Hi, I’m running an MX5 mk2.5 for sprinting at Curborough. I have Gaz Gold Pro adjustable coil overs and dampers fitted, Can anyone tell me what percentage (front to rear) is a good set up for corner weighting please?
There’s two ways to do corner weighting…
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Same weight on each of the front wheels. This offers improved braking, and is less common.
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The “cross” weight balanced out to 50%. This means (Front Left + Rear Right) = (Front Right + Rear Left), and ensures the same understeer/oversteer balance on left and right handers. This is more common as it makes the car consistent to drive.
All needs to be done with your equivalent weight in the drivers seat, tyre pressures set correctly, and ARB drop links disconnected if you have adjustable ones. These are then added afterwards and lengthened or shortened to fit exactly so there’s no preload in the system. A properly flat floor is also vital, within 1mm across all 4 corners ideally.
The actual values will depend on your car, hence why its expressed as a percentage. You can only move weight fore and aft, or left and right, by physically relocating components - it can’t be done (to any measurable amount) by adjusting the spring platforms on your dampers.
sorry dude but say whaaaat?
although people do use equivalent weight in the drivers seat - probably critical if you are a top spec team racing - 70-80kg in the middle of the car is not going to do a lot of difference
mx5’s aren’t 50/50 weight biased
arb do not work when the car is stationary
but from all requirement for 1mm flat floor i think tops it all.
sorry dude I got an nc and my car isnt setup for sprints so my values arent identical but 51.3% front works extremely well in my car for trackdays and road use.
Each to their own 
If I’m going to do something, I’d rather do it properly. No point just chucking the car on some scales, reading the numbers off them and going “yep that’s been corner weighted” - 1) Because that’s just not true and 2) You aren’t getting any of the benefits of corner weighting.
ARBs do introduce load into the system and affect corner weights even when the car is stationary, if the drop links are under tension / conpression. 1psi tyre pressure difference will affect corner weight readings. A couple of mm variation in floor level will affect corner weight readings. These are facts - I’ve seen it on my own scales. If you’re anywhere near Preston (Lancs) I’d be happy to show you.
The chap wanted to know some good settings for his car so I gave them, supported by the reasoning 
(Experience: 15 years messing with / track daying MX5s of all versions, 5 years racing Mk1s and tons of podiums / race wins, a season supporting and prepping the car of a front runner / race winner in BRSCC Mk1 championship, team manager for an MX5 team that won their class at Race of Remembrance, plus more.)
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Thank you for the replies. Yes I have the car at a race prep shop at the moment and they asked me to nip on the forum and get some advice on settings. Thank you.
Hmm. Were they asking about corner weight settings or alignment settings? There is only really one way to corner weight a car… 
but lots of alignment settings!
Jmho arb are connected to the car so if you disconnect them because you reckon they are in torsion when the car stationery they will be connected when the car is moving so disconnecting them during measuring makes no real sense to me.
If you have adjustable arb links just make sure they aren’t in torsion.
I have no prodiums btw so happy to be corrected
Aah. We’re on the same page. I mentioned initially that disconnecting drop links is when you have adjustable links. Agreed that no point doing this with fixed ones
Corner weight settings. They just wanted to know more before they weigh it I think.
Just after fitting new suspension to my NC, it was about +/- 4%. I was able to adjust within 1% of 50:50 for cross values, with a similar result fore aft and side side. Correcting mathematically for driver made about 0.5% difference.
My best estimate of overall weight without driver and fuel is 1066 kilos (100 kg for wheels/tryres).
NC phrt
without driver
|293| 51.43% |301|
|49.70%| |50.30%|
|281 |48.57% |280|
Total Weight=1155 kg
with 80 kg driver distributed 80% on the rhs and 20% on the lhs
|301 | 51.34% | 333|
|47.77%| |52.23%|
|289 |48.66% |312|
Total Weight=1235 kg
difference 51.43% - 51.34%
imho fork all (but the lighter the car the bigger difference it will have)
Thank you.