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TR Notes and Queries

TR Notes and Queries

Q: Can I run my TR on unleaded fuel?
Q: I have a Revington TR rear damper conversion kit part No. RTR3003RJ. What rate springs shall I use?
A: The Revington TR rear damper conversion is intended for use with uprated springs. It is possible to use the damper kit with standard springs but the dampers will have to be set on their lowest setting. Unless the springs are in perfect condition this setting may prove to be to hard for some drivers. We recommend springs part No. RTR3101, which provide a 20% uprate, and give ground clearance of 145mm, after all if you are fitting our dampers you are undoubtedly looking for an improvement in road handling which these springs will provide in conjunction with our damper kit.

Order the following parts:
2x RTR3101 Springs
2x SPF2327K Polyurethane Spring Insulators. (Two in each kit) and/or
4x SPF2327-5K Polyurethane Spring Insulators + 5mm deep (Two in each kit)

Applicable to: TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: What are the advantages of fitting Revington TR suspension packages?
A: Please see the attached Revington TR information sheet.

Applicable to: TR2; TR3; TR4; TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF; TRI; TRS;
Q: Is any welding required with the Revington TR TR2-3B steering rack conversion and if so why?
A: Yes most definitely our rack conversion is WELDED on. We consider it unsafe to bolt on a kit to the brackets intended to carry the steering box, as the angular moment forces are too great. The chassis brackets crack in this area in standard form without putting more force on them. The welding required is minimal and can be performed with all the suspension and the body in place. One important consideration is that an electric fan will need to be fitted as the original fan and extension will need to be removed.

Applicable to: TR2; TR3;
Q: Having changed the clutch components inside the bell housing I now cannot engage 2nd or reverse gears. What could have caused this?
A: The clutch release operation on TR4A - TR6 cars is marginal at best. Think about when the clutch is worn out, the clutch slips. This is like disengaging the clutch without even placing your foot on the pedal. Conversely when the clutch is brand new it follows that the disengagement point will be at the very end of the pedal travel.
When the components in the pedal box/master cylinder area and the release parts associated with the slave cylinder are worn, there may in some cases be insufficient pedal travel to effectively disengage the clutch thus resulting in clutch drag. Second gear is the gear most likely to have a worn synchromesh and reverse has none at all making these gears the most likely candidates for a graunchy gear change under these circumstances.
The correct solution is to strip everything down and ensure all components are in perfect condition. This course of action may be undesirable but even if taken may still result in poor clutch operation until the clutch is somewhat worn.
The simple solution is to fit an adjustable master cylinder operating rod. This enables all the slop to be taken out of the system thus affording maximum pedal travel. Order RTR4136 for TR4A and RTR4357 for TR5-250-6

Applicable to: TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: I'm thinking about changing the original worm and peg steering system on my TR3A to the rack and pinion Steering system fitted to a TR 4 Can I fit a TR4, 5, 250 or TR6 Steering rack to a TR2-3B?
A: The TR4-6 steering rack is too wide. These cars are wider than the TR3A 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 RTR3202L (for left hand drive) or RTR3202R (for RHD) cost gbp365.00 If you currently have a solid column, not split, you will also need an upper column Kit RTR3315 cost GBP95.00 and a support kit RTR3406L or RTR3406R cost GBP29.50 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 alter the steering arms on the car, so these are exchange. We charge a surcharge until you send us yours back. All prices are subject to VAT where appropriate and may be changed without notice.

Applicable to: TR2; TR3; TRI; TRS;
Q: How do I measure cylinder head combustion volume?
A: To measure cylinder head combustion chamber volume, grease the valves and inset these and the spark plugs into the head. Prepare a piece of clear Perspex large enough to cover the combustion chamber, with two small holes in it, one. Grease this and slide over the cylinder head to cover the combustion chamber. Using a syringe or pipette introduce paraffin, light oil or water via one hole. The other hole lets the air out. When the chamber is full, read off the syringe or pipette the amount of fluid introduced in cubic centimetres (millilitres are the same. This is the volume of the cylinder head.

Applicable to: All cars
Q: How to install SuperPro Polyurethane trailing arm bushes?
Once the old bushes are out ensure the housing for the new bushes is completely clean. Using the grease supplied the new bushed (without the sleeve fitted at this stage) can be pressed in using a light press, a vice or can simply be hammered in with a piece of wood on top of the bush, ensuring of course that there is a support, the bench for instance, under the specific housing. When the bush is mostly in, it will 'pop' into place. The sleeve once again using the grease provided can be pushed in by any of the above means. Alternatively the bush can be pulled in with a threaded steel rod with with double static nuts, large washer and the bushing at one end and a deep socket, large washer and nut at the other end. By tightening the nut the fully greased bushing pulls through the eye hole into the large socket. It should be possible to push the sleeve in by hand.No other adjustments or reaming is required; the sleeve is correctly sized to allow the bush to rotate on the sleeve in service.

Applicable to: All cars
Q: I have a non standard cam in my TR4 and I find the push rods will not fit. I have not shortened the pushrods but have shimmed the rocker shaft pedestals. Is this correct?
A: This not necessarily the right thing to do. You need to establish half lift of the valves at which point the rocker must be horizontal so that the rocker operates equally about the centre point. This will require either shimming the pedestals or milling some off. THEN choose the push rods to suit. Pushrods longer and shorter are available. See section one for listings.

Applicable to: TR2; TR3; TR4; TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF; TRI; TRS;
Q: I have excessive negative camber on the front wheels of my TR4A-6. What can cause this?
A: Please see the attached Revington TR information sheet.

Applicable to: TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: I intend fitting a Revington TR overhead throttle kit and notice that you have a single and a double cable version, Which one would be the correct for a road car?
A: The single cable version is fine unless you are racing and need the reassurance of a constantly available second cable. The cable shouldn't break if the stops at the pedal as well as the throttle are set correctly.

Applicable to: TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: If I fit a plastic fan to the original fan extension or remove the fan and extension altogether, would I be risking crankshaft breakage or damage due to changing the dampening effect of the original fan/extension arrangement?
A: Irrespective of whether you use a wobbly aluminium fan or a wobbly plastic fan, the effect is the same. It helps (just) to cool the engine and that is all. In our opinion the amount of damping it offers is negligible. Dampers have been in use since the 20's where necessary. If Triumph (one of the largest sports car manufacturers in the world at the time) thought is was necessary they would have fitted one. We have been building TR2-4A engines with no fan and no extension for 25 years with NO broken crank related failures. As a result we are quite happy that an engine in good shape, from standard up to all bar the highest revving competition engines should not suffer ill effect by having the fan substituted for a later TR6 plastic type or having it and the extension removed altogether. If you do remove the fan altogether we recommend using a properly designed washer and bolt arrangement to hold the pulley to the crankshaft. Order part number RTR1027.

Applicable to: TR2; TR3; TR4; TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF; TRI; TRS;
Q: Is the TR4A IRS to TR6 rear suspension arrangement semi trailing arm or trailing arm?
A: The TR4A IRS to TR6 rear suspension is a semi-trailing link suspension arrangement as the arms are mounted at an angle and not perpendicular to the wheel base.

Applicable to: TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: What is the initial engine start-up procedure for TR's?
Q: Can I use an Extractor Manifold RTR2044 part of system RTR2042 with a triple Weber inlet manifold RTR4008 and RTR4008-1

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.


Applicable to: TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: Does the 4 cylinder TR engine require an harmonic balancer on the front of the engine?

The subject of balancers needs careful consideration. You can be sure that when BMW specify a harmonic balancer for a new engine they don't have an engineer thumbing through a catalogue over a cup of tea looking for one that might just fit- sort of - if modified a bit. It would be more realistic to assume thousands of hours of testing goes into the design for each application.
RevingtonTR have close contacts with a vibration specialist company who have designed a suitable damper for 4 cylinder TR use but agree with us that this only has a primary value above 5000 rpm. We use this damper when we install a billet crank into an engine that will reliably and continually run at 7500rpm. The company in question do work for Bentley so I think it is fair to assume they know what they are talking about. This damper needless to say is intended for use only where the engine fan has been removed. 
By contrast Neil Revington's TR2 has no damper on the front of the engine. This engine uses a standard crank and rods and has been used in competition and on the road for over 200,000 miles, much of which will have been at high revs, up to 6500 at times. It suffers no vibration and the engine is as smooth as the day it was built. Neil designed our aluminium pulley over 20 years ago which has been fitted to hundreds of engines built for road and competition use. We have had no complaints of torsional vibration that would need eliminating with a harmonic balancer. Coupled to this we have sold many hundreds of thin fan belt conversion kits incorporating out aluminium crank pulley all over the world with no negative feedback about vibration. Most of these kits are sold with an electric fan indicating their use without the engine fan fitted. It is naive to think the fan fitted to the front of a 4 cylinder TR engine is in some way a damper. The fan is a crude device and its design and the manner in which it is attached to the engine gives no suggestion of it having any anti vibration design intent.  It is interesting to consider that the TR250-6 fan is mounted on its crankshaft with an harmonic damper using the exact same part number small rubber bushes that TR's 2-4A use reinforcing the conclusion that they are there to try to prevent vibration being introduced by the fan, not as some form of harmonic balancing of the engines internal components.

Technical speak
A harmonic damper is a device fitted to the front (assuming the drive to the wheels is from the rear) end of the crankshaft of an internal combustion engine. It is essential in engines with long crankshafts (such as straight 6 and straight 8 engines) and is present on most engines as it reduces torsional vibrations that tend to peak at certain speeds. Torsional vibrations can greatly reduce crankshaft life, if not cause instantaneous failure, if the crankshaft runs at or through an internally generated resonance. Because of this, dampers are designed with a specific weight and diameter to reduce mechanical Q factor[1] and therefore damp out crankshaft resonances. Manufacturers will often re-size the damper in the same basic engine when modification to crankshaft material, thickness, weight, or throw is implemented. Even piston size and conrod shape/weight can affect the damper requirement.  With this in mind it is clear that dampers are very specific to an individual engine application and cannot with reliability be simply lifted from one application to another without first understanding the characteristics of the donor engine and matching that to the TR engine. It may also be argued that as the TR engine in question is a well-designed 4 cylinder with a massive and stiff crankshaft, that Triumph (who were not stupid and were at the time one of the foremost manufacturers of sports and saloon cars in the world) will have measured all this and concluded a damper was not necessary (Admittedly the bean counters would have had an input into this too!). Bear in mind that Triumph at the same time produced a very successful 6 cylinder engine on which they conclude a damper was necessary.

It is worth noting that early TR conversions to a thin fan belt arrangement used a pulley of another engine, notably an MGB, primarily due to ease of availability and relatively easy adaption to fit the TR2-4A engine. The fact that these dampers are harmonic dampers for their original application is of no relevance in the TR application. Another important consideration is that Triumph for commercial reasons applied limited balancing to their engine construction. Few engines fitted to TR's 2-4A these days will have escaped being rebuilt. This may have been done to a wide range of standards from good to downright appalling. These engines will produce vibration for a number of reasons some of which will be, but not limited to, rotational lack of balance, reciprocating balance and combustion balance. Added to that with twin carburettors an out of balance of the fuel delivery will introduce vibration. None of these vibrations are inherent torsional vibration needing a harmonic balancer. Consequently when an engine has been built correctly and balanced correctly it will be joyously noted that a harmonic balancer is not necessary!

So our conclusion is that the 4 cylinder TR engine does not need a harmonic damper when it is either a standard unit or one constructed with improved but mostly standard components (crank and rods especially) and used within or slightly beyond its designed rev range, especially when the unit had been carefully built and balanced. However, when a different crank, typically a billet crank, is used in conjunction with ʽHʼ or ʽIʼ beam con rods in an engine revving to 7500 rpm then an harmonic balance will be beneficial to some extent but this will be a little bit 'hit or miss' for the reasons stated above vis a vis the amplitude and specific rev range of the harmonics (if any).

[1] In physics and engineering the Quality factor or Q factor is a dimensionless parameter that describes how under-damped an oscillator or resonator is and characterizes a resonator's bandwidth relative to its centre frequency. Higher Q indicates a lower rate of energy loss relative to the stored energy of the resonator; the oscillations die out more slowly.

Kind Regards

Applicable to: TR2; TR3; TR4; TR4A; TRI; TRS;
Q: How do I know if I have wide or narrow port cylinder head

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.






Applicable to: TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: I could do with some assistance in operating the handbrake on steep slopes. Is it advantageous to fit a piece of kit to increase the length of the operating lever at the back plate?

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.


Applicable to: TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF;
Q: I have a new hood/surrey top/tonneau cover which appears to be too small for the car. What can I do?

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.

Firstly it is important to ensure the car is the right shape. If the car has been rebuilt and especially if the floor pans and sills have been replaced it is easier for the body shell to end up longer than standard, than it is for it to be shorter.  The chassis on TR4A-6 are notoriously weak and can bend in the middle which will result in the rear of the cockpit moving away from the top of the windscreen. Check your car against similar cars of good provenance to ensure your cockpit dimensions are correct. For reference on a car with a backlight frame to accommodate a surrey top, we know the dimension between the holes in the top of the windscreen frame for the surrey spider frame and the holes in the backlight frame to accommodate the spigots of the rear frame is 760mm.
Covers are made from hooding material which can either be vinyl or mohair. These materials when new are relaxed and must be significantly stretched when being fitted to ensure a taught fit in service. This stretching will require significant force which must be aided by ensuring the cover is not just warm but really quite hot, equivalent to a very hot summer's day in direct sunlight so that the cover becomes a floppy bag. In this way the cover will be taught at speed and on seriously hot days and not revert to a floppy bag. This level can be achieved with a hot air gun, hair dryers or a fan heater, ensuring all safety requirements are met. It will be surprising how far the material will stretch and how this amount of stretching when the cover is fitted will result in neat installation with no creases in the material.

Applicable to: All cars
Q: I have fitted a GRB211HD heavy duty clutch release bearing and it makes a shrieking noise when the pedal is first depressed. Is this normal?
New GRB211HD release bearings have very heavy grease in them when supplied. This means that when the clutch pedal is depressed and the bearing first touches the diaphragm of the clutch cover, it doesn't immediately rotate. This causes a momentary singing or screeching noise which disappears when the pedal is depressed further and the bearing rotates at the same speed as the clutch cover. This situation will continue for a short while until the bearing and its grease loosen up, a few days or weeks perhaps, depending on the amount of gear changes that take place in this time. After this the noise should go away and the clutch should operate normally.

The noise you will hear is the bearing sliding over the clutch cover diaphragm momentarily as the grease in the release bearing is initially stiff preventing the bearing from instantly getting up to speed with the clutch cover diaphragm which can be minimised by firmly depressing the clutch and not letting the clutch bearing rest on the diaphragm with a light foot pressure.

It is a good idea not to have the bearing in contact with the diaphragm at all time (this was the practice with TR's 2-4) and this can be achieved by installing a simple spring return device modelled on the TR2-4 system. We have devised a suitable kit to achieve this, order part number RTR1111K

Applicable to: TR2; TR3; TR4; TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF; TRI; TRS;
Q: I've got a Revington TR airbox fitted to my car. The lid is not airtight and rattles badly under hard acceleration and the 6 self tapping screws work loose. How can prevent the rattling and what form of seal/gasket and fasteners work best?


The retention of the lid can be improved by using 'U' nuts on the flange for the self-tapping screws to tighten into. Use RTR5032 nut and SS1060462 screw.

Sealant may not really worth it as the small amount of  unfiltered air entering will not affect the engine, however you can make an instant gasket with a tube of RTV rubber sealant. This can be purchased on the internet. Farnell sell a suitable product.

To ensure the sealant sticks to one side only, say the main part of the box, put cling film on the mating face of the lid and screw the lid down. Then the sealant has set you should have a  suitable gasket that will prevent almost all air entering and should prevent rattling too.


Applicable to: All cars
Q: TR4-6 second and third gears have excessive end-float on the mainshaft. Second gear bush is too short allowing excessive movement over the mainshaft.

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.


What often occurs is a late specification bush UKC956 and gear TKC454 are mated with the early thrust washers in the range 129941-2-3-4, when what is needed is thrust washers in the range UKC958-9-60-61
The late specification bush is shorter and the bore of the gear is correspondingly short, but the thrust washers are that much thicker, by around .080", which does make the 2nd gear thrust washers less likely to break.
We recommend fitting the early specification gear 105629 plus uprated steel bush 129939X (which is 1 x 153237+1 x 153239 sold as a kit). These must be used with thrust washers 129941-2-3-4. Also we have available a specially made thicker version of 153239 (originally approximately 0.123" thick), which we stock as 153239A (0.126" thick) which may be required to achieve the correct end float, measured using a new circlip 055707.
When correctly fitted to the mainshaft, if (say) 153237 is clamped against the 2nd gear thrust washer, using 153239, it should have 0.003" end float, irrespective of the total end float of the whole cluster on the mainshaft, which we suggest should be 0.004"endfloat. The same end float applies to TKC454 on UKC956, against thrust washers UKC958-9-60-61.
An alternative would be to fit TKC454 gear, UKC956 bush, with thrust washer UKC958-61. More often than not UKC959 is needed. If the gearbox has TKC454 fitted, carefully inspect the dog teeth, and if they are chipped and rounded, throw it away.
If you measure the length of the BORE of the gear, 105629 is approximately 1.375" and UKC956 is approximately 1.187", so it will be hard to mix them up. This measurement can be done with a steel rule for the purposes of establishing which gear you have.
All the thrust washer dimensions are shown on our website against individual part numbers.


Applicable to: TR2; TR3; TR4; TR4A; TR250; TR5; TR6CP; TR6CC; TR6CR; TR6CF; TRI; TRS;
Q: What is RevingtonTR's Personal Information Policy and how do you use my data?

Personal Data Policy and How RevingtonTR Use and Retain Your Personal Data. 

On the 25th May 2018 new regulations covering how personal data can be used and stored will come into effect. In line with every other company in the EU we will have to amend the way we correspond with you and store you data. To see what measures we have taken and how your data is handled please click on the link below.

To read the policy document and details please  CLICK HERE

Applicable to: All cars
Q: What is the correct definition of a Hood, a Hood Cover a Tonneau and a Surrey Top?
We appreciate that our English terminology (French actually in the case of Tonneau) can sometimes be confusing. Here are our definitions of a Hood, a Hood Cover a Tonneau and a Surrey Top.

In our modern world of global trading terms we use for products can be confusing. The products in question hear are particularly confusing as for example a hood to us in the UK is the cloth bit over your head, yet in the USA it is the bit over the engine (a bonnet to us). This FAQ should clear matters up.

A HOOD is the cloth part of the complete hood assembly that goes over the Hoodstick assembly from the rear deck to the top of the windscreen. Confusingly Triumph in some parts books refer to the hood as a hood cover. This is also often referred to in common language as a Soft Top.
A HOOD STOWAGE COVER is a tidy cover over the hood and hoodsticks (hoodsticks only in the case of TR2-3A) when folded away and sits around the back of the cockpit attached to the rear deck. A TR4 does not need one as the hoodsticks are folded behind the cockpit rear squabs. Most Triumph parts books refer to the stowage cover as a Hood Stowage Cover Assembly but in everyday language this cover is often simply refereed to as a hood cover.
A TONNEAU cover goes over the whole cockpit from the rear deck to the base of the windscreen and zips up the middle so it can be used whilst driving or as a complete cover whilst parked.
A SURREY TOP is the cloth part only fitted when the hard centre panel is removed from a hart top TR4, 4A, 250, and 5.

Applicable to: All cars