TR Notes and Queries

The TR4-6 steering rack is too wide. These cars are wider than the TR2-3B by 100mm This means that the inner ball joints are too far apart and will introduce adverse and unwanted steering effects. The worst of these effects is bump steer. This is where the wheel turns in or out as the wheel rises or falls under suspension loads making the vehicle very unstable especially on undulating surfaces. A well-known racer astounded me once by telling me he had eliminated the effects of bump steer by simply preventing the suspension from moving up or down too far! I could not believe what I was hearing as this is rather like closing the barn door after the horse has bolted! The correct solution if suspension travel is to be maintained is to ensure that the ball joints are in the right place. Not surprisingly Triumph had the suspension geometry correct for the tyres being used in the day. This geometry only requires a small improvement explained later. What you need is our kit part number RTR3202LK (for left hand drive) or RTR3202RK (for RHD). these kits include the correct length rack and employ bracket that weld to the chassis to ensure the correct rigidity and position the rack correctly to ensure the steerign geometry is correct.

If you currently have a solid column, not split, you will also need an upper column Kit 121154X and a support kit RTR3406LK or RTR3406RK. Please remember you will need to alter the horn and indicator arrangement. We have all the necessary switches to do this.

Lastly, the kit improves turn in by altering the Ackerman angle of the steering. To do this we supply redesigned steering arms which move the outer ball joint out sightly to change the Ackerman angle from negative to positive. All prices are available on our website.

The TR2-4 hand brake is both a parking brake and an emergency brake as the cars do not have dual circuits. As such it can arrest the wheels whist rotating. The TR4A-6 handbrake on the other hand is a parking brake only. It is only intended to stop the car from moving whilst at rest. Obvious I know but important; the standard TR4A-6 handbrake is more than capable of this on any usual gradient.

So where that leaves us is that if you feel improvement is necessary it is most likely because the system needs some attention. The obvious areas to look at are seized or partially seized cables and worn (or missing in the case of slave cylinder gaiters and retention plates) components but the critical area which is almost universally overlooked is the brake back plate. When all the plates that hold the slave cylinder in place are correctly assembled, the cylinder can slide back and forth to allow the two shoes to take up position in the brake drum. This is essential as the adjuster at the other end of the shoe is fixed.

With the cylinder removed it can be seen, on almost all back plates, that a divot has been worn into the back plate by the handbrake lever pivot bar. This then disallows the cylinder sliding when the handbrake is applied resulting in only one shoe being pressed fully onto the drum.

The solution is to remove the back plate, weld up the divot and linish off the weld to a smooth surface to restore the correct operation. As is obvious this is beyond a lot of TR owners who do not have welding equipment and consequently doesn't get done. However it is not a huge issue to remove the back plates and take them to a local garage who can affect the repair. With the system reassembled, cables lubricated and all the plates holding the slave cylinder assembled correctly the handbrake should operate satisfactorily.

Further background 

The input shaft in this gearbox has 22 teeth on the shaft and 35 on the countershaft gear. The spigot is 20mm long, but I think I need to lengthen this to 33mm, unless a gear exists that has the longer spigot.

I have found the problem with using the 20 mm spigot in a racing (200bhp) application, is that I believe the front of the shaft is not adequately supported when fitted to 4 cylinder engine, and the "skipping rope" action causes jumping out of 4th gear, and eventually, damage to the synchromesh dog teeth.

RevingtonTR Answer

Our TR5-6 Extractor Manifold was designed to maximise gas flow specifically with PI inlet manifolds fitted. 

These comments are specific to the Weber inlet manifold we supply but may be relevant to other manifolds as well. 

Several things have conspired to result in a potential interference problem between the Weber inlet manifold we suply and our exhaust manifold.

 1. Our inlet manifold supplier used to supply TWM then switched to Cannon. TWM used to fit but we are now aware the Cannon inlet manifold sits lower causing an interference problem with our extractor manifold. We believe the TWM (now not available as far as we know) manifold was canted up at a steeper angle.

 2. Our Extractor manifold has recently been redesigned to improve access to the mounting nuts and to optimise gas flow. We did this with the PI manifolds in place but having checked the Cannon inlet manifold there is an interference.

Our extractor manifold gives the best power of anything around, the long primary outlets are crucial to this power delivery and we don't know of another Weber inlet manifold, so if you are proposing to fit these two parts together then we would suggest the following:-

 1.The offending flanges on the inlet manifold can be filed away as much as possible

 2.It is permissible to plannish flats onto the tops of the exhaust tubes ever so slightly.

It will be surprising how close this brings the exhaust to fitting. However if this is not enough then the face of the inlet manifold which sits against the head can be machined to an angle by a couple of degrees to tilt the outboard end of the manifold up out of the way.

Only cars exported to the US had narrow port heads, these being fitted to TR250 and early TR6 both with the commission number prefix CC. It is the inlet ports that are different in this respect, the exhaust ports are the same throughout.

All TR5 and all TR6 other than CC prefixed cars have a wide spacing of the inlet ports. If you are considering changing your cylinder head, adding an extractor manifold or fitting a carburettor manifold, including Weber manifold it is essential to know which head you have.

To find out, measure between the inlet ports which are in 3 pairs.

CC cars: 17mm. The gasket usually has slightly larger diameter holes therefore the gap in the gasket will measure 15mm 

CP, CF and CR cars:  25mm. The gasket usually has slightly larger diameter holes therefor the gap in the gasket will measure 23mm

Note: - Many TR's have engines and heads from saloon cars fitted  so measuring is the only sure way.

Neil Revington explains: Firstly I am aware of the modification which is little more than a piece of metal extending the lever at the brake back plate. We have never sold these as to me as an engineer it misses the point completely.

The TR2-4 hand brake is both a parking brake and an emergency brake as the cars do not have dual circuits. As such it can arrest the wheels whilst rotating. The TR4A-6 handbrake on the other hand is a parking brake only. Admittedly the TR4A does not have dual circuit brakes as standard, but the industry was moving that way. This later parking brake is only intended to prevent the car from moving whilst at rest. Obvious I know but important; the standard TR4A-6 handbrake is more than capable of this on any usual gradient.

So where that leaves us is that if you feel improvement is necessary it is most likely because the system needs some attention. The obvious areas to look at are seized or partially seized cables and worn (or missing in the case of slave cylinder gaiters and retention plates) components but the critical area which is almost universally overlooked is the brake back plate. When all the plates that hold the slave cylinder in place are correctly assembled, the cylinder can slide back and forth to allow the two shoes to take up position in the brake drum. This is essential as the adjuster at the other end of the shoe is fixed.

With the cylinder removed it can be seen, on almost all back plates, that a divot has been worn into the back plate by the handbrake lever pivot bar. This occurred over time and can be deep enough to prevent the cylinder from sliding when the handbrake is applied resulting in only one shoe being pressed fully onto the drum. This of course means the handbrake is effectively on 50% efficient.

The solution is to remove the back plate, weld up the divot and linish off the weld to a smooth surface to restore the correct operation. As is obvious this is beyond a lot of TR owners who do not have welding equipment and consequently doesn't get done. However it is not a huge issue to remove the back plates and take them to a local garage who can affect the repair. With the system reassembled, cables lubricated and all the plates holding the slave cylinder assembled correctly and everything that moves lubricated the handbrake should operate satisfactorily.

Firstly most surrey tops, hoods and tonneau (I'll call these 'covers') are made to patterns that have been created from original covers that invariable have been removed from cars that have not been rebuilt. As many of these covers and patterns have been in use for many years it follows that whilst mistakes in manufacture can occur, it is likely that the problem lies elsewhere.

It is important when making this modification to a TR2-3B that full clearance for the kit is afforded especially where the bodywork flange is concerned. The fitting instructions supplied with the kit show what is required however if an interference occurs, here are some ideas of what might have gone wrong when installing the kit.

1.The callipers are displaced around the axle by one pitch of the 6 bolts

2.The body has not been cut away enough

3.The hose is orientated incorrectly. See the photo called ' front view with leaf spring in place' in the link below. Change the orientation of the hose to ensure its orientation keeps the hose out of the way of the body, check carefully on your own installation as this is a crucial safety consideration. 

This link takes you to the product page for kit RTR4410-1K where 5 images are available to look at to assist ensuring all parts are assembled as they should be..

4.You have no bump stops fitted to the axle or he bump stop hoops are missing or the bump stops are misplaced allowing the axle to move too far. follow this link to see the correct standard parts 21,22 and 23

There are two combinations of second gear bush and gear. What can happen over time is that the gearbox can be rebuilt with "early" and "late" specification mixed. It is often thought that the later specification must be stronger and Triumph must have made the changes for that reason, technically this is so, but we have found that the dog teeth on the late specification fail much more quickly than the early type did, although the bush part doesn't.

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