E-ticket ride

[bdkw1]

Rear tires, 325-60-15?

[yoshi]

[quote=HarveyMushman\";p=\"18170]

Originally Posted by "Gene\";p=\"18162":1oab3w7j

Harvey,
Welcome to the site.

The Sand Sports article was good reading. Iahad Scott make the same modifications to my engine. Your experience with that many reliable trips is great. Great looking car plus the dual sport idea is great.

You mentioned Ackerman in your post indicating that you made some modifications to the front suspension. Please describe what you did to achieve the desired geometry. How do the modifications change vehicle handling characteristics?

Thank you Gene. *Ackerman geometry is two straight lines (one for each side of the car) intesecting the center of the outer tie rod pivot (heim, etc.), the center of the vertical axis between the upper and lower spindle pivots (ball joints, heims, etc.) and the center (or virtual center) of the rear axle. *So you have two lines in a V shape, one for each spindle going back and meeting at the rear axle center point. *If your tie rods are behind the axles then the outer tie rod pivots would be slightly inside the spindle pivots. *If your tie rods are in front of the axles then the outer tie rod pivots would be slightly outside the spindle pivots.

Ackerman causes the inside front wheel to turn in a slightly tighter radius then the outer wheel so that the center of the turning radius is at the same point for each wheel. *This improves the handling characteristics in two conditions. *The first condition is driving around a corner at a slow enough speed that you are not drifting. *So when you are driving around a right hand corner you are steering right. *Ackerman (with exception to toe in or toe out) prevents the front wheels from scrubbing or creating friction that will slow the vehicle down. *The second condition is driving around a corner at a high enough speed that you are drifting (counter-steering). *So when you are drifting around a right hand corner you are steering left. *The outside front wheel has more weight on it than the inside front wheel thus it is doing most of the steering. *For this counter-steering while drifting or sliding around a corner Ackerman gives the outside wheel quicker steering response allowing more precise control to hold a steady slip angle through the turn. *Increased spindle caster increases the effective weight on the outer front wheel while counter-steering thus complementing the Ackerman effect.

Basically, when set up properly Ackerman helps make you a better driver.[/quote:1oab3w7j]Gene already knows what ackerman is, I believe he was asking you what modifications you made to the stock spindle to achieve it. *Did you start from scratch or just modify the old ones?

[yoshi]

hey Gene, just noticed your sig that says "transworks diff, tested by Yoshi"

You might want to change that to "currently being tested by Yoshi" since it's going back in my rail for the 7th. time next week to see if it will finally hold up.....lol

[Bugpac]

also, on a dirt car, from what we have talked about here before, ackerman is useless...how often when you turn are your wheels pointing in the direction you are turning? anyway there is 2 or 3 different threads on each suspension geometry factor, that has numerous iopinions etc, btw car looks good to...

[Gene]

Harvey,
Thanks for the explanation, plenty of folks will benefit from your description.

Yoshi is right, I'm also interested in what you actually did to the suspension both front and back. Any details and pics you can provide will be very helpful to other builders.

For example some members are buying SSC frames without suspension. Your knowledge if shared could help their cars perform well.

Bug is right too - there has been lots of talk about Ackerman and whether or not it matters in dirt. I say it can't hurt. I can see with my build that it is correct so I expect to benefit.

I remember reading that you built the bearing carriers for the 5 link. I wanted Sand Sports to show some good detailed photos of the suspension components. Ditto for front spindles.

[HarveyMushman]

Originally Posted by bdkw1\";p=\&quot

Rear tires, 325-60-15?

BF Goodrich Mud Terrain Radials LT325/60R15

[HarveyMushman]

Originally Posted by yoshi\";p=\&quot

Gene already knows what ackerman is, I believe he was asking you what modifications you made to the stock spindle to achieve it. *Did you start from scratch or just modify the old ones?

I just modified the Sandbullet spindles by moving the tie rod end mounting point outward to where they lines up with the spindle pivot and the center of the rear axle.

[HarveyMushman]

Originally Posted by bugpac\";p=\&quot

also, on a dirt car, from what we have talked about here before, ackerman is useless...how often when you turn are your wheels pointing in the direction you are turning? anyway there is 2 or 3 different threads on each suspension geometry factor, that has numerous iopinions etc, btw car looks good to...

Thanks bugpac for nice comment on car. *Yes, lots of 'opinion' on off-road suspension geometry. *Here is some more of mine on Ackerman (just opinion but based on experience): *In pure deep sand I agree that Ackerman is almost useless. *However as the surface gets harder I feel that Ackerman becomes more effective, somewhat proportionally. *Think of rally cars (which is how I drive my buggy), they have varying terrain from pavement to hard pack dirt roads to softer dirt roads. *Because my buggy is not a sand rail but rather a dual-sport I prefer having Ackerman.

[HarveyMushman]

Originally Posted by Gene\";p=\&quot

Harvey,
Thanks for the explanation, plenty of folks will benefit from your description.

Yoshi is right, I'm also interested in what you actually did to the suspension both front and back. Any details and pics you can provide will be very helpful to other builders.

For example some members are buying SSC frames without suspension. Your knowledge if shared could help their cars perform well.

Bug is right too - there has been lots of talk about Ackerman and whether or not it matters in dirt. I say it can't hurt. I can see with my build that it is correct so I expect to benefit.

I remember reading that you built the bearing carriers for the 5 link. I wanted Sand Sports to show some good detailed photos of the suspension components. Ditto for front spindles.

Gene,
Here is pic of modified front spindle. *Since my tie rods are forward of the axles all I did was move the tie rod end mounting point outward to get correct Ackerman.

The next two pics are rear suspension. *First my disclaimer, I am not a suspension specialist. *I used to road-race on pavement at Laguna Seca, Riverside (that dates me), Willow Springs and a few others. *Some sports cars but mostly in Superkarts which don't even have moving suspension components (although proper frame flex was critical). *I am a mechanical engineer with some machining experience and learned suspension from Carrol Smith which is primarily for road racing not off-road racing. *With that said, road and off-road suspensions are different. *Basic things like camber require similar geometries but for long travel it can be more complicated to get a specific camber travel over a large vertical radius.

I am not going to go into all my details and drawings but they did include an interative process. *I can say that if you know Solidworks CAD it can be very helpful in suspension design and travel simulation before cutting metal. *As for the specific camber arc, like bugpac stated there is alot of opinion. *I created a compound camber arc to my likings.

Sandbullet has gone from 5-link to trailing arms on their newer sand cars. On the stock 5-link Sandbullet frame the upper links were longer than the lower links creating reverse camber. *I changed the mounting points for the upper links to be shorter than the lower links. *I made the parts from 4130 and had them TIG welded. *The photos have 'red' circles at the stock mounting points and yellow' circles at the new mounting points. *The lower link mounting points did not change, I just circled them so' you could see the relationship to the upper mounting points.

I did not make the rear bearing carriers, they are Sandbullet. *I made caliper mounting brackets and had them welded to the carriers. *I did make the rear hubs.

[Bugpac]

interesting, you have ackerman but no king pin inclination, still looks good but seems you may have concentrated on the wrong geomtry, any way my car is a dual sport as well, i actually have negative ackerman, if you think about it, when your ass end is sliding around you, you have the outside tire facing right to turnleft, so your outside tire is turning farther away from the corner or something like that, i just researched the opinions here about ackerman, and decided to go away from it....