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Yeah, you definitely shouldn't bother reading the thread. It's too much work.
This is not an exaggeration, I have spent probably 4-6 hours in this thread in the past 4 days. If there is a post that shows the answers to the questions I asked above, I completely missed it.
On top of that, no one posts part numbers and the names of the different shock options are not consistent. So even when I find a post that I think applies to me, I can't be 100% sure.
It is tough to go through 2000+ posts and figure out what is going on for NA vs NB. For the NB B8s, are extended tophats required for use on an NA?
The posts are there to help you make an informed decision based upon your wants, needs, budget, and chassis. There is no one size fits all formula. I would offer that realistically, NA and NBs are same cars and suspension should be treated same.
NB Shortened shaft bilstein shocks are what you want. That's what I use on my NA running 550/350 springs. Also look into extended front and rear tophats.
Originally Posted by JD8
Got it, thank you for the help. NB shortened shaft being the NB B8 shocks, correct? Why not go with the NA B6 shocks and not have to worry about the extended tophats?
Originally Posted by JD8
This is not an exaggeration, I have spent probably 4-6 hours in this thread in the past 4 days. If there is a post that shows the answers to the questions I asked above, I completely missed it.
On top of that, no one posts part numbers and the names of the different shock options are not consistent. So even when I find a post that I think applies to me, I can't be 100% sure.
NB B8 shock for Na chassis. Run extended maruha front and rear top hats. People like maruha because they offer a lot of performance per dollar. I went with Good Win Racing Feal top hats front and rear on my na chassis because I didn't know about Maruha at the time. Their tophats do not fit for the fronts of NB's for anyone wondering, only na.
NB B8 shock for Na chassis. Run extended maruha front and rear top hats. People like maruha because they offer a lot of performance per dollar. I went with Good Win Racing Feal top hats front and rear on my na chassis because I didn't know about Maruha at the time. Their tophats do not fit for the fronts of NB's for anyone wondering, only na.
This is exactly the information that I was unsure of and why I was having trouble figuring out what to buy. So, if I am using NB B8 shocks on an NA, using NB tophats is not enough? I will need extended tophats front and rear? How do you know how much of an extension is required?
Is clanging/clunking in the rear as well as sleeve rub normal? I'm getting some rub a little more than half way up the 5x sleeves I'm using in the rear. I also am hearing something clunk around back there, but only when I'm going in/out of my driveway that has a bump for drainage. Speed bumps and train tracks are no problem. At first I thought it was a loose sleeve so I added more tape then siliconed it in place. It doesn't move at all and I tightened everything up real good.
I'm reusing my pretty new stock rubber bushings (both upper and lower). I saw a user above me say that using the 5x washers and bushings from the Fat Cat kit solved his problems, but I'm struggling to understand how those bushings can make that much of a difference. Not that I'm doubting it, just would like to understand before I try it as well and dump $80 into the hardware.
The springs aren't self centering in the tophats and you can see rub on the tops of the adjustment collars by the springs if they get over to one side or another. A rubber locator at the spring top where it meets the tophat will keep them from moving if it concerns you.
Final parts check, let me know if you see anything wrong.
Car is an NA that runs on Hoosiers for track days. I do not care about street manners.
Relevant info I found for people who get lost reading through 2000+ posts...
emilio700 (miataturbo.net, this thread I think)
"For years, we have recommended DIY Bilstein setups for budgets under $1000. FM or Tein lowering springs [current recommendation is Summit QA1] or ebay sleeves and 450-550 fronts paired with 300-350 rears. The Bilstein is the highest quality shock in this price range. Damping rates aren't perfect and the bodies are a tad too long but is as close as you are going to get until something better comes along. The next step is, well, you already know that answer. [referring to Xidas]"
"If you are not going to revalve them, I'd suggest sticking to 205 RS4's on 8" wheels and <150whp.. then 550/350"
"Bilsteins are perfectly valved for about 300/200 springs and 205/50 250+ treadwear tires. The world runs twice those rates on race tires so the question is, how much are you willing to compromise grip (which come from compliance and softer springs) and responsiveness, which comes from stiffer springs. I'm guessing a comp weight of less than 2350# and 205 RS4's. I would run 5.25" pinch weld heights and 450/300 rates. But what do I know :P "
concealer404 (MT.net, this thread a few posts up)
"Spec Miata runs those [referring to 700/325 spring rates] because rules. You don't have rules, so you don't need to run their compromised setups.
550/350 is about as far as anyone here will recommend going on Billies, and we like NB B8s. "
A data point. I found that NA shocks, with their shorter bodies work well with NB top hats, front and rear.
Extended top hats, with 36mm bump stops allow too much upper movement on an NB. Rear UCA woulld hit body. Front tires would touch fenders at full lock and full compression.
So, my experience would point to NB top hats for NA Bilsteins, Extended hats with NB Bilsteins.
A data point. I found that NA shocks, with their shorter bodies work well with NB top hats, front and rear.
Extended top hats, with 36mm bump stops allow too much upper movement on an NB. Rear UCA woulld hit body. Front tires would touch fenders at full lock and full compression.
So, my experience would point to NB top hats for NA Bilsteins, Extended hats with NB Bilsteins.
DNM
But isn't that the whole purpose of sizing bump stops. Regardless of the top hat choice I think the right move is to install the shocks with top hats and no springs and measure full compression to see how much bump stop you need before the tire is stuffed into the fenders.
When i did by Budget bilstein setup with front extended top hats I disassembled and reassembled with numerous height bump stops. I think my overall conclusion was somewhere around a 44mm bumpstop was the sweet spot for the front with my particular top hats (I think they offer 1 inch extended travel but it might be .75). That let the shock fully compress with the tire before hitting anything.
That’s why I did qualify bump stop length. Still, if I buy extended hats, it should be for extended travel. If I turn around and reduce travel with tall bump stops, then what I have accomplished is a highly progressive rate at the top of travel, and to be honest, I’m not smart enough to work out how I would balance that with roll centers and the front and back moving into the progressive regions simultaneously.
Rather, I want the bump stops to rarely come into play, and exist simply to prevent solid stops in crazy conditions, like a really big dip.
Kind of like Six’s idea that you should be able to hit the outside curbing in the middle of a max turn, and not hit the bump stops.
Again, just a data point from my experience/ journey.
DNM
EDIT: Andy, your process is also viable, and may be preferred. I’m just not sure I know how to know how much compression a bump stop will get to, so I wanted to allow for full, or near full compression before anything else touched, regardless of free state height.
Good info, thank you. I was trying to avoid having to buy/make extended top hats, but if it is needed then I will add those to the list.
Designing the suspension to regularly rely on bump stops does not sound right to me, but I am not a chassis engineer. I do plan on running pinch weld heights that line up with the supermiata race alignment specs.
That’s why I did qualify bump stop length. Still, if I buy extended hats, it should be for extended travel. If I turn around and reduce travel with tall bump stops, then what I have accomplished is a highly progressive rate at the top of travel, and to be honest, I’m not smart enough to work out how I would balance that with roll centers and the front and back moving into the progressive regions simultaneously.
Rather, I want the bump stops to rarely come into play, and exist simply to prevent solid stops in crazy conditions, like a really big dip.
Kind of like Six’s idea that you should be able to hit the outside curbing in the middle of a max turn, and not hit the bump stops.
Again, just a data point from my experience/ journey.
DNM
EDIT: Andy, your process is also viable, and may be preferred. I’m just not sure I know how to know how much compression a bump stop will get to, so I wanted to allow for full, or near full compression before anything else touched, regardless of free state height.
Fully agree. The thing is, you want the bumpstop to stop movement of your suspension before something else touches. However, you cannot calculate (easily that is) the "block height" of a bumpstop; you just pick a reasonable force value from the force-displacement curve (say 800lbs) and see to how much displacement this corresponds. Subtracting that displacement from the original length is what gives you your compressed length. You can accomplish the same thing with long and "soft" or short and "stiff" bumpstops.
That’s why I did qualify bump stop length. Still, if I buy extended hats, it should be for extended travel. If I turn around and reduce travel with tall bump stops, then what I have accomplished is a highly progressive rate at the top of travel, and to be honest, I’m not smart enough to work out how I would balance that with roll centers and the front and back moving into the progressive regions simultaneously.
Rather, I want the bump stops to rarely come into play, and exist simply to prevent solid stops in crazy conditions, like a really big dip.
Kind of like Six’s idea that you should be able to hit the outside curbing in the middle of a max turn, and not hit the bump stops.
Again, just a data point from my experience/ journey.
DNM
EDIT: Andy, your process is also viable, and may be preferred. I’m just not sure I know how to know how much compression a bump stop will get to, so I wanted to allow for full, or near full compression before anything else touched, regardless of free state height.
Completely understandable. My issue was with Nb style front top hats and the 36mm bump stops I had originally, at rest at my ride height of about 12.4 front and 12.6 rear (as measured from center of wheel to fender lip) had my bumpstops already touching sandwiched between the top hat and the shock. So while stationary my bump stops were already slightly engaged. The solution seemed that either you could cut the bumpstop shorter to give more upward travel and not have it engaged while stationary or I could extended the top hat and extend the bump stop a lesser amount than the top hat was extended. My top hat increase in size was approximately 24mm while my increase in bump stop material was about 8mm. So my back op napkin math says that I increased my stroke length by 8mm. But not really because bump stops squish as they get compressed. So it is a bit more than 8mm before the bumpstop goes to infinity rate.
In addition the rate of force with more material on the bump stop would change the curve of force on it to be more gradual. If my bump stops were cut shorter instead, to give me back stroke length then they would hit infinity rate faster and I think that would yield some unpredictable results.
With all of this said, I don't really have any knowledge in what I am talking about other than the measurements I took on my car and what my results yielded for me. At my present ride height with 44mm of bumpstop material and my extended front top hats while stationary I have more room before my bumpstops are engaged. And my bumpstops were sized to prevent my tires hitting the chassis.
I did not do any calculations as far as bumpstop force, I only put them on my suspension and measured how much material I needed before the tire made contact with anything else and sized it accordingly.
My belief is that the suspension should be tuned to never engage the bump stops and steady-state cornering. We are going to drop wheels off the edge of the track, hit Apex curbs, that sort of thing. That's going to use up that last bit of travel. It is here where damping sort of takes over. The right blend of low and high speed rebound damping we'll keep that stored energy in the bump stop from making the car oscillate. Desert trucks and off-road vehicles use position sensitive damping to help control effects of coming off the bump stops. Top level race cars use a third shock to create a balance between heave and single wheel inputs. In a typical dual Duty Miata that is also tuned for acceptable ride quality on the street that can be quite the challenge without those other tuning options. In the case of a system using stock valved bilsteins, the answer is a taller ride height and a more progressive bump stop. Essentially limiting the amount of energy that can be stored and released in the bump stock to match the relatively low rebound damping available.
I'm a newly miata (NB) owner and looking to upgrade/improve the whole car basically :P I wanna thank you all for taking the time to write stuff here and share knowledge / opinions; I have learnt quite a lot already just be reading over the past days.
Thanks for letting me know Bilstein is the way to go; I was actually thinking of Tein with quite an insterest !
i'm putting a DIY parts list for my 2002 NB and it looks that springs, sleeves, adjusting nuts and isolators are going over 400 without including shipping fees. No bumbers either lol.
I'm thinking to buy the Tein Street Basis Z for the same amount of money (or street advance Z for 100 more) which come with springs of 6.89" length / 2.75" I.D. / 400 vs 335 inch/lib (front vs rear) which is pretty close to the setups mentioned here along with the billies. And with all the parts from the kit I can DIY my billies... Thoughts ?
And I do get the shocks as well for the same price. Shocks which I can use, sell, revalve, whatever... Makes sense ? Am I missing something big?
05-29-2020, 10:10 AM
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