Built a B class mini 65 for banter mainly between friends…then tuning of it took over! I have it handling well, I know the issues of FWD but one problem i cannot dial out is how im getting feedback in the controller as high as 6k rpm on the straights! Its after i have - or thought - got traction out of the turn it doesnt seem to get it down properly, any ideas?
I’d think that having a higher front rebound and rear bump might help prevent the weight from shifting off the front wheels a bit, it’ll effect handling though. I’m not entirely experienced in FWD’s though, so I couldn’t really tell you how it would.
accidental double
Thanks mate I’ll give it a try. I don’t usually spend to much time with FWD myself but you know how it is when you do something for a joke…3hrs later your still on the ramps!
I tried watching the telemetry last night for a couple laps, didn’t look like suspension was topping or bottoming out
Well the thing is, from what I understand of grip, for optimum straight line grip in an FWD you want as little weight transfer to the back wheels as possible, you want the front to keep pointed at the ground and the ass from squatting. Also you want as high of a percentage of the weight over the front wheels, so like intercooler and oil and cooling upgrades and turbos and things can help to root the front. Aero can really help root things down even in a straight once you get moving a bit, and every bit of grip helps ya know?
The problem is some of these changes can make cornering worse, but nothing that you couldn’t tune around with enough effort.
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So slapping the front aero on might plant the tyres some more? I tried messing around with tyre temps last night, couldn’t get down from 230 then found out the 180-210 rule was for FM4!
Above suggestions are going in the right direction.
Front end needs traction = downforce, higher front rebound, higher rear bump, higher rear spring, higher rear ARB, higher rear ride height, AND/OR lower front bump, lower rear rebound, lower front spring, lower front ARDB, lower front ride height, etc. would all help front traction.
Higher accel differential (as high as 100%), if not already done.
Lower gear, to reduce wheelspin, would also help.
Once the traction has been sorted out, then you can work on the over/understeer balance by using springs/damper/ARB/ride height/tire pressure.
Good luck!
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Thanks for the in depth reply, one thing…hight diff accel??? Thought to cure under steer this should be low (as it pushes out of corners if not careful also)
For RWD, higher accel diff leads to understeer (after a threshold) because rear wheels are pushing and front wheels are steering.
For FWD, front wheels are steering + pulling the vehicle therefore the wheels are pulling the vehicle in the direction the wheels are pointing to. If the diff. is low, the inside wheel will spin because the inside wheel is being unloaded = reduced traction. This forces the outside wheel to provide cornering + acceleration = traction overload.
Now I’m not saying do ALL of the above; just do the minimum necessary to remove the understeer.
I suppose having a wider front tire would also help reduce understeer. Use of wider tire requires more careful diff set-up.
B class FWD, however, is a tough order.
100% accel on diff. The higher the accel setting the more power you can put down before causing wheelspin, but when you DO exceed to available traction the understeer will be more severe. If you find yourself exceeding traction all the time even at 100% accel then you’ll get most benefit from practising throttle control.
As an aside, more accel = more torque transferred to outside wheels. More torque to outside wheel (and less to inside wheel) creates rotation (a.k.a. oversteer) which is always a good thing on a FWD car. However the increased traction will mean increased rearward weight transfer meaning less grip at the front tyres, causing understeer. The only way to find out which of these two effects will dominate is to test on track.
Those are excellent points!
More than anything you need a fine tuned right index finger.
That is correct! (My right index finger now has a callus.)
Thanks for all the feedback gents! I think I’ve got decent throttle control, like I say my problems were in a straight line ! I’ll try going through the above points again & again until it completly sinks in!
i been playing with fwd this week and i found full aero on front and higher rear springs and dampers than front works well also arb close together settings and diff at 100% stops torque steer, rear camber under 2 as well and seems to keep temps even across tire with front camber around 2.8 tames wheel spin hope this helps