[ROVERNET - UK] P6 Design & Rear Suspension Function

Vern Klukas vern at inkspotco.com
Mon Apr 7 19:33:33 BST 2008

>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 

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 
>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?


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

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