My S-Ltd is undrivable over speed bumps, potholes etc running what I assume is the original Bilstein suspension and very low springs.
I know it’s unfashionable, but I want to go to standard dampers and maybe a 30mm lowering spring, but I’m totally bewildered by the choice, especially of dampers. Don’t want cheap rubbish. Any suggestions welcome!
ps - I will keep the original suspension in a box for the sake of retaining originality if anyone every wants to.
Buy standard Mazda dampers for the standard car and standard car springs and go down to 14" wheels.
That makes them very nice.
OK they lose some rear end grip if you are throwing the car about but 95% of the time they are just great
The S-Limited used what Mazda called the Bilstein suspension package; shocks, slight different springs (they’re same length as standard), uprated front anti-rollbar, shock tower brace. The Bilstein package rode 10mm lower than standard, and that was achieved not by shorter springs, but by a 10mm lower spring perch, so unlike a lowering spring set, here is no danger of coil binding. The bumpstops are an integral part of the suspension design, because they compress gradually. So the car is meant to hit them a bit. But, with stock bumpstops, with a 10mm drop, Mazda obviously anticipated you would be riding on the bumpstops too much. This results in the rough ride you get on b-roads. So for the 1.6 Bilstein cars, Mazdsa modified the bumpstop; a tad shorter than stock. Also, because the car is 10mm lower, the steering geometry is screwed up, so to compensate, modified track rod ends were fitted.
When everything is as factory spec, a Bilstein package car rides pretty nicely. Its certainly no limo quality, and has a sporty feel, but is by no means uncomfortable. The problem is when someone fits lowering springs, which is what you found.
Stock Showa (or equivalent OE) shocks will be overwhelmed by 30mm lowering springs. 30mm lowering springs are shorter than stock, to achieve lowering. This is generally achieved by less coils. The wire might be a bit thicker. On cheap springs, I have seen the wire is thinner. These cheap springs go from -30mm to -55mm in short order. The stock shocks compression/rebound rate is wrong for lowering springs. Because there are less coils, lowering springs are ALWAYS stiffer than stock. The factory Billies have a compression rate only moderately different from stock, but the rebound rate is much higher.
If you fit stock stocks and lowering springs, you will have a stiff ride. Your bumpstops/gaiters will by now be shredded. So you want new ones. But the shorter Bilstein bumpstops are NLA. So you will have a lowered car, stiffer than stock, and riding on bumpstops most of the time. So the ride won’t change really, and you will be disappointed.
One approach is a fully adjustable coilover set, which come with their own bumpstops and usually a shorter shock body.
Standard 1.6 springs are 167 pounds up front, 97 pounds rear. On Bilstein cars, the fronts are the same 167 pound rating, but the rears went to 110 pounds. One of the effects of the stiffer rear spring is to make the handling increase oversteer, making the car feel a bit more sporty on the slalom. Mazda paid attention to rear spring bias. Many aftermarket springs makers did now, with some making the rears too stiff relative to the fronts, really hiking up the oversteer behaviour.
But ride quality isn’t just about spring ratings. My 1.8 is on now defunct Performance 5 Puredrives; a Protec shock combing with pigtail springs and Mk2 top mount hardware, and some generic bumpstops. The front springs are about 500lbs and the rars around, I think, 300 pounds, The ride is silky smooth due to good spring-shock matching, and decent rwar bumpstop setup. On another car, I had Meister R Zeta Pros, with a similar springs rate, but I found that much harder to set up to cope with minor road imperfections, such as cats eyes.
I would consider replacing the springs with original spec springs (I don’t think you can get the S-Spec springs anymore, but try your local Mazda dealer, they may be able to order the right parts from Japan), provided the Billies are in good order; Krupps reckoned these shocks will still be at 95% after 200k kms unless there was external damage. These shocks are still available new (MX5parts), and there are several shock builders around who will economically rebuild these to new condition (about £70 a shock), and fit new standard bumpstops (Mazda, forget the cheap Chinese made copies).
Alternatively, consider a complete Mk2 setup; shocks with the Mk2 top mount and all the Mk2 bushings Will bolt right up. With standard Mk2 springs, the car will ride high, because Mk2s had a higher kerbweight. So fit moderately lowering Mk2 springs. The Mk2 setup improves the rear shock travel, so less riding on the bumpstops, and then improved ride. Mk2 lowering springs will give a nice ride height.
S-Limited were fitted with 14" BBS wheels as standard.
Thanks both, and especially Saz9961 for taking the time to give such a comprehensive reply.
Sounds like I need to take it to someone who really knows these cars to find out what is actually fitted now, and take it from there, considering all the options you mention.
Best wishes, Howard