Ride height confusion

Wheels, Suspension, Brakes & Tyres questions and answers

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RS2000
Racing Driver
Posts: 680
Joined: Mon Nov 25, 2013 7:38 am
Vehicle: NB8A
Location: Newcastle

Ride height confusion

Postby RS2000 » Sun Dec 15, 2013 8:19 am

Hi,

I'm new to MX5's & have bought a track only NB with Tein S/S coilovers. I have read every post I can find about ride height on this forum, & it seems the concensus on lowering front ride height is:

1. 315-320mm ride height is about right
2. Don't take lower control arm below horizontal

My question is, how can you achieve both of these at the same time?
With the front inner lower control arm bolt the same height above floor as the outer bolt (near ball joint), my ride height (centre of wheel to under side of guard) is over 330mm.

Are people measuring control arm 'horizontal' some other way?
BTW, my garage floor is flat & horizontal & the car is not bent!

All thought appreciated,
Cheers

Magpie
Speed Racer
Posts: 7468
Joined: Fri Feb 11, 2011 12:49 pm
Vehicle: NA6
Location: Purga, QLD

Re: Ride height confusion

Postby Magpie » Sun Dec 15, 2013 8:38 am

Measure from the pinch welds. From personal experience 100mm at the front pinch weld and 105 at the rear pinch weld dropped my front splitter down to about 75mm, not good for the road!

Adjusting height should only be done in conjunction with corner weighting, especially if it is a track only car. Random changing of heights effects corner weights and hence handling.

What pressure is in your tyres? You should have them at hot pressures as this will affect ride height.

A good guide is here http://949racing.com/miata-race-alignment-info.aspx

RS2000
Racing Driver
Posts: 680
Joined: Mon Nov 25, 2013 7:38 am
Vehicle: NB8A
Location: Newcastle

Re: Ride height confusion

Postby RS2000 » Sun Dec 15, 2013 9:27 am

Thanks Magpie,

I agree about ride height adjustment & corner weighting etc.

This car was very low when bought, with the front lower control arms & steering tie rods pointing greatly downwards towards centre of car. I reckon it would probably bump steer without raising ride height or lifting the steering rack (which I don't intend to do at this stage).
I have only started looking at the front height, but will raise all 4 corners the same amount to start with - will get corner weighting checked then.
I just dont see how you can get car reasonably low & keep front lower control arm horizontal. As stated ride height has to be 330+mm & pinch weld height at jacking point 145mm (with 225/45x15") to get lca horizontal.
Maybe the lca can be below horizontal with no adverse effects?

cheers

project.r.racing
Speed Racer
Posts: 3722
Joined: Sun Jan 18, 2009 10:16 pm
Vehicle: Non MX-5
Location: Glasshouse Mountains, QLD

Re: Ride height confusion

Postby project.r.racing » Sun Dec 15, 2013 12:32 pm

its a double wishbone suspension, things like that aren't as bad than on macpherson style suspensions.

RS2000
Racing Driver
Posts: 680
Joined: Mon Nov 25, 2013 7:38 am
Vehicle: NB8A
Location: Newcastle

Re: Ride height confusion

Postby RS2000 » Thu Dec 19, 2013 7:50 am

Thanks project.r - I remember reading that

Cheers


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