gingerfold:
Again with hindsight what money was available in the truck division of BL probably went into other areas rather than vehicle R&D. For example, was a new engine building plant necessary at that time? When TL12 engine production was transferred from Southall to the new engine plant at Leyland was the end product any better than those built at Southall on machinery over 20 years old? I have never heard of, or seen anything in writing to suggest that it was. When DAF snapped up Leyland Truck and Bus the main attraction for them were modern assembly and production facilities.
Firstly going by the video posted previously Southall seems to had some quite reasonable up to date machinery shown there.
As discussed previously the TL12’s limitations were more about its design than how or where it was made.In that it would have taken something very special to have made it worth Leyland carrying on with its in house engine manufacturing operations at least at that level and a less than 6 inch stroke,let alone one of less than the 680,just wasn’t going to cut it by the standards of the rate of 1970’s truck development,as opposed to Rolls and ■■■■■■■■
IE the choice of Rolls/■■■■■■■ v TL12 was by then a no brainer with the only surprise being how long that Leyland tried to keep production of it going.Just like all the cash wasted on the Marathon and T45 cab development and production instead of just going to MP and saying we need something just like the SA 400 and then just put the usual ■■■■■■■ and Rolls options under it.
Southall had its last major engine plant machinery investment in 1959 when the AV590 / AV690 and its variants were introduced, so 15 years or so later for the TL12 introduction and the machinery was still viable. Unlike, for instance, Gardner who was still using machinery in the 1970s that dated back to WW1 and the 1920s.
I know that in the past CF you’ve slated the TL12 for its lack of future development potential, but again, hindsight and speculation are wonderful tools. In 1973, TL12 sign-off for production date, no one could foresee what the future power requirements would be. Realistically the TL12 had the potential for probably 340 to 350 bhp at 38 tonnes gvw. It gave 320 bhp in T45 Roadtrains. 340 bhp was competitive for later in the 1980s and was deemed adequate by most operators and major fleets, so around 9 bhp / tonne (at 38 tonnes). What is the default bhp / tonne for the vast majority of large fleets in the UK at 44 tonnes gvw? Well the answer is 10.45 bhp / tonne (460 bhp). Oh, I nearly forgot to mention, the TL12 bhp rating is in the old imperial BS AU 141a : 1971 criteria, so to convert to modern day equivalent rating increase my quoted figures above by 9%. Taking the TL12’s known output of 320 bhp and add 9% = 348 bhp, making it more than competitive for the 1980s.
gingerfold:
I know that in the past CF you’ve slated the TL12 for its lack of future development potential, but again, hindsight and speculation are wonderful tools. In 1973, TL12 sign-off for production date, no one could foresee what the future power requirements would be. Realistically the TL12 had the potential for probably 340 to 350 bhp at 38 tonnes gvw. It gave 320 bhp in T45 Roadtrains. 340 bhp was competitive for later in the 1980s and was deemed adequate by most operators and major fleets, so around 9 bhp / tonne (at 38 tonnes). What is the default bhp / tonne for the vast majority of large fleets in the UK at 44 tonnes gvw? Well the answer is 10.45 bhp / tonne (460 bhp). Oh, I nearly forgot to mention, the TL12 bhp rating is in the old imperial BS AU 141a : 1971 criteria, so to convert to modern day equivalent rating increase my quoted figures above by 9%. Taking the TL12’s known output of 320 bhp and add 9% = 348 bhp, making it more than competitive for the 1980s.
If it was all about only the peak power to weight figure we could just put a Cosworth F1 engine it it.
Realistically it’s the torque figure that matters and it’s obvious that the TL12’s short stroke was always going to be at a disadvantage v ■■■■■■■ and Rolls in that regard.I’d agree that the TL12 was probably ok by the standards of 1973 but not in the case of the Marathon 2 nor its existing Ergo cab development.In which case both the Marathon 2 and arguably even the T45,were a case of unnecessary design and production expenditure when the right engines and possibly cab were already available better and cheaper from outside.In this case the ■■■■■■■ E 290 and DAF 2800 and SA 400 type cab design seeming to be the relevant benchmarks that Leyland ( should have been ) going for by the late 1970’s.
railstaff:
I think the lack of charge cooling played a major problem,a cab not really designed to facilate an air to air cooler.In all fairness the TL12 wasnt a bad lump,a ■■■■ sight better than the TL11 which in my opinion took a backward progression when it mophed from 680 to TL11.
Firstly we know that DAF made the basic architecture of the 680 work.Which just leaves the fact that there’s no substitute for leverage at the crank as opposed to trying to compensate for lack of it by putting more shove onto the piston and thereby overloading the piston/conrod to crankshaft assembly chain.Which is ultimately why the Rolls and ■■■■■■■ won out in terms of stress v output arguably also against even against the best case DAF 680 development let alone the TL12.We’ve had the similar discussion before elsewhere in which the conclusion was that the AEC engine design architecture wouldn’t allow for any further development for a longer stroke measurement.
At which point the writing was already on the wall for the AV 760/TL12 the only surprise being why did Leyland waste so much of its limited resources in continuing to flog a dead horse in that regard.
Thats correct Daf did make it work but with a 680 block not the latter TL11 block.Dont get your logic on over square/under square.The TL,855 and eagle were all under square,the stroke was bigger than the bore.Dont forget how advanced the TL was,Bosch fuel pump,end to end cooling,piston cooling,treated crankshaft.I doubt weather a longer stroke would have been needed.
I take CF’s point about torque being an important force that partly determines the performance of an engine, but manufacturers don’t put a badge on the side of the cab stating the engine’s torque rating, but they do state the engine’s bhp. I would wager that of those operators that run trucks with 600 bhp plus engines then 9 out of 10 of them won’t have a clue what the torque rating is.
In all honesty though it wasnt exactly short on torque,nearly 800 lbs ft,scanias DS 14 only had 880 lbs ft and that was at 350hp.Much of Rolls success came from the use of very small diameter exhaust manifolds,exactly the same as the high hp 855 with small exhaust port heads.I also doubt that at 280hp its work load was that high.
Carryfast:
At which point the writing was already on the wall for the AV 760/TL12 the only surprise being why did Leyland waste so much of its limited resources in continuing to flog a dead horse in that regard.
Thats correct Daf did make it work but with a 680 block not the latter TL11 block.Dont get your logic on over square/under square.The TL,855 and eagle were all under square,the stroke was bigger than the bore.Dont forget how advanced the TL was,Bosch fuel pump,end to end cooling,piston cooling,treated crankshaft.I doubt weather a longer stroke would have been needed.
The difference was that both the Eagle and ■■■■■■■ had a 6 inch stroke measurement v 5.5 for the TL 12.With the 680 also having a bit more than the TL12. The shorter stroke motor was then always going to be at a disadvantage in terms of stress levels,to compensate for the smaller leverage available at the crank,to provide the equivalent amount of torque.The problem being that the basic architecture of the AEC block only allowed for an increase in bore size relative to the AV 691 at which point the DAF development of the 680 and the Eagle,let alone 14 litre ■■■■■■■■■■■■ always going to be ahead and win that race.
gingerfold:
I take CF’s point about torque being an important force that partly determines the performance of an engine, but manufacturers don’t put a badge on the side of the cab stating the engine’s torque rating, but they do state the engine’s bhp. I would wager that of those operators that run trucks with 600 bhp plus engines then 9 out of 10 of them won’t have a clue what the torque rating is.
In the case of a truck engine and even car engines for those of us who don’t like high revving screamers it’s the torque figure that matters most.With engine speed then being a given ( in this case as low as possible ) torque is then the only figure that determines the power output.While the more leverage that can be created by the crank throw in that regard the less force needs to be applied to the con rod to get the equivalent output.Which is why those 600 + engines like the FH16 are now using a 6.5 inch stroke measurement to create the torque,that creates the power,at the required ( given ) engine speed and without breaking the engine to do it.
gingerfold:
I take CF’s point about torque being an important force that partly determines the performance of an engine, but manufacturers don’t put a badge on the side of the cab stating the engine’s torque rating, but they do state the engine’s bhp. I would wager that of those operators that run trucks with 600 bhp plus engines then 9 out of 10 of them won’t have a clue what the torque rating is.
At the end of the day it`s how they perform and reading ex Marathon drivers comments the majority seem to say the same thing , they were fast pulled well were good on fuel and reliable ,what more do you need. Obviously someone will disagree
I understand that the Fuller gearbox installation was good in the Marathon - and so it should have been with that gearstick pushing directly up through the floor to meet the driver’s hand (just right!). The model names bandied about in the last dozen or so posts have utilized the excellent Road-Ranger constant-mesh 'box. However, the installation differed enormously from one make to another. It was poor in the SA 400 and in the DAF 2800, so much so that it was almost as if the 'box were made by someone else. The installation was excellent in the ERFs and even better in the MANs of the period (I believe the Iveco was good too). Fodens were weird because of the cable change but drivers soon got used to those. With a constant-mesh 'box, good installation is everything, if only because missed gears cost diesel, time and driver’s patience. Truck mag’s 1975 Euro Test showed an ERF with a superbly-installed Fuller take nearly all the prizes, while a DAF 2800 with a poorly-installed Fuller staggered back over the mountains of the Ardenne 45 minutes behind the ERF. Even allowing for a bit of massaging, that tells a story worth attending to. So if, indeed, the Fuller in the Marathon was up to scratch, it is beginning to look to me as if it has ‘enjoyed’ a pretty shoddy press since the demise of BL - especially the Marathon 2. Robert
ERF-NGC-European:
I understand that the Fuller gearbox installation was good in the Marathon - and so it should have been with that gearstick pushing directly up through the floor to meet the driver’s hand (just right!). The model names bandied about in the last dozen or so posts have utilized the excellent Road-Ranger constant-mesh 'box. However, the installation differed enormously from one make to another. It was poor in the SA 400 and in the DAF 2800, so much so that it was almost as if the 'box were made by someone else. The installation was excellent in the ERFs and even better in the MANs of the period (I believe the Iveco was good too). Fodens were weird because of the cable change but drivers soon got used to those. With a constant-mesh 'box, good installation is everything, if only because missed gears cost diesel, time and driver’s patience. Truck mag’s 1975 Euro Test showed an ERF with a superbly-installed Fuller take nearly all the prizes, while a DAF 2800 with a poorly-installed Fuller staggered back over the mountains of the Ardenne 45 minutes behind the ERF. Even allowing for a bit of massaging, that tells a story worth attending to. So if, indeed, the Fuller in the Marathon was up to scratch, it is beginning to look to me as if it has ‘enjoyed’ a pretty shoddy press since the demise of BL - especially the Marathon 2. Robert
Interesting comments Robert , I drove a few Ivecos 300s 360s 480 all with the 13 speed Fuller all easy to use , I had a Foden with a 9 speed Fuller that was equally as good ,I drove a Daf 2800 with a 9 speed Fuller for a short while and cant remember having a problem with it , I think the SA 400 installation is a well known one , but the 16 speed ZF in our MANs is totally different to the same box in our Dafs someone told me MAN use a hydraulic■■?■■?? system for the linkage , whatever they use it isnt a patch on the Dafs installation
The late Pat Kennett thought highly of the TL12 Marathon, but he was an ex-Leyland Motors service engineer, so he could have shown a bit of bias. In the main he was objective in his road tests so his comments do carry some weight.
ramone:
Interesting comments Robert , I drove a few Ivecos 300s 360s 480 all with the 13 speed Fuller all easy to use , I had a Foden with a 9 speed Fuller that was equally as good ,I drove a Daf 2800 with a 9 speed Fuller for a short while and cant remember having a problem with it , I think the SA 400 installation is a well known one , but the 16 speed ZF in our MANs is totally different to the same box in our Dafs someone told me MAN use a hydraulic■■?■■?? system for the linkage , whatever they use it isnt a patch on the Dafs installation
The 13-speed Fuller installation in MAN 280s and 281s was superb and very much better than the synchro-ZFs they also used at the time . Robert
ramone:
Interesting comments Robert , I drove a few Ivecos 300s 360s 480 all with the 13 speed Fuller all easy to use , I had a Foden with a 9 speed Fuller that was equally as good ,I drove a Daf 2800 with a 9 speed Fuller for a short while and cant remember having a problem with it , I think the SA 400 installation is a well known one , but the 16 speed ZF in our MANs is totally different to the same box in our Dafs someone told me MAN use a hydraulic■■?■■?? system for the linkage , whatever they use it isnt a patch on the Dafs installation
The 13-speed Fuller installation in MAN 280s and 281s was superb and very much better than the synchro-ZFs they also used at the time . Robert[/quote
Fuller in Octopus, Marathon n ERF slick as you like, Defender, Borderer stirring mud.
gingerfold:
The late Pat Kennett thought highly of the TL12 Marathon, but he was an ex-Leyland Motors service engineer, so he could have shown a bit of bias. In the main he was objective in his road tests so his comments do carry some weight.
It’s obvious that the last thing that Leyland needed was one of its own condemning it’s only credible heavy truck product which could have possibly finished the whole truck side of the Group.
However realistically at this point in terms of engine design at least it’s all about the ■■■■■■■ E290 + v TL12 and to an extent Rolls Eagle.In which the ■■■■■■■ at least could only have been the more powerful and lower stressed,not to mention more fuel efficient,option.Which leaves the cab issue in which the goal should have been let’s do a Leyland version of SA 400/DAF 2800 also in the realisation that whatever its merits,like the Ergo cab development,unfortunately like the TL12,just wasn’t going to cut it.Who knows that might have been just what Pat said behind closed doors.
Hence the T45 with Rolls and ■■■■■■■ by the early 1980’s.On that note saying that outsourcing was cheaper was probably better than the bad publicity of saying that neither the TL12 or Ergo development Marathon cab were up to the job.In which case the Marathon 2 could only have been a mistaken Heath Robinson stop gap which actually damaged potential customer interest in the T45.Bearing in mind that all the ingredients,to make an even better T45,were actually there at the time.
Foden used the Fuller box well before the cable change system came out though and it was a nice box to use, the Sed Ak installation I had no problems with either as long as the bush wasn’t worn or missing on the gear lever socket, though this affected the 200’s more and then they were a nightmare!
gingerfold:
The late Pat Kennett thought highly of the TL12 Marathon, but he was an ex-Leyland Motors service engineer, so he could have shown a bit of bias. In the main he was objective in his road tests so his comments do carry some weight.
It’s obvious that the last thing that Leyland needed was one of its own condemning it’s only credible heavy truck product which could have possibly finished the whole truck side of the Group.
However realistically at this point in terms of engine design at least it’s all about the ■■■■■■■ E290 + v TL12 and to an extent Rolls Eagle.In which the ■■■■■■■ at least could only have been the more powerful and lower stressed,not to mention more fuel efficient,option.Which leaves the cab issue in which the goal should have been let’s do a Leyland version of SA 400/DAF 2800 also in the realisation that whatever its merits,like the Ergo cab development,unfortunately like the TL12,just wasn’t going to cut it.Who knows that might have been just what Pat said behind closed doors.
Hence the T45 with Rolls and ■■■■■■■ by the early 1980’s.On that note saying that outsourcing was cheaper was probably better than the bad publicity of saying that neither the TL12 or Ergo development Marathon cab were up to the job.In which case the Marathon 2 could only have been a mistaken Heath Robinson stop gap which actually damaged potential customer interest in the T45.Bearing in mind that all the ingredients,to make an even better T45,were actually there at the time.
There is no disputing the 855 was in a league of its own,but when relating to work rate stress,neither were stressed lets remember none of the small cams had piston coolers and only the big cams over 250 hp had piston coolers,the BMEP work rate shows this with only a difference of 150 BMEPS in favour of course the 855.Also after reading road tests it would appear the TL12 beat it on fuel economy too.The average 14 litre returning 6.97 v 7.63 of the Tl12 and with pumping equipment.(source CM)Although 855,s were bomb proof at under 300 hp they were volumetrically inefficient,they seemed to brake even at 500hp.
gingerfold:
The late Pat Kennett thought highly of the TL12 Marathon, but he was an ex-Leyland Motors service engineer, so he could have shown a bit of bias. In the main he was objective in his road tests so his comments do carry some weight.
It’s obvious that the last thing that Leyland needed was one of its own condemning it’s only credible heavy truck product which could have possibly finished the whole truck side of the Group.
However realistically at this point in terms of engine design at least it’s all about the ■■■■■■■ E290 + v TL12 and to an extent Rolls Eagle.In which the ■■■■■■■ at least could only have been the more powerful and lower stressed,not to mention more fuel efficient,option.Which leaves the cab issue in which the goal should have been let’s do a Leyland version of SA 400/DAF 2800 also in the realisation that whatever its merits,like the Ergo cab development,unfortunately like the TL12,just wasn’t going to cut it.Who knows that might have been just what Pat said behind closed doors.
Hence the T45 with Rolls and ■■■■■■■ by the early 1980’s.On that note saying that outsourcing was cheaper was probably better than the bad publicity of saying that neither the TL12 or Ergo development Marathon cab were up to the job.In which case the Marathon 2 could only have been a mistaken Heath Robinson stop gap which actually damaged potential customer interest in the T45.Bearing in mind that all the ingredients,to make an even better T45,were actually there at the time.
The Marathon wasnt available with the E290 until very near the end of production, so it couldnt have been TL12 v E290 , but if you bothered to read the road test of the Marathon E290 the testers from CM repeatedly said that to get the best out of it you need great discipline with your right foot , they also mentioned it wasnt as flexible as the TL12 , so in basic terms you needed a feather foot to get the best out of a E290 ,now explain how you get every driver to drive with great discipline .... it wouldnt happen . The Marathon 2 was a test bed for the T45 ,the TL12 was a very good engine in its day just read the road tests and for a change listen to the drivers that had them long term .
I had E290’s and 14 litre E320’s in Seddon Atki chassis, hardly light footed on bulk but still attained respectable fuel figures all the same.
However they benefitted from Rockwell axles so high final drives, in the case of the E320 a 70mph cruise was @ 1100 rpm, though the engine would pull cleanly and seemingly on almost full torque from around 700rpm.
I wonder if the Marathon had been fitted with similar final drive gearing whether the E290 test results would have been better.
I recall the T45 we had, again with an E290 was similarly too low geared to take advantage of the ■■■■■■■■ effortless 1000rpm cruising ability where it gave it best fuel.
Juddian:
I had E290’s and 14 litre E320’s in Seddon Atki chassis, hardly light footed on bulk but still attained respectable fuel figures all the same.
However they benefitted from Rockwell axles so high final drives, in the case of the E320 a 70mph cruise was @ 1100 rpm, though the engine would pull cleanly and seemingly on almost full torque from around 700rpm.
I wonder if the Marathon had been fitted with similar final drive gearing whether the E290 test results would have been better.
I recall the T45 we had, again with an E290 was similarly too low geared to take advantage of the ■■■■■■■■ effortless 1000rpm cruising ability where it gave it best fuel.
I thought the weak link of the Marathon was the Leyland axle which they did eventually replace with the T45 but not at launch. The testers gave Leyland great credit for the gearing on the test vehicle but kept repeating that you had to hold on to gears before down changes (let `em lug) otherwise the fuel consumption went up . They said it was a different style of driving which took some getting used to but once you did you would get good mpg figures … or words to that effect
ramone:
The Marathon wasnt available with the E290 until very near the end of production, so it couldnt have been TL12 v E290 , but if you bothered to read the road test of the Marathon E290 the testers from CM repeatedly said that to get the best out of it you need great discipline with your right foot , they also mentioned it wasnt as flexible as the TL12 , so in basic terms you needed a feather foot to get the best out of a E290 ,now explain how you get every driver to drive with great discipline .... it wouldnt happen . The Marathon 2 was a test bed for the T45 ,the TL12 was a very good engine in its day just read the road tests and for a change listen to the drivers that had them long term .
Let’s get this right I’m referring to the critical time between 1978-80 in the lead up to the introduction of the T45.The E 290 was available to use during that time.Instead of which Leyland not only lumbered the Marathon with the TL 12 it also did the same thing during the critical customer acceptance period of the T45.As for using the excuse that drivers couldn’t drive the ■■■■■■■ properly,as Juddian pointed out,that’s bollox too.Which leaves the question where was gingerfold’s mythical 300 hp +,or for that matter more importantly the ■■■■■■■ 930 lb/ft torque output,ever seen from a TL12 in production form.As opposed to possibly temporarily on a dyno with silly unsustainable boost levels at which point,all too predictably,there was no way that it could maintain the type of torque output required,to compete with the ■■■■■■■■■■■■■■■ breaking.
On that note the comments here regarding the T45 and the TL12 are just as valid as things stood in 1978.While also confirming that Leyland needed the T45 with big cam ■■■■■■■ power from that point.Not the Heath Robinson effort of the Marathon let alone that being lumbered with the wrong obsolete engine in the form of the TL12.Arguably even the T45 also following the wrong Ergo developed Marathon cab with the less wrong T45 one.IE history suggests that the retrograde Marathon 2 and the TL12 motor played a large part in the downfall of the Leyland truck group.With the fiasco of the T45 being lumbered with the same motor and weird bulbous cab ,when it needed an SA 400 type cab with big cam ■■■■■■■ under it,finishing the job.
. Robert