Suspension Installation

One of the great things about the Exocet is that it uses off the shelf Miata parts for brakes and suspension.   Since the Miata is the most raced car on the planet, there’s lots to choose from.  For obvious reasons, I turned to Flyin’ Miata for advice and parts.

Shocks and springs are critical.   Dual adjustable coil overs from Afco were the best available at the time.  Today, the Fox parts might be better.  Maybe.   Anyway, I have the Afco’s.

There was a small problem with one of them.  The shocks come with the tops assembled, and the bump stops in place.   All you have to do is slide the adjuster over the top, and then slide the spring onto that. Unfortunately, the aluminum top was bigger around than the threaded adjuster.   I had to trim that piece down a little for it all to fit.    Not a big deal.

Adjuster doesn't fit!
Adjuster doesn’t fit!
Shock assembly
Shock assembly

The rest of the install is pretty much the same as a stock Miata.

Front suspension
Front suspension
Rear Suspension
Rear Suspension

FM sells a shock spacer for the front.  It moves the top of the shock and spring mount down about 2″ or so.  That is needed for stock and some aftermarket suspension parts.  it is not needed for the Afco suspension.

Sway bars were installed front and rear.   The rear bar is pretty straight forward. Just install that exactly like you think it should be done.

The front bar was a bit more difficult.   The LS1 sits a little further forward than the Miata engine.  And that blocks the installation of the front sway bar.   I had to move the frame bar mounts foreward about an inch to clear the front pulley.   Of course, that also moves the mount on the lower arm forward.  Because of the close relationship of the tie rod end, I had to use differant end links.  Not a problem, just another process to work through.

Frame mount for the front bar was moved forward a bit to clear the front engine pulley.
Frame mount for the front bar was moved forward a bit to clear the front engine pulley.
Front sway bar end link
Front sway bar end link

Another builder used a front bar from a BMW e36.   It has a deep dip in it, so it mounts to the stock Exocet mounts and travels under the front pulley.   He had to move his frame mounts back a little.  It was an excellent fit, and a better solution than what I have done.

You might notice there are numbers written here and there with a paint pen.  Those are the sizes of the nearby nuts and bolts.  Since I don’t work with metric stuff much, I can easily see what size socket/wrench I need for that particular fastener.

Brakes are also Miata replacement parts.   You can shave a lot off f your lap times with good brakes.  So bigger is often better.  But this car doesn’t weight much, and the Miata chassis is very sensitive to unsprung weight.  On Keith Tanner’s advice,  I’m using the FM Little Big Brake Kit.   It works well with the stock Miata master cylinder.

Rear Brakes.
Rear Brakes.
Little Big Brake Kit
Little Big Brake Kit

My Cobra uses big Wilwood brakes, and a CNC dual master cylinder.   Those brakes are excellent, and I can outbrake most other cars on the track.  The dual MC’s are infinitely adjustable, and work very well.  BUT… they don’t last long!  I have to rebuild them every 2-3 years.   I don’t like that.

Stock Miata master cylinder
Stock Miata master cylinder

I used the stock Miata master cylinder and power booster.  Notice where the proportioning valve is located.  By sheer luck, it fits there.  A better spot would be on the other side of the booster, next to the clutch master cylinder.      Also, take note that the booster check valve is inside of the rubber hose, NOT attached to the booster!   Don’t discard the rubber hose, and don’t put it on backwards.

Brake hose tabs welded to the frame.
Brake hose tabs welded to the frame.

You’ll also need to attach some tabs to the frame for the brake line connectors.   You can buy them already made, but they’re pretty easy to make yourself.

Notice that wheel spacers are required.  No one makes a wheel with the right amount of negative offset for the Exocet chassis.

Otherwise, these wheels seem to fit well and look good.   They are very light, too.  Significantly lighter than my Cobra wheels and tires.

front wheel 3
front wheel 3
front wheel 2
front wheel 2

IMG_7536

Rear tire without spacer
Rear tire without spacer
Rear tire, with spacer
Rear tire, with spacer

After tires are mounted, there’s very little room in there.  Some people have had trouble with tire rub in the rear.  This should be OK, but we’ll see what happens on the track.

Wheels are Holeshots, 15×9, with 0 offset.   I wanted a 15×10 -20 or -30,  but nothing was available.

Tires are Hoosier R6 275/50R15.  I’v tried a number of tires over the years.  I like the Kumho V710 – excellent grip and lasts a long time.  The Hoosier R6 has better grip, but doesn’t last as long.  And the A6 has ridiculous amounts of grip, but falls off fast on the road course.   In this application, it boils down to who has the right size.   I have two new sets of the R6, and that should last all season.   In 2017, I’ll probably switch to the R7.

I used a Toyo 888 for a short while on my Cobra.  What a horrible tire.  Did not wear very well, and got hot and greasy really fast.  I got rid of them after only two events.