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Spring rate
ChrisLeary - 19/9/12 at 06:18 PM

Evening all,

I've had a search and I understand that spring rates are very much individual to a car, but can someone please give me a rough idea of spring rates I will need for a tiger locost, 2l zetec silvertop with irs.

I'm not sure what's fitted at the moment, but the springs are too long so they need changing anyway.

Thanks in advance,

Chris

rodgling - 19/9/12 at 10:07 PM

I think most run in the 150-350 range, depending on car weight...

ChrisLeary - 20/9/12 at 12:09 PM

Cheers for the reply Rodgling, only 150 to 350 is quite a large range...

Anyone any ideas?

Many thanks,

Chris

Bluemoon - 20/9/12 at 01:51 PM

Ring tiger?

ChrisLeary - 20/9/12 at 05:40 PM

quote:
Originally posted by Bluemoon
Ring tiger?


I would if it was, but it's a locost based on a tiger chassis as far as I know...

Chris

Toltec - 20/9/12 at 07:52 PM

The chap who designed my car told me a rule of thumb to get close.

Take the corner weights and add each side together so you have a front and rear weight in kilos.

Front springs subtract 50KG and spring rate in lbs should equal the weight in kilos

e.g 250Kg - 50Kg = 200lb/inch springs

Rear springs add 50Kg and spring rate in lbs is the weight in kilos.

Having done some reading recently and being of a more mathematical mind I did a bit of analysis with a spreadsheet for my car and his suggestion was pretty good.

There are some interesting articles on http://www.optimumg.com/technical/technical-papers/ in the springs and dampers section.

[Edited on 20/9/12 by Toltec]

ChrisLeary - 20/9/12 at 08:02 PM

quote:
Originally posted by Toltec
The chap who designed my car told me a rule of thumb to get close.

Take the corner weights and add each side together so you have a front and rear weight in kilos.

Front springs subtract 50KG and spring rate in lbs should equal the weight in kilos

e.g 250Kg - 50Kg = 200lb/inch springs

Rear springs add 50Kg and spring rate in lbs is the weight in kilos.

Having done some reading recently and being of a more mathematical mind I did a bit of analysis with a spreadsheet for my car and his suggestion was pretty good.

There are some interesting articles on http://www.optimumg.com/technical/technical-papers/ in the springs and dampers section.

[Edited on 20/9/12 by Toltec]


Thanks Toltec, thats great, I'll have to get some heavy duty scales and get some corner weights and go from there then.

Thanks again,

Chris

Toltec - 20/9/12 at 08:38 PM

Should mention my car is mid-engined so it might not hold for front engine cars.

The equation solved for spring rate in the first pdf is easy to set up in a spreadsheet.

I ended up with a frequency of about 2.3 hz and the rear at 13% higher and the spring rates came out to those suggested for my car.

scutter - 20/9/12 at 10:00 PM

Chris, Does This help from about a year ago.

My live axle car runs 275 fonts and 180 rears.

ATB Dan.