Alternative to ISC top hats
 

Just saw this on Facebook. No affiliation.

Looks like a decent product that competes with ISC top hats. I'd give them a shot if I'd be in the market for top hats. $200 for a set of 4. They are made out of aluminum. I'd put a rubber bushing on the top though.

https://www.facebook.com/twosixmotorsports

https://scontent-b-sjc.xx.fbcdn.net/...67&oe=53FD9DD4

I've been looking into the ISC rears, and it seems that the biggest complaint is that there's no integral centering ring on the spring side, and users have to glue something in place to keep the springs from shifting around. Based on the photo, unfortunately these don't seem to have one either.

Can anyone with ISCs comment on that issue?

That's only if you run no preload on your springs I assume. My current top hats are flat and don't have spring centering rings. They are just fine, but I run a little preload on them.

I have the ISC, and have had absolutely no issues with them.

$200 for 4 vs. $41 each for the ISC. Is the weight savings worth 35 bucks?

I run ISC's as well and I find no issues with the springs moving around that I have noticed.

OK, thanks for the input on them. I was doing some research on tophats in general, and ISC hats specifically, as I'm a n00b when it comes to setting up a suspension. I ran across a thread on M.net, but the author actually sounded intelligent so I figured they may be some truth to it.

Notes on ISC topmount/tophats - MX-5 Miata Forum

That's a simple and easy fix if it is necessary, but perhaps there's not a problem with every application. Maybe it's a function of ride height making a difference there.

springs will shift without an isolator or spring locator in general. its not an ISC specific problem. Preload works well to replace that, but not everyone runs "threaded shocks" (Bilsteins for example).

I think the NB stock showas use a piece of rubber actually (mostly for noise) lol, but once again those have preload.

Alright, then I'm not going to sweat it. It sounded like there was a risk of the spring moving around enough to get in the way of the shock body, but I'll be preloading them and I have some isolators I can glue in place if necessary.

I just picked up Jake's MSM Bilstein/eBay sleeve setup and the rear hats are not tall enough for the shock bodies. Is there any reason why I should go with taller than normal ISCs (which are 1.5") back there? My typical ride height is 4.5f/4.75r, give or take.

Garage Star also has a set if anyone is interested, $55 each, shipped.

Garage Star - Top Hats

Taller hats reduce droop. Why do you suspect the top hats aren't tall enough for the shocks?

Well, they are hitting hard over med-large bumps, like my previous setup did when I had coil bind problems. Jake mentioned that he felt the shock body was hitting the tophat so I didn't look into it any further (msm billies and nb hats). I'm going to have a look at the coils this weekend to see if they are making contact, and I have a set ot 8" springs that cured my bind issue last time that I can install if so.

Do the zip tie test.

Because it's MSM shocks with stock NB hats with coilover sleeves. :party:;)


It NEEDS extended top hats.

Will do that, great suggestion.

Never heard of it. Please elaborate.

Ziptie tight around shock rods, go drive and bottom out, see if they are pushed all the way up against the hat.

At least, that's my guess.

pretty much. if you are bottoming out and the zip-tie isn't touching the bumpstop, then you were stupid for buying these silly things.

How about we take some measurements and see what touches first?

If it's the tire or subframe there's too much bump travel and you need shallower top hats (might as well get that bump travel back as droop instead of limiting the travel of the shock)

If it's the spring then you need longer main springs with less preload or shorter main springs with helpers if you're already at 0 preload

If it's the bumpstop by a large margin that's when you buy the deep top hats to free up some bump travel.

What else can touch? Sway bars with stock endlinks maybe?

Thanks for the list of possibilities, Failure. Looks like a bit of legwork is in order. I'll spend some time with the car in the air tomorrow and figure out what's hitting what.

If math isn't your thing and wrenches are, you can also try taking off the spring and sticking a jack under the wheel so you can raise and lower the wheel. You'd still have to calculate coil bind but that should show you what's going on with everything else.

Or maybe that's a terrible idea, I don't know. Use your own judgment.

Played around a bit with this today. The shock body definitely hits the tophat before the upper arm hits the frame, as shown in the photo. If the bumpstop were removed there would be about a 1cm gap above the upper arm when the shock body contacts the isolator under the hat.

https://www.miataturbo.net/attachmen...1&d=1400366023

I know there's some math hiding in here, but without knowing exactly how much taller a 1.5"/4cm ISC hat is than a stock NB hat, I don't see how I can calculate anything. And I can't seem to find that information anywhere online. Best I can do is use this comparison I put together which is as close to scale as possible. NB on the left, NA on the right, 2.5" ID spring for scale.

https://www.miataturbo.net/attachmen...1&d=1400366023

I'm assuming that when a height for a taller hat is noted it refers to the shock rod shoulder cpntact point. It looks like the upper shock rod shoulder is approximately at the same height as the upper spring perch on the NB hat. As noted above, with no bumpstop and the current NB hat, I'd have about a 1cm gap above the upper arm. It seems that with a 1.5"/4cm ISC hat the arm would make contact with about 3cm of dead space above the shock body.

So if I use a bumpstop that's a little thicker (for safety margin) than the 3cm of dead space at full compression, I should be able to use the ISC hats and avoid frame contact with the arm. At that point, it seems that I could figure out spring perch vs spring block height so that I don't bind and have the compression worked out.

Does this sound correct?