Corner weights of a 1303

[andy1303]

Anyone have any idea how heavy each corner of a stock 1303 is? I'm trying to work out spring rates and don't have a gauge....
Ta

Andy

[Chris Percival]

I had my car weighed when I got my T4 engine tuned up a couple of years ago. Its a 1973 1303. With me sat in it it weighed 939kg, and the following at each wheel:

Front left 200kg
Front Right 213kg
Rear left 246kg
Rear right 279kg

[andy1303]

Excellent, thanks for that. Surprising isn't it really. That's not as much difference as you'd expect front to rear. Will we see your car on track this year?

[Chris Percival]

Yeah, it is. I have the battery in the front wheel well which helps. On average its a 44/56 split, front and rear, thats supercar territory..

Hopefully on the road, but probably not the track this year, maybe next..

Chris

[Steve C]

Hi Chris

Is your car adjustable in the corner weights? Having the corner weights correct can really make difference to a cars behaviour.

I want to have my corner weights correct in my next car, Im on the lookout for a cheap way to do this. I've thought about making a hydraulic apparatus that could lift each wheel, I could then read the hydraulic pressure needed to lift the car at each corner. It wouldn't give me kilograms per corner like you have, but I could compare oranges to oranges, but the kilograms per corner could be worked out if I knew total weight of the car.

Steve

[Chris Percival]

As I have adjustable struts, the wheel pressures could be modified by adjusting the strut height I expect.

What about using heavy duty scales, and just weigh one wheel at a time, adjusting them until they're even?

[Steve C]

Hi Chris

Proper race teams have pressure pads that they drive cars onto, these are out of the price rangfe of the average enthusiat. I imagine getting the car onto a scale would upset the suspension.

what I was thinking with my hydraulic apparatus was I would drive the car and place it on 4 pieces of thin but tough piece of plastic, i would then lift each wheel in turn until the plastic sheet could just be moved and make a note of the pressure reading at each corner. There is software available to calculate corner weight results.

To get your corner weights right you would need to adjust the rear torsion bars as well, that would be pain unless you had adjustable spring plates or unless you ran coil springs all round like andy1303 is doing.

Steve

[Steve C]

Hi

Just found some software to do corner weights, I used weights that Chris posted.

Steve

[AggieDave]

I imagine getting the car onto a scale would upset the suspension.

Bah. A "trucker's scale" used for individual axles/tires could be used with small sheets of plywood glued together to be at the same height as the scale. Jack up the car, put the scale under one tire and the wood under the other three. Rotate as needed to weigh each corner.

Instead of purchasing such a scale, simply contact a local shipping/freight company and see if they have such a thing. If not then your local Co-Op should, since they have to have some way to weigh their grain trucks.

If MacGyver could build a nuclear powered submarine out of a waterbong, a paperclip and a ball point pen, then this should be easy.

[Steve C]

Hi AggieDave

Your idea would work in a fashion.

What I was getting at by upsetting the suspension is, as we all know the suspension will slightly tuck under during lifting and the only way to settle it back to the correct ride height is to move the car, this tuck would raise the suspension throwing out fine corner weight measurements.

Steve

[Chris Percival]

Get one scales and 3 dummy scales. Drive the car onto the 4 items, measure. Drive off, swap the scales around, drive on. K.I.S.S

[super vw]

your car and scales need to be on a perfectly( or near to it) level surface. otherwise you will get incorect readings, theres no way around it period.
You can use adjustments for ride height to shift weight and you can also simply use dead weight (such as lead) to do the same. its all a balancing act.

with adjustable 944 spring plates you can do a lot.
the goal is to get your cross weights near 50%

[AggieDave]

Originally Posted by Steve C

Hi AggieDave

Your idea would work in a fashion.

What I was getting at by upsetting the suspension is, as we all know the suspension will slightly tuck under during lifting and the only way to settle it back to the correct ride height is to move the car, this tuck would raise the suspension throwing out fine corner weight measurements.

Steve

Sure but I was pretty much assuming that someone on these forums asking this sort of question wasn't worried about that. Basically that if someone was worried about the cornering weight to that degree, that they'd have a source for scales in pit row at the track. Even then, after the crew chief sets up a car "perfectly" for which ever type of race they're racing that weekend, after some practice laps the driver always comes back and wants it changed for his/her liking.

So all the measuring, weighing, knowledge and skill about suspension on the mechanics side is tossed out by the worlds finest judge...the driver's butt.

[andy1303]

There are cheaper corner weight gauges available which use a lever assembly that hooks under the top of the wheel rim. push to lever down to lift the car and then the gauge shows the weight.
http://www.merlinmotorsport.co.uk/SU...325/index.html
but I decided I couldn't afford it....

[Chris Percival]

Much cheaper to just go somewhere (like http://www.raceshack.co.uk) and borrow their corner weight scales.