Making weight on the Spec Miata - East Street Racing Ballast System

For 2012, SCCA and NASA both increased the weight for the 1990 - 1993 Spec Miata to 2,300 lbs including driver.  The car weighed 2,275 lbs last year with my ~185lbs and I barely made weight with some fuel.   My car is a 1990 model.  The VIN confirms that it is an early build car and was actually built in 1989.  This car started life as a base model, no options car - so one of the lightest Miatas.

With the new rules, I needed to add weight to the car.  I've seen a lot of other cars running the kind of weights you normally see around the gym mounted to the floor boards with long bolts.  Ever see the floor boards of the Miata?  They are paper thin and move if you breath on it let along mount weight to it.  With all the Miatas in the world, somebody had to have made something better than gym weights, right?

Researching revealed a few options:

1. Get in touch with your local race fabrication shop or roll cage builder and see what ideas he as.  Chances are they probably have some ideas.  I thought about doing this but using the power of Google search stumbled upon another blog from a racer who took a different route...
2. Local racer Brian Ghidinelli dealt with the issue on his blog: Ghidinelli ballast blog post  He had a local metal retailer cut some metal plates to fit the floorboards of the Miata and bolted the plates in.  Good approach but I didn't quite like it since it still relied upon being bolted to the flimsy floor boards.
3. Rennenmetal makes some ballast plates that fit the curvature of the Miata's floorboards and includes mounting brackets.  Pretty nice but I still don't like the idea of bolting that much weight to the Miata's flimsy floor boards.  Check these links for Rennenmetal's parts:
Rennenmetal Miata Ballast Plates
Rennenmetal Miata Ballast Mounts

4.  East Street Racing Spec Miata Ballast System - I stumbled upon these on MazdaRacers.com.  East Street Racing developed a ballast system that bolts to the OEM passenger seat mounts.  This decreases the risk of the weight loosening or ripping out of the floor boards if something were to happen.  The stock passenger seat mounts were designed to hold a normal sized human being so they are probably good to about 200lbs or so.  While a little pricey, my safety is worth it.  

I highly recommend the East Street Racing Ballast System if you are looking to add ballast to your car. They came nicely wrapped, shipped quickly and install easily.  The bottom plate seems to be bent/formed so that one particular side fits better on the front than the rear seat mounts.  Test fit the bottom plate and you'll figure it out.  The bottom plate also has 4 nuts welded to the bottom to facilitate mounting the extra top plates.  Nicely thought out and very well fabricated system.

You'll need some bolts to mount the top weight plates.  They are 1/2" coarse thread.  A 1.5" length bolt will fit the bottom plate and 1 or 2 top plates.  I only have one plate mounted so far and it seems to have plenty of length to fit another plate.  I bought some Grade 8 bolts and washers from the local hardware store.

You can buy them here: East Street Racing Ballast System

The plates are not painted so I decided to paint them prior to installing so that they don't rust.  This led to me painting the passenger side floor boards and hitting them with a wire wheel to get some surface rust off the floor boards.  I basically got some brush on Rustoleum from the local hardware store and got to work.  I was too lazy to paint the whole interior so I stopped at the passenger floor.

Here are pics of the final product installed.

Enjoy.

Here is a view from the front seat mounts.