything but those (4) uprights and the (4) bolts for the rod end to screw into the A-arm. Seems the nut's I bought to weld in on the end, ... need to have the threads chased with a die. They wont screw on, but they screw on to the Nylon insert nut's bought for the bushing bolts.

I will tac-weld the bushings to the A-arms and then the spindle brackets to the rest of the front end. I have the final parts for the front end coming, well, ... tomorrow and Wednesday. I will add the rest of the goodies and see just what to do with those uprights in the end.

Anyhow here are a few pictures.

 

[The_Machine]

Wouldn't want you to redo something this pretty, so I'm just checking - If the rack doesn't shorten down enough, shim out the upper wishbone mounts so the tie rod pivots are in line with the upper and lower wishbone pivots, then shorten the upper wishbone. If you don't, the wheel(s) during travel will toe out or in. (can't remember which in case of rack being too long) You probably already know this, though.

Love your precision. what's up with all the writing on the parts? perfectionist with old work habits?

 

[Bill CNC]

Wouldn't want you to redo something this pretty, so I'm just checking - If the rack doesn't shorten down enough, shim out the upper wishbone mounts so the tie rod pivots are in line with the upper and lower wishbone pivots, then shorten the upper wishbone. If you don't, the wheel(s) during travel will toe out or in. (can't remember which in case of rack being too long) You probably already know this, though.

Love your precision. what's up with all the writing on the parts? perfectionist with old work habits?

Hello Machine,

Hmmm, ... well since I am new to the Karting world, ... I have no idea what you are talking about.

I made the front area (big square block, steering rack, and bushings locations) are per the plan. They have a functioning kart so I am assuming that the recommended setup it a proven deal.

However, ... if you could further explain it to me, I would sure appreciate it.

 

[Bill CNC]

Well a couple of things on the front I needed to deal with today.

1). Called BMI to try to find a tracking # for my order so I can be sure to be here when it arrives. last time I had to go to UPS at 8:00PM because they needed a signature. Well it turn out they were out of stock on some bolts and they would arrive have them tomorrow so I should bet my stuff a week from then. Agrrr, .. they could have emailed me about this so I wouldn't have to call and say, ... WTF? Anyhow, the gal on the phone was apologetic, ... so I told here it was OK.

I then told her about the issues with the Spindle brackets being of poor quality and the holes were off on (5) but (2) were completely unusable for use as a hinge point, so they are throwing (2) replacements in the box.

Thank you BMI!


2). I found out that Azusa Engineering, is on my way to work!!!!! Looks like I wont be getting my wallet cleaned and pressed by the shipping company's ANYMORE, ... well, ... If I can help it. They just emailed me the current catalog and price sheet. Looks like I'll be visiting them here in a day or so!

3) I modified my modified bushings. I wasn't exactly thrilled with the way the "RED" silicon O-rings were gripping the bolt. I could tell, it was going to be a real P.I.T.A trying to service them so I changed them a little bit.

A). I went with a slightly larger O-ring that the inside diameter was clear of the bolt, and silicon ones were not, they rubbed when threading them on the bolt. The new O-rings are slightly larger in the ID and the OD diameter and they are more chemical resistant than the silicon ones were so I went with them. The bushings are very simple to service now.

Here is a before and after picture for the new O-rings modification.

Another modification I did was to the bolt. I cut a .100" wide x .032" deep groves in (2) locations, to hold extra grease.

 

[The_Machine]

bumpsteer is what i'm talking about. it's very simple to get rid of.

In this picture you see on the left, the upper and lower ball joints with a line going through. On the right you see the heim(ball) joints that attach to the frame. on the left there's already the imaginary line, on the right you can imagine it on your own. You want your tie rod ends to fall as close as possible in these lines or you will get bumpsteer (the toeing in or out of your wheels during suspension travel, not just on jumps and bumps but when loading your suspension or drooping under acceleration or braking) caused by the incongruent geometry.

I can't see the rest of the hubs and spindles or the schematics so I can't know for sure that it is designed out. You just said it's your first go kart and bumpsteer is usually the only problem on most people's first build. But you're mechanically inclined. Just read about bumpsteer and you're sure to figure it out for yourself. (if it's even gonna be a problem)

EDIT: Here I found this. Good read. http://www.mustangandfords.com/techarticles/suspension/mufp_0611_bumpsteer_explained/index.html

Learn about a properly designed suspension setup while you're at it, and you'll see why I'm asking you to heed caution.

 

[redsox985]

That looks great. Even your metal looks good lol it's so shiny.

Machine, all of the writing is how Spider Karts names their pieces. If you label them, they're easier to assemble and identify while looking at the plans.

 

[Bill CNC]

bumpsteer is what i'm talking about. it's very simple to get rid of.

In this picture you see on the left, the upper and lower ball joints with a line going through. On the right you see the heim(ball) joints that attach to the frame. on the left there's already the imaginary line, on the right you can imagine it on your own. You want your tie rod ends to fall as close as possible in these lines or you will get bumpsteer (the toeing in or out of your wheels during suspension travel, not just on jumps and bumps but when loading your suspension or drooping under acceleration or braking) caused by the incongruent geometry.

I can't see the rest of the hubs and spindles or the schematics so I can't know for sure that it is designed out. You just said it's your first go kart and bumpsteer is usually the only problem on most people's first build. But you're mechanically inclined. Just read about bumpsteer and you're sure to figure it out for yourself. (if it's even gonna be a problem)

EDIT: Here I found this. Good read. http://www.mustangandfords.com/techarticles/suspension/mufp_0611_bumpsteer_explained/index.html

Learn about a properly designed suspension setup while you're at it, and you'll see why I'm asking you to heed caution.

Machine,

THANKS!

To be honest, .. at first, I didn't understand, as the drawing is barely readable. I then goggled up "bumpsteer" and I found this; http://www.pirate4x4.com/tech/billavista/PDFs/Bump_Steer_by_Longacre_racing.pdf

After a quick read and it has the same diagram with some verbiage that helped my dense brain wrap around what you were saying. I must say, ... you probably saved my but. I do know the ends on the rack "will" move in more than what I have shown. I will be sure to have the pivot line #1 in the diagram "dead on" the pivot point of the bushings.

Hey, while I have your ear, ... Can you point me in a good direction as to constructing an ISR system? I have seen another post were you were talking about it, but not much was there. I just don't know what components would be required. I'm sure I can construct one, if only I had all the particulars that are involved.

I have seen some pre-made stuff for a $1,000.00 or more and that's just completely out of the question.

Again Machine,
Thanks

Bill

 

[Bill CNC]

That looks great. Even your metal looks good lol it's so shiny.

Machine, all of the writing is how Spider Karts names their pieces. If you label them, they're easier to assemble and identify while looking at the plans.

Yup, ... I had a majority of the parts cut and in a pile. As I was fitting thing together, ... here I was looking for the parts;

I was going through pieces like I was assembling a Jig Saw puzzle, nope, nope, .. not that one, or that one, ... Agrrr, were the hell is it!

So I decided to conform and write the part numbers on the respective pieces. I even went as far as writing what # out of how many. Example; (1 of 4) and (2 of 4) and so on.

It works like a champ.

 

[Bill CNC]

That looks great. Even your metal looks good lol it's so shiny.

I bought it from IMS (Industrial Metal Supply in Burbank Ca. Their stock rotates so fast, ... it has no chance in hell of rusting, well along with all the oil they have on them. Along with that, ... and a little WD-40 on the metal before I put it away, .,. it stays nice and shinny.

 

[The_Machine]

Iindependant rear suspension? that'd be IRS, not ISR. Had me looking everywhere...

It depends what you want in your suspension Bill. Like theo says, single a arms work fine for off road fun karts but if you wanna build something high performance use doubles.

 

[Bill CNC]

Well the rear will be just like the front, with the exception of bumping up the size of tubing I will use. I got the A-arms figured out, it's just everything else (drive line parts) between the wheels that I need info on.

Sorry about the ISR I changed the original post to IRS.

Thanks
Bill

 

[r97]

the main thing youl need for drive line is cv axles. are you cleaning your metal with wd-40?

 

[theo]

Bill if you check out Edge buggies they have a 3D of a rear dual a arm setup using Porsche CVs. now this can get real expensive. The center section is 1 3/8 6 spline shaft (I think you can get it in a 12" length. There are weldable hubs that you will need to adapt the Porsche CVs, sprocket and brake disc to. Check here.
http://www.ggmfg.com/products.aspx?category=Weldahubs&subcategory=Spline Bore

Here is the shaft.
http://www.surpluscenter.com/item.asp?item=1-2938-6&catname=powerTrans

 

[redsox985]

CV axles would be the most reliable without a doubt. I found that Roketa, a good kart company, has used a setup like this. Sizes would depend entirely upon the shocks you use and how much travel they have. It would be driven to a jack shaft with sprockets on each end.

 

[sebastiaan]

Wow very nice work!
You should really use a light powerfull engine on that thing. Something like a Honda cr125 or cr250 dirtbike 2stroke engine

 

[Bill CNC]

ATTENTION: Arachnid Builders

After tack welding the bushings to the A-arms and the bushing mounts to the front suspension block I was able to look at the issue of "Bump-Steering". It seems something is up with the steering rack and the front suspension block. This was pointed out to me/us by "The Machine" in post #26, #29 and #31.

The front suspension block "IF" built to the plans the bushing pivot bolts center to center are 7.750". The 8" steering rack from Desert Karts that the plans RECOMMEND, is 8.250" between the rod ends, ... And that with them screwed in ALL the way!!!

Seems the center pieces part# SB5-45 and the center piece for the steering rack mount of the front suspension block need to be lengthened. Also Part# SB05-30 of the upper shock mount will also need to be lengthened.

As for the amount, ... I will take measurements and post the information later today.

It would be nice to hear from the designer about this issue, ... SpiderCarts, ... but the post about general questions on the Arachnid I made on his forum, http://www.spidercarts.net/forum/topic.php?id=28 ... has gone unanswered for weeks.

Product support, ... Hmmm, ... You decide. :toetap05:

Here are a couple of pictures to show the problem at hand.