Building a Track Car – sweating the details

Many times the modifications that take place on the Miata are pretty cut and dried.  One item is unbolted and the replacement is put back in its place.  It takes time and a little care, but no reengineering required.

Then there are times when a modification requires additional thought and preparation in order to ensure that everything works properly and in harmony with each other.

The front sway bar (anti-roll bar) is one of those pieces of the puzzle that requires a bit of work.  For one thing, the design of the factory brackets that support the mounts on this Miata are a bit flimsy.  They work well enough with the standard bar and in most street driving, but they are a known point of failure when the car is tracked with a larger sway bar and very sticky tires are employed.

A shot of the bracket with the angle welded in place

There are a couple of aftermarket solutions out there.  They work very well, but their cost can range from $50 to $150 or more.  Fortunately Mark has fabrication and welding skills so he listened to my concerns and came up with a great solution that will keep the sway bar secure and not even dent my budget. 

From another angle

He reenforced the existing brackets with strategically placed and welded angle iron. 

With a little paint applied

The stock front sway bar is being replaced with a 24mm bar from Whiteline out of Australia.  It comes with new brackets and polyurethane bushings.  And there is another engineering challenge to deal with.

New clamp brackets with original sized bushings

Because the new bar has a greater diameter than the stock one, the bushing in which it mounts is taller than the stock bushing. 

The new bushing on the left is a lot taller

In the past I would have just cranked down on the mounting bolts until the metal bracket was secure and compressed the heck out of the new bushing.  I would have done so out of complete ignorance of the fact that in doing so I had compromised the proper operation of the sway bar.

New bushings, new bracket, and Mark's custom made spacers

With all the clamping load required to compress the new bushings I would have just about locked the sway bar in place and inhibited its ability to rotate in the bushings, as it should.  This would have resulted in unpredictable handling as the bar struggled to act as a torsion spring between the two sides of the front suspension.

Compression of the bushing is now going to be proper

With all the above in mind Mark and I put our heads together once again.  The outcome was a pair of spacers that would raise and support the brackets as well as limit the compression of the bushing and allow the bar to rotate as a proper torsion spring.

Just the right amount of lift

All I had to do was source a longer set of bolts.  Ace Hardware solved that little problem.

It is great to have clever and creative friends.

A pair to be proud of

This entry was posted in Automobiles, Car Stuff, Care and Feeding, Cars, Life and Cars, Modifying Cars, Racing, Road Racing, Sports Cars. Bookmark the permalink.

One Response to Building a Track Car – sweating the details

  1. mark says:

    Ugh, Jim your camera is really good and those welds look a sight. Welding upside down is more challenging and I probably could have made it look a lot better if: 1) I had cleaned all the paint off the box member before using gas shielded MIG. With clean metal, the weld puddles are more uniform – paint, rust, and other contaminants detract. 2) I should have welded in short pulses, just enough to create a puddle and then moved over a bit and repeated instead of trying to run a bead. When welding in the overhead position, I’ve found that works better. The nozzle also fills with splatter and needs to be cleaned too. Luckily, I think the supports will function better than they look…

    I was more pleased with how the spacers turned out. Was nice to use the bandsaw to cut rough sizes and then the mill to finish them. Milling the slots was so much better than drilling 2 holes in close proximity and wallowing the drill bit back and forth. I guess I could have milled the corners off at 45 degrees to match your brackets…..

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