430LikesUnderstanding F1 Tuning: Let’s break it down
04-09-2018, 08:09 PM
#228
Thanks for all the help. I've got a bunch of things to try out next practice session. I should have mentioned that I ran Tamiya kit tires on the front and Shimizu tires on the rear.
04-10-2018, 10:50 AM
#230
Is there a similar front tire I can get that is preglued? Maybe Volante medium hard or hard???
04-10-2018, 11:54 AM
#232
The hard front is in my bag of tricks for when the traction is REALLY bad but you do give up quite a bit more steering which means if you are still loose it can be even harder to keep it under control.
Worth a try tho
04-10-2018, 03:01 PM
#233
Tech Addict
I agree with most of this, except that wings are a very small part of things outside of weight, and bodyshells do nothing. Front roll center is actually useful, but I think the lower arm height is what you really have to alter more than upper arm angle. The upper arm seems more like camber gain than the effect it has on roll center. I had pretty good results with the tamiya carbon front end changing the height of the lower arm on asphalt to get the car what I was looking for.
Honestly, I think steering geometry is a huge part of getting the car to do what you want. Ackermann and toe can really change the car, but you have to check the car on a setup station to make sure everything is constant run to run when making changes, which is time consuming,
I have run massive amounts of front toe (like 3* per side) to calm the car down. The problem here is that it can kill the tires in the last half of the run, especially on carpet. A lot of toe seems more useful on lower traction asphalt.
The same thing with the bump steer adjustments. Vertical servo output shaft vs. horizontal on a direct steer setup is a big choice. Seems like the vertical shaft (output shaft pointing at the ceiling) is more linear, but maybe more steering overall, and horizontal (shaft pointing at the front of the car) is more aggressive initially, but loses some steering mid corner...? Again, it takes a while to changeGenerall this stuff back and forth, so I don't have really solid conclusions, but that is what it seems like to me.
Beyond initial servo orientation, generally the more angle in the tie rod from servo/bellcrank to the knuckle as viewed from above is more aggressive feeling, but feels like it binds up mid corner (less ackermann). I like it a little more on asphalt, some of the drag is almost a brake effect. Straighter tie rods seem to roll through the corner better. This stuff is why the option xray bell crank with the fine tooth adjustment is great. With direct steer, the servo saver also plays a role, since the distance between ball studs makes a difference in the wheel angles as the car steers. Closer together felt more aggressive to me.
Generally, if the tie rod is higher at the knuckle, viewing the car from the front. it will be more aggressive at turn in. If the rod is higher at the servo saver/bellcrank, it will turn more mid corner and exit. It's hard to give 100% concrete rules on this as all the stuff mentioned above plays into how the car steers since it's all dynamic.
Honestly, I think steering geometry is a huge part of getting the car to do what you want. Ackermann and toe can really change the car, but you have to check the car on a setup station to make sure everything is constant run to run when making changes, which is time consuming,
I have run massive amounts of front toe (like 3* per side) to calm the car down. The problem here is that it can kill the tires in the last half of the run, especially on carpet. A lot of toe seems more useful on lower traction asphalt.
The same thing with the bump steer adjustments. Vertical servo output shaft vs. horizontal on a direct steer setup is a big choice. Seems like the vertical shaft (output shaft pointing at the ceiling) is more linear, but maybe more steering overall, and horizontal (shaft pointing at the front of the car) is more aggressive initially, but loses some steering mid corner...? Again, it takes a while to changeGenerall this stuff back and forth, so I don't have really solid conclusions, but that is what it seems like to me.
Beyond initial servo orientation, generally the more angle in the tie rod from servo/bellcrank to the knuckle as viewed from above is more aggressive feeling, but feels like it binds up mid corner (less ackermann). I like it a little more on asphalt, some of the drag is almost a brake effect. Straighter tie rods seem to roll through the corner better. This stuff is why the option xray bell crank with the fine tooth adjustment is great. With direct steer, the servo saver also plays a role, since the distance between ball studs makes a difference in the wheel angles as the car steers. Closer together felt more aggressive to me.
Generally, if the tie rod is higher at the knuckle, viewing the car from the front. it will be more aggressive at turn in. If the rod is higher at the servo saver/bellcrank, it will turn more mid corner and exit. It's hard to give 100% concrete rules on this as all the stuff mentioned above plays into how the car steers since it's all dynamic.
Im surprised wings dont make much difference to you. On my car they make a huge difference, especially the front wing. I wonder if the track size/speed affects it, as I usally race on a big asphalt track.
Mike
04-10-2018, 05:09 PM
#234
04-11-2018, 12:13 AM
#235
Tech Regular
My experience is exactly the opposite - body and wings have significant influence on the car behaviour, albeit at higher speed. I was very skeptical at the beginning that aero work could have any noticeable influence on what the car does. By testing I came to the conclusion that even at speeds as low as we run (max speed at our asphalt track with a 21,5T is something about 40 mph, average 20) it has huge impact. Just by removing the front flaps on a serpent wing (5-6g) the car turned from undrivable (oversteer) in the sweeper to extremely understeering.
04-11-2018, 07:45 AM
#236
My experience is exactly the opposite - body and wings have significant influence on the car behaviour, albeit at higher speed. I was very skeptical at the beginning that aero work could have any noticeable influence on what the car does. By testing I came to the conclusion that even at speeds as low as we run (max speed at our asphalt track with a 21,5T is something about 40 mph, average 20) it has huge impact. Just by removing the front flaps on a serpent wing (5-6g) the car turned from undrivable (oversteer) in the sweeper to extremely understeering.
04-11-2018, 01:14 PM
#239
Tech Regular
You could do a test. Take the rear wing as it it and just move it down (at x1 the lowest mounting position). After you test in such configuration move it to the highest mounting position and test again. The biggest difference will be at the end of the back straight. Midfield makes not noticeable difference....
04-11-2018, 03:39 PM
#240
Hi All, I’m sure this is somewhere else in the forums...but ran out of time looking. What would be a baseline fdr for 21.5 (team scream, 12.5 rotor)?
Thanks!
Thanks!