KTM Spindles

[troybilt]

You guys should check into running the KTM front spindles they are really nice setup, compared to the 450r spindles. Just a thought...

http://i74.photobucket.com/albums/i260/robltc/my%20250r%20Build/DSCN0969.jpg
http://i74.photobucket.com/albums/i260/robltc/my%20250r%20Build/DSCN0968.jpg

[Higgy87TRX425]

Those spindles look alot like my 400ex spindles, I just got done polishing up. Thats what you need to do with those, lol. Are those going on you bike?

[troybilt]

No, not on this next build... I'm borrowing these for another design project. They look very high quality, ...comparing them side by side to the 450r's that I also have... also the scrub is much less on them also. I'll snap another pic and show you. The mounts for the brakes are very close to the same spacing as the 250r brakes....

...its just a thought.... that's all.

[YFZ_Racer42]

With four-pistons calipers!!!!!!! KTM have the best braking system I ever tryed, it would be awesome on a R

[troybilt]

Originally posted by YFZ_Racer42
With four-pistons calipers!!!!!!! KTM have the best braking system I ever tryed, it would be awesome on a R

Thanks a good point! forgot about the KTM brakes...

[YFZ_Racer42]

hey is it SX or XC spindles?

Hans would be proud even if KTM’s are designed by KiskaD…KTM is the only manufacture that continues to further 2 stroke Research & Development. Quality side by side with Innovation drives KTM Engineering.

The spindles like all KTM parts are top quality products…

Carlos.

[troybilt]

Originally posted by YFZ_Racer42
hey is it SX or XC spindles?

SX spindles

[hontrx265r]

the biggest plus here is the location of the lower mount on the spindle. If you know anything about geometry that spindle blows away a 400ex and on top of that I'm def considering a shot at can am spindles on my next build. Got the protrax on this one so can't stray away.

[rustyATV]

Originally posted by hontrx265r
the biggest plus here is the location of the lower mount on the spindle. If you know anything about geometry that spindle blows away a 400ex

How's that?

[troybilt]

Originally posted by rustyATV
How's that?

I think he's refering to the distance vertically from the spindle shaft axis to where the lower aarm mounts. Ideally you want that as close to zero as possible. While also eliminating the scrub, or offset. The KTM spindles do a much better job of that than the 450r's.

Here's a buggy concept where the lower aarm mount and spindle axis is zero and the scrub is almost zero too. I've been toying around with this concept for atv's...

[troybilt]

Incidently enough, here is the 89 250r spindles and 04/05 450r spindles:

http://i74.photobucket.com/albums/i260/robltc/my%20250r%20Build/DSCN0860.jpg

[rustyATV]

Originally posted by troybilt
I think he's refering to the distance vertically from the spindle shaft axis to where the lower aarm mounts. Ideally you want that as close to zero as possible.

I'm not sure I agree with that being a large factor in suspension geometry. Ground clearance, maybe.

Any source on where that's implied?

[troybilt]

I'll try and dig up the source, most I've read is all with buggies, since that's what I've studied most. Again, he may be referring to something completely different than I am... I was just guessing...

[troybilt]

I screwed up on my equation is should be Cosine not sine... Ooops... I'm still trying to wrap my head around around it...

Thoughts?

[troybilt]

I guess you could say it does the same thing that reducing "scrub" does. By reducing the vertical axis has the same effect as reducing the scrub.... does that make sense? i.e. reducing scrub radius...

Straight from Can Am:


...enables placement of the ball-joints and kingpin axis deep inside the wheel for reduced scrub and steering kickback, as well as self-correcting behavior under hard braking...

[troybilt]

More from Can Am:

Short Spindle Length
The spindle acts as a lever on the steering ball joints. The longer the lever, the more kickback is transmitted to the steering when the wheel hits an obstacle. With a long spindle lever, small impacts are felt as annoying kickback, tracking in brake bumps requires steering corrections, and bigger impacts take a toll on a rider's wrists. The DS 450’s short spindle lever reduces the negative steering feedback, providing a more confidence- inspiring ride.

Longest A-arms Possible For A Given ATV Width
When a double A-arm suspension travels up and down, the wheel moves in and out, in a "butterfly" motion. A short A-arm results in a pronounced arc and produces a significant amount of scrub. This sideways movement of the wheel causes loss of tire lateral traction and makes the vehicle dart from side to side in whoops sections. The DS 450 has longer A-arms so the radius of the arc produced by the A-arms is larger, resulting in less scrub – or outward movement of the wheel. The result: more predictable and precise handling.

Negative Scrub Radius
When braking, there is often a difference in grip between the two front wheels. This difference sends the ATV pivoting around the wheel that has more grip. This effect is amplified by a positive scrub radius, because that wheel is also being steered outward by forces acting on the tire – the positive scrub radius acts as the lever turning the wheels out around the kingpin axis. However, a negative scrub radius will cause the wheel to turn in under braking loads. So the turn-in effect fights against the pivoting motion of the bike around the front wheel that has more grip. The result: self- correcting behavior, providing the confidence to enter corners faster, and brake harder and later.

[rustyATV]

That image doesn't correctly describe what scrub is, or how it relates to the Can Am descriptions. A moment (torque) is a force times a perpendicular distance. What's labeled "scrub" is just the perpendicular distance component of the moment. The vertical offset isn't a factor in a moment.

Scrub is the tire sliding across a surface during the action of the suspension in two instances.

One, is lateral movement of the tire (actually, I'm not sure this is called scrub, but I'll have to look into it). Longer suspension arms move in a larger radius, which results in less lateral movement of the tire in droop and rebound. Basically, the track width stays more constant, but this doesn't have anything to do with the spindle.

The other type of scrub deals with turning the tires and is the distance from the point where the center line of the tire meets the ground to the point where the line of action of the top and bottom ball joint meet the ground.The vertical location of the lower ball joint isn't as much of a factor in this as is the relation between the upper and lower ball joint to the spindle (kingpin inclination).

See here:

http://en.wikipedia.org/wiki/Scrub_radius

What's important to note is that scrub radius is determined by the entire spindle/hub/wheel/tire assembly, and not the spindle itself.

The only things I see the lower ball joint position affecting are ground clearance (actually an important factor in an off road vehicle) and "jacking", which is the lifting of the chassis as the vehicle corners. See Chevy Corvair or, in a little shameless self promotion, watch the BajaSAE vehicle in the below video at 2:40 as it does the 270 around the tree stump. See how the car lifts up and picks up the inside tire.

http://www.youtube.com/watch?v=x9yPhFqxmBI

[troybilt]

Originally posted by rustyATV
That image doesn't correctly describe what scrub is, or how it relates to the Can Am descriptions.

I have scrub offset labeled correctly, I just didn't include the offset of the hubs, wheels, etc... SINCE the topic of this thread was spindles... the vertical component of the moment equation (i.e. vertical offset in my mind is valid in the calculation) cause the Force P does not always act on the tire in the vertical direction, if the tire hits a bump on the bead of the tire for instance, so P would be at some angle to the tire... In a perfect world on flat pavement, I could see where the vertical offset could be omitted in the calculation. I should have added an angle in the drawing...

Anyway, if you see it differently that's cool...

[hontrx265r]

Yes you guys are on the right track. Thats exactly what I was getting at with scrub radius. A friend and I have also been after the idea and plan to build an aarm/spindle setup, that basically takes what they've learned in trucks and apply that to quads. In reality the factories have never really done much with changing the front end of quads (except canam's attempt to step forward) Now I've also thought about the fact that I'm not sure if quads even have enough travel to really take advantage of the idea. But in theory its better... and well nothing else to do might as well make some ****.

[Roach250r]

The tie rod mount on the KTM is on a different angle than a 250r 400ex 450r.
Post a picture of them side by side with the tie rod mount showing. What type of ball joints and tie rods are you going to use. You might have a problem with the tie rods running out of travel before full compression or rebound.

[troybilt]

I'm not going to use them myself, I'm using them for a totally different project, I just thought I'd show the differences bw. the spindles...

[YFZ_Racer42]

I found a set of spindles, calipers, hose, master cylinder, hubs and disc for 250$... I'll try them on my bike and see if it's a great set-up

[cdrookie]

my buddy has a 505sx. was racing up at ashtabula and got tagged in the front wheel on the 1st turn, result? a bent spindle.

i'm not saying they're weak, i'm jus sayin...

[JM317]

I also own a KTM 525XC and the spindles rub the front brakelines on the stock setup, they've formed a small groove on my spindles and I'm not the only who's had this problem with them. Just wondering if they would do the same on a 250R?

[troybilt]

I'm simply comparing spindles ktm vs. 450r vs. 250r... when you are comparing scrub on spindles, all else constant, hubs, tires, wheels, then my scrub dimension is valid... I'm not designing the entire front end suspension with a quickk sketch from paint... I think I've mentioned that several times.... And yes the cosine is used. Its not hard, when a load is applied at an angle, you have to break it into the vertical and horizontal components, i.e sine and cosine... i.e. trig... I drew the load vertical so if you using my drawing as gospel then yes the consine is not valid as you stated, cause it the total load is vertical... I do free bodies daily that's my job. You right there is an inclination, and many other factors... not mentioned... I drew that in paint not CAD... I was NOT!!!!!!! drawing the free body to calculate the entire suspension, I was only using that drawing to illustrate what I thought hontrx265 was refering too, and I made the mistake of adding too much on the drawing without drawing them perfectly in CAD you asked the question.. GEEZUS man!

One thing we do agree on is there is alot more than the design of the suspension than the just the spindles... not arguing there.... The argument is whether the vertical component makes a difference or not. I say it does, you say it doesn't... THAT IS ALL I WAS TRYING TO CONVEY!!!!!!!!!!!!!! doesn't look like you're going to get it... so this conversation is done. thanks for ruining my thread.

[rustyATV]

Sorry, was just trying to get to the bottom of things.

[troybilt]

No I made the mistake of posting a picture that was not accurately drawn. I was in a hurry and threw it together and probably confused everyone more than it helped illustrate, => poor judgment on my part.

I was just irritated when you said I was using cosine "wildly"...

[jcs003]

to TRY and simplify a discussion that could get further out of hand. if we break it down simply, weight is the factor a well engineered front end suspension is attempting to combat. lightening the front end components while utilizing the the info we already know will improve the overall handling charastics of any machine.

another thing alot of people dont consider is a big factor on front end handling characteristics is the ratio of front to rear. we know they spend massive amounts of time and money in the automotve racing industry to get the ratio as balanced as possible.

[All250R]

On a side notes with these later model spindles... Rusty/Marc a while back maybe on youtube made reference to the lack of ackermann in the spindles of the 450R and it looks at rough glance that the KTM's version is similar.

Do you guys have any opinions on the practical use of either style? I've always thought the 250R style worked well for everything I've thrown at it...

[troybilt]

Doesn't decreasing ackerman (i.e. anti-ackerman), help with push in the hard corners, I read that awhile back? I thought that was supposed to give the outside tire more bite in the hard corners. ...I maybe all wet on that as usual...

[jcs003]

in this article they talk about the LTR spindles...whats the benefit?

http://www.facebook.com/l.php?u=http%3A%2F%2Fwww.atvriders.com%2Farticles% 2Fmoto-xperts-2010-atv-engine-builder-race-shop.html&h=2c38c