Re: Advice on suspension

[Chris.Prael@xxxxxxxxxxx (Chris Prael)]

> Date: Thu, 11 Feb 1999 13:28 -0800 (PST)
> From: djbender@domain.elided
> Subject: Advice on suspension
> 
> When I bought my '74 GTV it had the following suspension mods:
> 
> Shankle Supersport springs front and rear Sachs gas shocks front 
> and rear
>  
> I since added a Shankle heavy duty (but not race) sway bar in the
> rear

Why?  The principal problem in getting the 105/115 chassis to handle
well is the VERY high rear roll center.  The stock sway bar is a
wretched excess to begin with.  Putting in a stiffer one only screws
the car up more.
>  
> I also added adjustable upper links in the front (the single best
> mod you can make for the track for my money...completely cures the 
> understeer)
>  
> I also cut a turn off the rear Shankle springs to level the car out.
>  
> I tried a Shankle heavy duty front sway bar, but at tracks with
> plenty of turns (Laguna Seca, Buttonwillow) it made the car too stiff 
> on turnin for my taste.  It may be good at a high-speed track like
> Willow Springs.  Also I had some fitment problems, requiring putting 
> on a large heavy washer so it won't come off the spindles.

You must have done something wrong if you had problems fitting the
front sway bar.  Mine went in with no problems.
>  
> in an effort to make the car more competitive on the track I bought 
> a pair of Ward & Deane springs for the front, and put them on.  These 
> lowered the car another 1/2 inch or so, making it drag on speed bumps. 
> They also seemed to overpower the shocks, making the car a little 
> "bouncy" at the front.  Makes me wonder if the gas shocks are all that 
> effective.  I want to go measure the springs but I think they may be 
> W&D 'race" springs, that's why they are so stiff.

Stiffer springs is not the way to go.  I expect that you are right and
the springs are overpowering the shocks (which are for a street setup).
>  
> So I went back to the Shankle front springs for now anyway.  
>  
> Here's my question...in people's opinion, what's the best thing to do 
> to further improve the handling at the track
>   - Konis 
>   - other shocks (Boge?)
>   - Ward & Deane springs at the rear but not the front
>   - Ward & Deane springs all around and learn to live with speedbump 
>     scraping
>   - leave well enough alone

No, I would fix you mistakes.

1. Mount the shankle 26mm sway bar in front.
2. Remove the HD sway bar in back (you can refit the stock sway bar,
but I would advise against doing that).
3. Stay with the Shankle springs.
4. Fit Koni competition shocks.
>     
> Doug Bender

If you want to go faster than this setup will allow, the next step is a
panhard rod or (better) Mumford link rear suspension.  Either requires
replacing the trunion with a link that is ball jointed at both ends and
ball jointing the trailing arms (as is also done for the sliding block
system used on the GTAs).  

I would advise against going to the sliding block system.  While it is
a major improvement on the stock trunion set-up, it is significantly
inferior to the panhard rod system and even more inferior to the
Mumford system.


Chris Prael

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