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Post by enigmas on May 8, 2015 14:04:40 GMT
How much movement Warwick?
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Post by Deleted on May 8, 2015 15:01:53 GMT
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Post by Phil Nottingham on May 8, 2015 17:46:19 GMT
Yes I have a pair of OE Contrasonics I am keeping for now which I bought at the BMC rally in Peterborough some years ago for £10 right under George "lagain's" nose
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Post by Colin McA on May 8, 2015 22:15:26 GMT
Just realised who JTW is and read the post properly.
Colin
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jtw
Rover Rookie
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Post by jtw on May 9, 2015 7:54:38 GMT
Hi Colin.....It's me and we're of to the Isle of Man today in the saloon, so I hope i've put it all back together properly. I'll let you know when we get back,see you at the SARR in two weeks time...........JTW or you know me better as Jim or Wee Jimmy
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Post by Warwick on May 11, 2015 3:17:49 GMT
How much movement Warwick?
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Post by richardlamsdale on May 11, 2015 9:15:59 GMT
How much movement Warwick? Hi Warwick, a very useful drawing. However, I understand from the Workshop Manual that the front bush is fitted with the bolt hole at 1 o'clock as you view your drawing, not at 6 o'clock as shown. That would also make more sense as the thicker part of the bush would be supporting the cars weight, and the eccentricity would lessen the overall lengthening (albeit very slightly).
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Post by Deleted on May 11, 2015 9:36:03 GMT
Hi Warwick, a very useful drawing. However, I understand from the Workshop Manual that the front bush is fitted with the bolt hole at 1 o'clock as you view your drawing, not at 6 o'clock as shown. That would also make more sense as the thicker part of the bush would be supporting the cars weight, and the eccentricity would lessen the overall lengthening (albeit very slightly). Looking at drawing two, I'm a bit puzzled at the statement "what spring should look like on the car" as the illustration doesn't look anything like the drawing in the W/M. The camber looks too extreme IMO. It's also interesting to note that the Contrasonic bush is shown in shear in the W/M as the two studs through the spring are shown as out of line with the studs in the shackle housing.Also, if the contrasonic was mounted on the spring as shown in drawing two, I don't see how it would fit into the shackle. When I find some level ground, I'm going to take the measurements on my own car to see how much settlement has actually taken place.
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Post by johnwp5bcoupe on May 11, 2015 10:32:13 GMT
Hi Warwick, a very useful drawing. However, I understand from the Workshop Manual that the front bush is fitted with the bolt hole at 1 o'clock as you view your drawing, not at 6 o'clock as shown. That would also make more sense as the thicker part of the bush would be supporting the cars weight, and the eccentricity would lessen the overall lengthening (albeit very slightly). Sadly Richard there are loads of mistakes in the manuals/parts book and this is one of them on the car the sleeve in the bush is about 7 oclock, another example is they show the prop shaft out of Phase
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Post by richardlamsdale on May 11, 2015 11:56:03 GMT
Hi Warwick, a very useful drawing. However, I understand from the Workshop Manual that the front bush is fitted with the bolt hole at 1 o'clock as you view your drawing, not at 6 o'clock as shown. That would also make more sense as the thicker part of the bush would be supporting the cars weight, and the eccentricity would lessen the overall lengthening (albeit very slightly). Sadly Richard there are loads of mistakes in the manuals/parts book and this is one of them on the car the sleeve in the bush is about 7 oclock, another example is they show the prop shaft out of Phase Hi John, as I'm about to get new bushes fitted, could you clarify why we think the WSM is wrong, as it seems to make more sense to fit the front bush as per the WSM? The ones currently fitted to my car (no idea when they were fitted, but they are made by Metalastik) are fitted as per the WSM as well. I'm probably missing something obvious but obviously I'd like to get it right. Thanks.
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Post by johnwp5bcoupe on May 11, 2015 16:10:37 GMT
Hi Richard I am not saying I am correct I was going by Warwick's Cad drawing and he is very good at it and normally doesn't make mistakes I was just pointing out there are loads of info in the WS manual/parts book which are wrong so best to double check before having your bushes fitted. I just had a look under my Coupe and it's hard to say where the sleeve is as the two large rubber washer block the view, mine were two new OEM springs so are correct not that it helps at the moment, here are Miguels Springs Best to question now before having yours fitted Richard!
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Post by Deleted on May 11, 2015 16:31:35 GMT
Hi Richard I am not saying I am correct I was going by Warwick's Cad drawing and he is very good at it and normally doesn't make mistakes I was just pointing out there are loads of info in the WS manual/parts book which are wrong so best to double check before having your bushes fitted. I just had a look under my Coupe and it's hard to say where the sleeve is as the two large rubber washer block the view, mine were two new OEM springs so are correct not that it helps at the moment, here are Miguels Springs Best to question now before having yours fitted Richard! And follow the link to the thread "P5 in the nude" It seems to show the bush with the bolt hole at between 6 & 7. I also tried to have a look at my own original springs but the large washer blocks the view. I'll take a torch out and have another look tomorrow if I can. It's very frustrating when there are different views as to the correct orientation Just a thought but your springs are likely to be original as few get changed so what's the current orientation? roverp5.proboards.com/thread/5600/p5b-coup?page=3
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Post by Warwick on May 12, 2015 5:11:43 GMT
Thanks John, for the kind words. However, you may want to edit your post after reading the following: It was this drawing in the WSM that prompted me to measure and draw the spring, so as to see how it should really look on the car. My springs look exactly like the WSM drawing - dead flat. In fact they couldn't be flatter. I believed this drawing to be wrong for a couple of reasons. Firstly, it made no sense. A designer would not set up a leaf spring to be flat at the normal rest position because when the car was moving and the springs doing their job, the leaves would be forced into reverse camber, to varying degrees, with every irregularity in the road. Secondly, the Contrasonic shackles on my car are clearly under quite a bit of rearward stress when the car is at rest and the springs are flat. At the time, I had a spare set of original springs from a car a friend had wrecked (broken?), so I carefully measured the length and thickness of each leaf, the positions of the bolt holes, the diameter of the eye and bush at the leading end, and the position of the eccentric sleeve in the bush. (It was an original Metalastic bush). I carefully entered all these dimensions into AutoCAD as straight lines. This is the top drawing and is how the new spring would have looked if the manufacturer had assembled it before bending each leaf. For those unfamiliar with AutoCAD, it was drawn at full scale. So there are no scaling errors possible. Dimensions are enter in millimetres, exactly as measured. The only errors possible are measuring errors, and I was measuring in millimetres. Next I took the dimension B5-B6 from the WSM (drawing above), and opted for the maximum length within the tolerance stated. (i.e. +3mm) I created a new copy of the first drawing (flat spring), and then bent it within AutoCAD until the centre of the hole through the front bush was exactly 1,253mm from the Contrasonic shackle mounting holes in the rear of the top leaf, measured in a straight line. And when I say exactly, I mean just that. If you tell AutoCAD the distance is 1,253mm, it will be exactly that. This gave me the middle drawing. IF the dimension B5-B6 given in the WSM is correct, then the middle drawing is exactly what the spring should look like on the car when the Contrasonic shackle is under no fore or aft deflection. Finally, I asked a few people to measure sets of reset springs not yet fitted to their cars. This gave me the fore-aft distance needed to create the bottom drawing. As you can see from the photo below, there is no bend at the end of the top leaf, where the Contrasonic shackle mounts. The angle of the lower mounting surface of the shackle on the leaf, relative to the upper mounting surface between the shackle and the body mounting point, is entirely dependent on the bend in the spring. If the body mounting point is parallel to the ground (and I haven't checked), then the upper surface of the rear of the top leaf won't even come close to being parallel to it unless the spring is almost straight. Now for the embarrassing bit, and it's gone unnoticed since 2009 until Richard pointed it out. I've drawn the front bush upside down! I just checked the photos I took when measuring the springs in 2009. I have no idea how that happened and why I didn't spot it. Particularly when I thought the sleeve's placement at the bottom to be all wrong. Hence my comment at the bottom of the drawing. So, it is actually placed to put the most rubber between the load-bearing surfaces - where it should be. The other reason I did the drawing was to find out what effect the eccentricity had on the lengthening of the spring as it flattened under load. As you can see, it makes no effective difference at all. Richard, given John's comment about the accuracy of the WSM, before you refit the springs, perhaps you could accurately measure the distance between the bolt hole on the body bracket for eccentric front bush and the bolt holes for the top of the Contrasonic shackle in the body bracket at the rear. (i.e. Dimension B5-B6) Maybe it's wrong in the WSM. If it is, I'll redraw the spring. I'm going to have to edit the drawing anyway to fix the upside down front bush.
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Post by johnwp5bcoupe on May 12, 2015 7:49:07 GMT
Never mind Warwick no one is infallible It makes sense to have the ferule at the top as there is more of the bush to take the weight as Richard pointed out. At least it will be a guide for other guys in the future
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Post by Deleted on May 12, 2015 8:11:18 GMT
The spring length will increase as the settle,the angle the spring makes to the mount will also alter.Any rubber mountings should be fitted to that at rest they are under minimum strain. (These 'Contrasonic' mounts will be under some compressive strain as they are bearing the weight of the car).
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Post by richardlamsdale on May 12, 2015 9:09:25 GMT
Hi Warwick, I'll measure the distance and let you know. My springs were flat on the car, same as your photo. I'm going to take my springs to Brost Forge and will photograph the before and after, then see how they sit when refitted - that may provide some guidance as well, although we'll never know exactly how they left the factory.
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Post by Warwick on May 12, 2015 9:13:03 GMT
The spring length will increase as the settle,the angle the spring makes to the mount will also alter.Any rubber mountings should be fitted to that at rest they are under minimum strain. (These 'Contrasonic' mounts will be under some compressive strain as they are bearing the weight of the car). Exactly, Kev. IF the dimension B5-B6 is given correctly in the WSM AND IF the shackle is under no strain, other than vertical compression, when an unloaded new car was sitting at rest, then when the spring is flat due to vehicle loading or aging springs, the lower part of the Contrasonic is forced rearwards by nearly 30mm and the rubber is twisted through 23 degrees. The vertical load on each shackle's rubber will be approximately 1/4 of the weight of the rear half of the car.
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Post by Deleted on May 12, 2015 9:22:17 GMT
Agreed,and their action is more complex than it seems.
A 1960s explanation of the action of 'contrasonic' springs was that they were designed to 'modify the action of (curved) leaf springs operating as flat when under normal load' The rubber mounts actually operate as part of the springing not merely to suppress vibration. Under normal load they should be under no shear forces,but their shear resistance is used to modify the springs action (increasing its rate as its effective length alters) under load and on rebound. The design was actually patented by Dunlop in 1958.Hence soft rubbers or rubbers distorted over the years will not function as they should.
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Post by Deleted on May 12, 2015 9:55:50 GMT
Never mind Warwick no one is infallible It makes sense to have the ferule at the top as there is more of the bush to take the weight as Richard pointed out. At least it will be a guide for other guys in the future John, as your car is on OEM springs and have only been there a few years, I would be very interested to see how the Contrasonic bush looks on your car. I assume you have JRW replacement "contrasonics"? Can you post a picture when you've got some time or describe the distortion if any? Thanks.
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Post by Deleted on May 12, 2015 10:01:22 GMT
Agreed,and their action is more complex than it seems. A 1960s explanation of the action of 'contrasonic' springs was that they were designed to 'modify the action of (curved) leaf springs operating as flat when under normal load' The rubber mounts actually operate as part of the springing not merely to suppress vibration. Under normal load they should be under no shear forces,but their shear resistance is used to modify the springs action (increasing its rate as its effective length alters) under load and on rebound. The design was actually patented by Dunlop in 1958.Hence soft rubbers or rubbers distorted over the years will not function as they should. Trouble is Kev, most of us have either got "new" springs (either OEM or JRW) "old" springs as fitted, "new" hard as iron contrasonics as supplied by JRW or very rarely NOS contrasonics. I would suggest that NONE of us have OEM springs AND NOS contrasonics so we'll never have the original happy combination as they left the factory as the JRW replacement contrasonics will not behave as well as the original metalastic ones.
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Post by Warwick on May 12, 2015 10:32:35 GMT
Hi Warwick, I'll measure the distance and let you know. My springs were flat on the car, same as your photo. I'm going to take my springs to Brost Forge and will photograph the before and after, then see how they sit when refitted - that may provide some guidance as well, although we'll never know exactly how they left the factory. Thanks Richard, This could give us a really good opportunity to answer these questions once and for all. If you could accurately measure the distance from the centre of the hole in the sleeve in the front bush, to the centre of one of the two holes at the rear end of the top leaf, I can compare it with the distance on the drawing. It sounds like Brost Forge could be the best chance of getting as close to original spring characteristics as possible. Then, if after you fit them, you find that your car sits with the correct stance at the rear, we will know that the springs are close to original. While your springs are off, would you mind measuring the distance from the centre of the hole in the forward spring bracket to one of the lower studs beneath a new Contrasonic shackle bolted to the body. Finally, what I'd like to know is this. After the new springs are fitted and with your car sitting on flat, level ground, what is the distance from the ground to the centre of the forward spring bracket's bolt hole? What is the distance from the ground to the underside of the spring between the lower Contrasonic shackle bolts? This will give me the difference in height between the front and rear of the spring. My drawing assumes that they are the same and that the line between them is horizontal, but I'm sure it isn't. I'd also like to know the angle (off horizontal) of the spring leaf where the shackle bolts on. With all this information, I can modify the drawing and we'll know a lot more.
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Post by Warwick on May 12, 2015 10:47:42 GMT
Resurgam,
Would you please carefully measure your NOS Contrasonic shackle, before you fit it, looking from one end? i.e. The sides of the triangular base. The position and length of the lower studs. The width and height of the rubber blocks. The location and lengths of the upper studs.
I can then add these details and we can get a better picture of how it all moves.
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Post by Deleted on May 12, 2015 11:02:51 GMT
Resurgam, Would you please carefully measure your NOS Contrasonic shackle, before you fit it, looking from one end? i.e. The sides of the triangular base. The position and length of the lower studs. The width and height of the rubber blocks. The location and lengths of the upper studs. I can then add these details and we can get a better picture of how it all moves. No problem. I've fitted one and I have one unfitted. I'll take the measurements ASAP.
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Post by Warwick on May 12, 2015 11:17:03 GMT
Great, thanks. Might be easier to do this by email. You could send a scanned sketch, I can drawing in AutoCAD and send it back for checking. I'll PM you my address.
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Post by Deleted on May 12, 2015 11:20:18 GMT
Richard,I think you have pretty much hit the nail on the head. By coincidence,I've just got back from a test drive in another 70s luxury car,its ride is much superior to the rover,its quieter and its for sale. At least I'll no longer have to worry about contra whatsits.
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