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-   -   Corner balancing with non-adjustable sway bars (http://forums.pelicanparts.com/porsche-911-technical-forum/108431-corner-balancing-non-adjustable-sway-bars.html)

logician 04-28-2003 03:36 PM

Corner balancing with non-adjustable sway bars
 
Hi,

Question: when corner balancing and adjusting the ride height on a stock suspension -- non adjustable sway bars -- do you disconnect the sway bar links? I know that you do disconnect them when working on adjustable sway bars, but that is because you can change the link length, and set them to neutral before reconnecting them. For a stock suspension, there is no such adjustment, so it seems that you need to have the links connected, lest you change the balance when connecting up the links if they don't end up neutral. Is that right, or is there some trick for stock suspensions?

-Juan

Joe Bob 04-28-2003 03:58 PM

Corner balance involves the adjusting of the torsion bars, not sway bars. Stock 911 front ends are easy to raise and lower. The rears are more of a problem stock....it involves re-indexing the torsion bars unless you have adjustable plates in the rear.

masraum 04-28-2003 04:04 PM

My thought would be adjust with the swaybars attached, that way if there is any sort of preload it will be considered. I could be wrong.

911pcars 04-28-2003 04:58 PM

Corner balancing (via ride height adjustments) should always be done with the sway bar links disconnected, otherwise the attached sway bar effectively links the front (or rear) corners together. This affects the weight each corner supports - each corner should be independent. Ideally, if the corner heights on one end are exactly the same after corner balancing, then the sway bar preload is zero (which is what the adjustable links allow you to do). However, slightly different ride heights are more often the case. You can corner balance using the factory sway bar links, then upgrade to adjustable links at a later date.

Hope this is not too confusing.

Sherwood Lee
http://members.rennlist.org/911pcars

logician 04-28-2003 08:29 PM

Hi Sherwood,

> Corner balancing (via ride height adjustments) should always
> be done with the sway bar links disconnected, otherwise the
> attached sway bar effectively links the front (or rear) corners
> together. This affects the weight each corner supports - each
> corner should be independent. Ideally, if the corner heights
> on one end are exactly the same after corner balancing, then
> the sway bar preload is zero (which is what the adjustable
> links allow you to do). However, slightly different ride heights
> are more often the case.

Right. So if everything is straight and perfect, then the sway bar links will be neutral after corner balancing, so no link adjustment would be necessary. But this is unlikely in realitly because of tolerences, so in practice there would almost certainly be some preload introduced when the links are reconnected.

I'm coming to the conclusion that some compromise is required. To minimize preload, you might have to accept that both sides of the car might not be identical height. Thus you would adjust the relative side to side ride heights to minimize preload, rather than the equalize height. To do this, you would have to disconnect the links.

Once the ride height compromise is reached, and the car corner balanced with the links disconnected, you would reconnect the links. This would introduce a bit of preload, so you would need to tweek the corner balance again. In this way, the corner balance could be achived with minimum preload.

> You can corner balance using the factory sway bar links,
> then upgrade to adjustable links at a later date.

I agree, the best is to have adjustable links, so you can eliminate the preload altogether. Are there aftermarket adjustable links for front and back that work with the otherwise stock sway bars? If they aren't too expensive, they would be worth it. Otherwise, I would prefer to save my dollars for eventually getting TRG sway bars, and also for maintenence. I am gradually replacing all of the systems in this '73 as they break. The latest is the alternator that went out yesterday. :(

-Juan

Tyson Schmidt 04-28-2003 08:42 PM

You could still remove the pre-load from the stock non-adjustable swaybars by disconnecting the cross bar mounts and installing a shim of the appropriate thickness between the mount and body on the side that needs it. This is of course for the rear only on an early car and for front and rear on '74 and later.

dd74 04-28-2003 09:19 PM

Well, I bought a pair of SC springplates that I'm not entirely sure I need now.

My car's height has been adjusted, and I like it the way it is. I might corner balance it, but not until I get new sways.

Is it worth it to still have these put on at -- WOW 10lbs a piece?

IROC 04-29-2003 04:13 AM

I've never worried about leaving my factory, non-adjustable sway bars connected during corner balancing. I think it falls into the "close is good enough" category. Poly bushings and the friction inherent in suspension pieces will make repeatability difficult anyway, so trying to get it absolutely perfect is a waste of time IMHO. Heck, I can corner balance my car to within a couple of pounds at each corner, go drive around the block and suddenly it's off by 15 lbs. I've seen this same thing on other cars, too (even with the sway bars disconnected). Then you get out on the track and have a slightly different fuel load and it starts deviating from your "ideal" in the shop, too....

IMHO, "close" counts in corner balancing and atomic weapons. Don't worry so much about the sway bars....

Mike


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