Making Your Classic
Car Handle
The aim of our service is to develop good suspension set ups for
any vehicle, straight "out of the box". Or at least a good baseline set
up. Our ideas have been tested in Historic racing with quite stunning results. Our
methods readily transfer to road cars. On the road we want good handling, while
still maintaining reasonable ride quality. In some cases, we can actually improve ride
comfort, while increasing handling, response and grip.
For the owner of a sporting classic car, it means great drivability at an affordable
cost. There is no need to live with questionable handling and stability. In fact, some
historic or classic cars can have exceptionally good handling, even by todays's standards.
For example, front running British sports cars in Historic racing (SA and SB) run
faster lap times than some high performance late model road cars (assuming unmodified) eg
– Subaru WRX, Honda Integra R and Toyota Celica., 140 Kw, six speed gearbox.
We can work three ways:-
- We do the complete job in our own workshop.
- We supply a kit of parts (springs, bars shocks etc.) for, say, a vehicle where we have
already designed and tested package.
- We work together with you and/or your repairer, to complete an analysis of the car, and
design/specify components. The first step is to fill out the Smithees Weight Transfer Worksheet.
We can work with a professional restorer, or owner/restorer. For (1) or (3)
above, the only restriction is that we must start with a complete vehicle, so that
measurements and weights can be taken. Ideally, work could begin before a vehicle is
stripped for restoration, or the car could be retro fitted with the required
modifications.
Springs, Anti-Roll Bars and Shocks
Weight transfer considerations are the key to a good set up - ie choosing springs and
anti-roll bars (and then shocks) that will enhance grip, improve response and set the
understeer/oversteer balance of the car. We use the Smithees Weight Transfer Worksheet, to help us
determine what is required.
A unique feature of what we do is determine the spring frequencies, using the Smithees "Bounce Test". Before this
test was available, it was not possible to easily assess what the wheel rates really are.
Calculation of wheel rates for suspensions with poor motion ratios at the front,
and leaf spring rear, is not accurate. Only with the knowledge of these wheel rates,
and the relevant suspension frequencies, can you move forward and confidently consider,
what springs you would like to run.
If you run a limited slip, or locker differential, the set up will be different.
If you need an LSD, contact us.
It does seem as if the Phantom Grip could be good. Low cost, and OK to run on either
road or race car.
Recommended Procedure
- Weigh and measure the car and put the figures in the Smithees Weight Transfer Worksheet.
- Looking at the results from the above, design and manufacture components.
- Take wheel alignment readings, (casters, cambers, front wheel set back, rear axle
alignment etc.)
- Remove suspensions front and rear. Inspect chassis and repair. Correct any
bad chassis alignment.
- Inspect suspension components. Crack test eg uprights and axles. Replace worn/damaged
components.
- Perform any upgrades (where they are allowed for racing, or road cars where it is common
practise on the model to upgrade to a later part spec on safety grounds.)
- Re-assemble suspension with regard to the suspension settings we have decided upon for
the initial set up, and also with regard to proper procedure. (Errors we have seen.
Cutting of rubber bushes to make them fit. Often the rubber is meant to be
highly compressed on assembly, and the suspension movement is by wholly or partly twisting
in the rubber itself. If urethane or delrin bushes are used, the opposite applies.
The bushes must not be compressed excessively. They are often designed to
rotate on crush tubes or pins, and require lubrication on all friction surfaces. If
compressed excessively, bad suspension binding will result. Be especially carefull with
drag links (any steering bind will be bad for handling.)
- Check ride heights (or corner weights if scales available). Adjust ride heights
with spacers as required. This is a pain to do, but extremely beneficial, because
older car chassis may not be all that square, but you can recover most of what you want by
correcting ride heights.
- Go back on the wheel aligner and do the best possible with the steering angles and
suspension geometry static settings.
- If it's a race car, go testing. If it's a road car, enjoy the great handling.
For details about specific models, see the links on our home page
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