Toe-In Under Suspension...??

[Lessen]

I have a curiosity... When I first built my TTR S3 I noticed that the setup allowed a massive change in extra toe-in when the front suspension was compressed. I never really gave it much thought other than that I didn't like it. Not from driving it but just because it didn't make much sense to me. So my question is... Is this a common design? Do other buggies do that? Why?

 

[HeartBreak]

My MBX5 Prospec does the same thing. It has WIDE toe out when the arms are at full downward extension, and massive toe in when it compresses. I've no clue as to why it is that way, either.

 

[evan811]

whats toe-in and toe-out?

 

[Lessen]

toe is a term referring to the angle at which the wheels point either in or out of the vehicle along their vertical plane

for instance.. looking from above the vehicle facing forward...

/ \ that's toe in

\ / toe out

My MBX5 Prospec does the same thing. It has WIDE toe out when the arms are at full downward extension, and massive toe in when it compresses. I've no clue as to why it is that way, either.

the only thing I can think of is that it would help it from darting in either left or right upon landing a jump, also help straight line stability under hard braking.

 

[redhatman]

i can understand what your saying, but I'm trying it on my hyper 7 right now and its not doing it. I guess it could be what you said about landing. I think thats the most reasonable.

 

[Lessen]

interesting.. thanks Pat.

2 yays
1 nay

 

[Izze-Racing]

Bumpsteer, A pro driver (trying to remember his name) said to double up on the mbx5 and prospec bellcranks in order to avoid this.

 

[evan811]

What would you want toe in or out for? I always try to get them at straight ahead as I can....

 

[Lessen]

Bumpsteer, A pro driver (trying to remember his name) said to double up on the mbx5 and prospec bellcranks in order to avoid this.

what exactly do you mean by double up?

It's all in the geometry for the TTR. What I did to my S3 was attach the tie rods to the top of the steering knuckle instead of the bottom like it's supposed to be. I had to use a different rod end to make it work but it does.. however I have very little clearance between the rod end and the inside of the wheel.. probably less than 2mm. It tends to wear down the rod end due to agressive suspension action. I think that small amount of infrequent drag is a small price to pay to get rid of the bump steer.

What would you want toe in or out for? I always try to get them at straight ahead as I can....

toe out in the front makes the car easier turn when cornering but is less sensitive at center making turn in less stable.

toe in at the front makes the car harder to turn when cornering but is more nimble at the center making for more precise turn in.