[ROVERNET - UK] P6 Design & Rear Suspension Function

Glen Wilson rovercar at comcast.net
Mon Apr 7 18:50:04 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.

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.  
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) 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. 

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. 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?


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