Corner weighting

[fergus]

I've read in several books that corner weighting should look to equalise the diagonal weights on the car to make turn into both right handers and left handers the same. However, the last two corner weight setups I've had (by suspension 'gurus'), have both sought to balance the weights over the front axle - presumably to prevent lock up of one particualr wheel under hard braking. When I've looked at the print out from the scales, the diagonals are some way off.

Anyone shed any light on what they think is the correct 'target' , i.e. front axle balance or diagonals being equal (this is the way the NASCARs, etc are setup, with 'wedge' or without).

Rather than pay £150 upwards for someone to wind up the spring platforms, I know my target ride heights and have access to a set of CW scales, so will do the job myself (with an assistant obviously, as I'll be in the car!).

The FAQ on blatchat/7FAQ seems favour the equalise the diagonals method....

[fergus]

cheers chaps. just confirmed the car is not going down to a well known specialist behind brands again then.

[fergus]

Stuart,

What would your target be? All literature I've read seems to point to optimising the cross weights (allan staniforth, carol smith, don alexander et al)

many thanks

[fergus]

SimonY said:

... heading blindly for either matching fronts or equal crossweights no matter the driver is not the way to do it ....

I was only curious as to what people do in practice, as all the books suggest equalising the diagonal cross weights. Surely this would minimise the amount of torsional energy compared to car not balanced across the diagonals?

What are the undesirable effects you mention? PM me if necessary. Many thanks

[fergus]

Finchy172 said:

Remember a nascar goes round in circles, and has IRS.

A caterham has the mass of a driver on one side, and a de dion rear axle.

This is the reason Nascars have 'wedge' built into them to help them turn left. This is the amount that the car is not setup to have 50% over the diagonal.

A Nascar also doesn't have the driver in the middle, although they do have the ability to physically move weight around the car in the form of ballast.

Finchy - What would be your preferred target approach?

I'm spending some time with someone who works as a suspension engineer on a touring car team at the weekend, so will ask them for their thoughts on the subject.

I believe you work for Hyperion, and I'm not asking for a "trade secrets" type setup, just what you aim for when setting up the race cars

1) equal over front axle
2) 50% diagonal split
3) something else

kind regards

[fergus]

bse said:

...and with regards to the 'well known specialist near Brands Hatch', I've spent plenty of laps chasing cars and records set by caterhams that he has set-up, so I wouldn't be critical of his work!

I was making a tongue in cheek reference to how his approach (seemingly to balance the fronts according to the scales print outs I have) is at odds to most race engineers setup apprach, namely to optimise the diagonals. Although, this may be a quirk of Caterham chassis'.

I think Gary obviously knows his stuff, however, if I want my car setup on the diagonals method, this would appear to differ from his chosen approach, so I will go elsewhere for the setup.

I'll set ride heights (with 15mm rake), then do the corner weighting, then recheck the ride heights, etc, etc.

My inital post was to see how people set their cars up, not how specialist A or B sets customers cars up.

Many thanks.

[fergus]

racecardoctor said:

Stuart gets my vote, equal fronts on a caterham

Is it not impossible to have equal ride heights and equal axle % on a non-single seater?

[fergus]

Dave J said:

set the springs at the same position on the front dampers - count the threads (after measuring the springs), then set the rear rake and equalise the threads on the rear dampers then add 4 extra threads on the drivers side rear damper (increasing the ride height to account for the driver)

bet you wont be far off

Or use some digital scales and do the job slightly more accurately I agree that the rule of thumb method above won't have you miles out.