My billie build consists of:

NB B6 (Hard S) bilsteins from tirerack
Allstar threaded coil perches
QA1 450/300 7" springs
ISC extended tophats 1" front 1.5" rear
Torrington bearings from summit racing
Energy suspension spring isolaters

And this is how I secured the isolaters to the tophats:


Just a mockup, as I've still gotta fit them on the car without springs, ensure travel is good (and tires aren't contacting tub), cut bumpstops, trip coilover perches, repaint tophats, then final assembly.


Finally, I do seek some opinion. The ISC tophats, according to ISC documentation, should be installed directly onto the strut with no lower bushing. Seems like this would be NVH'y to me, and not allow the tophats to have any coaxial play to match the angel of the springs, so I've mocked them up using the lower bushings that came with the tophats and some OEM bushings on the top. Seems like it's going to work pretty well this way, any opinions? I already know these aren't the best tophats by any means, just looking to make the best out of what I have.

 

Coaxial movement is needed. I would always have a top and bottom bushing.

 

I'm starting to make a parts list to build a set of these for my 91 NA. As far as shock choices, if I were to buy new, what would be the best Bilstein option for a NA6? NA HD or NB b6 or NB b8. Looking for a pretty minimal drop 3/4" or so (roads are total **** here). Mostly fun street driven, few autox here and there. I have read a good amount of this thread and searched, but overwhelmedness comes on quick.

 

Hey Sean. I read and re-read this entire thread before settling on my setup (two posts above). I have yet to install them, but it's probably a good starting point for your build. I went with the NB b6 struts due to their dampening curve and availability through tire rack at $100 ea. new. I went with extended tophats since I'm putting them on an NA, and I went with 450/300 rates as they are supposed to match the strut pretty well and be comfortable on the street. I too live in a place with very **** roads. I wont be able to install them until the spring but I'll report back then.

 

This is enough of an answer for me and matches what I was thinking.. Thanks.

My next question is, do I just slam some bushings on there and call it a day, or do I drill out the hole in the tophat so that the rubber locating nipple on the lower bushing can slide in and center the shaft, similar to how the OEM tophats work. I'm leaning towards doing this already, but any input is welcome.

 

Excellent, thanks!

 

I would recommend to fit Your car with B6 from NB, they have better valving setup than NA. If your area is full of bad roads B6 from NA can be annoying.

 

I read the thread. Most of it, anyway, and I see very little information on people using NA dampers with NA top hats. Is there a specific reason not to?

 

NA top hats are trash. The aftermarket NA Bilsteins have bad valving and you need weird shoulder nuts to bolt to the top hat, so most use the NBs instead.

 

Interesting, thank you. What makes the NA hats trash?

 

Trashy top hats are one issue, in term of valving they are really harsh. The are rebounded to much let say. Nb bilies are rebound oriented as well but valving is better balanced

 

Ok, I’ll go with NB top hats, but I already have NA dampers. In the low-buck spirit of this thread, I’ll just work with those. Anyone have an opinion on the pros and cons of using the fancy purple FM top hats on the rear and FCM in the front vs. FCM at all four corners?

 

save your money from buying the fm rear and instead buy the good win racing extended top hats (I think the picture shows them as green) for both your front and rear. Cut bumpstops accordingly.

 

NA Bilsteins here, NB top hats in the front, with the shoulder nut and cut bushings spec miata style. 1.5" extended top hats in the rear. 450/325 setup, not the best ride as others have said but they do the job. You end up with more travel than you can use in the rear so I'll reiterate the important of the rear bump stop length. Tune it based on your ride height and tire size.

 

I don't see the need to get extended top hats at all with the NA HDs. I tested mine without a spring and the tire is pretty well stuffed at full compression. Save your money and just buy a set of used NB hats.

 

Likely not needed on most cars. My use case was for a specific track, with a large bump at the end of the front straight that would cause the back end to get very loose after it banged off the bumpstops. Same damper and spring setup with extended top hats = soaks up the bump no problem.

On the street or most tracks you'll never need them, I agree.

 

Getting ready to build a set of these for my '94 M-edition using MSM bilsteins that I have.

Looking for opinions as I am having a hard time deciding between 450/300 or 550/350 as it seems both are very common in this thread. I am also looking for opinions on which top hats are regarded as the best, and if 1.5" is necessary for the rear on NA, or if I can get a set that is 1" all around.

-MSM Bilsteins
-Allstar Sleeves/Collars
-Poly spring isolators
-Ridetech Delrin Spring Washers
-QA1 450/300 or 550/350

-Looking for opinions on what top hats to use.

Thanks for any help you guys can provide. After reading through these few threads over the past few days there is a ton of good information but I'm still not positive the best route to go.

 

Pretty sure you’ll get plenty of different responses.

On mine, I used 550/350 (or 550/400, it’s been 4 years and I sourced springs from Summit brand) and for top hats I used the TwoSix Motorsports here: Shock Mounts - 1” and liked them.

 

If its your daily, I would go for 450/300, they are super comfy with minimal body roll.

 

Not a daily, more of a weekend car, mountain cruises that sort of thing. I was leaning towards the 550/350 setup but comfort is nice. Is the 450/300 already a bit stiffer than say the stock mazdaspeed springs would be?