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Re: [T3] Purest Type 3 group? (lowering)

On 12 Mar 2004 at 23:37, Patrick wrote:

> "I have seen some people remove the rubber stoppers to lower the car even
> more and this really exasperates the shock loads on the bearings and
> bushings in the beam which are so hard to obtain and replace."
> How do you figure this? Why would the shock loads be any different on these
> parts if adequate suspension travel was present?

In the stock configuration the trailing arms ride about the horizontal, so that 
the vertical force is at right angles to the lever arm. When you change this 
you effectively stiffen up the suspension.  

Taken to the extreme, for purposes of illustration only, if the arms are 
straight up, there is NO compliance left in the suspension, so that any shock 
loading that the tires do not absorb gets transmitted straight to the swing arm 

In between these two extremes you have lowered cars with the stress on the 
swing arm bearings increasing as the trailing arm angle increases.  

The amount of shock loading transmitted directly to the bearings will go as 
F*sin(theta) where theta is the angle between the horizontal and the swing arm 
and F is the shock force from the ground.   

At the same time, the suspension stiffness goes up with cos(theta). I suspect 
that this is what most people like the most about their lowered rides.   

> "I've seen bent frame heads because the car bottomed out in a dip and
> hit the clamps." 
> This was due to improper lowering technique's. Other wise known as a
> hack job. A properly done car won't do this. 

I don't see that technique has anything to do with it. It's only a matter of 
how much you lower and how rough a road you drive on. Clearly you can lower as 
much as you want if the road is perfectly smooth. FI cars can get away with a 
total of ~1" of compliance in their suspensions, half of which is in their 
tires, only because the tracks are smooth.  

> I drove my fastback for 3 hours straight (did have to stop for gas
> once) at 110mph lowered 3 notches in front and 2 notches in the rear.
> It was rock solid and stable the whole time. It was very comfortable at
> that speed other than the engine being at 4800rpm the entire time. 

Nice smooth road?  

Lots of the potential problems from lowering disappear if all your roads are 
nice and smooth. Bump steer, for example, won't happen if there are no bumps.  

I couldn't even get a lowered car into my driveway, and it's a very normal 
residential driveway. But there's a dip at the gutter and the road has the 
normal amount of crown that makes it a close call even with a stock suspension. 
I trim a bevel into the bottom of my tailpipes to avoid grinding them off on 
the pavement.   

Too bad there isn't an easier way to do dropped spindles on type 3s. That 
wouldn't help with driveways, but it would help with the other problems.  

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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