Ghia Road Course Setup

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Ol'fogasaurus
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Re: Ghia Road Course Setup

Post by Ol'fogasaurus » Fri Mar 16, 2018 8:01 pm

Bruce's way of lowering is correct, you take some of the preload out but there is a suspension softening that goes with it.

FJ's idea I have never heard of before but if I understand it correctly it acts the same as a lowering block on leaf spring cars. Very creative and I guess it must work.

I seem to remember that some guys raise the rear torsion assembly in the car but that is a lot of work!

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Fri Mar 16, 2018 10:46 pm

Yes, you can reindex. That's the right way. But lots of guys get indexing wrong (inner and outer splines) which is why dropped spring plates, adjustable spring plates, etc., were invented.

The simplistic adapter plate I described was used back in the 50's on 356's and Bugs.

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petew
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Re: Ghia Road Course Setup

Post by petew » Sat Mar 17, 2018 12:24 am

Hmmm... ok. Like to see a pic of that.

I also don't really get drop spindles. From everything I've read about torsion bar front ends (and roll centre), lowering is often to the detriment of handing.

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Sat Mar 17, 2018 10:35 am

Image

Drop spindles actually work very well and don't change front end geometry.

I prefer to lower our Ghia with tires, 50, 60, and 65 series.

FJC

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petew
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Re: Ghia Road Course Setup

Post by petew » Sun Mar 18, 2018 12:49 am

:lol:

Gold. Love it. You haven't answered my query about roll centre though. Allen Staniforth describes the roll centre as being 'on the ground' with a torsion bar from end (beetle or Porsche) at standard height.

https://www.amazon.com/Competition-Car- ... 1844253287

Page 46. So I might be misunderstanding, but basically, if you lower the front beam... the front roll centre ends up lower than the ground... Ouch. :?

Which is why I guess, so many porsches/early VW race cars appear to be reaching for the sky up front. It also explains why swingaxle beetles were so prone to rolling over with a higher roll centre at the back and all the weight there too.

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Piledriver
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Re: Ghia Road Course Setup

Post by Piledriver » Sun Mar 18, 2018 9:22 am

On a pure trailing arm suspension, (like t1 front end) the roll center is at the ground regardless of ride height.
...and the lower the car, the closer the cg axis is to the roll center.

Also note that the instant the inside tire lifts, the roll stiffness is infinite on that axle, so the roll center is ~out of play.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Sun Mar 18, 2018 11:10 am

Image

Front roll center is at ground level on a VW/Porsche beam axle.

And the rear roll center is right about middle of the transaxle.

A thousand words is worth a picture.

TheViking
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Re: Ghia Road Course Setup

Post by TheViking » Wed Jul 25, 2018 11:41 am

Do you have some kind of three stage setup with irs as you have with swing axle? Live the post!

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Wed Jul 25, 2018 1:05 pm

Image

I didn't go into a lot of detail on the IRS because we think it's good the way it is.

We run stock torsion bars, half a degree negative on the rear, and zero toe. We run no rear swaybar to add the safety of understeer at high speed, and we have 16mm and 19mm rear bars. The image above (Daytona infield) shows the results of no rear bar. Even the 16mm rear bar would have kept the front tire down.

FJC

TheViking
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Re: Ghia Road Course Setup

Post by TheViking » Sun Jul 29, 2018 1:26 pm

Thank you so much!

eskamobob1
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Re: Ghia Road Course Setup

Post by eskamobob1 » Mon Aug 06, 2018 3:39 pm

So what are your opinions on lowering an IRS rear end? If I am looking to lower purely for handling on a 74 standard beetle, does the lower cg make up for the loss of upward suspension travel (and as such, likely requirement of stiffer bars)? Also, you seem to recommend adjustable spring plates due to their adustability, but other than that, are their benefits/disadvantages to maintaing stock down travel (as opposed to reindexing where you increase your down travel by however much you lower)?

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Re: Ghia Road Course Setup

Post by eskamobob1 » Mon Aug 06, 2018 3:39 pm

So what are your opinions on lowering an IRS rear end? If I am looking to lower purely for handling on a 74 standard beetle, does the lower cg make up for the loss of upward suspension travel (and as such, likely requirement of stiffer bars)? Also, you seem to recommend adjustable spring plates due to their adustability, but other than that, are their benefits/disadvantages to maintaing stock down travel (as opposed to reindexing where you increase your down travel by however much you lower)?

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Mon Aug 06, 2018 4:39 pm

Image

Adjustable spring plates are the next best thing to coilovers to balance or move weight around in the suspension. See the jacking screws on our '73 Super LeMons bug? We actually get all our lowering from 50-series tires. Raise the rear end to counteract understeer. Lower to really plant the rear tires in a corner.

FJC

eskamobob1
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Re: Ghia Road Course Setup

Post by eskamobob1 » Fri Aug 10, 2018 10:22 pm

FJCamper wrote:
Mon Aug 06, 2018 4:39 pm
Adjustable spring plates are the next best thing to coilovers to balance or move weight around in the suspension. See the jacking screws on our '73 Super LeMons bug? We actually get all our lowering from 50-series tires. Raise the rear end to counteract understeer. Lower to really plant the rear tires in a corner.

FJC
So just to be kind of clear, you realistically dont recommend lowering a beetle (outside of adjustable plates for finer tuning) as far as performance tuning suspension goes? My largest concern is a bit better aero characteristics tbh (already planning on a front damn, but I have a standard I am building, so flat windscreen), but I dont want to do anything detrimental to handling.

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FJCamper
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Re: Ghia Road Course Setup

Post by FJCamper » Sat Aug 11, 2018 12:07 pm

I believe we're talking about two different things, street vs racing applications.

For street, you can do whatever you like, because weight jacking, suspension balancing, and quick ride height changes are not a big factor.

Just lowering a Bug 2" front and rear really transforms it.

FJC

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