Modern Jaguar build quality issues?
Discussion
RoverP6B said:
A V8 in itself is a bit of a compromise, it's not an inherently balanced layout, the only way of making it at all balanced is to fit a massively counter-weighted 90-degree crank. A V6 can only be balanced, I understand, with a 120-degree bank angle - but if you've got room for that, you may as well go for a flat six. The solution, therefore, is to halve the bank angle to 60 degrees and either put up with the vibration or add balancer shafts to damp them out. A 90-degree V6 that is just a V8 block with the two rearmost cylinders blanked off is not in any way ideal. The only reason Jaguar went down that route is because the supply of Duratecs from Bridgend was ending and they needed something to fill the gap while they developed the Ingenium straight six.
Packaging a straight six need not be a problem. The advantages of the layout are such that it's worth making space for it.
As a degree educated Mech Eng who actually understands this issue of 2nd order balance, you are grossly overstating the problem. There are so many far more important aspects to engine design than achieving natural 2nd order mechanical balance. The problems associated with torque transmission down long crankshafts are far worse with a crankshaft 6 throws long than one 3 throws long and you solve that problem with extra metal which could just as easily be used in a balancer shaft if needed at all, all of which in a physically compact engine which fits between the cabin and the axle giving nice small 2nd moments of inertia, maintainability and a layout which is crash worthy.Packaging a straight six need not be a problem. The advantages of the layout are such that it's worth making space for it.
The 90 deg V6 was used by Rover and their KV6 and that was not a bobbed V8. Height of an overall engine is very important too. Lower crank to head height buys more room for efficient inlet manifolding, or space between the banks for a supercharger.
Seriously, you should just let this 2nd order balance thing go. It's really not a hard issue to engineer around and it can buy many more useful attributes in the both power delivery and making a good car out of it all.
A big quad cam 60deg V12 with ITBs and equal length primary exhaust headers would be great, but you'll struggle to find a sports car you could actually fit it in that doesn't end up with the track and wheelbase of a Transit van.
esso said:
How does a 75 degree V8 with a flat-plane crank work?
Short answer: it doesn't. The vibration you get from a narrow-angle V8 (especially with a flat plane crank) is significant. Quite how Yamaha sorted out their 60-degree V8 for Volvo I really don't know. Jaguar tried a 60-degree V8 (based on the V12) for the original F-type project back in the late 60s but they couldn't get the vibration down to acceptable levels.jamieduff1981 said:
On the subject of the 1990s era S-Type, mine has been solid. Both perceived and mechanical quality exceed BMW and Audi observations. It's 10 years old this year.
You clearly don't have to work on older cars for a living: if you did you would have an entirely different perspective on this.The S type was a seriously flawed car in terms of reliability and cost of repair. The other fly in the ointment with all Jaguars of this era is rust; tons of it and a great deal of it hidden.
Fixings that are of cheap quality and not plated inserted into alloy housings with no protection whatever, not even a lick of grease. It makes you wonder if Jaguar have ever heard of electrolysis, but it would appear not. E bay is full of 90s Jaguars selling for washers due to serious corrosion. Components that are virtually impossible to access without massive amounts of labour time. Try changing a turbo on a 2.7 diesel S Type and you will know exactly what I mean.
My Audi A6 is utterly rust free, has done 146K and the engine is virtually silent. By the way it is 16 years old. Audi solved any balance or vibration issues on the V6 by developing a split crank. This was the way to solve vibration caused by the fact that opposing pistons were using a common crank journal resulting in unsuitable valve and ignition timing.
The Audi V6 in normally aspirated form of this era is one of the finest engines ever made and was streets ahead of the Jaguar unit in every respect.
By the way, it's not my engineering degree that tells me that; it's over forty years of hard bitten experience in the field.
J
jith said:
jamieduff1981 said:
On the subject of the 1990s era S-Type, mine has been solid. Both perceived and mechanical quality exceed BMW and Audi observations. It's 10 years old this year.
You clearly don't have to work on older cars for a living: if you did you would have an entirely different perspective on this.The S type was a seriously flawed car in terms of reliability and cost of repair. The other fly in the ointment with all Jaguars of this era is rust; tons of it and a great deal of it hidden.
Fixings that are of cheap quality and not plated inserted into alloy housings with no protection whatever, not even a lick of grease. It makes you wonder if Jaguar have ever heard of electrolysis, but it would appear not. E bay is full of 90s Jaguars selling for washers due to serious corrosion. Components that are virtually impossible to access without massive amounts of labour time. Try changing a turbo on a 2.7 diesel S Type and you will know exactly what I mean.
My Audi A6 is utterly rust free, has done 146K and the engine is virtually silent. By the way it is 16 years old. Audi solved any balance or vibration issues on the V6 by developing a split crank. This was the way to solve vibration caused by the fact that opposing pistons were using a common crank journal resulting in unsuitable valve and ignition timing.
The Audi V6 in normally aspirated form of this era is one of the finest engines ever made and was streets ahead of the Jaguar unit in every respect.
By the way, it's not my engineering degree that tells me that; it's over forty years of hard bitten experience in the field.
J
My sills are solid. I can't say the same about 10 year old Audis though with crumbling wheel arches and paint that scrapes off front wings with a finger nail.
Steel bolts have never been an issue in alloy threads on my Jags. I've no idea where you're seeing all these problems.
Maybe I've been exceptionally lucky with my Jags and you've been exceptionally lucky with your A6 - but our observations definately do not align. I wouldn't own an Audi if I was given it for free.
Edited by jamieduff1981 on Tuesday 20th October 10:33
jith said:
The other fly in the ointment with all Jaguars of this era is rust; tons of it and a great deal of it hidden.
Surely they can't rust faster than a noughties Mercedes, they'd make Fiat blush :-)At least MB used to offer a 30 year body work warrantee (as long as it was main dealer serviced) and seemed to be quite happy to swap panels, door, tailgates etc... of a frequent basis. But that might explain why they dropped the 30 year warrantee.
OK, so my X300 is pre S Type, but rust hasn't been a problem (OK a few stone chips behind the wheel arches after 18years).
RoverP6B said:
esso said:
How does a 75 degree V8 with a flat-plane crank work?
Short answer: it doesn't. The vibration you get from a narrow-angle V8 (especially with a flat plane crank) is significant. Quite how Yamaha sorted out their 60-degree V8 for Volvo I really don't know. Jaguar tried a 60-degree V8 (based on the V12) for the original F-type project back in the late 60s but they couldn't get the vibration down to acceptable levels.The AJP8 doesn't idle particularly smoothly, but the car hardly shakes itself to bits - nothing buzzes or rattles from vibration. Overall vibration levels at idle are still less than most 4-pot diesels at idle. What that configuration bought was a 4.2 or 4.5 litre engine which weighed 120kg fully dressed and was narrow enough to get good tubular exhaust headers for exhaust scavenging not available with cross-plane engines between the chassis rails of a sports car that was small enough to be agile on public roads. Combined with individual throttle bodies it gave the AJP8 one of the highest specific power outputs for a naturally aspirated engine ever seen in a car at that time. Devoid of unnecessary rotational mass and with light weight skirtless slipper pistons to minimise recipricating mass it's also exceptionally responsive and mixes strong torque with a willingness to rev.
Compare that to the contemporary Speed Six engine which at 3.6 or 4 litres weighed 200kg, wasn't really any narrower because it had to be slanted to contain its height and from a practical first hand experience viewpoint, doesn't make any material difference to the refinement of otherwise same car (but spark plug changes are awkward - they're already quite fiddly on cylinders 7 and 8 on the V8). The Speed Six is capable of slightly better specific power output, but only because it has a 4-valve per cylinder head design compared to the AJP8's 2 valve per cylinder design.
I am getting sick of saying this - but 2nd order balance is just not that important in the grand scheme of car design.
jith said:
You clearly don't have to work on older cars for a living: if you did you would have an entirely different perspective on this.
The S type was a seriously flawed car in terms of reliability and cost of repair. The other fly in the ointment with all Jaguars of this era is rust; tons of it and a great deal of it hidden.
Fixings that are of cheap quality and not plated inserted into alloy housings with no protection whatever, not even a lick of grease. It makes you wonder if Jaguar have ever heard of electrolysis, but it would appear not. E bay is full of 90s Jaguars selling for washers due to serious corrosion. Components that are virtually impossible to access without massive amounts of labour time. Try changing a turbo on a 2.7 diesel S Type and you will know exactly what I mean.
My Audi A6 is utterly rust free, has done 146K and the engine is virtually silent. By the way it is 16 years old. Audi solved any balance or vibration issues on the V6 by developing a split crank. This was the way to solve vibration caused by the fact that opposing pistons were using a common crank journal resulting in unsuitable valve and ignition timing.
The Audi V6 in normally aspirated form of this era is one of the finest engines ever made and was streets ahead of the Jaguar unit in every respect.
as one
By the way, it's not my engineering degree that tells me that; it's over forty years of hard bitten experience in the field.
J
I've never owned an old Audi myself but I am aware that their 90s cars were exceptionally well engineered and long lasting, with plenty of the original A6 models (based on the old 100) still trundling around happily. A colleague has a very slow 2.0 8V one with moon mileage on it that still looks new. The new ones appear to be marketing driven tat though.The S type was a seriously flawed car in terms of reliability and cost of repair. The other fly in the ointment with all Jaguars of this era is rust; tons of it and a great deal of it hidden.
Fixings that are of cheap quality and not plated inserted into alloy housings with no protection whatever, not even a lick of grease. It makes you wonder if Jaguar have ever heard of electrolysis, but it would appear not. E bay is full of 90s Jaguars selling for washers due to serious corrosion. Components that are virtually impossible to access without massive amounts of labour time. Try changing a turbo on a 2.7 diesel S Type and you will know exactly what I mean.
My Audi A6 is utterly rust free, has done 146K and the engine is virtually silent. By the way it is 16 years old. Audi solved any balance or vibration issues on the V6 by developing a split crank. This was the way to solve vibration caused by the fact that opposing pistons were using a common crank journal resulting in unsuitable valve and ignition timing.
The Audi V6 in normally aspirated form of this era is one of the finest engines ever made and was streets ahead of the Jaguar unit in every respect.
as one
By the way, it's not my engineering degree that tells me that; it's over forty years of hard bitten experience in the field.
J
Your experience of the S-type echos mine entirely. Every time I had to work on it becausead some s
tty component deep in the bowels of the thing had died I would end up drilling out corroded fasteners and having electrical connectors break to splinters. The car was 6 years old at the time. It needed both turbos done under warranty, the EGR system fouled up, the torque converter crumbled to pieces and destroyed the gearbox, washer pumps died repeatedly, the suspension was done in at 80K and needed near total replacement and there were a constant myriad of niggling failures.This was a 2004 car used almost entirely for motorway work. The crap design made every single job a huge ordeal, and there were plenty of jobs.
The corrosion he refers to is probably on the aluminium bodied X350 and he is quite right, it is as if nobody at Jaguar had ever heard of galvanic corrosion or (more likely) in fine British car building tradition they just didn't give a s
t. It is a crying shame because IMHO the S-Type was miles and miles ahead of the contemporary rivals to drive, with a stunning combination of ride and handling that nobody else seems to be able to master. I love the way they look, I love the interiors and I want to support British jobs but every time I go and look at them and have a good poke around I can see they are still half arsed in all the bits your average consumer never looks.
jamieduff1981 said:
Esso is a fellow Cerbera owner. We both have direct experience of a 75 degree V8 with flat plane crank.
The AJP8 doesn't idle particularly smoothly, but the car hardly shakes itself to bits - nothing buzzes or rattles from vibration. Overall vibration levels at idle are still less than most 4-pot diesels at idle. What that configuration bought was a 4.2 or 4.5 litre engine which weighed 120kg fully dressed and was narrow enough to get good tubular exhaust headers for exhaust scavenging not available with cross-plane engines between the chassis rails of a sports car that was small enough to be agile on public roads. Combined with individual throttle bodies it gave the AJP8 one of the highest specific power outputs for a naturally aspirated engine ever seen in a car at that time. Devoid of unnecessary rotational mass and with light weight skirtless slipper pistons to minimise recipricating mass it's also exceptionally responsive and mixes strong torque with a willingness to rev.
Compare that to the contemporary Speed Six engine which at 3.6 or 4 litres weighed 200kg, wasn't really any narrower because it had to be slanted to contain its height and from a practical first hand experience viewpoint, doesn't make any material difference to the refinement of otherwise same car (but spark plug changes are awkward - they're already quite fiddly on cylinders 7 and 8 on the V8). The Speed Six is capable of slightly better specific power output, but only because it has a 4-valve per cylinder head design compared to the AJP8's 2 valve per cylinder design.
I am getting sick of saying this - but 2nd order balance is just not that important in the grand scheme of car design.
Thank-you for your knowledgeable answer to this James....my reply is much simpler as I`m not a mechanical engineer......the 75 degree flat-plane crank V8 in my Cerbera performs very well !...cannot say that I have noticed any `vibration`!The AJP8 doesn't idle particularly smoothly, but the car hardly shakes itself to bits - nothing buzzes or rattles from vibration. Overall vibration levels at idle are still less than most 4-pot diesels at idle. What that configuration bought was a 4.2 or 4.5 litre engine which weighed 120kg fully dressed and was narrow enough to get good tubular exhaust headers for exhaust scavenging not available with cross-plane engines between the chassis rails of a sports car that was small enough to be agile on public roads. Combined with individual throttle bodies it gave the AJP8 one of the highest specific power outputs for a naturally aspirated engine ever seen in a car at that time. Devoid of unnecessary rotational mass and with light weight skirtless slipper pistons to minimise recipricating mass it's also exceptionally responsive and mixes strong torque with a willingness to rev.
Compare that to the contemporary Speed Six engine which at 3.6 or 4 litres weighed 200kg, wasn't really any narrower because it had to be slanted to contain its height and from a practical first hand experience viewpoint, doesn't make any material difference to the refinement of otherwise same car (but spark plug changes are awkward - they're already quite fiddly on cylinders 7 and 8 on the V8). The Speed Six is capable of slightly better specific power output, but only because it has a 4-valve per cylinder head design compared to the AJP8's 2 valve per cylinder design.
I am getting sick of saying this - but 2nd order balance is just not that important in the grand scheme of car design.
esso said:
jamieduff1981 said:
Esso is a fellow Cerbera owner. We both have direct experience of a 75 degree V8 with flat plane crank.
The AJP8 doesn't idle particularly smoothly, but the car hardly shakes itself to bits - nothing buzzes or rattles from vibration. Overall vibration levels at idle are still less than most 4-pot diesels at idle. What that configuration bought was a 4.2 or 4.5 litre engine which weighed 120kg fully dressed and was narrow enough to get good tubular exhaust headers for exhaust scavenging not available with cross-plane engines between the chassis rails of a sports car that was small enough to be agile on public roads. Combined with individual throttle bodies it gave the AJP8 one of the highest specific power outputs for a naturally aspirated engine ever seen in a car at that time. Devoid of unnecessary rotational mass and with light weight skirtless slipper pistons to minimise recipricating mass it's also exceptionally responsive and mixes strong torque with a willingness to rev.
Compare that to the contemporary Speed Six engine which at 3.6 or 4 litres weighed 200kg, wasn't really any narrower because it had to be slanted to contain its height and from a practical first hand experience viewpoint, doesn't make any material difference to the refinement of otherwise same car (but spark plug changes are awkward - they're already quite fiddly on cylinders 7 and 8 on the V8). The Speed Six is capable of slightly better specific power output, but only because it has a 4-valve per cylinder head design compared to the AJP8's 2 valve per cylinder design.
I am getting sick of saying this - but 2nd order balance is just not that important in the grand scheme of car design.
Thank-you for your knowledgeable answer to this James....my reply is much simpler as I`m not a mechanical engineer......the 75 degree flat-plane crank V8 in my Cerbera performs very well !...cannot say that I have noticed any `vibration`!The AJP8 doesn't idle particularly smoothly, but the car hardly shakes itself to bits - nothing buzzes or rattles from vibration. Overall vibration levels at idle are still less than most 4-pot diesels at idle. What that configuration bought was a 4.2 or 4.5 litre engine which weighed 120kg fully dressed and was narrow enough to get good tubular exhaust headers for exhaust scavenging not available with cross-plane engines between the chassis rails of a sports car that was small enough to be agile on public roads. Combined with individual throttle bodies it gave the AJP8 one of the highest specific power outputs for a naturally aspirated engine ever seen in a car at that time. Devoid of unnecessary rotational mass and with light weight skirtless slipper pistons to minimise recipricating mass it's also exceptionally responsive and mixes strong torque with a willingness to rev.
Compare that to the contemporary Speed Six engine which at 3.6 or 4 litres weighed 200kg, wasn't really any narrower because it had to be slanted to contain its height and from a practical first hand experience viewpoint, doesn't make any material difference to the refinement of otherwise same car (but spark plug changes are awkward - they're already quite fiddly on cylinders 7 and 8 on the V8). The Speed Six is capable of slightly better specific power output, but only because it has a 4-valve per cylinder head design compared to the AJP8's 2 valve per cylinder design.
I am getting sick of saying this - but 2nd order balance is just not that important in the grand scheme of car design.
The exhaust on a TVR very successfully masks engine vibration from the V8. I guarantee if you fitted this engine in a big Audi or a Jaguar you would be very disappointed at the amount of actual engine vibration when properly silenced. The split crank design and harmonically tuned exhausts on the early Audi V6 is what makes it such a turbine of an engine and vitrually silent and vibration free when cruising.
J
Here's the thing: with those TVR engines, the Speed Six, with a softer cam profile and a quiet exhaust, would swap nicely into an old Jag or somesuch doing duty as a refined cruiser. In fact, I've an idea it began life as a Jaguar AJ-6, albeit then being redesigned out of all recognition. Likewise, a 3.9 litre Rover V8 can sound thunderous in a TVR Griffith or Chimaera but soft and burbly in a Range Rover Classic. The V8 in the Ford GT is derived from that in the Crown Victoria and Lincoln Town Car.
The TVR AJP-8, on the other hand, is good at only one thing: making a lot of power and noise. There is no way that it could ever be made refined.
The TVR AJP-8, on the other hand, is good at only one thing: making a lot of power and noise. There is no way that it could ever be made refined.
.....well there is one thing we agree on there!....yes the AJPV8 does make a lot of power & noise and that's why I like it....it makes a unique sound and I wouldn`t change it, the power delivery is brutal unlike the V6 in the Jaguar...the power delivery in that is very smooth and comes in very quick.
Edited by esso on Wednesday 21st October 21:07
Gassing Station | Jaguar | Top of Page | What's New | My Stuff