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I have a bolt which has sheared off on one of the rear bar's mounts. Discovered this because the car is understeering and was looking to firm up the rear bar. Is this unsecured mount the issue?


sway bar mount broken by cpdmaz, on Flickr

Well your rear bar is effectively not connected to the car any more so that could possibly be a cause of the understeer.

Either way that needs sorting straight away!

Thanks Deviant.

It is still attached by the end links by the link ends of course but some potential for underside damage for sure. I am dropping it in to a workshop tonight.

Explains the understeering and also gives me an excuse as to why I wasn't able to hit a new p.b. in the races at Wakefield!

No worries. It needs the attachment to the body of the car to work, the anti-roll bar actually twists when the end links move up and down with the suspension. With it not attached to the body it will not be twisting, it would just move around.

Yep I understand that now .

This has been a little 'sway bar theory 101' lesson for me

Now to sort it and have another crack at my pb! (to be honest with those pesky quick minis it would have been difficult to crack my pb no matter what my setup was)

Thks again.

Was the understeer more on RH turns than LH turns ?

Yep. (not too many left's at Wakefield )

And given the broken mount is on the right also stacks up.

Wouldn't have made a difference if it was LH or RH turns. The swaybar require to solid points to hold and twist from. You only had one.

Wouldn't have made a difference if it was LH or RH turns. The swaybar require to solid points to hold and twist from. You only had one.

Looks like the upward movement has been restricted but not the downward
Could be a new way of making a sway bar adjustable for left and right hand turns
Wakefield has lots of medium RH turns and 1 sharp leftWouldn't have made a difference if it was LH or RH turns. The swaybar require to solid points to hold and twist from. You only had one.

Thanks for the input everybody. Just got back from dropping it off to have new mounts fitted. Looking forward to getting back on track with a more nailed down front.

Anytime Mazmad, its what we are on the forums for!

What sort of spec is your car? Do you run it on semi slicks?

Remember that the faster you go on track the more diligent you need to be with your post track checks and service.

Check your brake discs for cracks. Get underneath and do a 'spanner check' of steering joints, sway bar mounts (hint), subframe bolts, under body brace bolts, exhaust bolts...pretty much anything you can find!! Particularly stuff that carries suspension and brakes. You can just use an adjustable spanner, you will find out straight away if something is loose and then you can get the appropriate tools to tighten it correctly.

It has beefed discs and pads, coilovers and semi's on 6uls. Engine unchanged.

Actually it had a pre-race check in the workshop but obviously this was not picked up.

Good lesson for me though - double/triple check everything yourself.

deviant wrote: Get underneath and do a 'spanner check'

Abso-bloody-lutely from now on

Just found this on 949's site: my condition to a tee (even the accelerated hair loss.... ).

Sway bars (anti-roll bars)
Disconnecting the rear sway bar on a lowered Miata allows the inside wheel in a turn to droop further. Since the inside front with swaybar still attached will not droop, rake changes. This means the front stays low, the rear jacks up in a turn. The effect is slight but it changes the roll axis, camber gain and a few other things. For autocrosser, this compromise is usually worth it as it will greatly reduce wheel spin and reduce oversteer during low speed transitions. For track use however, this will usually result in terminal understeer that will have you pulling your hair out trying to get rid of.

Superpro bushes fitted to rear sway brackets. Now to see how it handles. Cannot believe I was such a numbskull not to identify the source of the problem. Fiddling with tyre pressures, looking for cause. Inexperience. Live and learn!!!!!!

However: still managed to match previous pb at Wakefield, so now who knows.