Front Spindle Angle or Position

[worldwidewalt]

Hi,

I've noticed alot of different front spindle bracket positions on various barstool racers. Some are straight up and down, some are tilted back at the top, some arerotated toward the rear and some are a little bit of each! What are the best positionsand angles for the the front spindles and why? Any input would be greatly appreciated.

Thanks,

Walt

[Mike Bean]

When I built my bar stool racer I cut the ends at 25 degrees and faced the angle to the back of the bar stool racer. If you cut at more than a 25 degree angle you then run into the problem where the cut is larger than the spindle brackets width and you can not weld it correctly.

As for why there is an angle involved... I never really put much thought into it, I would assume it has to do with positioning of the steering rods and how much the actual spindle can moved inward before the spindle hits the spindle mount.

At 25 degrees I have all the steering I can possibly get left to right without the spindle hitting the spindle mount. This really allows for steering with pretty much any wheel size.

As for mounting the spindle mounts. I would suggest you have your bar stool racer on the ground with the back wheels on and the frame level from front to back. Now assemble the wheel to the spindle and the spindle to the spindle mount. Then place the spindle up to the frame were you are going to mount them and be sure your wheels are straight and the spindle mount is square.

Below is a photo of a bar stool racer that I was setting up the front spindles this past weekend. It is pretty self explanatory.

Hope this helped...

[RUBICON]

This is an area that I am interested in also. The max speed I am geared in for is 40mph. I have a digital bicycle speedometer ( under $10 @ Wallmart ). At this speed the stool is a handfull on very smooth pavement. I need advice on caster and toe setup. I would expect that most kart guys use a setup for cornering with your but 2" off the ground and I doubt it would be the same for stable straight line handling. Any thoughts on this?

ps: Ackerman geometry is a subject in itself...any advice on this?

[stool-sample]

I used racing heim joints and blocks. You can set it anyway that you want and use the heim front end to adjust castor and camber (mailto:castor@camber)

[RUBICON]

Thanks for the pic...I looked @ this closely @ a kart shop..I have the same conclusion as you stated...you can get precise setup....I learned a few things by trial and error...Funny thing...I asked a few kart guys about steering setups and they act dumb about it and I can't believe that...the only thing two said was to use toe-in...and ironically I found toe-out to handle more stable...As I said once " the setup is different if you need to turn @ speed in corners with your butt 2" off the ground than doin 40 on a straight sittin 30" in the air"....

What is your caster set @?
Is your spindle axle straight or angled down requiring the kingpin to slant in?
What is your toe set like?
What are your experiences with speed?

[stoolpigon]

I'm also very interested in hearing what people are running for castor and camber. I'm going to be welding on my spindle mounts so I only get 1 chance to get this right.

I've been doing some research on steering geometry and I think the reason you're seeing better handling with toe out is that the AZUSA spindles most folks are using has no ackerman so toe out helps the inside tire turn.

[Mike Bean]

stoolpigon,

I am not an expert on steering geometry, but after you weld the spindles, you can still adjust the tie rods in and out so you can adjust the toe in or out.

For the spindle position up or down, I leveled my frame with the back wheels on and then welded the spindle mounts so the tires would track on the whole foot print. This would allow the tires to ware evenly.

I think the toe adjustment is the most important, but as for the spindle mounts, I would just make sure the tire is flat on the ground.

I have a thread in here which shows and explains how I setup my spindles. I put the tires on the spindles like they were assembled and then matched them up to the frame to where the tires were square with the ground.

Here is the link to the post I mentioned. Read the second post down.
http://barflyracers.com/showthread.php?t=21

I just noticed the link is for this thread... :eek:

mbean
:hot:


I'm also very interested in hearing what people are running for castor and camber. I'm going to be welding on my spindle mounts so I only get 1 chance to get this right.

I've been doing some research on steering geometry and I think the reason you're seeing better handling with toe out is that the AZUSA spindles most folks are using has no ackerman so toe out helps the inside tire turn.

[stoolpigon]

Thanks Mike. I saw your post but I was thinking that people were using jigs and protractors to get precise castor and camber angles, similar to the way a car is aligned to precise specs.

I guess I'm overthinking the problem, I was planning to machine a jig on my friend's mill to precisely hold the spindle mount relative to the crossmember while I weld it. I guess that's not really necessary. I've got plenty of those red triangle magnets from HF so I guess I just saved some time.

[Mike Bean]

Stoolpigon,

I run my bar stool wide open (about 40 mph) and I was not even that precise with the toe adjustments and it handles fine.

I have read were other people say that if you run a small steering wheel on the bar stool, it can make it a little more difficult to handle at speed. I used the simple T handle approch made it about the same with of the frame and it handles great at speed.

It's just a barstool racer, don't worry about being exact like a car.. :smash:

Mike

[webfooted]

May I suggest that the easy way to set the kingpin angle (caster) is to draw a line thru the kingpin bolt. Where this line touches the ground should be aimed at the leading edge of the tire contact patch. This will give you directional stability. If this line touches the ground ahead of the tire patch at low speed the steering will flop over at low speed and be very directional at high speed. If this line touches the ground in the middle of the tire contact patch or toward the rear then the steering will be erratic even at low speed and at high speed it will become almost suicide. One other thing, the larger the tire the larger the contact patch, so you see that tire diameter will make a differance to your handling. HTH.........Terry

[RUBICON]

THANKS for the reply...on the subject of Ackerman....the spindles don't create the Aackerman geometry..what does is the way the tie rods are attached to the pitman arm ( bracket )..example..if you have a single point where BOTH tie rods attach you have no Ackerman...this results in both wheels being at the same angle when in a turn...If you have a pitman arm with 2 attachments lets say 1" apart then when the steering is turned the inside ( of the turn ) wheel will turn in at a greater angle than the outer wheel....check me if I'm right...surf for "Ackerman"...you will get a better explanation I am sure....

[RUBICON]

I did what you are planning to do...I used welding magnets to set the kingbin tubes...but if you have a spindle that is not designed @ 90 degrees ( I have a kart spindle that has a slight angle like positive camber ) and when you allign the spindle horizontal the spindle will effectively increase camber or decrease camber in a turn...I guess this is an asset when set properly to load the outer wheel in a turn....all I have to offer is that whatever works is important @ high speed....we will all pay for poor judgement when a guess fails....for me ...I still fear the day...and hope it never happens...that a slight twitch puts me over the bars at speed on asphalt...I did several times about 30 years ago...I healed faster then....A good "ENDO" as we used to call then would put me six feet under or at least in disability if I survived.....crazy stuff.....you know now that I think of it...most guys I read about are not kids if you catch my drift....be safe...there are lots of crazy stuff left to do yet...

[RUBICON]

WOW! someone with experience..I am an old...and I emphasize old...bike mechanic...I put myself thru college wrenching bikes in the late sixties and seventies...I watch all the bike build shows and it while all is very interesting...some of the stuff that is being built is for looks parked at a curb...not for riding...we called it "rake and trail"...the exact same principal you described...and it is the Bible.....If anyone doubts it watch a streached chopper make a intersection turn...it's a hoot!...both feet out like training wheels...I know from experience and have made money twice...first chopping to a customers request and second when I cut it up and reduced the rake....bondo...repaint..."told you so! ".....great stuff...life is an adventure ...ENJOY THE RIDE

[stool-sample]

http://www.compgoparts.com/Technical/ This site here tells alot about chassis and how they work. Its helped me a bunch. Im sure it will help others here as well. Glenn

[Guy]

Here's a visual on Ackerman....
http://www3.sympatico.ca/dhaughey/ack1.htm

[sniffles]

I used racing heim joints and blocks. You can set it anyway that you want and use the heim front end to adjust castor and camber (mailto:castor@camber)

what are blocks? i see they are in the predator spindle kit on your site but dont understand how they work. thank you.

[Ironfist104]

I put plenty of caster It drives just like a car let the wheel go and it straightens out by it self at low speed ya can go with no hands....

1042

[sweav]

When I sat my front end up, I put in 15 deg caster and 0 camber. Set up the ackerman, theres a thread in steering about how to get this set up right. It handles great, if your running a live axle, the caster will put the wheight on the front wheels and will lift one rear wheel slightly to let just one wheel drive through turns, this way your not fighting both rear wheels driving through turns and will turn alot easier. Ironfist is right, with the cater setting the front wheels will always center themselves.

[RUBICON]

I like the suspension design...simple but independent...send more pics as you detail it...GOOD STUFF!....remember "LIFE IS A JOURNEY...ENJOY THE RIDE!"

[monkey-1]

I wonder with the suspension do you get any bump steer? Thats my main concern with building front suspension onto a BSR.

[Ironfist104]

I wonder with the suspension do you get any bump steer? Thats my main concern with building front suspension onto a BSR.
I made it really rigid its just enough to take big bumps but as for bump steer hardly it has to be on hell of a bump....if ya hit a bump that big at that speed u'r toast anyways...lol

[RUBICON]

Monkey-1....make a sketch.....start with the center point of the pitman arm of your steering shaft....now draw a line to the end of the tie rod to your spindle......now sketch the lowest the spindle will be.....now sketch how high the spindle will be...maybe 2 inch range at max....now....calculate how much the radius of that range changes......so little it will not matter....think about it...

[RUBICON]

Monkey-1....make a sketch.....start with the center point of the pitman arm of your steering shaft....now draw a line to the end of the tie rod to your spindle......now sketch the lowest the spindle will be.....now sketch how high the spindle will be...maybe 2 inch range at max....now....calculate how much the radius of that range changes......so little it will not matter....think about it...

[voodoo_stepchild]

Most Karts run what is called a 10 degree setup (excluding european karts). The idea on a kart is you want the spindles to twist the frame if you will. Karts are designed to "flex" from corner to corner. When your steering is correctly setup and you make a turn, the tire and wheel on the inside of the direction that you are turning will also drop down. IN other words, the tire is lifting the front inside corner of the chassis up and forcing the chassis to flex and weight the outside tires fron and rear. By setting the spindle bracket back 10 degree and or setting the king pin back 10 degrees (towards the inside of the chassis) this will give you this effect. HOWEVER!!!!!!!!! wheel spacing and chassis play a huge role in all of this working together. If your set up wrong the front end will "push" or simply slide straight ahead with the wheels turned one direction or another. I will post some pictures from my tony shifters so you can see what I am talking about

Voodoo:cheers:

[elvergon]

What i´ve understood about ackerman and the easy way to go is like in my pic. You should have all your barstool built. Then when positioning the rod ends, you should "draw" an imaginary line from the spindle bolt to the half of your rear axle (shown in red), AND the position of your steering rod (shown in yellow) should be over this imaginary line. That will complete the ackerman angle.

[BAR-TAB]

When Im doin @25-30 its all fine, but as I punch the gas and increase speed, I feel {every couple of seconds or so} a slight pull to the left and right. Its a pretty uncomfortable feeling. What should I do?

[Ironfist104]

When Im doin @25-30 its all fine, but as I punch the gas and increase speed, I feel {every couple of seconds or so} a slight pull to the left and right. Its a pretty uncomfortable feeling. What should I do?


To do this the easy way make yurself a stick with two pieces of stiff wire taped to the end somthing like clothes hanger......then ya make them so ya can slide the wire in and out (telescopic) Now ya got a primitive alingment tool......place the stick between the wheel at at rear part of the rim then at the front ,while adjusting the tie rods....till ya get them both at the same distance front and back....now alll ya got to do is make a bit of toe in usually 1/4 in is plenty may be even too much.....ya going to have to experiment.....hope this helps....

[walkinwounded]

Well another friend of mine built a cart and he useda rack and pinion out of a NEON you want to talk bump steer,I used to be a wrench until my back surgery's( 2 in 10 weeks ) no my brain just designs and my aother buddy does the wrenching for me.I have a old school wheel adapter but it is too big.If you want to make it really close.Go to a carquest storethey have a magnetic scale that sticks to the hub,and it has a dial so you can adjust postive or negative.Really miss wrenchin' but I can't wait to ride mine ,back brace and all.Goin' to just giver.......

[VashRazr83]

I'm to lazy to read the whole thread, but this idea on your front wheels is quite simple and not worth all the stress. The idea is just like a stock car, not a go-kart, you need to tilt the spindle mount slightly toward the rear a few degress or less then 10, mine are at 8 degrees, and then slant your tires top toward the center of the frame just enough so when put against a straight edge with the back tire alligned the thing is just slightly off, this will allow your tires to become any supension you might need, and it will go straight as an arrow at 34 mph*i've done this countless times* and to get mine up on 2 wheels, you have to go into a corner at max speed *34 mph* and this is due to both tire pressure, and the way I have it set up.

Hope this helps some for anyone who is clueless on caster and camber and don't want to look it up