Formula Vee Ackermann Angle
Formula Vee Ackermann Angle
(OP)
Hi all,
I've just bought a Formula Vee racing car, and one of the previous owners has moved the steering rack rearwards from its original position.
I'm not sure if his intention was to straighten the steering rods from a loading point of view, and whether or not he considered the ackermann angle when doing so.
According to Race Car Vehicle Dynamics (Milliken), moving the rack rearwards like this will increase the ackermann angle. Could somebody verify that this is true, and perhaps give their opinion on whether or not increased ackermann effect is beneficial (or otherwise) to a Vee?
Please find an image of the steering system at the attached link.
Thanks,
- Kronos1
I've just bought a Formula Vee racing car, and one of the previous owners has moved the steering rack rearwards from its original position.
I'm not sure if his intention was to straighten the steering rods from a loading point of view, and whether or not he considered the ackermann angle when doing so.
According to Race Car Vehicle Dynamics (Milliken), moving the rack rearwards like this will increase the ackermann angle. Could somebody verify that this is true, and perhaps give their opinion on whether or not increased ackermann effect is beneficial (or otherwise) to a Vee?
Please find an image of the steering system at the attached link.
Thanks,
- Kronos1





RE: Formula Vee Ackermann Angle
There are sound arguments in favour of:
negative ackerman (outer wheel steers more than inner wheel)
parallel steer
some %age of the theoretical ackerman steer
100% ackerman steer (if you drive a coach on gravel driveways)
Over ackerman steer.
So you have at least 4 things to think about. If you use the search function you will find previous discussions. Read them and get back to us.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Formula Vee Ackermann Angle
I would also be more concerned to find out where the opposition was
cheatinginterpreting rules very loosely to find an advantage with their engines and match their effortsRegards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Formula Vee Ackermann Angle
Second, the class has been around for over 40 years with rules that have changed little in that time. Not a great deal of difference between a new model and older pre '70 model. Anything and everything you could try, has been...to death!
Something else in the Vee classes in vintage racing, there is no question you can ask that your fellow racers are not willing to answer, loan you parts and tools or, even do the job for you.
http://www.vararacing.com/info/?id=5300
Give them a call. FV # 291, Kim M. is the class representative.
Rod
RE: Formula Vee Ackermann Angle
My observations in FV here are that they all cheat, but to the same degree so no one stands out.
They have sealed engines, but I believe that most have managed to duplicate the seals.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Formula Vee Ackermann Angle
Greg, I've had a read of the previous posts regarding ackerman - but none I came across discussed it in the context of a racing car. (Drifting was the closest, but still very different)
Perhaps you could provide some of the arguments for and against negative ackerman, parallel steer and some % of full ackerman.
I don't think that full or over ackerman would be beneficial because of the drag of the inside wheel on fast corners - but perhaps I'm mistaken.
Pat, you're not the first person to highlight the importance of bump steer on a Vee! - it's true they have a LOT of suspension travel. Would you have any advice on how I could produce a bump steer curve for the car?
Rod, where I'm racing the engines aren't always sealed - so I imagine it's a regional thing. The engines also have different specifications around the world - I know the UK engines are more highly-tuned than in some other areas.
Regards,
- Kronos1
RE: Formula Vee Ackermann Angle
The rear ends also bump steer quite a lot, presuming they still use the swing axle rear end.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Formula Vee Ackermann Angle
RE: Formula Vee Ackermann Angle
Also bear in mind that toe out is fake ackerman, and that ackerman varies as you turn the wheel.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Formula Vee Ackermann Angle
Just say it toes in on bump and toes out on droop, what does that do to each wheels angle relative to direction of travel.
At least on a FV you have equal length tie rods. A beetle sedan had a short and a very long tie rod. With left and right fronts changing toe at substantially different rates and with the rear also changing toe and camber substantially, drifting through undulating corners was ummmm, interesting and required some unique skills to be developed.
I expect FV has some of the same tendencies but to a significantly lesser extent due to equal length tie rods and much less roll and actual travel.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Formula Vee Ackermann Angle
As I've said before, I really don't like tuning with ackerman in the front steering on most RWD cars. I've just never found it necessary to have a good handling race car. I have parallel steer in out Lotus Cortina...had it for years...no problems. Much less difficult to set up the car for different tracks...just one more thing to worry over is my opinion.
If you need it, as the Mini does...just deal with it. No matter, you need to test, test, test...In the very particular case of FV, why re invent the wheel if you don't know what want or need?
Rod
RE: Formula Vee Ackermann Angle
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?