Monaco Set up: the misconception of wheelbase

Monaco’s layout presents unique demands to the teams. As we are all aware, it’s all about slow and tight turns, thus devoid of any long straight or fast turns. Other tracks have low speed turns (Hungary) and there are other tight turns (La source at Spa). Monaco combines all of these and adds the issue of public roads. Complete with; camber, bumps and kerbs, plus the ever present Armco barriers lining the trackside.
Thus Monaco requires an exclusive set up to cope with these demands. It’s well known that teams run maximum downforce here; the drag that this inefficient aero set up brings bears no penalty as there are no straights to speak of.  With the addition of aero devices limited now with the 2009 rules, teams cannot add the plethora of add on winglets and flaps to add downforce.  This year a few teams will run add-on winglets in the 15cm free zone in the middle of the rear wing, but little else aside from maxed out wings and gurney tabs will be used.  Ferrari have added a small winglet to the tail of their shark fin engine cover this weekend for a little extra downforce. Additionally a floor and diffuser that work well at higher ride heights will be beneficial, although teams do not run Monaco specific floors. Obviously to cope with crowned road and bumps, teams run their cars at higher ride heights around the principality. Added to this softer springs and roll bars will induce more wheel travel and see the aero move through a greater range of attitudes than normal. For Monaco the resulting aero penalty is offset by the greater mechanical grip. 
Due to the low average speed, Monaco is much more about mechanical grip than aero; this is an area where misconceptions exist.  Wheelbase, although its a fundamental fact that shorter vehicles have tighter turning circles, in F1 terms wheelbase account for very little at Monaco.  With wheelbases over three metres, the difference in team’s wheelbases is just a few percent and not enough to have a primary advantage over the other factors differentiating the cars.  Long wheelbase cars have won at Monaco and in testing teams and drivers have never found wheelbase a key factor through tight turns.
Frank Dernie quoted me a couple of perfect examples; “when Brabham were concerned about their 1983 long wheelbase car around Monaco because it was around 12″ longer than the previous car, Nelson said he did not notice it at all” and pulling directly from his experience when at the start of the Eighties Williams were testing the FW07 six wheeler (a standard FW07 with an extra rear axle).  “The Williams 6-wheeler obviously had an effective long wheelbase and one of the first things we tried, before committing to the project, was a tight circuit test at Croix-en-Ternois to make sure it was not a disaster. Jacques Lafitte said he forgot he was driving the six wheeler after a few laps.” 
Mercedes GP are bringing their previous front suspension to Monaco.  This results in the car resorting to its previous short wheelbase set up.  This is not aimed at creating a shorter more nimble car, but simply not being enough long wheelbase wishbones available to the team.  Unfortunately for Mercedes this will push weight forwards in the car, which is counter productive at a track where rear tyre traction is critical.


So while wheelbase is not a primary factor in rounding tight turns, then what is?  Steering lock accounts for most of the solution, only Loews at Monaco (the tightest turn in F1) and La Source are turns where the driver has to turn the wheel beyond half a lock.  Drivers sometimes having to remove one hand from the wheel, to get enough clearance for their crossed arms.  If the front wheels can turn enough then the car will get around a tight turn, of course a longer wheelbase car will need slightly more lock for the same turn a short wheelbase car.  To allow the front wheels to steer enough a few mechanical alterations are required.  Firstly the steering racks can be altered with a different ratio to the rack and pinion.  But more commonly the outboard end of the track rod is brought closer to the uprights kingpin (steering) axis, resulting in more ‘steer’ for the same rack displacement.  This can bring an extra 5-degrees of steering angle.  To allow a power steering system to have a longer stroke, the teams need to alter the pistons that assist the rack in moving, by also making them longer.  Then at the outboard end of the wishbone, the pivot bearing should have enough freedom to steer the wheel through the required angle, but clearance between the wheel and the wishbone often requires the wishbones to be altered.  This is normally just a notch moulded in the rear leg of the upper wishbone.  Teams do also fit more robust wishbones for brushing the Armco, as well as tougher drive shafts.  Although the latter is as much about accelerating over bumpy surfaces, than the side thrust from a wheel touching the barrier. 

So who ever goes well at this weekends GP, will be as a result of a mechanical set up and downforce that are matched to the tyres. How long their wheelbase is not going to be the deciding factor. Although who actually wins may be as much down to luck as any set up parameter!

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11 thoughts on “Monaco Set up: the misconception of wheelbase

  1. Ok I understand it is not particularly important in twisty tracks, but is a longer wheelbase better for high speed corners for stability. Or is the effect still negligible?

    • From everything I’ve been told wheelbase itself is not a factor. IT does however lead to layout benefits such as space for aero devices or better weight distribution, which are a primary factor in stability

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  3. Pingback: F1 Car Setup for Monaco | My Digital Life

  4. Interesting reading about Mercedes’ revised setup for Monaco.

    Can we assume this is why Nico was back to his (small) advantage over Schumacher in qualifying? We know Michael likes a responsive front-end which seemingly he didn’t have again this weekend.

  5. If an F1 car and a fast kart had a race around a kart track I would bet on the kart winning. I realise the F1 car would probably have to be modified to give it enough steering lock to get it around the super tight turns but even thus modified I think the kart would win. In extremis a short wheelbase can make a difference.

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