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Anyone have specs for the spring rates for the various NA and NB models? I'm particularly interested in if NA6 and NA8 models used the same spring rates, were the NA Clubman springs stiffer and how do NA rates compare to NB?

NA6, NA8, & NA8 Clubman used the same springs, however NA8 Clubman used Bilstein dampers.

Actually there were tiny differences:

Early NA6 164/97 lb/in with 19/12 mm sways
Later NA6 154/94 lb/in with 19/12 mm sways
Std NA8 154/94 lb/in with 19/11 mm sways
NA8 R package 154/94 lb/in with 20/11 mm sways, but that might have been the US version only
All NB 162/118 lb/in with 22/11 mm sways
NB Mazdaspeed 215/158 with 23/14 mm sways (presumably the same on the AU delivered SE?)

Just going on those figures alone the first model NA6s had the sportiest handling (lowest FRC of 58.9%) then they got progressively worse from there until you got a Toyota Corolla-like 66.9% with the stock NB.

PS divide lb/in by 55.88 to convert to Kg/mm

manga_blue wrote:Actually there were tiny differences:

Early NA6 164/97 lb/in with 19/12 mm sways
Later NA6 154/94 lb/in with 19/12 mm sways
Std NA8 154/94 lb/in with 19/11 mm sways
NA8 R package 154/94 lb/in with 20/11 mm sways, but that might have been the US version only
All NB 162/118 lb/in with 22/11 mm sways
NB Mazdaspeed 215/158 with 23/14 mm sways (presumably the same on the AU delivered SE?)

Just going on those figures alone the first model NA6s had the sportiest handling (lowest FRC of 58.9%) then they got progressively worse from there until you got a Toyota Corolla-like 66.9% with the stock NB.

PS divide lb/in by 55.88 to convert to Kg/mm

Yes SE's have the same setup as a Mazdaspeed. Oversteer galore. NB8B chassis just adds oversteer, and the stiff rear end doesn't help.

Front Roll Couple means nothing if you don't also factor in the power of the car plus many other things like Diff type, Rake angles, weight balance, tyres.... The list never ends.
That's a brave call saying the NA6 is the sportiest based just on FRC values.


Old topic below for talk about the differences Clubman's and USA R Models had.
http://mx5cartalk.com/forum/viewtopic.php?t=30041

manga_blue wrote:Early NA6 164/97 lb/in with 19/12 mm sways
Later NA6 154/94 lb/in with 19/12 mm sways
Std NA8 154/94 lb/in with 19/11 mm sways
NA8 R package 154/94 lb/in with 20/11 mm sways, but that might have been the US version only
All NB 162/118 lb/in with 22/11 mm sways
NB Mazdaspeed 215/158 with 23/14 mm sways (presumably the same on the AU delivered SE?)

Just going on those figures alone the first model NA6s had the sportiest handling (lowest FRC of 58.9%) then they got progressively worse from there until you got a Toyota Corolla-like 66.9% with the stock NB.

PS divide lb/in by 55.88 to convert to Kg/mm

MX5 sway bar sizes with some slight variation:

93_Clubman wrote:NA6: 19mm Front & 12mm Rear (except on the 1993 NA6 red LE which were 19 & 11mm - note USDM 1993 NA6 red LE had Bilsteins which ADM didn't so variation may be possible)
NA8: 19mm F & 11mm R (USDM standard Packages: 19mm F & 11mm R)
NA8 Clubman w TorSen: 20mm F & 11mm R (USDM R Package w TorSen: 20mm F & 12mm R)
NB8A: 22mm F & 11mm R
NB8A 10AE w TorSen: 21mm F & 12mm R
NB8B: 22mm F & 12mm R
SP: 22mm F & 12mm R
SE w Torsen: 23mm F & 14mm R
NC1: 21mm F & 12mm R
NC2: 23.5mm F & 11.5mm R

Luke wrote:Front Roll Couple means nothing if you don't also factor in the power of the car plus many other things like Diff type, Rake angles, weight balance, tyres.... The list never ends.
That's a brave call saying the NA6 is the sportiest based just on FRC values.

Perhaps so, but it's a good starting point, especially when you're talking only about stock standard cars where rake, springs. shocks, etc are all unadjusted. I've probaby dríven about 40 or 50 stock MX5s, includng all NAs, NBs and NCs, except the SP and SE, on the track as part of new driver familiarisation. Those basic FRC figures do bear up in my experience. The early NA6s always seemed the best balanced and most neutral in the handling while understeer creeped in the further you went along the model lves. The two really outdstandng cars that I drove were a mint '89 NA6 and Zossy's original white clubman with a silky smooth turbo setup.