Thanks to API.
 

Thanks for the corner weighing and hospiality on my visit earlier in the week.
I was not expecting the figures to be that close.
Obviously the corner weigh is essential for setting up any adjustable suspension. Thanks.

Thanks H, any time. You're right as ever, how can you possibly fit and sell coil overs without corner weighting the car whilst doing it?

Some do, and I just question how the car can ever handle properly unless you do. Maybe the car owners are suckered into thinking that because it's expensive and shiny, it must be better.

Nah!, that wouldn't happen - would it ??

I too, was surprised at how well your car weighed for a 10 year old standard [ suspension ] car as set up by Subaru all those years ago.

Just goes to show; you get a car that weighs correctly. fit un-weight checked coil overs..... and it handles better ??

One car we double checked after it had coilovers fitted [ elsewhere ] was 48 kilos heavy on the drivers side [ compared to the near side ] at the front and 38 kilos heavy on the opposite rear corner compared to its opposite side.

Would have handled like a donkey in a swamp, but 'cos it cost £xxxxx it MUST be better.

Ah well such is life.

David APi
www.apiengines.com

I think it very much depends on who fitted/setup the suspension to begin with. When Powerstation used their corner weights on my new Type-25 it was within 1kg :D and they recently did a trackday P1 which was within 3kg.

Iain

My point exactly - you need a corner weight checker to be sure of the setup.

David APi

David : I cheated a little bit in that I knew from the STi 6 Wagon what the corner weights were generally so I knew where to concentrate weight reduction. I was still impressed with the closeness.
If somebody is working on suspension setups all the time I guess they will get it reasonably close but I agree it is nice to know for sure and not guess.

I didn't know you did corner weighting David :thumb: What do you charge for that please?

I wasn't offered corner weighting at PS so I didn't realise the could do it. Strange!

F

Floyd, It's a recent innovation I believe at PS. We charge a blanket £75.00 for the measure and adjustment. That assumes that the adjuster rings are not seized solid and we don't have tpo spend an amount of time with WD40 etc to get things moving freely.

Sometimes the adjustments are quite small and we need free movement of the rings else we end up going backwards and forwards past the correct point because the ring takes a big lurch.

While you wait, but by appointment, Saturdays seem to be less manic than most weekdays.

David APi

Would you need to re check geom?

F

Tough one that, theoretically no, but if the car needs moving some distance on the struts to balance it up, it would be safest to just pass it over the Laser tracker.

Nothing like being sure rather than guessing.

The toe in of a car changes whilst passing through full droop to level to full compression. It has to, as the arc of the steering tie rod is different to the arc of the lower wishbone and the difference of the two arcs is what creates the changes. It's called bump steer.

Therefore, if you move the suspension up or down by a reasonable amount, the toe in must change. It just needs to be checked.

David APi

Thanks for the explanation! If you have had bump steer removed, then what?

Cheers
F

On a production motor car it's next to impossible to remove, as the suspension and tracking settings are too much of a compromise.

On a formula racing car the tracking and suspension are purpose designed and limited in movement it is controlled at the manufacture stage. Within reason, road cars have a compromise set up and that's largely where it will always be.

By making a rack and pinion that has the pivot points at exactly the same point as the lower wishbone and as close to each other on a plane level, it can be controlled. But inevitably the length of the wishbone is different to the length of the ' track rod ' [ the bit that comes out of the rack that the steering joint is threaded on to ] that the arcs must differ.

On a production car that is used at a race track it is likely that the suspension travel can be limted and thus the arcs are kept fairly similar. In that case you can pick an optimum point and have minimal bump steer.

On a road car with up to 9 inches of up and down suspension travel it will always be a compromise. You can make it feel better by picking what is considered the optimum point, but the moment you drive along a cambered or potholed road [ typical poorly maintained British roads ] It goes completely to pot.

David

We've had corner weight scales for about ten years, As a general rule we only do corner weighting on competition cars unless otherwise asked for by the customer.
Although in recent times with the influx of "trackday" cars, we have brought it to the fore!
The reason we generally dont do corner weighting on road cars is because as a general rule there are too many variables (passenger quantity, fuel quantity, shopping, golf clubs............)


Curtis.

In my case I would corner weight the car in track trim/weight/configuration and take the road trim compromise for day to day.

F

Yup right; Floyd, who cares on a road car?, the wheels are never in the same plane at any one time once it is moving. Near enough [ within 5 Kg's will do ] on a road car.

48 Kgs out, on the drivers side, across the front WITHOUT a driver is not in any way close.

David

Daft question.......what about the 72KG human in the drivers seat ??

Do you do the setup with him / her in the car ??

Shaun

IIRC, that's how John does it and it makes sense. The car will be the quickest with just the driver in it :D so optimise it for that!

I wouldn't worry about setting it up for passengers as well unless its the same person and all the time.

F

On a track car it is essential. On a road car it is customer choice. It was never set up crooked [ IE for one person alone ] by the manufacturer. So it is up to the owner what they want us to do.

We can either do it with a sack of spuds etc or with the customer in it.

David APi

Thanks :D I was just curious

Shaun


PS they must do big sacks of spuds round your way LOL

Or about 4 boxes of AST's :D


Andy

Spuds are cheaper :p