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 "Every Racer's Guide to Suspension Tuning"

 Recommended for every one interested in handling, especially for racing and high performance
Dale Thompson, December 2015,


Triumph TR 2,3,3A and TR4


TR2,3 and 3A have similar front and rear suspension.  The TR4 has wider track front and rear, and is the same front and rear suspension, except that the front suspension has some caster built in, vs zero caster for the earlier cars.  The TR4 has a steering rack and pinion.  TR2/3 have a steering box, although many have been converted to steering rack (see below).

You can't do the suspension set up on a car from a parts catalogue.  Our TR set ups are developed in the Weight Transfer Worksheet (WTW), and tested in the the many TR suspension set ups we have done, both for road and racing. (see sidebar)  

The TR suspension was designed around bias ply tyres.  With such low grip tyres, the thinking behind critical handling issues was not fully developed.  The latest radial ply tyres are the single biggest contributor to better handling, but only if the suspension is set to take advantage.   Therefore whatever race or rally setups were used in the 60's and 70's will not be optimized - in fact, probably not even close.  The theory hasn't changed, but there is greater understanding about the role of the tyre, as described in detail in the Technical Pages of this web site. 

If you follow F1, or V8 supercars, you will be aware how important the set up is in professional racing.  Likewise, our classic sports cars benefit from suspension set up technology.

Let us know your intended use for your car, and we will put together a suggested package.

Front  (Prices incl. GST)

Coil Springs                                       $330.00 pair

"Soft ride"  250lb/inch  (Softer than standard.  All cars TR2-4 used 300lb/inch springs as standard. Modified spring plate needed to fit softer springs - see pictures.)
415 lb/inch springs, tarmac rally/racing (Factory racing coil was 380lb/in)
550 lb/inch racing
650 lb/inch racing

Shock Absorbers, gas pressure over oil.  $200.00 pair. Very reliable.  two years warranty.  Better performance, better ride than a hydraulic oil only shock.  The gas pressure helps the shock consistency on the change of direction, bump to rebound.
Racing shocks, QA1 rebuildable       $790 pair.  Uses deflective disc technology.  Digressive valving for ultimate control, compared to road shocks.  Valving and dynoing by us.  We can show you the extra control on the shock dyno graphs. Better valving and control than any of the single adjustable, or rebound only adjustable shocks on the market.

Front Anti-Roll Bar Kit (ARB)           $395.00   20mm or 22mm

Upper inner pivots for camber adj.     $295.00 pair  ($169.00 for one)

Modified Spring Plates                No longer available       

Steering mods required OR use steering rack and pinion with ackerman and bump steer correction, which we can advise on.
Needs front end rebuild, which we can advise on.  Changing to positive caster set up on TR2/3 cars gives great results. 


8mm main leaf, for spring pack                 No longer available
Rebuilt rear leaf springs,                           No longer available
Lever shocks, upgraded                            No longer available
Panhard Bar Kit, bolt on                           $495 

Diff ratio is important.  A shorter diff and the 22% overdrive makes the car very responsive in the regular highway driving speed range, and at the track.  For effortless highway cruising, the standard 3.7 diff and overdrive is great, if you have a modified engine with sufficient torque.

Coil Springs and Front ARB

Springs and anti-roll bars determine the ride stiffness, or suspension frequency, and the degree of roll.  The 300lb/in standard front coil spring already gives a firm "ride rate" compared to other sports cars and is a good choice for performance road cars. 

But "roll rate" of the standard car, causes the car to be unbalanced - too much oversteer on modern tyres.  We recommend a 20mm dia. ARB with the standard springs.  Any road going TR will feel remarkably improved with this ARB.  The 9/16 inch period anti-roll bar is way too soft to be of value.

For fantastic ride and handling in any road going performance TR2-4, fit the "soft ride" springs.  Exclusive to Racing Car Technology.  For a description of what these springs are all about, refer to the photo, top of the centre column, and caption, and below in this column.

We also have tarmac rally and race spec coil springs.  For competition cars, we recommend to do a Weight Transfer Worksheet (WTW), as per the front page of this web site.

We recommend modified lower control arm spring plates (see picture).  The cutout is important.  It helps to be able to get the springs in and out of the car easily, so as to be able to adjust ride height. 

Depending on the ride height of the vehicle it may be necessary to adjust the spring seat angle (see picture).  We have test data that shows excess bending of the spring will increase spring stiffness up to 20%.

*NEW*Softer Ride Front Springs, Racing Car Technology Exclusive

Refer the picture at the top of the page.  This chassis is fitted with our softer than standard front springs (250 lb/in) and also used on Bill's TR shown at the right.  These springs are always mated with our 22mm front anti-roll bar.  The advantage of such a stiff anti-roll bar is that, as well as giving the car the right balance of oversteer/understeer, it gives better initial turn in.  This is a characteristic of anti-roll bars that is not generally well known.  The TR responds very well to the extra roll stiffness, and proves the theory in this regard.

There are no over the top modifications on this car.  It is just a great balance of good power, handling and braking, with aftermarket seat and  seat belt to keep the driver held while it's all happening. 

There no dip, shake rattle or roll and the car tracks flawlessly, with good ride quality.  At the wheel, you get good feedback from the road.  It's a nice track day car.  For racing, it needs quicker response (stiffer springs and competition shocks) and quick ratio steering rack.  

You can see the adjustable upper inner pivots, that can adjust for negative camber.  TR2/3 type top arm indicates this is a zero caster car.  Can also use our camber adjusters with TR4 trunnions and top arms, to give around 2 - 3 degrees caster.

Chassis stiffening at the "cross", at the centre of the car, reduces chassis twisting, and improves handling response.    


Modified TR3 front suspension showing the softer ride 250 lb coil springs, Comfort Gas shocks and 22mm anti-roll bar.  This heavy duty anti-roll bar is required with these coils to control roll.  If you run standard 300lb/inch springs, we recommend the 20mm anti-roll bar.  

Soft ride front coils can only be fitted if the lower control arms have been modified (see below). 

The combination soft ride coils, heavy duty anti-roll bar controlling roll, with Comfort Gas shocks delivers unbelievable ride and handling for any
road going performance TR.


Page 2

To order any TR parts and kits you see here, contact us

Read about early
sports car set up here, and also Origins of Weight Transfer Concept



Anti-roll bar mount is welded to the front of the square section chassis rail.

This QA1 racing shock has extended mounting, which allows extra shock travel.  Note also the all important cut out in the lower control arm spring plate, which allows you to fit the coil springs easily,

This is the cutout that allows the spring plate to swing down further, and allow easy coil spring removal.  This is for TR2-4.  TR5-6 do not have the same problem.  The spring seat angle has been changed as well, so as to push the spring straighter.  Our tests show that bending of the spring in the front suspension can add around 20% to spring stiffness.

Bill's TR in road trim, with chrome wires and Pirrelli P600 tyres.  Car also has Compomotive alloys and 205  50 15 tyres to improve on track performance.

Steering and suspension geometry has been optimized along with our suspension components.  The car has the "soft ride" front springs and our rear panhard bar.  Engine power is increased - flowed cylinder head and spec camshaft, that allows high compression without pinging.  Does require premium unleaded fuel.