Triumph TR7 Sprint

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Triumph TR7 Sprint

Figure 1: TR7 Sprint
Overview
Manufacturer Triumph Motor Company
Production 1977
59–62[1][2]
Assembly Speke, Liverpool, England
Designer Harris Mann, Spen King
Body and chassis
Class Sports car
Body style 2-door coupé
Layout FR layout
Related Triumph TR7
Powertrain
Engine 1,998 cc (2.0 l) 16-valve Slant-4
Transmission 5-speed manual
Dimensions
Wheelbase 85 in (2,159.0 mm)
Length 160 in (4,064.0 mm)
Width 62 in (1,574.8 mm)
Height 50 in (1,270.0 mm)
Curb weight 1,083 kg (2,387.6 lb)
Figure 2: TR7 Sprint from rear
Figure 3: TR7 Sprint Engine Bay from Left
Figure 4: TR7 Sprint Engine Bay from Right
Figure 5: TR7 Sprint Chassis Plate

The Triumph TR7 Sprint was an intended development of the Triumph TR7 sports car, from the Triumph Motor Company (part of British Leyland). The main development from the TR7 was to be the replacement of the 105 bhp 2-litre, 8-valve version of the Triumph Slant-4 engine with the 2 litre 16 valve version,[note 1] which was already in use in the Dolomite Sprint.[1][3] In that guise, the 16-valve version was specified at 127 bhp; however, "reliable sources claimed that well built and tuned engines, with stock components, had been known to give a sustained 150 bhp on the factory test bed".[4]

The TR7 Sprint was apparently ready for full production when there was a major strike in 1977-8 at the BL Speke plant, where the TR7s were then being produced. Following this, the plant was closed, production of the TR7 was moved to Canley, Coventry, and the TR7 Sprint was cancelled.[1][3][5][6] However, while it did not reach full production, about 60 prototype and preproduction cars, both left and right hand drive, were manufactured between February and October 1977, in fixed head coupé form only.[1][3][2] Also, the TR7s used by BL in rallying from 1976 until 1979 used 16 valve 2 litre Sprint engines and were, in effect, TR7 Sprints.[7]

Technical specification

Engine: Triumph Slant Four 1,998cc 16 valve

Capacity: 1998 cc

Valves: 16

Compression ratio: 9.5:1[8]

Fuel system: Twin 1¾" choke SU HS6 carburettors[8]

Maximum Power: 127 bhp @ 5200 rpm (estimated)[8][note 2]

Maximum Torque: 122 lb ft @ 4500 rpm (estimated)[8][note 2]

Performance Data

0 - 60 mph: 8.5 seconds (estimated)[8]

Max speed: 120 mph (estimated)[8]

The (estimated) top speed and 0-60 times of the TR7 Sprint are almost identical to those for the US specification carburettor version of the 3.5 litre 135 bhp Rover V8 powered Triumph TR8,[1] which are 120 mph and 8.4 seconds.[9] One of the then Triumph engine development engineers is quoted as saying "The real test was the 30-50, 50-70 [mph] times and here the Sprint was significantly superior to the 2V [2 valve per cylinder] engine and even challenged the TR8's abilities. Certainly, if we were going 'off site' the preferred vehicle to 'borrow' was a Sprint TR7 over all others and that includes the TR8."[3] The 150 hp power output given for "well built" Sprint engines must be very close to the 153 PS DIN (±5%)[10] that was given by the Rover V8 engine in the UK Specification TR8.[1] Hence, it is possible that had Triumph produced the TR7 Sprint and TR8 to UK specification, as was apparently planned at one time,[3][6] there would have been significant debate of their relative merits, some of it probably rather partisan in nature.

Distinguishing features

"There are a [comparatively] large number of privately built Sprint conversions about... Buyers should beware of this if they are asked a premium price for an alleged 'genuine' TR7 Sprint":[1] all the essential parts to turn a TR7 into a functional copy of a TR7 Sprint, though not an identical one, can either be sourced from a Dolomite Sprint or remain available from suppliers; several companies sell conversion kits online; and several sources provide information and advice on this TR7 Sprint conversion,[11][12] as well as a number of websites.() According to one of these sources, "this upgrade brings you into the same power band as an original TR8, but for a fraction of the cost, effort and time."[11]

It seems that there is no disagreement that "[a]ll [factory TR7 Sprint] cars were fixed-head coupes",[1] that the period over which they were built spans the changeover between the 1977 and 1978 year model bodies,[note 3] and both right and left hand drive cars were produced.[1][3]

Engine and interior

Figure 6: TR7 Sprint Engine number stamping (CH62HE)

The factory produced TR7 Sprints have chassis numbers that are prefixed with letters ACH; whereas, UK/Australian/European specification TR7s of the time were prefixed ACG:[1][3] Figure 5 shows a chassis or commissioning plate from a TR7 Sprint car, mounted on the left hand door, below the door lock. The TR7 Sprint engines are also prefixed with CH, rather than GC on the TR7's and VA on Dolomite Sprint engines; however, the TR7 Sprint engine numbers can, at least in some cases, be very hard to read (see Figure 6).

Figure 7: TR7 Sprint Interior

There are a number of parts specific to the TR7 Sprint, i.e. not used on the TR7, TR8, or Dolomite Sprint; however, there are alternative parts or alternative methods for all of these: the cast steel exhaust manifold,[1] and the front pipe of the exhaust system (which has been remanufactured, RB7385); a water transfer plate, at the back of the cylinder head (also remanufactured, RB7240); there are at least two different Engine information panels (UKC 8605 and TKC 5228), on the underside of the bonnet, some of which only indicate TR7, but provide slightly different information to that on the equivalent TR7 part (UKC 6246); the front disks, although the callipers and dust shields, etc., were as those used on the TR8;[1] so TR8 disks fit. There are online photographs of some of these parts.() A number of parts in the throttle linkage are also unique to the sprint, most obviously the link plate between the two carburettors (just visible in Figure 3, and partially obscuring the inlet manifold in Figure 4), which was not fitted to the Dolomite Sprint; and the throttle lever/link rod (visible just over the air box in Figure 4), which looks the same as the TR7 part, but is longer to allow for the carbs being further apart. Internally, within the cabin, at least some of the cars were fitted with the large semi-circular pad on the steering wheel from the US specification TR7 (RKC82) (see Figure 7).

There is one unsuported claim that "Having a higher-revving engine, the Sprint received a recalibrated rev counter".[1] However, this is incorrect: both engines had a rev limit of 6500 r.p.m. indicated on the rev counter, though both owners manuals give the "Maximum recommended engine speed (intermittent)" as 6,000 r.p.m.[13][14] Hence, the TR7 and TR7 Sprint shared a common rev counter.

Exterior

It appears that the exterior of the pre-production TR7 Sprints was, and presumably the production cars would have been, indistinguishable from the TR7 of the day, apart from the decals and side stripes. However, it is reported that a number of different decal sets were being tried out on the prototype cars.[1][3]

At least one of the earlier cars carried side stripes with the word "Sprint" on the rear wings. These are shown in a photograph of what appears to be a US Spec., 1977 y.m. car; the caption to which states "The sides of the TR7 Sprint were supposed to have received this striping treatment, designed by John Ashford, had the car gone into production."[3] These stripes are also shown in contemporary pictures of an original, but unidentified, TR7 Sprint from the press garage, which are available from the British Motor Industry Heritage Trust (BMIHT).[15][16] The TR7 Sprint shown in figures 1 and 2 is, in this respect, identical with these photographs, except for the colours. The stripes themselves were reworked for the TR7 Premium edition after the TR7 Sprint was still born.[3] They were, at one time, listed by Moss Europe (previously TriumphTune) under BL part numbers YKC2082-2087.[17]

There are also photographs of TR7 Sprints bearing small 'SPRINT' decals on the front panel and boot lid[1][3] below the 'TR7' decal that was standard fit on Speke built TR7s.[1] This uses the same font as this TR7 decal and in the stripes used on the TR7 Premium edition. There is also a, presumably contemporary, photograph of one of these decals on a V8 powered car.[18] There is also a description of a car with the triumph TR7 decal on the left side of the boot lid, and a large Sprint decal on the right.[1] These sprint decals were also at one time available from Moss Europe (in three sizes), though they do not seem to have been catalogue items nor are they identified by BL part numbers. One size is still available as supplier part No. RB7206BLACK/SILVER/GOLD.

However, it appears that there are no photos or descriptions of the Sprint decals on the front or rear of an original, unrestored TR7 Sprint that is identified as being home market specification; neither are these decals identified to BL part numbers. Whereas, the BMIHT photos of the press garage car should be definitive of this specification,[15][16] and the side stripes they show are identified by their designer and their BL part numbers. Hence it may be speculated that the small Sprint decals and the Sprint side stripes were designs that were tried out on the prototypes, but the Sprint side stripes were selected for the production version, as claimed.[3]

Production details

Figure 8: Press Garage TR7 Sprint Registrations

The exact number produced is a subject of speculation, as it is claimed that "[s]urviving records are incomplete."[3] According to the BMIHT archives, there are build records for chassis numbers ACH/4 to ACH/25, and ACH/00501 to ACH/00536 and ACH/00700: 59 cars.[2][note 4] Also, ACH 1 is identified by the TR Drivers Club, as UK registration WAC 274S, and that ACH 2 and ACH 3 existed might have been inferred from this: "One source [unattributed] states that there were three batches of Sprints, ACH 1 to ACH 25, ACH 501 to ACH 536 and ACH 700 on its own, a total of 62 vehicles."[1] What build records there are at the BMIHT do not provide registration details from which cars might be traced; however, some further details of the cars known to have been produced are provided by the TR Drivers Club.()

While there is agreement that all the ACH chassis prefixed cars were built at Speke,[1][3] a Triumph engine development engineer is quoted as saying "Some if not all of these cars were definitely converted at Canley from 8-valve to 16-valve";[3] however, another Triumph employee, responsible for engineering liaison between Speke and Canley, is quoted as saying that "At the changeover in July 1977 (to the new common underframe) we built a batch of thirty TR7 Sprints."[3]

The TR Drivers Club website gives details for only two of the first group of 25 chassis numbers: what was presumably the first prototype WAC 274S, and one other, WAC 253S. It is suggested that most of the other cars in this batch were LHD and sold abroad.[1] Both known cars from this group were registered in Coventry.

The first two cars of the second group were both white, and registered in Coventry as VVC 696S and VVC 697S. These were, according to an owner written article in the TR Driver's Club Magazine from 1991,() used for reliability testing. While there are no reliable details for BL's use of these actual cars, according to one source the procedure used with the TR7 and TR8 was to run a test car on the Belgian pavé track at MIRA for 1000 miles, "effectively providing wear harder than a vehicle might experience in a lifetime of normal use". The same source also states that "A related assessment exercise for the TR7 was the '90 day corrosion test', for which a prototype was built without the usual zinc primer or anti-corrosion treatments and the body painted white, the best colour to show up any rust streaks." A Triumph engineer is quoted as saying, "this prototype was run around a variety of road surfaces under wet conditions and then the damp areas were checked. The vehicle was then fitted with a series of nozzles which sprayed salt solution into these same areas".[19]

Thirty cars from this second group were contiguously registered SJW 521S to SJW 550S (see Figure 8) in Birmingham, and went to the BL press garage at the Canley site, Coventry; presumably for publicity purposes.[20] It is claimed that these press garage cars were stripped and re-trimmed, and possibly also re-sprayed.[3] Another car of this group was registered in Coventry as ARW 181S. According to a letter from the then archivist, reporting the research of the BMIHT records, "This car was originally intended for display at the 1977 [ Daily Express ] Motorfair in Earls Court, London. We can not verify whether it was in fact displayed here."[21]

The addition of two leading zeros to this second group of chassis numbers to make them five digits,[note 4] the same length as production TR7's chassis numbers, may indicate these were pre-production cars, not prototypes. However, the differences in where and by which division of BL they were registered (from their (V55) registration documents), indicates that they may still not have been manufactured as a single batch. Hence, it is possible that the press garage cars were the "batch of thirty TR7 Sprints" built at "the changeover in July 1977", and the cars in the first group, and possibly some of the second, may have been those built as 8-valve and converted to 16-valve at Canley.

Cancelation

The usual reason given for the cancelation of the TR7 Sprint is the 17 week long strike at the BL Speke plant in 1977-8, where the TR7 and the few TR7 Sprints were manufactured. This resulted in the closure of the plant in May 1978, the move of production to Canley, Coventry, and led to the cancelation of the TR7 Sprint.[1][3] However, this is itself blamed, ultimately, on the "replacement of the aristocratic Lord Stokes with South African businessman Michael Edwardes" as managing director in 1977.[5] Another reason given is that the BL marketing department caused the cancellation, because the 0–60 time and top speed was not sufficiently different from the TR7's.[3]

However, it is also the case that, unlike the TR7 and TR8, the Sprint's 16 valve engine was not suitable for the emissions control equipment needed for the US market, which was the main target market for the TR7 and 8. Development of the 16 valve version of the slant four engine that would have addressed this emission control issue had been underway for the Triumph SD2 - BL Specialist Division’s project, after the Rover SD1 -, which was, apparently, intended to replace the dolomite range.[3] However, the SD2 had been cancelled in 1975, and the Dolomite was replaced in 1981 by the Triumph Acclaim, based on the Honda Ballade and with a Honda designed engine.

When the TR7 Sprint programme was cancelled, and the cars became redundant, "most were sold off to private buyers"[1] and some went into BL's management car plan and were leased to BL employees.[3]

Publications

The BL TR7 Repair Operations Manual, AKM3079A, covers both the 4 and 2 valve (per cylinder) engines; however, an erratum stuck to the title page states "At the time of going to press the 4 valve engine referred to in this manual has not been fitted to the Triumph TR7".[22]

An owner's handbook, AKM 3967, was also produced for TR7 Sprint in 1977, but is apparently for the 1977 year model: it shows the interior light in the headlining not the doors. It also lists only the 5 speed (LT77) gearbox, unlike the similar handbook for the TR7, RTC 9210, which lists the 4 speed and the 5 speed as an option. However, some of the information contained in this TR7 Sprint handbook is incorrect for the TR7 Sprint, i.e. pictures show the 8 valve engine and the TR7's AC Delco distributor.[13]

Use in competition


The TR7s used by BL in rallying, from their advent in the Welsh rally of 1976, until the coming of the Rover V8 3.5 litre TR7V8 rally cars in 1979 used tuned 16 valve 2 litre Sprint engines and were, in effect, TR7 Sprints. These rally cars proved competitive on asphalt, winning a number of events including the Belgian Boucles de Spa rally in 1977.[7]

It is unclear exactly how the TR7 was homologated (for group 4) with the 16 valve engine, close ratio sprint gearbox and overdrive, and heavy duty rear axle before any TR7 Sprints were produced.[23] Rally journalist and historian Graham Robson does refer to the "famous 'inventive homologation' skills" of Bill Price, then BL Competitoins Dept. Manager, and to him "perhaps, taking lessons from Ralph Broad, who was an old hand at the black art of 'reading the rules'", and states that "Bill [Price] managed to gain approval for a TR7 which was only loosely related to the production car." Robson also quotes BL Motorsport director John Davenport remembering "that the '100-off' rule applied to alternative engines at the time (which explains why Ford was able to race 24-valve four-cam Capris in 1974), but this waiver never applied to transmissions."[7] Bill Price himself wrote on this issue "Careful consideration was given to the existing specification with the result that we decided to list the 16-valve Sprint cylinder head to enable us to virtually transplant the Sprint rally engine into the car. The Sprint gearbox was homologated as the 77mm five-speed [LT77] gearbox was not yet available and it would take time to produce close ratio gears for it. The heavy duty axle which would be standard with the five-speed gearbox was also listed as an option".[23]

Four of the later BL works rally cars bear the registrations of cars from the press garage, SJW 533S, SJW 540S, SJW 546S, and SJW 548S. SJW 533S was initially campaigned as a 4 cylinder 16 valve car, and later as a V8 3.5 Litre TR7V8 specification. The other three were only ever campaigned as TR7V8s.[citation needed] However, it is not clear whether or not the four rally cars bearing these registrations actually were, in any real sense, the TR7 Sprints from the press garage, or whether only the registrations were used. There is a story at one TR7 related website (), and already current in the 1980s, that John Davenport, "needed white cars without sunrooves [sic] and these were the nearest four." However, according to the press garage data (Figure 8), SJW 533S was russet, SJW 540S was java green, SJW 546S was brooklands green, and SJW 548S was carmine; though none had sun-roofs. While there are suggestions that the cars sent to the press garage were re-trimmed and even possibly re-sprayed,[3] there are no suggestions that their paint colours were changed, and the competitions department could, presumably, have managed that themselves, were it significant. Equally anecdotally, a more complete reproduction of the 1991 owner written article from the TR Driver's Club magazine states "Although the SJW TR7V8 rally cars began life as TR7 Sprints, the rally cars were scratch built using bodies taken off the line and prepared by Safety Devices. So only the registration numbers from the sprints were used."()

See also

Notes

  1. ↑ The 16 valve engine was commonly referred to by BL as the "4 valve" or "4V" engine, for the number of valves per cylinder - with the 8 valve engine commonly being referred to as the "2 valve" or "2V" engine.
  2. ↑ 2.0 2.1 The power and torque figures given are for the 16 valve, 2 litre, slant four engine in a Dolomite Sprint. The TR7 Sprint had a different exhaust manifold - as the Dolomite one interfered with the bulkhead -, which may have been less restrictive and given more power/torque.
  3. ↑
  4. ↑ 4.0 4.1

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 Piggott B., Clay S., Collector's Originality Guide Triumph TR2 TR3 TR4 TR5 TR6 TR7 TR8, page 312-5, 2009, MotorBooks International Company, ISBN 9780760335765.
  2. ↑ 2.0 2.1 2.2 British Motor Industries Heritage Trust Archives, Heritage Motor Centre, Gaydon, Warwickshire, England: accessed June 2013.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 Knowles D., Triumph TR7 The Untold Story, 2007, pages 110–5, Crowood Press, ISBN 978-1-86126-891-4.
  4. ↑ Classic Motor Monthly Archives, The Triumph Dolomite Sprint, Retrieved 2009-04-13.
  5. ↑ 5.0 5.1 Marren, Brian (2009). Closure of the Triumph TR7 Factory in Speke, Merseyside, 1978: ‘The Shape of Things to Come’?. Retrieved 16 July 2010. 
  6. ↑ 6.0 6.1 Robson G., Langworth R., Triumph Cars : The Complete Story, 2005, Motor Racing Publications, Limited, ISBN 9781899870721.
  7. ↑ 7.0 7.1 7.2 Robson G., The Works Triumphs: 50 Years in Motorsport, 1993, J H Haynes & Co Ltd, ISBN 978-0854299263.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Retrocaricons, Triumph TR7 Sprint Retrieved 03-Jan-2013
  9. ↑ Classic and Performance Car, , Retrieved 13-Sept-2013
  10. ↑ Department of Transport Type Approval No. 377
  11. ↑ 11.0 11.1 Williams R., How to Improve Triumph TR7, TR7-V8, TR8; 2007, Veloce, ISBN 9781845840457
  12. ↑ Moss Europe LTD, MOSS Performance Manual, MGL 9800, no date given
  13. ↑ 13.0 13.1 Leyland Cars, Triumph TR7 Sprint Handbook, Leyland International, Publication Part No AKM 3967.
  14. ↑ British Leyland UK Ltd., Triumph TR7 Handbook, Publication Part No RTC 9210.
  15. ↑ 15.0 15.1 BMIHT Picture ref. T-105516
  16. ↑ 16.0 16.1 BMIHT Picture ref. T-105514
  17. ↑ Moss Europe LTD, MOSS Parts Catalogue, MGL 6900, September 1993
  18. ↑ Hardcastle D., The Rover V8 Engine, J H Haynes & Co Ltd; 2nd Revised edition (15 May 1995), ISBN 978-0854299614.
  19. ↑ Knowles D., Triumph TR7 The Untold Story, 2007, page 51, Crowood Press, ISBN 978-1-86126-891-4.
  20. ↑ Thoroughbred & Classic Cars, January 1979 edition
  21. ↑ Clausager, A. D. (BMIHT Archivist), untitled letter detailing BMIHT records research on ARW 181S, ref "PRI Triumph", dated 24th February 1989.
  22. ↑ British Leyland, Triumph TR7 Repair Operation Manual, 1978, Leyland Cars, Publication Part No AKM 3079A.
  23. ↑ 23.0 23.1 Bill Price, B.M.C./B.L. Competitions Department: 25 Years in Motorsport - The Cars, the People, the Events, 1989, J H Haynes & Co Ltd, ISBN 978-1859604397.
  24. ↑ The significant differences between 1977 and 1978 year model cars are in the sizes of the filler cap, the 1977 year model having a very large one and the 1978 model having a smaller one; and in the positioning of the interior lights, the 1977 having a light in the headlining and a map light behind and between the seats, and the 1978 having rocking-switch lights in both doors. These modifications were necessary for the TR7 convertible, which was also in design/prototype/pre-production in 1977-8.
  25. ↑ This chassis number format is taken from BMIHT Production Record Trace Certificate Number 90/5959 for VVC 697S, dated 25th April 1990, which indicates it as being "RHD, Home Market" Specification. The leading zeros are also visible on the chassis plate shown in Figure 5 and on one shown at '5'.

External links

  1. TriumphTR7.co TR7 Sprint Conversion Page
  2. Mike Jeffreys' TR7 Sprint Conversion Page
  3. Copy of owner written TR Drivers Club article TR7 Sprint Conversion from 1991 issue 2
  4. Club Triumph TR7-8 Forum thread covering TR7 Sprint Alt. Water Transfer Plate
  5. Yorkshire TR Drivers page on specific TR7 Sprint parts
  6. TR Drivers Club List of known TR7 Sprints
  7. Copy of owner written TR Drivers Club article TR7 16 Valve Sprint from 1991 issue 2
  8. TR7 & TR7 V8 Rally cars
  9. More complete reproduction of owner written TR Drivers Club article TR7 16 Valve Sprint from 1991 issue 2
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