Resetting bushings after lowering car.

[jacobrjett]

I read that there was a possibility that resetting your bushings after lowering your car could lower the car further.

The theory is that the bushes on the control arms are tightened down at the vehicles standard weighted height. When the car suspension is compressed, the bushing cushions the control arms.

When lowering springs are installed, the suspension might as well constantly be compressed and the bushings were tightened at the vehicles factory height - now the car sits lower there is a constant strain on the bushings.

This strain is also holding the car just slightly higher - loosen the bushing and the car will drop ever so slightly more.



The vehicle must be weighted when you tighten the bushings down. As in, you cannot jack the car up and do this. You must have the car on a ramp, or in my case I just drove it up onto some small bricks and climbed underneath.

For my car, I already had king lows in there and changed to dobi superlows. Maybe if you go to superlows or coilovers from factory height there will be more of a difference.


Here is the car before starting:


The following circles outline the bolts I loosened that were holding the bushings in place. some of these were very tight.





As far as I could tell these were the only ones that would make a difference.

I loosened up these bolts, then jumped on the back of the car bouncing it up and down to get the bushings to settle.

Afterwards this is the result:


Nothing. Absolutely no drop in height whatsoever.

Was it worth it?

Possibly. For all I know the bushings could last longer now, however I have no way to compare a set of used bushings.

[jacobrjett]

Perhaps if I had more of a drop it would have made a difference. I came from king lows to dobi superlows that didnt even lower it that much more.

I would do this experiment again if I ever went from factory height suspension to superlow/coilovers again. Perhaps there will be a difference then.

[XSVWGN]

Those rear bushes are always hard to undo. I will be doing this with the front of mine in the weekend as I have put new bushes in my lower control arms but its not to lower my car further but to give a bit of life to the bushes

Matt

[Bling]

I don't see where the movement will come from in that arm? The bolts go through a tight hole do they not? So It can't move to a new location. To me, the shock / spring combo is what determines the height. Messing with other areas may change the camber etc, but I just don't see how it can go lower if the shock/spring stays the same.

Perhaps the previous springs were just shagged. You are running AE92 shocks and springs (dobi) now correct?

[Malcolm]

I don't see where the movement will come from in that arm? The bolts go through a tight hole do they not? So It can't move to a new location. To me, the shock / spring combo is what determines the height. Messing with other areas may change the camber etc, but I just don't see how it can go lower if the shock/spring stays the same.

Typically OEM rubber bushings don't have any sliding surfaces, rather the rubber flexes to allow the movement of the arm (the centre sleeve is clamped tightly and the rubber is so tight in the arm it doesn't move). What this means is that as the rubber twists it creates a torque that counters the movement, effectively applying a small amount of preload to the suspension. I presume that when you "reset" the bushings, you loosen off the through bolt which allows the central sleeve to rotate and relieves any twist in the bushing at ride height.

IMO the force from the bushing twisting would be negligible compared to spring/damper forces and vehicle weight, but not having your bushings twisted could help them last longer.

[iOnic]

I always tighten bolts through suspension bushes with the car at normal rideheight (not on a hoist with the suspension drooping) but not because it makes the car lower but to stop the bushes twisting apart. You always want them in their neutral state at normal ride height so they can do their job when the suspension compresses/extends.

[jondee86]

Standard installation instuctions for the AE86 stipulate that for
rubber bushed suspension arms, you assemble the suspension
without torquing the bolts up. Then you put the car on its wheels on
level ground, bounce it a few times, and then torque the bolts up
up while the car is sitting at its natural ride height.

I can tell you for sure it made about 20mm difference to the ride
height when I was putting TRD rubber bushes in my car. That is,
the first time I tightened the bolts, the suspension was at full droop
with the car on jack stands.

Cheers... jondee86

[Mr Revhead]

As above, if you do it right the first time, then you are effectively doing what you are doing by "resetting" them
In other words. It's BS

[jacobrjett]

I don't see where the movement will come from in that arm? The bolts go through a tight hole do they not? So It can't move to a new location. To me, the shock / spring combo is what determines the height. Messing with other areas may change the camber etc, but I just don't see how it can go lower if the shock/spring stays the same.

Perhaps the previous springs were just shagged. You are running AE92 shocks and springs (dobi) now correct?

[jacobrjett]

As above, if you do it right the first time, then you are effectively doing what you are doing by "resetting" them
In other words. It's BS

realistically how many people out there that have installed lowering springs do you think have done this after replacing the factory springs/lowering their car?

sure this may be common practise at the workshop, but obviously a lot of people dont do this.

[jacobrjett]

In other words. It's BS

Also I am not trying to say this will lower your car more, as you will see in my original post I found it did not alter the height of my car whatsoever.

[Mr Revhead]

I see what you are saying. If the bush was that tight, what do you think it would do to suspension movement?

When you install a new bush with the car jacked up, think of the droop. there is a massive difference between that, and where it will sit on the ground.
However the difference between normal ride height and lowered ride height is stuff all
As you have found out

[Bling]

Might look a bit lower if it wasn't sitting on 10s

[wde_bdy]

As above, if you do it right the first time, then you are effectively doing what you are doing by "resetting" them
In other words. It's BS

Most people don't do bushes the same time as springs so yes dropping 50mm out of your ride height will require "resetting" the bushes.

Callum

[Mr Revhead]

I really don't see how seeing as the movement at the arm is going to be quite small.

[jacobrjett]

Might look a bit lower if it wasn't sitting on 10s

haha, well i was a bit disappointed with the height of the superlows to be honest. I am really wondering if the shocks are slightly longer then they are supposed to be when they got replaced, when it had king lows in it before the back sat higher the front.

well I put about 100 kilos of stuff in the boot, which absolutely sacked it, and went for a cruise last night with my mate, we went around town a bit and down makara, after removing all of the weights in the boot it seems like its settled the springs super fast. Its actually almost low now.

[jacobrjett]

oh, i didnt put stuff in the boot to pretend it was low, i did it to see if it would settle the springs. springs settling could be another big debate etc. but i thought there would be no harm in trying to speed up the settling process if there was one, and its definately worked.

i havent put the front superlows in yet, as because the back seems to be sitting high, with superlows in the back and lows in the front it seems to sit level...

[tsoob]

wait wat.

angle grinder cuz that will sort your issue

[tsoob]

seriously tho, always take measurements before you lower a car.

If you are using springs you will get some sort of spring settle over time but wont be heaps.

[allencr]

Old or new bushings???????
If they're old, any unintentional pre-load put into them by lowering & not resetting them will amount to almost zero height difference.
How much weight does it take for the lower(and I assume also higher rate) springs to move 1cm?