If you drop both right side bars on the chassis, would this increase rollsteer if the RR travel stays the same?
Printable View
If you drop both right side bars on the chassis, would this increase rollsteer if the RR travel stays the same?
During compression travel, the rr wheel will be closer to the rf wheel than it was with the bars higher. I call this less roll steer.Quote:
Originally Posted by shadowj38
Well that kills my theory. Been having trouble with my car not driving straight enough off the corner. Someone advised me to drop both right side bars. I did that for this past Saturday and it seemed to have little affect on my car. Now the track was a little more slick than usual but I still expected this change to be fairly noticeable. But the car felt pretty much the same. Thought maybe that change may have move the RR back creating more roll steer and that is why I didn’t notice much of a change? But maybe the track was quite a bit more slick than what I realized and lower both right side bars wasn’t enough of a change to keep up with the track conditions? Just trying to think out loud?
You may want to check how much your birdcage indexing was changed. It's possible you gained birdcage rotation during compression and loaded the rr spring more. The shorter your rr bottom is, compared to the top, the more you will see this.
Loading my RR spring is what I was trying to counteract by lowering my right side bars. I was gaining a lot more temp in my RR tire than I was in my LR. So I took a bunch of static load out of my RR then added some rubbers to gain my dynamic load back. That seemed to really help with my tire temp. But I’m assuming because of the added spring rubbers making the spring act stiffer, that was causing the car to want to drive off the corner sideways. So I lowered both right side bars to try and drive straighter off the corner. Am I making this harder on myself than it needs to be?
You are dealing with two parts of exit, that everyone has to figure out. There is the need to load the two tires correctly and the need to get the axle pointing the right direction. You can get the car driving neutral but have bad traction if both are wrong, but helping each other. Say you are almost all rr weight, but you have the axle pointing toward the infield. Car can go straight, but won't have much grip.
If you think loading is good, try to make adjustments with less side effects. Say, just a static wheelbase change.
I’m glad you mentioned where base. I lengthened my left side bars for the feature. But unfortunately got caught up in a mess that ended my night on the second lap. But from trying to get heat in my tires under pace laps I believe I was getting close to where I needed to be. Just wish I could have ran some laps to see.
Do you have any idea what your RR travel is? I don't mean compression.
I can guess it compresses roughly 2.5 inches from my static ride height by looking at my shock tattle tale but that’s the best I can do. I have no idea what the total travel would be.
You missed my point. I said not talking compression so that leaves rebound, stop and think about the RR rebounding and what moving those bars down does when the car raises over ride height on the RR.
Note: The RR isn't below ride hieght very long and is above ride height most of the time
Billet, not trying to sound dumb, but I thought that was the point of lowering the top bar? To keep the RR from standing up on the bars as much? (Above ride height)
But I’m assuming what you’re getting at is with the bars lower, it doesn’t pull the RR ahead as far when the RR is in rebound meaning the right side wheel base is actually longer on the rebound than it would be if the bars were higher?
If you lower the top, but it still has enough thrust to reach your travel limit, dropping the bar may have slowed that action, but when you reach the limit, only steer matters. You are correct in what he is getting at.
So given the situation I have, lowering the top bar had little effect on what I was trying to accomplish? Atleast without making other adjustments to go along with it?
Just so you know where I’m working from. With my bars in standard holes and my car at ride height, the RRT rod is 21.5 degrees and the RRL rod is 2 degrees. I dropped one hole on each and as long as I figured my math right the RRT rod would have been 19.1 degrees and the RRL rod would have been real close to -.5 degrees.
You are correct. However let me say this: Just as MasterSbilt_Racer pointed out, in some instances that loss of thrust by lowering the bars is still enough to make the RR climb just the same and reach the same point. So some/many times you won't see much effect from the bar change, if the track is more sweeping on the straights where you still have a fair amount of lateral force on the car the RR will tend to stay down more from that change then say a track with really straight straightaways. So it boils down to how far the RR lifts for the most part (I'm leaving out a few things for simplicity)Quote:
Originally Posted by shadowj38
Again it boils down to how far the RR moves and at what parts on the track it does this and if the bar change altered those points on the track. Obviously the higher the bars the more the RR pulls forward as it raises, but with the relative shallow angles and limited travel of the RR (compared to LR), one hole change usually isn't a ton of steer difference but it's for sure there.Quote:
Originally Posted by shadowj38
Very, very possible. If 1/2 a second after you pick up the throttle the RR is already above ride hieght, then it likely had very little effect you could feel. But if the car stays over on the RR and below ride or is now way slower to reach it's travel limit, then you should have seen an effect.Quote:
Originally Posted by shadowj38
I'm not trying to be cryptic, but what the RR is actually doing is key to knowing whether or not you going to get much effect out of that change. Sometimes it can be almost nothing and other times pretty noticeable.
Billet, thank you for your time and knowledge. Same to you Mastersbilt. Glad I asked about this. You guys have made a few things click in my mind that I had not taken into consideration before. Now I just wish my race season hadn’t ended Saturday so I could go try some things!
Add some rebound to that RR shock, see how that grabs ya.
Krom, I’ll put it in my notes to try for next year. Thanks