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I have a 1966 3.8 S-Type. My understanding is that the 420 is a close cousin to it, and I was wondering what sort of mechanical similarity there is? Roughly speaking, what percentage of the parts in them are interchangeable or swappable? Are some sections more or less identical, while two or three are quite different? Also, where would the 340 slot in as far as mechanical compatibility?
The S Type and the 420 are quite similar, the differences are the engine size, and the 420 was originally negative earth electrical with an alternator instead of the generator and positive earth of the S Type. The 420 has a different front suspension and brakes, a different dash, and a different steering box and power steering system. The tach is different, and also does not have the cam driven generator.
The 340 is basically a late Mark 2, but with the 3.4 engine, with the exception that I believe some for North America came with a 3.8. Others can correct or verify that. The 340 has a live axle instead of the S Type's independent suspension, but I believe the front suspension, steering and brakes are the same as the S Type. Electrically, they are very similar.
So they are all developments of each other, but not identical.
As per the above lots of similar and interchangeable parts. The 420 was slightly more up to date so had dual brake lines, three pot front calipers, power steering as standard which was the Adwest Marles fitted to the last S Types built but a different PAS pump. Negative earth electrics with an alternator. The dash was different for safety reasons. Most of these items have been used by S Type owners to upgrade their S types even changing out the engines.
The front and rear subframes are identical as are all the suspension parts, Springs and shocks. Same size wheels and the wire wheel hubs can be transferred across.
The gear box is different in that the S Type auto box started as the DG250 and the last models had the BW35 whereas the 420 with the higher torque 4.2 engine needed the older Borg Warner model 8 gear box.
Externally the S Type and the 420 shared near enough everything except the front wings, grill and front lights.
Interior such as door cards seats, carpets, head lining and 90% of the wood is all interchangeable.All the dials and switches apart from the Rev counter and clock are interchangeable.
The 340 is a single fuel tank, single fuel pump design;
the S type and 420 are twin fuel tanks, twin fuel pumps design, the design that Jaguar anticipated for the XJ design that debuted in 1968.
The 340 is a re-badged MK-2 with the S type front bumper and a 340-only rear bumper design.
Above all, remember that the Mk2 (and Mk1), with their bullet nose, tapered tail and live rear axle, probably won as many races as any Jaguar, won a European Touring Car championship, was driven by almost all the great racing drivers of the time and was the personal choice of F1 world champions.
Above all, remember that the Mk2 (and Mk1), with their bullet nose, tapered tail and live rear axle, probably won as many races as any Jaguar, won a European Touring Car championship, was driven by almost all the great racing drivers of the time and was the personal choice of F1 world champions.
Peter that was because there was no S type in those days !
Jose, Somewhere, there's a quote from Graham Hill on the relative merits of the Mk2 and the S type! I don't need to say which he favoured. Personally, I think that they are all great; they are just different optima.
Yes Jose ~ and as John Bolster wrote in Autosport & was echoed by other scribes in multiple publications.
Quote
"As regards the performance of the S-type, this can be defined as slower than the Mk 2 in figures but faster across country. The more luxurious car is naturally heavier than its smaller brother, but its independent rear suspension allows it to corner faster. Furthermore, the rear passengers receive a much less hectic ride, which again encourages the driver to press on." Unquote.
And press on he did! In the person of John Bolster, Autosport tried out an overdrive model rather less than a year later for their issue dated 14 May 1965. The car was EDU 482C, which also figured in other road tests of the time. In Bolster’s hands, the car took just 10.2sec to reach 60mph from rest and went on to a maximum of 122mph (196km/ h) – incidentally demonstrating just how much automatic gearboxes of the time harmed both acceleration and maximum speed. The maximum of 110mph (177km/ h) achieved in direct top showed exactly how valuable that overdrive was for highspeed motoring, and Bolster commented that the car still felt ‘wonderfully lively in top gear’. The gearbox – by this stage Jaguar’s new all-synchromesh unit.
One of the US magazines pushed the car to 126mph.
Motor magazine, like others, was particularly enthusiastic about the car’s ride quality, describing it as ‘probably unexcelled by any other European car’.
The S Type was the most aerodynamic of all the compacts.
Last edited by Glyn M Ruck; Mar 16, 2021 at 11:57 AM.
Not quite Jose the S Type was used for racing and with it's better rear suspension was a better handling car than the Mk2 but.... The problem was Jaguar had a long history of motor sport and had a racing division through the 50s and early 60s. Unfortunately around 1963 when the S Type emerged the racing division was winding down due to lack of funds and in 1964/65 it was closed down completely and in 1966 Jaguar merged with The British Motor Company. There were a lot of highly developed Mk2 Jaguars still running and used by privateers but there was no Jaguar racing team and the S type was not developed for racing by the factory. Those that were raced were as good if not better than the Mk2 but without the Jaguar factory development money few were turned in to saloon car racers.
The Mk2 Jaguar has a reputation for being a great saloon car but really the stories are greater than the sum. Jaguar were beaten in both 1961 and 1962 to the British saloon car championships by the humble mini.. Lighter better handling cars such as the Lotus Cortina were also a quicker car and won in 1963 with Jack Sears and Jim Clark won the championship with the Lotus Cortina in 1964 so the S Type being a big heavy car would never have been able to compete with the lighter better handling cars and no one ever tried to develop it for racing with much success.
John Bolster was a very good road tester. His opinions were honest and to be believed unlike some of his contemporaries that tended to gloss over faults in cars from larger manufacturers. However, his stop watch wasn't always consistent. Performance figures are generally, but not always, more reliable from other magazines.
Overall, I agree with all you S type owners. It's sad that Sir William decided to shake off the boy racer image that he feared the company had gained. Otherwise, we might have had a lightweight Mk2 - S type hybrid. That would have been a car! I presume that it would have had the IRS, though a lot of people (such as Frontline Developments) claim that a live axle can be made to work very well.
Wasn't part of the success of the smaller cars in the BSCC due to it being run by class? Jack Sears would drive a Lotus Cortina or a Ford Galaxie to some extent depending on the circuit, etc? I have to admire Sears driving a Galaxie around Crystal Palace - the car must have been as wide as the road in places. Certainly, the Mk2 was squeezed out by lighter cars on one hand and more powerful on the other.
If you go to any present day classic saloon racing, our old models are still quite spectacular and don't disgrace themselves against other machines.
I could be quite happy with either a well restored Mk2 or S Type. Both great cars. Depends what I wanted to do with it. I nearly went for a Mk2 but then I would have built it to Coombs spec sans bonnet louvres. I have a few gripes with the Mk 2. I find the standard front seats uncomfortable. Probably more to do with my build than anything else. I also find the rear suspension positively crude with Panhard rods pulling out of their mountings etc. They are terminal understeerers. I would probably do something like Callum did to the rear. I find the S Type the prettier of the two but then I prefer the Aston DB6 styling to the much loved DB5. It's personal.
Racing drivers generally drove heavily modified units with improved handling.
They are two cars with very different characters & we all love them for different reasons.
Last edited by Glyn M Ruck; Mar 16, 2021 at 01:52 PM.
John Bolster was a very good road tester. His opinions were honest and to be believed unlike some of his contemporaries that tended to gloss over faults in cars from larger manufacturers. However, his stop watch wasn't always consistent. Performance figures are generally, but not always, more reliable from other magazines..
Yep. In the case of the S Type his figures were the same as many others apart from one off song car that funnily broke into the high nine seconds on acceleration but would only do 115mph. A trip to the factory for a tune up rectified that & the car matched Bolster's figures. I think I have every road test ever done on the S Type. Including SA's Car magazine. We only built 3.8's here. Engine machining & all from raw blocks & heads to get around the local content program. Lyons was a smart operator.
Last edited by Glyn M Ruck; Mar 16, 2021 at 01:14 PM.
"If you go to any present day classic saloon racing, our old models are still quite spectacular and don't disgrace themselves against other machines."
"Racing drivers generally drove heavily modified units with improve handling."
Two very true comments. So much prefer the classic saloon car races from Goodwood to modern jelly mould racing today. Glyn is quite right that the racing Jaguars were very heavily modified. Uprated suspension, lightened and stiffer body shells. The engines were highly tuned and probably not 3.8cc. You look at the Mk2s now going around Goodwood and they are not on standard 185 profile tyres. I had this conversation before when someone suggested that Mk2 Jaguars were great handling cars. Unfortunately they were consistently bad handling cars but better than most of their era. At goodwood the Mk2 Jaguars being lapped by the front running Mk2 Jaguars are the standard cars. The ones at the front have had a fortune spent on them to make them run at the front.
This is a picture of my father racing his standard 3.8 Mk2 Jaguar YUF650 in 1967 in a local sprint on an old airfield. A bit of body roll going on there that you do not find on the cars being thrown around Goodwood today.
Yes, the handling of the Mk2 was generally better than most of its competitors most of the time. But if you passed its/your limits with it, it became totally evil.
Local & US competitors with no real sporting pretensions like Humber & Rover maybe. The Italians were a different matter. Alfa's of the era, as an example, would totally spank it in the handling stakes & were forgiving when pushed beyond their considerable limits for the time.
Last edited by Glyn M Ruck; Mar 17, 2021 at 05:42 AM.
Yes, small Alfas were great cars. I loved my old GTV. It's brilliant handling saved us from a frontal collision when we met someone who was on the wrong side of the road on a blind bend. Sadly, it made my Mk2 look rust free. It's interesting that the Giulias, Giuliettas et al were so good in spite of steering boxes and live axles. I don't think any country matched Italy for consistently producing good handling saloons. My suspicion is that it was in part thanks to lightweight engines allowing decent caster and camber at the front and well located axles that didn't cause roll over-steer otherwise misbehave. Of course, if you drive anything today from decades ago, the chances are that it's either clapped or better than new.
Yes ~ I went through a long string of Alfas in my crazy youth until my first company car came along. Even then I kept one for quite a while. GTV's, Giulias, Giuliettas, Spyders, Berlinas.
My first Alfa was a Giulia TI pre Super with a 1750 engine & stage 3 cams with stock road Weber 40 DCOE side draughts which were standard with that engine. The only suspension mod I did was to fit a 1750 Berlina front end to get the discs up front as the huge 3 leading shoe drum brakes were not up to the job. Koni shocks. Twin Lockheed Bonaldi boosters.
That little Alfa was highly competitive at our 'Varsity track days at Cape Town's Killarney circuit ~ earned plenty of silverware. Track still used & basically unchanged apart from resurfacing a facilities improvement. McLaren (road cars) were out here testing a while back. Cape Town & Kyalami in Johannesburg give them a great opportunity to test at coast & altitude cheaply.
All great fun. Rust was less of an issue here but I had every cavity on my cars pumped full of Tectyl on acquisition. In the UK's climate rust must have been a huge issue. Well protected they were not.
Last edited by Glyn M Ruck; Mar 17, 2021 at 09:38 AM.
Frankly the S the is a more advanced ( read 'complicated') car then the Mk2.. its ride and handling is considerably improved... the 420 is an evolution of the S type..more torque, taller geared,, better brakes..However:- neither the S type or the 420 gained anything near the popularity (read value) of the Mk2 ..... the 420 is perhaps one of the least unappreciated jaguars ever made.. close second to Mk10/420G that respect..
S-type similarities to 420, 340?
