After reading a long and sometimes bitter thread on Pistonheads about axles, I thought I'd ask here.

I'm planning to swap the atlas axle for a IRS based on the MX5, mainly cos I can and the LSD's are cheaper.

To the question of the mo, apart from spring rate changes which way would the damping need to change (softer/harder)? running Protechs at the mo, so either the factory or asking Matt at Procomp to revalve them.

Regards Dan

less weight so technically i less damping, if your dampers have already been re-valved for the 7 then chances are they are already in the correct ballpark so only minor adjustment should be needed. usually somewhere around 220-250lbs for springs on a irs car

Cheers fella, that's roughly where I was thinking too.

Regards Dan.

Could I just ask whether it makes any difference if the weight is sprung or unsprung? I don't fully understand what would be classed as sprung or unsprung weight, but I'm guessing the atlas axle would be unsprung?

(Excuse the really bad question, I'm still learning here!)

Strictly speaking it's the ratio of Sprung Vs Unsprung mass that defines the damping rates.

Reducing the unsprung mass (axles and some elements of the suspension in an IRS) will mean that less damping is required.