johnx85dt

Hello everyone. I am posting here in lack of finding any info anywhere about this.

Recently I purchased my first miata (you can read about it in the meet and greet section) https://www.miataturbo.net/meet-gree...veryone-96217/ and am really pleased with it but....

The car has a set of HSD dualtechs (not sure what version or production year) which i think are awfully set up from previous owner / alignment shop. Being a shock which you can independently adjust the ride height from the spring preload, I am pretty sure the settings are messed up, especially at the rear. As you can see in the photos the front shock seems to have a 'decent' spring preload adjustment, while the height looks like it is near the maximum height available on the threaded part of the body. At the rear it looks to me that the spring preload is adjusted way too stiff (correct me if I'm wrong), and height-wise it seems that it is not so much on the limit like the front ones.









Everything I speculate above is just by comparison with photos of the shocks before installation like the one above, as I didn't have any time to fiddle with the settings before I left Greece (and it will be two months before I go back). Trying to search on HSD's official site, as well as forums, google etc. I didn't find any info on how much is the maximum ride height available from these shocks, other than they can go at "almost stock ride height", which is clearly not the case in my raked blue miata... They do suggest though that the spring should be adjusted, before installation on the car, so that it barely touches the top hat and the ring, and then tightening the ring half a turn more just to keep the spring from clanging when the shock is unloaded.

My questions are:

1) Does anyone have experience with these shocks and knows what the maximum height available is?
2) Do you think the fronts can be adjusted any higher?
2) Does it seem to you that the rear spring has too much preload, or is it just me?
3) The general rule of thumb that the threaded part should be at least half the diameter of the body, can be applied here or not? Can it be less or should it be more?

I'd like to get the suspension sorted out before I start driving it again, because now the car is very harsh on the road and at big humps I am hitting the rear bump stops.

I know this is not enough info because I don't have any measurements yet, but I'd like to know your thoughts on this, as most of you are experienced with coilover adjustment on these cars and maybe you can tell just from the photos if something is way off. Also If anyone has these shocks on, it would be very helpful if you can share a photo or two just for comparison.

Thanks in advance and sorry if this post is something you've seen a million times over, but for the life of me I cannot find any info whatsoever... Maybe I am not searching in the right intrawebs places... I don't know...

spencer9474

iTrader: (1)

I'd start by adjusting preload as you described, so that the spring just stays tight on the top collar while the suspension is unloaded. Your range of ride heights will then only be adjustable with the bottom mount and collar.

Leafy

iTrader: (1)

These are just ebay shocks. Tons of brands with the same china shocks. As far as I can tell anything beyond the shock shafts not snapping off at the top mounts is a gift.

Bronson M

iTrader: (1)

"Being a shock which you can independently adjust the ride height from the spring preload"

No, that's not how it works. Pre-load is a completely useless thing to measure or worry about. Just adjust the collars for the desired ride height and whatever the preload ends up being it doesn't matter. Yes in an ideal world it would be best for the spring to have a tiny bit of preload to keep the springs seated at full droop but there is no performance benefit and you have much bigger issues to worry about with those coil overs .

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acedeuce802

iTrader: (1)

Preload indirectly matters. It does not matter in the sense of "you need a bit of preload to keep the springs seated". It matters because for a given spring rate and shock stroke, preload will directly relate to bump/droop ratio. If you completely ignore preload and jack the car up with the spring perches, you will probably have no droop with these shortened coilovers and it'll ride like crap. Spring perch should be set to desired bump/droop ratio then ride height set with bodies. You have to take advantage of the small travel with these body adjustable coilovers because they have much less travel than a standard coilover.

OP, good luck with those threads, I've bad experiences trying to adjust coilovers that look that corroded. See if you can find out how much travel you have in either direction (jack up car and take note how much coilover extends, find a way to load up car and see how much it compresses). Playing with the spring perch will change how much bump and droop you have, and you don't want to run out of either, and you also want similar amounts front/rear. If the coilover extends more in droop, then you are free to raise the spring perch to raise the car.

ryansmoneypit

iTrader: (6)

These are EBAY shocks that should go in the trash can, and the thread is still going. why?

sorry op, its the truth.

johnx85dt

Thank you for the replies and the suggestions.

You are pretty sure those are Ebay shocks. I have to say I am really bummed right now, but how can you tell? I am not saying they aren't, I'm just asking what are the differences between the originals and the china shocks? How can I tell them apart in the future? The shocks came with the car and the previous owner had bought them from a reputable store, which i guess just owned him and took his money...

Thanks

Leafy

iTrader: (1)

All the shocks that have the bottom mount not fixed to the shock will be ebay china shocks. There might have been some half baked other big name shock back in the day with that setup like JRZ but no matter who makes them they just dont have enough travel to be fast or have an acceptable ride on the street.

Bronson M

iTrader: (1)

All the high end shocks in the industry don't have separate adjustable bottom mounts, I'm talking exida, afco, FCM, you name it. No matter what shock you have you need to set the maximum bump travel to prevent tire to metal interference, whether thats done with trimmed bump stops on a fixed length shock or adjusted with a set of these Uber cheap China shocks it doesn't matter. Once the max bump travel is set the droop is dictated by the shock length.

Again looking at the preload on the springs is useless, it's about setting up your max and min travel.

johnx85dt

Ok gotcha! So the problem with these kind of shocks, if I understand correctly, is due to this design (adjustable lower shock mount) you are sacrificing useful bump travel? Thanks for the insight guys.

DaWaN

I think these HSD shocks are not well known in the USA, but in the UK I think they are better known (and also sold more).
Not exactly sure of their origin, but they are from Asia (and not Japan).
Their price is higher compared to eBay kits, so they might be better built.
The HSD monopros suffered from coil bind in the past (click here to read), so they are not very well engineered for the MX-5/Miata platform...

johnx85dt

Yeah I can understand they are not known in the USA and also it's 110% sure they are made in China. I read the thread you sent (thanks!) and confirmed my suspicion that the rear travel is really small (75mm on the monopros). Regarding pricing, it's always a factor that people correlate with the quality of a product and in both ends of the scale. When something is priced a little bit higher that its competition our brain automatically assumes a better quality and vice versa. That's where experience and many tests come into play.

I always had in mind that these kind of coilovers are more 'drift' and 'stance' oriented which is something I am not interested in, so from the moment I purchased the car I have the suspension system in my "to do" list. I just wanted to try and adjust the HSD so they can serve me until I move to a better quality and tested/proved set of shocks. If I cannot achieve a decent ride quality with the HSD then I guess new shocks move up my list. But hey... in the meantime there is always the option of Bilsteins coilover conversion... maybe I'll give this a go! Ultimately my goal is a firm but not stiff/harsh ride for daily driving and maybe some spirited runs on the twisties. No intention of tracking the car at all.

damir130

Just keep in mind that we never got the MSM bilsteins that everyone is using in the EU. The valving on the others is still better than anything with a Driftworks or HSD label on them, but nothing near the best you can do.

jacob300zx

I would start by fixing the rake, it looks like you have a 2" difference front to rear.