[ROVERNET - UK] P6 Design & Rear Suspension Function

[Vern Klukas]

>Vern Klukas wrote:
>>
>>As for the effectiveness of the P6 vs SD1, on a smooth surfaced 
>>road there is probably not much between them, but introduce a rough 
>>road with potholes, undulations and camber changes and the P6's 
>>rear wheels will stay planted while the SD1 rear axle will be 
>>dancing about.
>
>I wonder if that was more of an advantage in 1960's Britain (no 
>offense) because roads in the USA (PA, NJ, MD, DE, at least) are not 
>that rough. One thing I can tell you is that my SD1 would (and did) 
>leave P6's in the dust when it came to freeway on/off ramps and 
>other corners where absolute cornering power was involved, and body 
>lean was not an issue. I'm sure the SD1 had wider tires, but the P6 
>was heeling over like it was about to leave the road and had to slow 
>down while the SD1 was perfectly stable.

Body roll has very little to do with road holding (and, btw, has 
nothing to do with a car overturning, that is dependant on lateral 
roadholding, the track width and the car's centre of gravity), and I 
would suggest that it was the driver lifting in the P6 that allowed 
you to pull ahead. When the boys and I would take customers cars out 
for "road tests," I never had trouble keeping up to a SD1 in a V8 P6. 
In a 4cyl P6, the SD1 would walk away on the straights but I could 
stay with him on the twisty bits.
>
>So, I'm not knocking the P6 suspension, but I'm not sure that all of 
>the complexity bought you all that much for all of the expense and 
>service hassles. The SD1 had a well-located live axle that wasn't 
>all that different from what was installed under Volvo sedans up 
>into the 90's.

Beg to differ there, the SD1 was much more sophisticated than Volvo's approach

>  If the people at Triumph/Jaguar would have let Rover put some disks 
>on the rear axle they would have had something. Not that disks were 
>needed because the SD1 back wheels are proportioned to do almost no 
>braking at all, but the SD1 drums were no fun to service, either. (I 
>prefer disks when they are in a place where they can be serviced.)
>
>All of the engineering oddities add to the charm of the P6, but 
>mostly they contributed to difficulty and added expense in servicing 
>for very little gain in performance. The expense of these oddball 
>designs apparently hurt sales since the car was overpriced for its 
>niche. The complexity made it more difficult and expensive to 
>service due to the time it took to do things like setting the valve 
>clearances (on the 4-cyl)

But how often do you set the valve clearances on a 2000?

>or servicing the rear brakes, to say nothing of having to source 
>front shocks that are valved in reverse to every other car on the 
>road.

Total red herring there Glen. The same can be said for any part of 
any car, that is unique to that particular model.

>
>The P4 and P5 were fine automobiles that were fairly conventional in 
>design while still being ahead of the competition in some 
>engineering areas. What was it that led Rover to jump off the deep 
>end when it came to designing the P6 and approving it for 
>production? It seems like they were trying to make some sort of 
>statement about their engineering prowess and ingenuity rather than 
>just make an excellent car that would sell. Were they trying to move 
>upmarket with this display of engineering creativeness? The P6 
>wasn't really an upmarket car.

It was an upmarket car though. Intended for the "young professional" 
who wouldn't be caught dead in a P5, and slotting in just under 
Jaguar in the corporate scheme.

>Was the P6 just a stepping stone to the P8 which would move them 
>upmarket? The P8 would have dumped the oddball front suspension

>for wishbones but retained a modified version of the DeDion rear end 
>incorporating hydraulic leveling.
>
>Maybe it was overreaching to attempt to battle Mercedes and other 
>companies with deep pockets and an established market share world 
>wide.
>
>It also sounds like Spen King (engineering) and David Bache 
>(styling) were not always on the same page about the intended market 
>for the cars. Wonder who was really running the show?
>
>Glen

Yours
Vern

-- 
Vern Klukas                             I'm a little . . .
Inkspot Type & Design
vern at inkspotco.com