Junkwhale

Speaking of crazy pistons, the DSSV dampers use these instead of shim stacks:


Such a cool design. You get the repeatability/consistency of a much bigger/more linear spring (than shims) that as it compresses allows progressively more flow through the those ports - the shape of the ports can be changed to allow different forces at any point in the dyno curve.

slowcarfast

Ha, yes, piston rod. That's the piece I was thinking of but using the wrong term. The principle is the same though, you lose that travel. How much that really matters in this application is debatable, but it's something. I'll edit my earlier post.

Leafy

iTrader: (1)

For those wondering NB billies with na spring perches and na top hats works perfect in the rear if you cut the snap ring groove 1/2" lower down. But in the front you only have a max of like 2.5" of compression stroke before the shock would bottom on the mount. Thats kind of bad.

Bronson M

iTrader: (1)

With any kind of performance oriented spring rate and without helper springs you'll have more shock travel than spring travel. So the shorter shock shaft will help in this regard in that you don't have to worry about the spring rattling around if you hang a tire. I think I have a good 2" of excess shock travel with my 800/450 spring combo....so they wouldn't even be short enough for me. Non issue.....

HarryB

NB Hard S eyelet center to circlip is 22.5cm and 14.5cm. I can also confirm your calcs are reasonably close to mine. I have made a spreadsheet for similar reasons, albeit less advanced, which I can share if you wish. Does it happen to know the OEM NB top mount depth from the spring seat up to the damper shaft mounting surface?

JoeTheZoe

iTrader: (1)

I have those exact measures in the shock reference table on the spreadsheet. And I have a set of OEM NB top hats in my garage. Meant to measure them this morning but forgot. Will check when I get home tonight.

Edit: A quick measurement showed about 3/4" (19mm) from the spring seat to the deepest portion of the top hat's "relief" (not counting the bushing and washer thickness, which is at least as thick as that relief). After the top nut is torqued and the stock bushings are preloaded, I would estimate that the top of the bumpstop would be aligned with the spring seat (stock NB top hat and bushing configuration).

AngelGdo

Hello, I'm in the process of building a budget autox car and I'm pretty exiced to have stumbled into this thread. I would appreciate some guidance from any Bilstein gurus out there.

1- What is a reasonable price for a set of Bilsteins B6 HD with unkown miles?

2- What Blistein model is the most desirable one, for autocrossing NA Miatas?

3- How long does a Bilstein shock last?

Thanks,

Angel

Junkwhale

1. Maybe $150? Adjust up or down depending on their condition if the miles are unknown. Look for leaks, damage to the shaft/rod, lower bushing/mount condition, check that there's good gas pressure still by trying to compress the rod all they way down (should require a good amount of weight/force) then seeing if it pushes the rod back due to the Nitrogen pressure. All 4 should be comparable in the force it takes to compress and the speed they reach full extension again.

2. Generally in order of best to worst MSM bilsteins, NB Bilstein B6 HDs (aftermarket OTS ones), NB Hard S (OEM ones), NA R package bilsteins, NA Bilstein HDs.

3. Pretty much forever. As long as the seals are fine (no leaking), gas pressure is fine and bushings are fine, you're good to go and they'll dyno similar to a new one for many years.

Leafy

iTrader: (1)

For a miata to auto-x in ST, R-package front and choose your own adventure in the rear. It wont be comfortable.

2slow

Hi All,

Just joined so I can ask some questions about Bilstein build. I'm interested in doing this for my 2001 that I have bought just last November. I've never really worked on cars before, but I'm getting the hang of it (done clutch replacement, all fluid changes, exhaust swap and leak repair, seat mount fabrication, etc) . Doesn't seem to be too complicated, but I do have a serious lack of knowledge in several areas, including suspension. I've read as much as I could (this thread, one on club roadster, miata.net and other sites), but at this point I'm more confused than knowledgeable. I would like to ask this collective mind for some advice. Most of the items I've bought here and there and second hand, which should explain why so many different parts (well, that, plus not knowing what I'm going after).

What I've got
- naturally aspirated 2001 Miata with basic track prep (roll-bar, seats, harnesses, intake, exhaust)
- full set of new NA B6 HD's
- 4" sleeves and threaded perches
- aluminum top spring isolators (they came with with Spec Miata rubber bump stop - big rubber bump that sits under tophat, but I doubt using them is a good idea).
- 2 old NB Hard-S front Bilsteins that I bought before I got new NA HDs
- 4 FM bump stops
- FM anti-sways front and back on the car
- Eibach anti-sway kit (new, in box). Single setting front 27mm, 15mm dual setting back.
- 2.5ID Eibach 2x 700lb front 6" and 2x 325lb 7" back springs
- FM NB Springs (318lb abd 233lb)
- 2 extra NB tophats
- stock 16" wheels with 340 tread Bridgestone RE760 (will replace both in future)
- 949 end links installed in the car


What I'm looking to achieve:
- suspension that works for my 80% daily, 20% track/performance driving
- controlled, but enjoyable ride
- something that can handle street driving and not be a boat around the track.
- I'm not into slamming or even close to it - I do want to be able to go over speed bumps and be able go up the driveway into the garage. So slightly lower than stock height is ideal. No lower than 12.5"F 13"R probably.

My questions and dilemas:
1) I've bout NA HDs not knowing that while they can be installed in NB, are not ideal due to valving and shorter shock length. While I can do NA->NB mount conversion with shoulder nuts, FCM style bumps and bushings, I'm wondering if I should try to get rid of them and just get NB HD's. I've heard NB HD's have better valving, plus I'm not going to get anything funky with mounting or right height.

2) Get two used rear Billies and finish a used set?

3) single spring or dual spring setup with helpers/tenders? My impression is that dual system allows to keep springs in place AND adds a bit of refinement to the ride quality due to soft springs taking care of very small oscillations that may otherwise transfer to main springs and through the car.

4) Spring rates - I was thinking to do something like 300-450, but I'm trying to find someone with Bilsteins and similar rates to test them out.

5) Extended tophats? How useful are they on NB and do they make sense only wtih NB HD's or they could be ok with NA HD's if I do decide to keep them?

6) Are FM bars decent enough or should I replace them with Eibach kit?

7) I plan to put either 15x8 or 15x9 and probably Ventus RS3 v2 (actually have Konig Dial-Ins in this size sitting in boxes). I've heard that to use them I need coil overs with spring IDs no more than 2.5" as otherwise they may rub. Perhaps trading them for some 15x8 would be best?

Despite what it may look like, i don't have a lot of money for this and can't afford Xida's, Ohlins or FCM Elites. I work two part time jobs in addition to my main job in order to afford buying all of this second hand, so budget Bilstein build seems like a good idea (plus i get to learn).

I know I'm asking a lot here, but I hope someone has the patience and can share some knowledge.

crispyBYM

Try and get matching NB shocks. I run a 450lbs/in front and 300 rear spring on NB HD's. Ride height is 12.25" Hub to fender front and 12.75" in rear with stock 16" wheels.

My car has been 99% daily since I put these on in May. Yesterday was my first "spirited" drive in a group of 20 Miata's. (I use quotes because these guys were going full tilt. It changed my definition of spirited for real) If I moved my ride heights up a bit these would be the most comfortable setup I've ever experienced. When I first installed them my heights were around 14". That felt glorious. RIght now I'd rank them higher than a stock MSM suspension. Pretty damn comfortable as long as you avoid potholes and similar obstructions. I'm also about to install 15x9's with 225's. I see no reason why it won't work!

To all you guys with better setups than mine. I felt very grip limited yesterday. My buddy in a white NA with zero racing experience, crappy A/S tires, and cut springs was able to outpace me in corners. Now I have no idea if he was just unafraid of the consequences (He did spin once) but I felt very limited in grip. When I jack the car up there is about a 1/4" of space between the bumpstop and tophat. My thinking is that I might need some extended hats but I don't know for sure. I've heard of the zip tie test. Where do I put the zip ties? What should I look for when looking at the results after a drive? I also have a sneaking suspicion that I'm running very soft rates for my height.

When I installed the suspension we didn't disconnect the endlinks, instead we disconnected the sway bar brackets at the bushings. I reinstalled them while the car was in the air. Should I find someone with ramps to disconnect and reconnect these brackets to see if that helps improve anything? My car was around 14" ride height when I first got the car on the ground with a slight amount of preload on the spring. (7" springs all around)

I've done so many hours of suspension research and I still feel like a noob. Definitely have mad respect for those who have real knowledge in the dark art of suspension!

2slow

You do need to adjust the endlinks with car sitting on the wheels or supports at the hubs. Sway bars need to be as close to horizontal as possible and as close to 90 degrees with endlinks as possible. At the same time endlinks should not have any tension in them. If you have adjustables with heim join - then just find the sweet spot where you feel no resistance and tighten it.

Leafy

iTrader: (1)

Not just that but they should be adjusted with the drivers weight in the seat.

Bronson M

iTrader: (1)

The zip tie test is null and void on your setup. The idea is to put them around the shock shaft to see if the shock is bottoming out on the bump stops. Considering you're running spring rates half as stiff as you should and have only 1/4" of shock travel which is less than 1/2" of wheel travel before you're relying on the bump stop the second you turn the wheel or git a crack in the road. Your spring rates don't matter and the bump stop stiffness dictates your handling. This is bad because bump stops are terribly progressive and no shock can handle a spring rate that goes from stiff to infinatly stiff in a 1/2" of travel.

My suggestion, run 700/400 or 800/450 springs and then take the time to pull the springs and reassemble without them, trim your bump stops so that you can jack that car off the ground and not hit fender with the tire. At this point your bump stops will probably be half the length they are now. Pot holes and speed bumps will still be miserable but over all your ride will be better than running soft springs too low as you're doing now. On top of that you'll be setup to take advantage of the grip of 225's on 9" wheels.

This setup with Rival S's is good for FTD at regional events against Corvettes, GTR's and any muscle car you'll find at an auto x.

crispyBYM

I would definitely have to revalve the shocks for that stiff of spring though wouldn't I? That isn't very easy since I'm going to uni in August.

The weird thing is I don't feel like I'm hitting bumpstops until I hit proper big dips in the road. Then I feel the stops engage hard. Still with my current setup I'll definitely need to up the rates to something like 550/350 or something similar for now. Do you recommend extended top hats front and rear? Trimming the bumps to 30mm is in the works as well. Currently they're 35mm.

I'll go out and measure how much the bumpstop is able to move under load tomorrow when there is light out as well. Any other information you guys need?

2slow

Anyone else can chime in on post #810 above?

Bronson M

iTrader: (1)

Nope, revalve not "required" sure it would be better but right now you're effectively running 1500lb/in springs because you're literally on there bump stops as soon as the car is moving. Your butt is lying to you, most bump stops are progressive enough you can't tell when you first engage them. You need to aim for 3/4" of shock travel which will be~1.5" of wheel travel before the bump stops engage.

Spec miata's use spring rates in this ball park with similar valving. In my opinion the low speed dampening is darn close, high speed is a little lacking. Low speed governs handling, high speed handles bumps. These shocks were designed to help dampen the factory bump stops since OEM miata suspension relied on them.

To be clear, you jack the car up without the spring installed to see if the bump stop can be shortened and by how much. You can't just cut them to some arbitrary length you read about on the internet.

crispyBYM

So you suggest 700/400 springs to keep off the bumpstops during hard cornering/dips in the road, then checking shock travel before the bumpstop engages and figuring the right top hat to give me around 3/4", trimming the bumpstop to fine tune it correct? What about droop travel?

What length springs would you suggest? 6" all around seems to be pretty popular. Do you think I should run helper springs to keep the spring seated at all times?

Like I said this car is primarily a daily driver. I do love the sound of being able to run on any car on track (my first track day kill was a C6 Corvette followed by an ISF, yay novice days!) but I'll be commuting a lot more next year and I don't want to be beat up. That being said if I didn't really want to be beat up I wouldn't be planning to run 225's on a 9" and riding on bumpstops either so...

Leafy

iTrader: (1)

no, set your bump stop length with the spring removed. Put the shock in and the tire on and trim the bump stop to the length that prevents the tire from hitting the chassis.

Bronson M

iTrader: (1)

Leafy said it right, the only reason you would want extended to hats is if your bump stops end up being less than a 1/2" long. Let's say you find you ideally you can utilize a 1/4" tall bump stop and still keep the tire off the fender. At that point a 1" extended top hat wouldet you use a 1 1/4" bump stop which will be much more forgiving when you tag it.

Ignore droop travel, you have about 4" too much of it and there is nothing you cam do about it nor does it affect anything .

There are quite a few folks here that swear by helper springs. I personally don't think they are worth it, I never hang a tire in the air with my 800/450 springs and that's the only time they help. Even then all they are doing is keeping the spring from rattling. They are never in play for daily driving or even cornering for that matter.