toe in / toe out on rear suspension on a FWD racing car
Discussion
What have you experienced playing with the toe in and toe out settings on the rear suspension on a front wheel drive racing hatch?
I want to make my car sharper on corner entry.
Rear is adjustable for camber and toe.
In simple terms does more toe in at rear make it turn in sharper or less sharp?
The car is a 750 kg hot hatch with 3 deg neg camber front struts and we use Yoko A048' tyres.
I want to make my car sharper on corner entry.
Rear is adjustable for camber and toe.
In simple terms does more toe in at rear make it turn in sharper or less sharp?
The car is a 750 kg hot hatch with 3 deg neg camber front struts and we use Yoko A048' tyres.
Try this for more info: http://www.motoiq.com/MagazineArticles/ID/1936/Pag...
OP is saying he wants a sharper corner entry.
More rear toe-in will generally increase rear stability at the sacrifice of turn in/responsiveness.
There is no hard & fast rule for FWD setup, characteristics will vary from car to car. I run a 1200kg Civic Cup car, usually with a modest amount of rear toe-out to get the rear working during trail braking.
The flip side is in the long, fast corners where too much rear toe-out can make the car loose, often in a way that is more snappy than progressive.
More rear toe-in will generally increase rear stability at the sacrifice of turn in/responsiveness.
There is no hard & fast rule for FWD setup, characteristics will vary from car to car. I run a 1200kg Civic Cup car, usually with a modest amount of rear toe-out to get the rear working during trail braking.
The flip side is in the long, fast corners where too much rear toe-out can make the car loose, often in a way that is more snappy than progressive.
Generally speaking in my experience...
More rear toe in = more understeer and less response with a typically less gradual transition into oversteer
More rear toe out = more oversteer and a quicker response but transitions more progressively. If taken to extremes will make the tracking stability poor down the straights (although who cares on a racing car)
On the front it tends to alter the responsiveness on turn in and the stability rather than the outright balance.
If I feel a car is transferring its weight ok and is generally working well and the general balance is close but needs a tweak in either direction then I'll give it a mm of rear toe one way or the other.
More rear toe in = more understeer and less response with a typically less gradual transition into oversteer
More rear toe out = more oversteer and a quicker response but transitions more progressively. If taken to extremes will make the tracking stability poor down the straights (although who cares on a racing car)
On the front it tends to alter the responsiveness on turn in and the stability rather than the outright balance.
If I feel a car is transferring its weight ok and is generally working well and the general balance is close but needs a tweak in either direction then I'll give it a mm of rear toe one way or the other.
+ 1
Also, 3deg is a lot on the front and you must have some horrific traction issues coming out of corners. I am not sure why you want a "sharper front end", it should be pretty dam sharp already.
The 048s are a great tyre but you can kill them in 4 or so laps if you put too much in to them. What are your pressures going from (at cold) and to (when hot of the track)? You could be over working the front tyre, causing it to blister & over heat and this will lead to understeer (as me how I know!!!). A big difference between the two (6 or more PSI) would tend to show this to be the case. Also if there is an imbalance in pressures left to right can also point to over working a tyre.
Finally, I found the best way to gain lap time was to sacrifice entry and deal with understeer by early turn in & trail braking and gain it all on the traction zones. I went from 3deg to nearly 1deg and whilst it wasn't pleasant to drive, I enjoyed the lap time gain more. I would also think carefully about massive springs on the rears and pumping up the tyre pressures. This worked for the Saxos in Stock Hatch but it won’t necessarily work for another car.
Also, 3deg is a lot on the front and you must have some horrific traction issues coming out of corners. I am not sure why you want a "sharper front end", it should be pretty dam sharp already.
The 048s are a great tyre but you can kill them in 4 or so laps if you put too much in to them. What are your pressures going from (at cold) and to (when hot of the track)? You could be over working the front tyre, causing it to blister & over heat and this will lead to understeer (as me how I know!!!). A big difference between the two (6 or more PSI) would tend to show this to be the case. Also if there is an imbalance in pressures left to right can also point to over working a tyre.
Finally, I found the best way to gain lap time was to sacrifice entry and deal with understeer by early turn in & trail braking and gain it all on the traction zones. I went from 3deg to nearly 1deg and whilst it wasn't pleasant to drive, I enjoyed the lap time gain more. I would also think carefully about massive springs on the rears and pumping up the tyre pressures. This worked for the Saxos in Stock Hatch but it won’t necessarily work for another car.
Thanks for the advice, after qualifying a lowly 20th out of 32 cars we re-set the rear toe to zero ( from 1 deg toe in) and the car was much sharper better turn in and in both races was able to get close to the top ten.
My previous race cars never had any adjustment at the rear and So I was just going on what the previous owner Suggested, glad to have changed it made a big difference.
My previous race cars never had any adjustment at the rear and So I was just going on what the previous owner Suggested, glad to have changed it made a big difference.
Gassing Station | UK Club Motorsport | Top of Page | What's New | My Stuff