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How do we preload a rear strut tower bar? For Ice racing? For Rally racing (gravel)? Road racing (tarmac)? Top of tower in? Top out? Car on jack stands?

Front bar?

Did not find answer searching.

Phil

The rear strut tower bar is meant to reduce the movement of the strut assemblies due to movement of the suspension in stress situations. By tying both sides together, it creates more even balance through the rear. It is not meant to keep a specific camber or castor setting. That would be done through modifications/changes to the rear alignment.

The bar I have I preloaded slightly by feel. I got mine primarily for the age-induced squeaks.

Steve

Swaybars don't really have "preload." At even rideheight, a swaybar exerts zero force on either side of the suspension. They only have an effect when one side is compressed more than the other. Adjustable units change the lever arm on the swaybar thus affecting the effective spring on the opposite side. In general, swaybars are used to change the amount of weight transfer between the front and rear. That is how they can change a car's understeer/oversteer characteristics. More weight transfer in the rear equals more understeer. Less weight transfer in ther rear moves that weight transfer to the front causing more oversteer. The same can be also done with spring rates, but spring rates are harder to change hence adjustable swaybars.

With ice racing, you would want less bar, since that weight tranfer will help with grip in slick situations. Same goes for gravel, to a lesser degree. Softly sprung cars do better in the snow for the same reason.

Tarmac is a different story all together. SInce the grip is exponentially higher on tarmac than on snow, ice or gravel, you can sometimes be better off distributing that load between the two tires and maintaining as much contact patch as possible, but I digress. Its all about controlling the weight transfer between the front and the rear depending on the situation.

Also, the size of the bar does not matter as much as the relationship between the two. For example, if you have a stock front bar and put in a huge rear bar, your car would oversteer like crazy. The opposite would be true if the front bar was huge and the rear was tiny.

Its all about balance.

A strut tower bar is different from a sway bar.

I suppose I coulda paid more attention when I read the post

That and a few beers....

Narini wrote:How do we preload a rear strut tower bar? For Ice racing? For Rally racing (gravel)? Road racing (tarmac)? Top of tower in? Top out? Car on jack stands?

Front bar?

Did not find answer searching.

Phil

You are overthinking this. Strut tower bar isn't made to "tune" chassis flex, they're made to keep the chassis from flexing at all.

When a roll cage is installed (in the case of ANY racing example you've given above), a portion of the cage will take the place of a strut tower bar, making the chassis as rigid as possible.