Marcos Maniacs

Hi guys,
First off, I don't consider myself an expert on suspensions. Having 
said that, lets look at some "facts".  

The Marcos 1800 came 175-13 inch tires and had a ground clearance of 
4.7 inches (Source Road and Track Magazine)and a toe in of 1/8 Castor 
of 7 1/2 degrees (source Motor Magazine)

The Marcos 1600 came with 165-13 tires and had a ground clearance of 
4.25 inches toe in 1/8. Castor 6 1/2, and camber 0 (source Motor 
Magazine) 

The Marcos 3 liter V6 came with 175-13 inch tires and had a ground 
clearance of 3 1/2 inches, toe in of 1/8, castor of 6 degrees, and 
camber of 0 (source Motor Magazine) 

The Marcos 3 liter Volvo engine came with 175 -13 inch tires, and had 
a ground clearance of 4 1/2 inches (Source Autocar Magazine)

The Marcos Mantula was still using the Triumph front suspension and 
came with 225/60VR14 inch tires (source Autocar magazine)No suspension 
settings noted or ground clearance.

So, if you are having ground clearance problems, you might want to 
measure what you have and compare that measurement to what the car had 
originally.  In addition to the problem modern tires pose with their 
lower profile and resulting lower rolling diameter, we also have the 
problem of what previous owners have done inaddition to other 
mechanical problems like tired springs etc. What exactly is scraping 
when you "bottom out".  Is it something that can be mounted closer to 
the body and farther from the ground?  I have spent a lot of time 
building my own exhaust system to get it up and out of the way.  The 
result is an exhaust system that doesn't scrape when I go over bumps.  
The only place that I have a problem scraping in on some LARGE speed 
bumps and the engine pan will scrape slightly if I am not careful.  I 
don't scrape going into and out of drives etc.

Wheel and tire combinations are endless. However, if you compare a 14 
inch wheel and tire with the exact thing in a 13 inch size (apples to 
apples) the 14 inch size will be heavier.  This doesn't mean that you 
can't find an 14 inch alloy wheel that is lighter than the 13 inch 
wheels that are on your car (apples to oranges). How this additional 
unsprung weight effects your car's handling will always be negative, 
if everything is equal (apples to apples).  It doesn't mean that a 14 
inch wheel with new modern low profile tires MAY perform as well or 
BETTER than your original 13 inch wheels and tires (apples to 
oranges). I simply don't know.  There are a lot of factors that would 
have to be considered if you want a really professional answer. If you 
are real concerned about the unsprung weight you can buy aluminum hubs 
that fit the Triumph front axles (two different style bearings) and 
have them drilled to either the Triumph pattern 3 3/4 (measured 
diagonally from centerline of stud to stud) or British Ford (Cortina) 
4 1/4(measured diagonally from centerline of stud to stud)to partially 
offset the additional weight of the larger wheels. You can also get 
lighter brakes either by buying some of the aftermarket units in 
aluminum or changing to the smaller and lighter Triumph units (Triumph 
made two different size caliphers that fit the front end of the 
Marcos)

Rolling diameters... In addition to everthing else, be sure if you are 
changing wheel size to gain additional clearance that your new tire 
/wheel combination nets you an increase in rolling diameter.  You can 
get 14 inch wheels and tires combinations (40 series tires for 
example) that are smaller than a 13 inch wheel with say a 75 series 
tire. Also realize that for every inch in height of rolling diameter, 
you only get 1/2 inch of increased ground clearance.

Anti-sway bars... Sway bars are fitted to the front of cars to shift 
part of the cornerning load to the rear tires.   Again, I am not an 
expert but how does your car corner?  If it understeers, it Might need 
a anti-sway bar.  If the car oversteers, it MAY need an anti-sway bar 
that is smaller in diameter or it MAY not need one at all.  (The 
Triumphs came with two different diameters,by the way.) Anti-sway bars 
shouldn't be added or changed "willy-nilly".  They are an engineering 
answer to a specific problem.  So make sure you have the problem 
before you start changing things.

Mike Denman
1966 Marcos 1800
Chassis # 4079