I am tuning a couple of cars which I am getting understeer at corner exit and wanted to gain knowledge how to best understand, then apply changes, to the telemetry readings for camber settings.
For example, I have a car with the following settings:
Tires: 28.0/28.0psi
Camber: -2.0/-2.0
Toe: 0/0
Caster: 6.7
Rebound: 13.0/6.9
Bump: 2.0/2.5
In my telemetry readings I get:
Tires @ 33.4psi when hot, seems good per Worm’s tuning guide and others.
Tire temp rages: FLeft (out) 233.1/231.8/237.5 (in), FRight 232.6/232.6/232.6, RLeft 232/231/231 and RRight 232/231/231 this is at corner exit (left turn)
My initial Front Rebound was set at 5.0 and I moved it all the way to 13.0, yet, I still have the corner-exit understeer. What could I change to better my exit response to understeer?
Many tuning write-ups suggest increasing the front rebound to help this problem. What other settings should/could I change? [ex. Increase negative camber in front]
Thanks Loco! So, seems I was tweaking the wrong setting? Several documents indicate to change front. Anyway, it obviously is not working right now. I will start tweaking rear since I had kept that setting the same.
Camber is one of the later items I would tune , I would first concentrate on why the tyres suffer with ‘edge burn’, looking at your currently posted setting I would suggest a slightly different method for working out you Bump and Rebound, as I think your tyres may be ‘bouncing’ at the edge of traction loss ( watch a slowed replay in advanced wheel view ). My suggestion:-Using the spring rate for the wheel in question the formula would look like this Front spring rate * 0.76 = front BOUND rate, as for the rebound I would direct you to the description panel for the almost common knowledge ‘Bound is usually 50-75% of the rebound’- this is because the idea of the rebound is to stop the ‘bouncing effect’ or better described re-bounding effect, so I would normally start about 60% and move in increments of 0.1 whilst driving on varying textures/surfaces to find the ideal setting. Stiffer tyre pressures require slightly increased damping where lesser pressured tyres would likely require slightly less as the tyre wall will absorb X amount of the energy.
Thanks Luny! Though very hard to see it, I actually now confirmed that the tires are indeed bouncing some amount, thus, loosing traction in some parts of the track. In my case I got a better view with the regular wheel view. The Wheel Advanced was very hard to notice with the shadow. So, where do I start fixing this issue? Is it still rebound/Bump? Or, is it Front Aero (which I have at min right now), other?
By the way, how did you know of the bouncing (loosing traction) from the information I provided?
A couple of questions… What do you refer to “edge burn”? Are the tires too hot on the outer portion? It seems that temp is somewhat evenly distributed from my previous readings. Is this not so?
When you mention BOUND, you refer to bump, correct!
I will follow you recommendations on the ratios for Rebound & Bump.
I just kinda guessed after looking at the Bump (bound) settings you listed and thought thats never going to stop/slow [DAMPEN] spring recoil when the tyre ‘bumps’.
edge burn - yes you got it - your data values showed a very slight amount but it is a common sign of bouncing when a tyre is not square to the road surface, of which the next topic-camber…
can be a big subject but I’ll try to break it down quick, as the tyre (wheel Hub) travels through the suspension travel the camber is affected in a positive or negative amount dependant on its position in travel and turning degree rate ( steering ). sort of , its good enough for what we need anyway.
the ‘Ideal’ camber for a tyre that travels in an exacting vertical motion would be 0.0 so that ALL the tread is touching the tarmack, that said…
their comes a choice- straights or corners?
straights - lower camber (-1.5 to-0.7)
corners - higher camber ( -1.5 to -3.7)
why the difference?
under cornering conditions you want the outside tyre to be as near to 0.0 as possible WITHOUT loosing too much Accel or braking when you’ve finished in the corner or entering the corner, higher cambers need to come with higher anti roll bars for best effect . I would first make sure I had a good balance between springs and ‘Sway’ bars controlling the motion of the car body then calculate the damping apply and adjust first the bump [Bound] small adjustments to the ‘loose’ formula (i’m sure someone’s got a real and proper 6 page calculation but if the simple method puts you in the Ball park…) then slowly advance the rebound until the results were acceptable…
OK, so I should work on TWO issues [after making sure I have balance between springs and ARBs]. (1) Bump then Rebound settings per your suggested ratios. Then, (2) Camber and if required ARB (for best effect if camber goes to higher value).
looks good sounds great- remember you can always re-adjust as many times as needed- dont allow yourself to settle in a rut when tuning, each car is different - calculations can only ever be a guide, experience and feel is what makes a tune stand out.
best of luck in the series fella
Giz a shout if I can help again
Thanks Luny! You were of great help already. Car is doing much better now (got rid of understeer, yippie!). I’ll keep you in mind for other learnings I am sure I will need. Agin, thank you!