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Post by enigmas on Dec 11, 2020 11:20:22 GMT
IMHO, I really don't believe the standard Rover V8 and BW35 as fitted to to a P5B would have enough torque to wind up the rear springs with either the OEM rear bushes or a fabricated set of shackles.
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Post by thomashb on Dec 11, 2020 11:26:55 GMT
IMHO, I really don't believe the standard Rover V8 as fitted to to a P5B would have enough torque to wind up the rear springs with either the OEM rear bushes or a fabricated set of shackles. And presumably that low risk is the same whether a shackle or a contrasonic / Y-bush?
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Post by enigmas on Dec 11, 2020 11:49:26 GMT
It's a great engine but it's not a torque monster. The factory rear leaf spring setup is quite beefy too. I've certainly never been able to induce rear spring windup with the 4.4 litre (P76 V8) in mine. Perhaps it's possible with a manual gearbox and a very high diff ratio but why would you gear a car like that!
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Post by dmaxwell on Dec 22, 2020 21:29:00 GMT
In reading the Taylor P5 book, he mentions that the ride was rough using shackles on the rear and that's why the Y-brushes were developed to remove the roughness.
David California
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Post by Warwick on Dec 24, 2020 8:24:43 GMT
That's interesting, David.
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on Dec 24, 2020 17:27:57 GMT
I have recently been researching the contrasonic bushings and have obtained some information from the company who acquired the Metalastik organization. I am pasting below an extract from a 1958 technical data sheet which talks about the Rover P5 application. The rubber used is a conventional natural rubber with a Shore A hardness of 50 and it seems as if the rubber was the same as used on engine mounts and not a special formulation for the contrasonic application. " CONTRASONIC* SHACKLES FOR LEAF SPRINGS *REGISTERED TRADE HARK PATENTED
Contrasonic Spring Shackles provide maximum insulation against road and other noises. In comparison with conventional shackles, they embody five times as much rubber without sacrificing stability. Careful selection of the mounting angle and the right amount of rubber meets a three-fold requirement: fore-and-aft and torsional flexibility; good sideways control and sonic insulation. On the Rover 3 litre car, the Contrasonic Shackles give a vertical deflection of i" from no load to full static load conditions - the deflections of conventional shackles being in the order of 0.020/; - 0.040''. The shear deflection of the Contrasonic Shackle for the Rover is ll'' from fully laden to full rebound positions and the torsional deflection 28°. Contrasonic Shackles can also be designed and fitted so that they help to provide a variable rate suspension or 'S' shaped vertical load-deflection curve, stiffening on bump and rebound but this is largely influenced by the spring camber and relative shear offset of the shackle at normal static load. To obtain the maximum benefit of Contrasonic Shackles, Metaxentric Bushes should be fitted in the front eye of the leaf springs."
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on Dec 24, 2020 17:40:54 GMT
I also found a section in an automotive suspension design text book which is interesting
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