Long-term storage: suspension loaded or unloaded?

[sf4018]

Question: When storing a car for say the winter is it better for the suspension to be unloaded?

[KnifeySpoony]

Conventional theory is any rubber bushings should be in a neutral position - so this means suspension should be loaded, unless you have all solid bushings i guess...

[sf4018]

On 8/24/2022 at 3:14 PM, KnifeySpoony said:

Conventional theory is any rubber bushings should be in a neutral position - so this means suspension should be loaded, unless you have all solid bushings i guess...

When I built the suspension, it was with the car raised on jack stands, so if I’m reading you right the neutral position of the bushings is the car lifted by the chassis? Or am I supposed to loosen and then retighten the bolts holding the bushings while the car is down?

[KnifeySpoony]

All bolts on rubber bushings should be tightened with the car at ride height, so the bushings are in an unstressed/neutral position at rest. Not doing so makes the bushings act like a spring when they shouldn't be. Also, conventional wisdom is that having the bushings permanently twisted can lead to degradation/failure. I'm not sure I believe that tbh- it seems like the suspension moving up and down rapidly while driving (ie normal operation) would be more stressful to a bush, then just being static-ly twisted (assuming it's not twisted beyond its intended operational range). 

[Alex-Ks1]

either way you wont notice any difference.  there are simple rules to follow, 1. just build it and drive it

                                                                                                                               2. If the enemy is range, so are you 

                                                                                                                               3. if it works, don't fix it 

                                                                                                                               4. parts that go together are shipped separately 

[MV8]

An actual bushing is not bonded to the inner sleeve or outer tube so it doesn't matter (i.e. poly or nylon plastic).

With a single-bonded "bushing" that is rubber and comes bonded to the inner sleeve, it is good practice to tighten at ride height but it isn't critical since it will slip at the outer shell. These are typically oem on Cats and triumphs from what I've seen.

A double-bonded "bushing" is also bonded to the outer shell that presses into a tube in the control arm (i.e. most oem applications). They typically have teeth on the ends of the inner sleeve to bite into the chassis flanges when tightened to ensure there is no movement, only a few degrees of twist that it was designed for. They also provide some dampening. Tightening at full droop may cause the rubber to tear, crack, separate, etc sooner.

[KnifeySpoony]

From what I can tell the all rubber metalastic bushes on my car are bonded to inner and outer sleeve.

[MV8]

I'd only tighten them when at ride height. Also, typical oem double bonded have a large to allow for the range or twist required without damage. I've noticed the rubber wall thickness is minimal on the Cats which would make it more critical.

Tightening in droop would preload to raise the ride height but would probably settle after enough cycles.

Edited August 26, 2022 by MV8

[IamScotticus]

dual bonded bushes only work this way if the inner sleeve is a wider width than the outer.  I have noticed that some of these type are very close to being of equal length.  

 

Can anyone say how the PowerflexUSA brand of poly bushes are constructed?  Preload or not applicable?

[MV8]

I'm not sure what you are saying? Unbonded need thrust surfaces to keep things centered laterally. Poly is not bonded.

[Alex-Ks1]

This is very interesting, a few years ago I belonged to an Electric vehicle fourm , like this thread it went on for a years or so . 

It's was about weather a tail gate up or down would be better for driving with regards of wind resistant, so some  said , Up some said Down , no one was sure if it made any difference, So an aerodynamic engineer was asked to put it to bed once and for all.

  

      He took a members converted S10 all battery power and did as much testing as he could , then he finally got permission to use a wind tunnel , some place in California, where he is located , test after test built up reams of paper work ....

Now he posted his results ..... IT Doesn't Matter, ......up or down the results were the same ,so  range was the same and speed was the same  as with the tail gate up or down , just a lot of wasted battling back and forth ,,,,, like here now , does it really matter ? ... You are not storing the car for two hundred years  . But it's your car do what ever makes you happy 

[KnifeySpoony]

4 hours ago, IamScotticus said:

dual bonded bushes only work this way if the inner sleeve is a wider width than the outer.  I have noticed that some of these type are very close to being of equal length.  

 

Even if the sleeves are same length, the fastener only clamps onto inner sleeve, so the effect is the same. If both sleeves were clamped by the fastener, then no movement would be possible at all.

Edited August 26, 2022 by KnifeySpoony

[wemtd]

How does this apply to self-lubricating  bushings made from Vesconite? My expectation is they won’t be affected by position, but I’m not an engineer.

[MV8]

If the bushing is lubricated, it doesn't matter. It's designed to slip/rotate instead of twist.