(Article 3
in a series of 4. “HANDLING”)
This is the third article on PFT-000
(Pretty Fast Truck), this time we look at why
the ‘C’ handled so differently to the ‘B’.
When the car was released to the “press” lots
of clever comments appeared in the UK magazines, one
of the most remembered being “The problem with the
C’ is to get it to go around anything”. The
press cars were supplied with low and equal tyre
pressures, for the roadster, this certainly exaggerated
the handling problems. The ‘C’ needs 3 or
4 PSI increase in the front tyres; preferably 34 PSI
front 30 in the rear for the GT. With our car on
185/65 MXV3A Michelins and our suspension settings 34 front and
30 rear gives slight oversteer 34/31 slight understeer and
34/30.5 neutral. I think we might be getting somewhere with the
handling and driveability; What a pity the factory were not
allowed to develop the car before sale.
Like the engine the handling was also an
‘enigma’ excellent ride, very stable and comfortable
with good roadholding; but a strange combination of
heavy understeer at low speeds with acceptable handling
at high speeds, this is for the GT with much
better weight distribution than the roadster.
To compensate for an extra 220 Kilo’s (roadster
‘V’ roadster) tyres were uprated to 165/80 series with
15 inch wheels & 5 inch rims. The ‘B’
equivalent was 155/80 tyres on 14 inch wheels and 4.5
inch rims. Both cars were undertyred even in the late
60’s. 10 mm extra tyre width to carry a heavy and nose
heavy car just defies logical thought. The ‘C’
should have had 185 tyres on 5.5 inch rims, preferably
195 mm tyres on 6 inch rims. To put this in perspective
a 1990 BMW 318Is (same weight as my
C-GT) came with 195/65 HR14 tyres on 5.5 inch
rims and it handled extremely well; this car came with
gas shocks and roll bars front and rear and was a superb
drivers car straight out of the dealership.
Weight distribution for the ‘B’ or
‘C’ models in % follows:-
‘B’ roadster, front 52.5
rear 47.5;
‘BGT & V8’,
front 50 rear 50;
‘C’ roadster, front 55.7
rear 44.3;
‘C – GT’
, front 54.1 rear 45.9.
So the ‘C – GT’ is a little better
than the roadster but a long way behind the ‘BGT’
which is evenly balanced with both engines. I was
recently reading a Road and Track article on three german sports
sedans and two of them had similar front to rear weight ratios
to the “C GT” and all handled extremely well; so weight
distribution is not the problem it was stated to be in the late
60,s; but Roll Bars were not well understood then and low aspect
tyres were still in the future.
The “press” decided in their infinite
wisdom that the real problem was the weight of the
‘C’ engine ‘V’s the ‘B’ and that the
only solution was to move the engine back into the
heater area and rework the bulkhead. Abingdon realized
this only too well when they found out that the new
engine was a lot heavier than planned. So the weight
distribution and handling was compromised and this
coupled with a 1940’s engine design really stopped the
‘C’ being the successful big brother to the still
very popular B & BGT. The Rover engine
should have gone into the “C” as the chassis, suspension &
brakes are much better than the “B”for a high speed touring car.
I re-read recently the weight distribution of the
MK-2 3.8 Litre Jaguar which people still regard as one of the
best sporting sedans of the 60’s, Front 58% Rear 42%. The
motoring press were not as concerned then about weight
distribution, or were more used to heavy engines and were not
comparing 4’s with 6’s in the same basic package. The Porsche
911 has a front to rear weight distribution about the opposite
of the Jaguars and they seem to satisfy the critics.
Road & Track (USA) printed a superb definition
of handling: - ‘When you are enjoying yourself and
your passenger is nervous; that is oversteer. When
you are nervous and your passenger is relaxed; that is
understeer’.
Now back to the story, as you will read, the
solution was relatively simple once we knew what to do,
30 years ago this knowledge belonged to serious
motorsport not to young MG car club members. Back
in the 60’s we used to go to Club sprint meetings at
Lowood and later Lakeside for
Standing ¼ mile; Standing lap and Flying lap events.
These were good fun days with lots of enthusiasm but
not so much skill, we learned more what ‘not to do’
rather than ‘what to do’ with tuning and driving
techniques.
The ‘B’ was a lot of fun particularly
at Lowood, if you went off you
disappeared into tall grass with no cement blocks or
armco to damage your car; just roars of laughter from
the mob. When I took the ‘C’ to Lowood,
what a surprise, it certainly was no MGB
just a strange handling machine unlike any MG
that I had previously driven. Very pronounced understeer,
lots of body roll, lifting rear inside wheels etc.. In
78 miles the right front tyre lost ½ the tread
depth over the outside ½ of the tyre; so it was
obvious that we had a big handling problem but what
to do about it was beyond us at this time.
After the straight was an acute left hand
turn followed by a big flat paved area,(Lowood was an old
WW2 airstrip) we tried to apply power thru this area
while turning with the front ploughing, while at the
rear the inside wheel lifted after finding the travel
limit of the rebound strap, then a wild rear slide
that did not respond to correction but produced an
equally wild slide in the opposite direction, meanwhile
the front just ploughed on (I was glad that I was
inside and not outside looking on, it would have been
terrifying.) our instructors tried to sort it out but
to no avail.
The only way to correct this situation was to
straighten up and brake, then try again. We now know
what the problem was; the rear rolled until the axle
reached the rebound strap on one side then bottomed
the bump stop on the other and so the wild slides,
back and forth etc..
I reluctantly accepted the journalists
explanation and just learned to live with the
Pretty Fast Truck. At Lakeside a
good ‘MK I B’ could lap in about 1 min 18 sec;
the best I could manage in the ‘C’ was 1 min
26 sec; some 3 Litre sports car. The Carousel
was an experience to avoid and I had to back
off for the Dog Leg. Now the car manages
(an old very hard 175/80 Michelin ZX’s which are 2% bigger
in diameter and raise the gearing to 27.49 MPH/1000 ) 1 min 22
secs, 4 seconds better than when I was much more
enthusiastic i.e. younger; a more competent driver
turned in 1 min 17.6 secs on the same tyres. John
Fraser suggested that with a set of new tyres it would probably
lap up to 3 seconds quicker; with Lakeside a distant memory I
can only guess at how it would perform now.
Many years passed and a mechanical engineer
friend said “what that car needs is some roll
stiffness, not by heavy springs but by correct roll
bars front the rear”. About this time I had read
all about the Light Alloy bodied competition ‘C’s
with 7 inch rims flared guards etc., all the drivers
commented how neutral the handling was and how good
they were to drive; tucked away in the article was a
mention of a Mini Cooper rear roll bar plus
telescopic shocks all round, so my interest was
awakened.
Various people in the UK commented that the
‘C’ was much better on the heavier “police”
springs plus Koni shocks all round; the police
vehicles had heavier springs to compensate for the
heavy radio equipment carried in the car. I discussed
this with my friendly engineer and he commented;
“Heavy springs increase roll stiffness at the expense
of ride and roadholding. On our roads, the standard
springs are OK but roll stiffness needs attention”.
By this time I had fitted a full set of Koni
shocks and found a great improvement with the car,
particularly the rear (I will cover this in article 4
as it applies equally to all ‘B’s). I enquired
about roll bars locally; one “expert” said rear
bars don’t work with the ‘C’, what worked was a
1 inch front bar but it tore out the mountings so
required special heavy mountings. I thanked him for his
advise and decided to look elsewhere. I have recently
modified my front Roll Bar chassis mountings by adding .080”
mild steel plates; pop riveted to the chassis and tapping out
the existing 5/16 nuts to 3/8 UNF to distribute the load
properly to the chassis rails. The chassis mountings were
flexing and after 10 years with the 7/8” roll bar had developed
cracks between the mounting nuts in the chassis.
I should mention what made fixing the ‘C’s
handing so necessary. In mid 1990 I bought a 318Is
BMW which came with M-Technik suspension, and
it handled better than any car I had ever driven. To
a driver brought up on MG’s this was a
“Whole New World” and really said that something
had to be done to my ‘C’. Both cars weighted
1165 Kilograms; why was one superb and the other
absolutely ‘bloody terrible’.
In ‘Classic & Thoroughbred Cars’
I noticed a ‘C’ handling kit from Ron
Hopkinson MG Spares in the
UK. Faxes confirmed that they had a 7/8 inch front
roll bar plus a full set of Bilstein Rally shocks
and this gave a great improvement in handling. I faxed
back to ask if they had a rear roll bar for the
‘C’. The reply was that they did not, but that
they had a 5/8 inch rear bar for the ‘B-GTV8’.
I could not see why a rear bar would work well on
a ‘BV8’ but not on the ‘C-GT’, so I
ordered both roll bars, ‘suck it and see’. Back
came the reply that they would supply the rear bar but
did not recommend fitting it to a ‘C’.
NOTE:
The
‘C-GT’ with 222 extra Kilo’s and a weight bias of
5% (C ‘V’ B) to the front has a front roll bar
just 1/8 inch thicker than the standard (optional,
originally) ‘B’ roll bar. It is now obvious why
the ‘C’, particularly the GT with more
up top weight, had so much body roll. The MGB
roll bar is 9/16 inch; the MGC roll bar is
11/16 inch and the Special Tuning roll bar for the MGB
Roadster is 5/8 inch.
Just before X-Mas 93 a card in the post said
my parcel was here; so off to the Post Office and
back with my roll bar kits. On X-Mas day I removed
the standard bar and went for a slow drive around my
suburb, what a surprise the car was absolutely
hopeless, swinging the wheel between 20 to 4 and 10 to 3
produced a lot of noise and great amount of body roll
but almost no change of direction; “Oh, What a
Feeling” but not as in the Toyota ad..
Back to my workshop to fit the new 7/8 inch
bar and then repeat the drive. Now it was “as the
Poms like to say” completely different, the car
swung from side to side with little tyre noise but
rather heavy steering. After lunch I drove over to
Toowong to let my mechanical engineer friend have a
drive (he knows a lot about suspension systems but says
little) a slow 25 to 40 KPH drive around the suburb
produced this comment; “That’s better now fit the
rear bar and that should further improve the turn in
and lighten the steering as well”.
Bright and early on Boxing day I opened the
fitting instructions for the ‘B-GTV8’ roll
bars and the opening sentence read; Quote :
“ Remove the existing anti-roll bar.” Note:
“Before commencing to fit the handling kit check that
the car is already fitted with a front anti-roll bar,
if not a fitting kit will be required”. Good old BLMC
again, a “B-GTV8” without roll bars must have been fun to say
the least.
So on to the rear bar section of the
instructions. The bar mounts in front of the fuel tank
under the boot floor, with the ends going forward over
the axle then by push/pull rods down to the bottom
spring plates. This is very neat and almost impossible
to see.
Because the ‘B’ has narrower brakes than
the ‘C’ the ends of the bar just touch the
heads of the bolts for the brake backing plates. This
causes no fouling or noise in practice; the only
modification required was to slot the bolt holes in the
supplied mounting plates slightly to allow for the 1/8”
width difference at each end of the bar to be
accommodated.
A test drive showed we now had a different
car, turn in is good, not a modern 3 Series to be
sure but a huge improvement on how the car was when
it left Abingdon in 1968. The steering was now
pleasantly light and much more direct even allowing for
3.5 (actually 3.45) turns L to L and 34 Ft turning
circle (the ‘B’ has 2.93 turns and 32 Ft for
comparison) so off to Toowong for comment. “That’s
much better, probably would be even better with 1/16
inch smaller diameter bar on the rear or a little
thicker on the front as now it oversteers slightly.”
Imagine a ‘C’ that oversteers; having grown up
with a ‘TF’ oversteer was not what I considered a
big problem, what terrifies me is a car that will not
respond to the “Helm” and heads for the
scrub.
Since I wrote this series Tom Pugsley from Canada has
brought in a 2.875:1 Quick Rack; rack and pinion for my “C” from
MGMotorsport in the U.K. approx AUD400 if you bring it in
yourself. Tom has fitted this kit to his “C” roadster and
assures me that it is well worth doing. With my Moto-Lita 15.375
inch Wheel instead of the 16.625 inch original this will give a
rim movement almost the same as my MK1 “B”. I have had the Quick
Rack fitted for 1,100 miles now and it is a big improvement,
the steering has some feel to it and you can feel it load up
unlike the 3.45:1 standard rack. This was a strong criticism of
my mechanical engineer friend who commented that as you could
not feel the steering you would not get advance warning when the
steering started to lighten as in slippery road conditions. The
Quick Rack is 2.875:1. The MK1 “B” 2.93:1 both with the
ginormous 16.5 inch wheels (the “C” with leather cover) With the
15.375” Mota-Lita wheel the steering is about the same muscle
wise as the car on original skinny tyres. I find that most
sporting sedans with power steering have a steering ratio of 2.9
to 3.0 so the MGB was always about right. More than 3.5 belongs
in the family shopping trolley class. I am waiting for 4
Minilite replica 15/5.5 inch center lock alloy rims to arrive
from the UK. I plan to fit these with 185/65 Michelin Energy
XM1 tyres to complete the handling package.
Since this last revision, the MINATOR 15/5.5 inch
center lock alloys have been fitted with 185/65 tyres and have
minimum clearance from the widest part of the sidewall to the
turn in on the rear wheel arches of 11 mm on the right and 12 mm
on the left. This is fine in practice and nothing rubs anywhere.
195 section tyres are 12 mm wider overall i.e. 6 mm less
clearance or only 5 mm right and 6 mm left which even if a
panhard rod were fitted would require turning up the wheel arch
edges to provide a safe running clearance.
Now the ‘C’ and the BMW
handled in a similar manner and interestingly both use
a 3 PSI pressure difference but the opposite
way around, i.e. BMW F30 R33 and ‘C’ F33 R30.
The ‘C’ now goes around Lakeside with ¼
turn of lock rather than handfulls of lock when
new(standard rack). The final ‘tweek’ was to
remove all the shims from the top “A” arms to
see what the camber was (as it arrived the right front
had ¼ deg negative and the left front ¼ deg positive
camber) we ended up with –1.125 deg Left and -0.75 deg
Right, with the lower wishbones horizontal i.e. parallel to the
ground. Toe in (currently) set at 5 mm.
Like the problems with the early MGA Twin
Cam once again Abingdon were forced to rush out a
new model without sufficient testing or development in
the field and once again a potentially good car was
hounded off the roads by the reported problems and very
bad press reports. Without spending money on the engine
just a few Pounds Sterling would have given the car
good shocks and both roll bars (which are necessary) and
transformed peoples impression of the ‘C’ which
might have survived long enough to get the Rover
engine.
My car can now keep up with other MG’s
on Wednesday runs without heading for an instant
“Off Road Experience” which as it arrived would
have been mandatory. I fed back my experience with the
roll bars both on ordinary road work and on circuit
training to Ron Hopkinsons people so that other
‘C’ owners might benefit from our experience.
So after 25 years of bit by bit development
I now have the 3 Litre sports and GT car that
I thought I was ordering way back in 1967. The final
article will cover specific technical items of interest
to all MGC owners. Basically the “C” is a very
good car it needs development as outlined in these articles to
make it what it could have been. The C-GT is the
better car for lots of reasons, it is stronger, with a
much stiffer chassis, has better balance and as a high
speed cruiser (no longer possible with the new draconian
legislation in Australia) is hard to beat; and it is quiet,
absolutely ideal for fast long distance trips.
(Article 4
in a series of 4 - “Technical Development”.)
This is the final article in this saga, it
is of interest to ‘C’ owners who do their own
mechanical work. Included are items that will be of
interest to ‘B’ owners in particular the rear
shock absorbers.
Any MG Club who has MGC owners
may run these articles if considered of interest to
their members, or make photocopies etc..
(1) : THE
BIG LUMP .
In article 2, I mentioned the valve guide
seals; these are neoprene rubber cups which fit over
the valve stems and plug onto the valve guides, they
have a raised bead inside the cup which is supposed
to fit into a groove in the guide and stay in
position. The caps come off the guides and work like
oil pumps for the inlet valves.
This set up is totally different to all other
MG engines. Early cars had the valve guide groove
machined in the wrong place (what’s new at BLMC)
replacement guides were (or should have been) fitted
under warranty; unfortunately the caps still come off.
If you have oily plugs remove the rocker cover and
have a look, you can see thru the springs if the
caps are in position or not. The only good cure is
to fit either TRW
