RR Body Roll?

[Kromulous]

If you notice a Car mid Corner, Full hike, and you see the body raise up over the RR tire, what would cause this?

To much J Bar rake ?

[MasterSbilt_Racer]

If you notice a Car mid Corner, Full hike, and you see the body raise up over the RR tire, what would cause this?

To much J Bar rake ?

Lift from the rr suspension?

[outlaw4j]

our car will do this. its usually after mid corner though and usually just when we have a bunch of traction. sometimes we will even hop a bit. i think its just lift from suspension. i talked with our chassis builder about it wondering if that's normal or if we needed to change something and they thought it was fine. we have an under rail so it stops on the rail, but a lot of the over rail cars use chains

[Kromulous]

Yep, Outlaw thats what i see too. Mid Corner it lifts, seems like the RC is migrating to far outside the Car and it begins using the Tire is a pivot and the spring unloads. Thats the way i see it anyway.

Could be lift from the RR bars, but i have minimal bar angle, and index the cage top and bottom to help that, and 3" split on bar lengths so i have virtually no indexing on the RR.

[Kromulous]

We get it when the tracks goes dry to slick, when there is sidebite it will continue to compress the RR.

Maybe thats a key, more force pushing the rearend to the left, which i would think the RC is just to high.

[MasterSbilt_Racer]

We get it when the tracks goes dry to slick, when there is sidebite it will continue to compress the RR.

Maybe thats a key, more force pushing the rearend to the left, which i would think the RC is just to high.

It lifts when your lateral acceleration is low enough that it doesn't combat the lift anymore. Index doesn't really have anything to do with the lift on the throttle. It's thrust and thrust angle.

You will see it more on a paperclip track vs one with bowed straights.

[Kromulous]

Yeah, i was just mentioning the indexing to say we wernt stacking up a bunch of rate, amplified by indexing. On a 175 spring, and rebound in the shock as well.

So that leads me to look at the bars again, i may have to much lower bar angle i guess.

Would having down angle in the lower bar keep the spring compressed when you pick up the throttle? Im thinking it can help.

[MasterSbilt_Racer]

Yeah, i was just mentioning the indexing to say we wernt stacking up a bunch of rate, amplified by indexing. On a 175 spring, and rebound in the shock as well.

So that leads me to look at the bars again, i may have to much lower bar angle i guess.

Would having down angle in the lower bar keep the spring compressed when you pick up the throttle? Im thinking it can help.

It would decrease the thrust angle, so it would help.

[ZERO25]

Pretty sure its been discussed that it hurts aero as well!

[MasterSbilt_Racer]

Pretty sure its been discussed that it hurts aero as well!

Rr up or down? If the car is going straight, like they put them in the wind tunnel, high rr adds load just like high lr does.

[ZERO25]

Actually it didn’t. At the bottom of the right rear spoiler was a big pocket of disturbance which caused the air to go up over the spoiler.

I think ghopper mentioned this as well in another thread.

This was on a late model with open sails.

[powerslide]

Our experience was either not enough rebound or alot of RR upper bar angle. As previously mentioned, the paper clip or drag race style tracks will see more of this

[MasterSbilt_Racer]

Yep, Outlaw thats what i see too. Mid Corner it lifts, seems like the RC is migrating to far outside the Car and it begins using the Tire is a pivot and the spring unloads. Thats the way i see it anyway.

Could be lift from the RR bars, but i have minimal bar angle, and index the cage top and bottom to help that, and 3" split on bar lengths so i have virtually no indexing on the RR.

Krom,

The roll center becomes the rr, when it's being lifted. Your eyes are good, you just have the chicken and egg backwards.

And keep in mind, just like the lr, softer spring on rr will aid lift.

[Kromulous]

MBR, I'm sure you notice this but let me describe what i am seeing with the Mods.

It looks like the faster cars that the body rolls into the Track, thats what it looks like, but some cars usually slower cars are rolling over or above the Track surface. It literaly looks like the body rolls up and over the RR, to me anyway.

After more bad runs LOL i figured out i had to much RR bar angle, also i added some more angle in the J Bar on the Frame side to help keep the LR hiked up.

Basically i want to get the right side to roll down and into the Track, visual, and stay fully hiked on the LR. I just cant seem to get the combo right.

It seems Florence Speedway requires extremes on adjustments. I have to go way farther with things there versus anywhere else and we never get any tire wear. Moler and LBurg can burn up a set quick, but Florence nothing.

[outlaw4j]

another thing we worked a lot on with my son was arcing into the corner. this helped a lot being able to keep the RR in and really helped him feel the RR. We also went to more of a cushion type RR shock, stiffer in compression than rebound to help in get the car in deep with feeling it dumping on the RR too fast

interesting on the RR tire heat / wear. We had one night last year where we could not get heat in the rear even, and especially the RR, and car was not good. never did figure that one out as we are at that track somewhat regularly.

And nights we are really good we usually work the RR good, but have really balanced tire temps.