E-Street Setup recommendations

Chuck Mathews -

Let me start by saying that what you read here is my opinion, based upon lots of trial and error over the years and theories that I currently hold to be true. YMMV

These setup instructions are specifically for the 1999-2000 NB1 Miata with the Hard-S suspension. My car is a 1999 Miata Base Sport Package car with no A/C or power steering. Setup shoud be similar on the NB2's. Bump stops were the same length on my 2001. Other years should be verified for compliance. You can check part numbers in the Mazda Motorsports store. The NA6 and NA8 are very different cars. I have been asked to help develop a 1997 Miata R Package to be a fast local competitor, so I may be able to give some guidance there later as well, but not at this time. 

Secondly, while I’ve had a good bit of success with my setup, it is considered controversial by some. It doesn’t follow the path that many others have claimed is the best. That being said, there’s more than one way to end up with a fast setup. This is mine and it works very well for the current crop of tires, the Bridgestone RE71R and the BFGoodrich Rival S 1.5. It also works well in the wet on the Continental Extremecontact Sport. Other tires may or may not work as well with these particular setup details. 

If you haven’t already, you really should listen to Cone Coach #19 where I discuss bump stops, suspension tuning, and my theories for car setup. One thing that has changed since the podcast is that Matt Waldbaum and I have started to develop a wet setup. It appears to help improve grip over the dry setup. So far, that only involves softening the shocks. 

The stock NB bump stops are 58mm in the rear and 60.5mm in the front. For E-Street, you need to follow 13.5.D of the rulebook:

A suspension bump stop is considered to be performing the function of a spring. Therefore, the compressed length of the shock at the initial point of contact with the bump stop may not be increased from the standard part, although the bump stop may be shortened. Bump stops installed externally and concentric with the shaft of a shock may be drilled out to fit a larger diameter shock shaft. Bump stops may be substituted provided they meet the length requirements and are in the same location as stock.

Fortunately, if you’re running Konis or Bilsteins, you just need to make sure the bump stops aren’t longer than the stock ones. If you run a fancy shock like a Penske (like I do) then you’ll need to do your own calculations to ensure you’re compliant. If you’d like to go down that road, Guy Ankeny does some wonderful machine work and will build you a set of Penskes that are rules compliant.

What I personally recommend for setup on the Konis or Bilsteins is as follows:

SFR Bar (State of the art) or Flyin’ Miata Bar (the budget minded option)

Soft setup:

Rear bump stop-->   55mm long Ohlins brown bump stop and the 0.125” packer (3.17mm)

Front bump stop-->   2-3/8” long (60.33mm) Penske white bump stop

Stiff setup:

Rear bump stop-->   55mm long Ohlins black bump stop and the 0.125” packer (3.17mm)

Front bump stop-->   2-3/8” long (60.33mm) Penske blue bump stop

If you already have a Racing Beat bar and don't want to swap it out, here’s an alternative:

You can use Penske black bump stops for both the front and rear, but you’ll need to trim the rears by 2.33mm or more. I think it’s easiest to trim them at the first dimple, but no matter where you trim them, you’ll want to make sure you get them even and measure them when you’re finished to ensure compliance with the rules. If you trim them at the dimple, then you’ll also need packers. When I trimmed mine I ordered an assortment of sizes so I would have exactly what I needed.

While this isn’t my preferred bar (I have a strong preference for a smaller bar), autocrosser Shane Johnson has used this setup with great success, winning PAX at his local autocross on the first outing in the car. We discussed his options at great length and part of the motivation for writing this blog post is to have a place to point people to that although I love talking about setup, I don’t always have time to discuss every detail.

Alignment:

I use a very simple alignment.

Max camber in the front. Max camber in the rear with one caveat.Make the split front to rear the same from side to side. i.e. LF -1.1       RF - 1.3LR -2.0       RR - 2.2

I run zero toe all around but have suggested 1/16” toe in certain cercumstances. 

Conclusion:

I’m hopeful that with this information we can see more people showing up with cars that are capable of winning. If you’re close enough to the Chicago area, please come out and autocross with us.

I'll update this post periodically with information that is useful for a good E-Street setup and change the last updated date at the bottom. Please keep the questions coming.

Resources:

Bump Stop Travel Sheets

RE Suspension bump stops vs Penske bump stops:

Some people have been asking what the difference is between the RE Suspension bump stops (that are also available through Fat Cat) and the Penske bump stops I recommend. 

Penske

- Blue - 225 lb/in

- Black - 155 lb/in

- White - 100 lb/in

RE Suspension

- Blue - 235 lb/in

- white - 141 lb/in

- Red - 85 lb/in

updated  06/27/19 with additional alignment details

updated  07/03/19 with link to bump stop information and clarification about tires

updated  06/27/19 with notes about which Miatas this applies to

updated 07/08/19 with comparison between Penske and RE Suspension bump stops

Thursday June 27th, 2019#