REPAIRS PAGE 17
SUSPENSION SETTINGS - PARTS 1 AND 2
Anyone that read my article in the last issue might just have noticed a
couple of things not quite right - such as omissions and the fact that the article 'stopped' halfway through!!
Apologies are due from me - it was in fact a half-written draft meant to
be developed for a future issue - but I inadvertently included it in a disc I
sent to our (over-worked) Ed Richard Morgan - it got accidentally included in
the inevitable magazine publishing deadline rush!
So, to put the record straight - I have rehashed the whole thing here so
that readers don't have to jump between 2 magazine issues to get the full
picture. Sackcloth, ashes and humble pie might be in order here - but at least I
am trying to repent my sins!
Here comes the updated version--
Whilst
there is nothing wrong with the standard N/A suspension set-up, wear and tear is
unavoidable over the passage of time. Springs lose some of their resilience,
rubber bushes wear, and dampers lose their resistance - but this all takes place
gradually and is not readily noticed. Certainly any MR2 still on its original
suspension is likely to need some attention.
'What's the best set-up?' is a question that I am occasionally asked but
struggle to give a quick answer.
Naturally the optimum setting is primarily determined by the type of
driving and road surface expected. Extreme cornering loads on a good racing
circuit would warrant significantly lowered and stiffened springs such as -55mm
and +50%, heavy duty dampers (+50%), and wide 17" wheels along with ultra
low profile tyres. (Don't take this as a recommendation -its purely indicative!)
As exotically attractive though as this might sound, it would not be at all
comfortable even on an excellent track circuit - the smallest pebble jars like a
boulder and the steering turns into an all-in wrestling match!
Oh- and that’s the good bit - take that car onto a normal public road
and within 10 minutes you can expect to part company with your fillings, teeth
(false or otherwise), sanity, and anything else that hasn't been treble welded
shut! (Not to mention the speed-bump beaching provided by the by your local
council car-phobocrats!)
Any road-going MR2 is obviously going to need much more of a compromise
set-up. Just how much is very subjective - what might be acceptable to one
driver might be too harsh to another. My experimentation with MR2 suspension has
been quite limited – it’s not the easiest thing to chop and change about,
but comments on my experience follow - with the proviso that they are subjective
from my own perspective. I'd like to think that I am somewhere near 'normal' for
an MR2 owner - preferring some firmness to sogginess. As always, comments from
others who have experimented would be welcome.
I have both an N/A and a S/C, and in this the N/A has stayed standard
with the S/C being modified.
The N/A as standard feels a little on the soft side - as if Toyota
set it up slightly more for comfort than performance. Nevertheless it is
perfectly acceptable, although if I could wave a magic wand I would stiffen it
to reduce rear-to-front weight transfer on throttle lift-off.
The S/C as imported was quite stiff and obviously not standard. Whilst
acceptable on good roads it was harsh on minor road surfaces, and the steering
(with Yokohama Grand Prix M5 195/50/R15 8ZV's - steel braced) was prone
to bump-steer. As a fair bit of my driving is on minor roads I decided to modify
it. When stripped down the springs and shocks turned out to be pukka TRD units -
top notch but very fast road/ race units.
Decisions here are inevitably an extremely subjective area - what might
feel 'good' to one person could be quite 'bad' for another. Ideally track
testing should be used to assess any changes as objectively as possible, but
this is the prerogative of racing teams - and not for us mere mortals.
I ended up changing the whole
system with the help of expert advice from Adrian at Fensport. Changes made were:-
1) Springs - +20% stiffness, -30mm height.
2) Dampers - KYB (Koyoba), +20% stiffness.
3) Suspension bushes - Polybush polyurethane all round.
Results:-
Ride more compliant and supple then before - but still harsher than a standard N/A (which incidentally
has Continental Eco-Contact tyres.)
The steering is still heavy-ish (although better then before) with some
bump steer on white lines, cat's eyes, speed bumps etc.
Handling in the dry on good surfaces is much improved. In the wet the
improvement is still there but less marked. (The wide tread pattern of the tyres
usually makes things worse for water clearance - and grip - no matter how good
the suspension.) Hence any suspension improvement is somewhat blunted.
Tyres clearly have an influence on any cars handling - but I'm not in a
privileged position to be able to test out many samples, so my experience is
necessarily limited!
If members have any comments on any of this I would be delighted to hear
them. There are a number of websites that contain test reports on tyres from
various motoring press sources - but obviously they are not MR2 specific.
www.tyres-online.co.uk. is a good starting point.
So that's it, my own tests necessarily limited by finance and time, but
at least its a start that others might find useful for shaping developments
ideas. If I have any thoughts on improvement - then if track days are in your
mind - then perhaps adjustable shocks such as Koni's etc would be more
appropriate.)
Inputs from all would be greatly appreciated to build up a MR2 specific
database - please! I don't even care if they might run counter to my
inclinations - they will all go into the democratic pot!
ALAN JONES
SUSPENSION OBSERVATIONS
After reading Alan Jones's recent report on the suspension modifications - some of it
twice. I thought I would give my input.
I have owned a few MK1 na’s and recently bought a supercharger. Having read probably
every article ever written on the car, most articles claimed that although the
extra power was nice the handling had suffered somewhat. After driving the
supercharger for the first time I would have to agree. The car which I ended up
buying was on standard springs, shock absorbers and wheels and even after only
driving it a few miles I knew all the reports were right and I would have to
spend some money on sorting the suspension out. I noticed much more body roll in
the corners and you could really feal the extra weight at the rear, changing
direction quickly made the car unstable. Upon braking hard the front would dip
heavily and you could easily lock the front wheels up. So something had to be done.
I spent a huge amount of time researching into how to sort the suspension out, the
internet being a great place to get information. I decided to go for adjustable
shock absorbers, which unfortunately are much more expensive but do give you the
tune-ability to use the car on the track where you want it very hard and on the
road, where you want it softer (oooer!).
I eventually narrowed it down to either Koni or Tokiko shocks. In the US the
supercharger has a big following and most owners there use the Tokiko, while
over here most people use Koni. Koni clinched the deal when I read a report by a
chap who was heavily involved in suspension development and he claimed that the
Konis give a better ride. The fact that they are also a little cheaper and more
easily available in the UK also helped.
Regarding the springs, I first had to decide between progressive and linear springs. The
difference is that progressive springs get stiffer as you compress them. My
thoughts were that progressive springs would give a better ride as the springs
would be soft over the small bumps and stiffen up as you corner harder. I spoke
to a number of people both here and in the US (including Fensport who were very
helpful) and as I also wanted to lower the car by approximately 1 inch, they
said go for the linear springs as using progressive springs will not give enough
travel for the spring. A few owners that I spoke to claimed when cornering hard they were
hitting the bump stop, i.e where the spring gets fully compressed.
This sort of situation can seriously affect the handling and could result in you
spinning the car mid corner as the suspension bottoms out. So I decided to go
for linear springs lowering the car about an inch
There are loads of different brands of springs available but I opted for the Fensport
springs as recommended by someone who was already using them.
At the same time and for completeness I also decided to replace all the suspension
bushes with Superflex Poly Bushes (available from Fensport) which will tighten
the whole car up and remove some of the sloppiness. A chap the US having just
done this claimed it was the best modification he has ever done.
The total cost amounted to around £900 including fitting, so it is not cheap but I
am so glad I have done it. On the soft setting it is a little firmer than
standard, on the hard setting it is really hard and too hard for most public
roads, ideal for the track though. It really has sorted the handling out, making
the car more balanced and much less body roll. You get a lot more feedback and
with a lot of the sloppiness removed the car responds instantly to changes in
direction. The braking is hugely improved as the front doesn't load up as much on hard braking.
The car sits marginally lower, not much though as obviously she had been sitting on the
same springs and shock absorbers for the last 12 years.
All in all I am very happy with my purchase and would recommend this route to both na and sc owners.
ANDREW O'BRIEN