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Post by Steve P5b on Jun 10, 2015 19:13:19 GMT
That's it , thank you for the link, a bit pricy though.
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Post by Deleted on Jun 10, 2015 20:36:04 GMT
That's it , thank you for the link, a bit pricy though. Yes, I agree. Both mounts look like a base plate with a mound of moulded rubber topped by a shaped dish or conical dish in the case of the Rover one.I assume that the large nut is captive in the concave metal base plate.As expected, the Rover one is designed to spread the load evenly over the rubber mound and I suspect the rubber is much softer than the remade one which seems to have a much smaller mound and looks as if it wouldn't last very long. Regarding the JRW one, it could be that both the "Y" bush and the rubber mounts are made and sourced from the same place but I've no idea. It doesn't look that difficult to take the Rover metal base and top and have new ones made to the original design. Probably best to leave well alone unless replacement is absolutely necessary.
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Post by Phil Nottingham on Jun 10, 2015 21:22:25 GMT
The mounts should not be too soft - Rolls Royce/Bentley used a similar design on the chassis mounts for 1950's Shadow/S1, S2 S3 but had a steel wool/mesh instead of rubber I understand. The P4 had a simpler design which was basically a loose rubber washer around a disk with a concentric outer
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Post by enigmas on Jun 10, 2015 22:14:49 GMT
Rresurgam said,
Resurgam...the comment above is truly 'looking through rose coloured glasses'. There was an enormous amount of R &D that went into developing the 'new' mount. Most of the effort can be attributed to a retired CSRIO engineer whose life focus was based on repairing/fixing mechanical/electrical systems for that company. In the event that the rubber insulator somehow separates from the metal that it's bonded to, the component will still not separate. This was one of the original design parameters by the factory and reproduced in the component.
It's a pity the rear 'contrasonic' leaf spring mounts weren't similarly designed!
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Post by Deleted on Jun 11, 2015 7:56:53 GMT
Rresurgam said, Resurgam...the comment above is truly 'looking through rose coloured glasses'. There was an enormous amount of R &D that went into developing the 'new' mount. Most of the effort can be attributed to a retired CSRIO engineer whose life focus was based on repairing/fixing mechanical/electrical systems for that company. In the event that the rubber insulator somehow separates from the metal that it's bonded too, the component will still not separate. This was one of the original design parameters by the factory and reproduced in the component. It's a pity the rear 'contrasonic' leaf spring mounts weren't similarly designed! No offence meant and, of course, I haven't actually seen the one(in the flesh) you illustrated or the JRW remade one. I was only commenting based on my own experiences with remade rubber components, most of which leave me a bit disappointed. If a lot of work went into developing the new mount, why was it necessary to produce something which looks quite different to the original? In fairness to our old friend, the "contrasonic Y bush" most lasted for 30 to 40 years and many cars probably still have the original fittings!
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Post by Deleted on Jun 11, 2015 8:03:30 GMT
Here's a link to a maker of this type of mounts. I've used them to hold generators and marine engines in the past.
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Post by enigmas on Jun 11, 2015 11:53:39 GMT
There's a similar factory not to far from my home called Mackay Consolidated Rubber Technology, Kev and they produce similar product. I don't believe it's a lack of knowledge or technical skill that's responsible for poor quality reproduction pieces, there just isn't the economies of scale or enough demand for the 'serious' manufacturer.
Resurgam no offence taken, but a quick assessment based only on a photograph of a specific component doesn't yield any hard evidence about whether the component is either durable or suitable for it's intended purpose. There are some club members in OZ that have fitted the 'new' subframe isolators and at least one I know of, posts to this forum.
Moving on. I took a good look at the subframe mounts on my coupe today (whilst rebuilding my OMVL LPG convertor), and they are truly past their use by date. At least 2 and probably the front 4, have rubber either oozing out or being slowly extruded between the two pieces of metal. The 2 at the rear of the subframe look to be perfect as they haven't been subjected to oil and other contaminating substances that leak out of old Rovers.
Although I do have mounts to replace these, I wouldn't mind burning out the remaining rubber from an old mount and welding the 2 pieces together, to form a solid mount. I'd only do this for the front 4, as they currently appear to be fully collapsed. This would substantially 'join' the front subframe to the body, reducing any tendency for it to squirm about under cornering and braking. This may even reduce the vagueness of the factory power steering slightly. Surprisingly the car still rides quite nicely!
Holden's of the early 1960's in OZ (FBs & EKs...looked like a small 56 Chevy) had the complete front clip bolted to the firewall of the car. These were also monocoque cars (chassis-less.)
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Post by Deleted on Jun 11, 2015 12:12:52 GMT
Wouldn't a solid connection be very stressful in respect of the forces transmitted up to the bulkhead without any cushioning?
Once again, It's only my opinion but replacing a rubber mounted joint by a solid one seems a bad move IMO.
I'd never given these mounts a second thought until a few days ago. I think mine are ok.
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Post by enigmas on Jun 11, 2015 15:17:08 GMT
Resurgam...that's what a car's suspension is supposed to do...absorb the shock and smooth the ride for the occupants (if it's working properly and not riding on the bump stops most of the time.) Have you checked yours? Isolation bushes/mounts are a remnant of when car bodies were directly mounted to a chassis. The P5 is an in between car. How bad could it be if the original mounts are already completely compressed?
Here's a method to check your mounts. Place a screw jack or similar under both front jacking mounts on your car. Raise the car until the front wheels are just of the ground. Now check to see how far the subframe has dropped? Any drop at all manifests itself in compromised handling, braking and steering quality. Most of it can be felt as a weird shimmy from the front end.
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Post by Deleted on Jun 11, 2015 16:36:19 GMT
Resurgam...that's what a car's suspension is supposed to do...absorb the shock and smooth the ride for the occupants (if it's working properly and not riding on the bump stops most of the time.) Have you checked yours? Isolation bushes/mounts are a remnant of when car bodies were directly mounted to a chassis. The P5 is an in between car. How bad could it be if the original mounts are already completely compressed? Here's a method to check your mounts. Place a screw jack or similar under both front jacking mounts on your car. Raise the car until the front wheels are just of the ground. Now check to see how far the subframe has dropped? Any drop at all manifests itself in compromised handling, braking and steering quality. Most of it can be felt as a weird shimmy from the front end. All I'm saying is that how can it be satisfactory to replace a cushioned mounting with a solid one when the original design called for a rubber one? I do think an accumulation of "mods" is sometimes the reason why these cars have a poor ride. If you start replacing components with unsuitable ones, eventually something is going to feel wrong. Unsuitable low profile wide tyres + poly bushes+ lorry springs + wrong shockers = poor ride (IMO) My own car appears to have satisfactory sub frame mounts, is not on the bump stops, has rubber bushes, Woodhead shockers, 80 profile tyres, "contrasonic" Y bushes, original rear springs and rides very nicely with no wandering or shimmy. I know I'm a bit of a "traditionalist" when it comes to these cars but why some people mess around with them so much is beyond me! No offence to the modernisors but it's not for me. (apart from electronic ignition, radials and soon to be fitted hazard warning switch) Wandered off topic a bit.Sorry!
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Post by Steve P5b on Jun 11, 2015 17:20:27 GMT
If the subframe has any movement relative to the body caused by old or even new mountings, how is it that the brake pipe that supplies the rear brakes does not shear of fracture in the area of the pipe junction block on the off side. From memory the junction block is located to the subframe and at least one pipe to the car body. A bit dodgy I'm thinking!!!
I would consider connecting both half's of the mountings together mechanically to prevent movement.
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Post by Phil Nottingham on Jun 11, 2015 18:09:15 GMT
The mounts are stiff and just cut out vibration - the brake pipe should not shear as it has a loop in it to allow sufficient flex.
As with SS exhausts vs mils steel the rubber mounts on the sub-frame and rear springs are what Rover intended to make the ride better than a Rolls Royce of the period. A design for some P5's which are almost 60 years was not that bad - better lasting than SS electronics and micro-processors that are much younger and do not work any more (at all!) used on cars nowadays
I know which I prefer
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Post by johnwp5bcoupe on Jun 11, 2015 18:19:20 GMT
The mounts are stiff and just cut out vibration - the brake pipe should not shear as it has a loop in it to allow sufficient flex. You can see the important loop bottom left
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Post by Steve P5b on Jun 11, 2015 18:35:50 GMT
Thinking on this a little more, I would suggest the mounts do very little to remove vibration , but their real purpose would have been to take out manufacturing inaccuracies between the body and the subframe at the points where they join together. To design and build a moving brake pipe doesn't seem good practice when a flexible hose would suffice if movement was intended. From memory there is no "loop" on the pipe that supplies the rear brakes which is connected to both subframe and body in the area of the junction block. The loop you refer to is as I see it would be to aid assembly in the manufacturing stage of the car.
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Post by Phil Nottingham on Jun 11, 2015 19:20:37 GMT
Mk1 & Mk2 Minis whose bodies were made by PSCo (then PSF) as with the Rover had solid sub-frame mounts front & rear. The fronts on Mk3's on had Metalastic flat bushes to cut out vibration which they did as I converted my wife's Mk2. Stress fractures were caused on Minis floors because of the solid mounts. The P5 rear sub-frame brake pipe has a joint with sufficient loop in it to take up any movement. I have never known brake pipe fracture in those areas but corrosion may eventually take its toll Some have converted the P4 body mounts to solid - not much point really as they are readily available from the usual eg Wadhams - you can see our P4 mount on the left Attachment Deleted
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Post by enigmas on Jun 11, 2015 23:46:43 GMT
Most of the modifications I do to my car are invisible to the uninformed. I purchased the car largely intact but significantly rundown and very tired with regard to body interior and mechanicals. The coupe was my sole form of daily transport for over 23 years covering an average of 300 kms per week. It has been primarily fueled by LPG all this time. There is no petrol option. All the changes/modifications have been done to improve it as a driver. Eg., Added 3 degrees of caster to the steering, 4 wheel disc brakes (vented discs at the front), cruise control, a taller diff ratio for more relaxed cruising and less engine wear, various electronic relays (so the original switch gear isn't cooked with modern headlights/etc), radial ply tyres (because the poor handling on cross plies is dangerous in modern traffic) inertia reel seat belts (for obvious reasons), an alternator (for electrical efficiency), an aluminium 4 core cross flow radiator (as the summer temperatures where I live can reach 40C or more at times), electronic ignition...and probably several more that I can't recall for the moment.
As for the subframe mounts, I can always revert back to factory specs if I'm dissatisfied with the handling or ride quality, (but now you do have me thinking about the brake pipe that transitions from the subframe to the main body structure.)
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Post by Steve P5b on Jun 15, 2015 14:10:06 GMT
Attachment DeletedAttachment Deleted you do have me thinking about the brake pipe that transitions from the subframe to the main body structure.This should keep things from moving around and much cheaper than Wadhams replacements!! Attachment Deleted Just need to add a few self tappers and JOB DONE
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Post by Deleted on Jun 15, 2015 15:18:50 GMT
You'd better get a wooden washer for the engine stabiliser whilst you're at it
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Post by Steve P5b on Jun 15, 2015 19:12:58 GMT
You'd better get a wooden washer for the engine stabiliser whilst you're at it Next job on the list now you've spotted it.
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Post by enigmas on Jun 15, 2015 22:49:14 GMT
Yes that component is 'stuffed' Steve. I like your instant solution.
A couple of questions. How much 'free' movement or 'give' is there between the 2 parts of the component given the condition of the bonded rubber? Can you separate the 2 parts easily?
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Post by Steve P5b on Jun 16, 2015 6:30:42 GMT
A bit of an update for the mountings, as you can see after removal they look in a terrible state, but with a clean up and inspection things are not looking too bad. Attachment DeletedTaking on board the comments about what these are for and what too expect after removal, a decision was made to take a good look at things. Three appear to be in much the same condition and one has far more of what looks like extruded rubber "oozing" from within. Overall the dimensions are the same within a 2mm, but the crucial bit is that they all performed the same under test as far as I can tell. By squashing them to there full deflection and measuring the force applied in stages each one has the same resilience through out to a maximum force of 72 Ib ft with absolutely no lateral movement through out . Attachment DeletedNow it was my intension to overcome soft rubber in these mountings and to mechanically fix the two moving parts by welding a washer the underside with the two half's compressed to the thickness of them when fitted to the car. Here's a "mock up" Attachment DeletedI'm non to sure this is a good thing to do as mentioned previously regarding stress fractures etc. my major concern would be that I could not compensate for this:-
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Post by Steve P5b on Jun 16, 2015 6:45:49 GMT
Attachment DeletedAs can be seen the mounting have remained in the shape as fitted to the car and clearly you can see that two have cocked over at some angle where the two mating surfaces in the car are. This in my opinion is why these components are used , to allow for manufacturing intolerances. I would be unable to weld these at this angle when under compression so have decided it against the idea. So, my conclusion is there is virtually no lateral or compressive movement with these mountings which is not what I expected. Making an assumption they are at least twenty years old they are still performing satisfactory and would consider using them again. Obviously I have nothing to compare them with. The one area where I suspect movement between the subframe and body is taking place is in the area where the large locating bolts pass through the body. From memory as I write this, half inch diameter bolts in a 3/4 inch hole? A bit strange and scope for movement if the bolts are not torqued up .
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Post by Steve P5b on Jun 16, 2015 7:26:13 GMT
Hi Vince, as mentioned above I'm assuming my mountings are in reasonable condition but do not have good examples to compare . The overall height of mine out of the car are 36.25mm on average. Any chance of measuring yours for comparison please? Thanks, Steve
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Post by Steve P5b on Jun 16, 2015 7:38:08 GMT
These arrived today for the mod. to the mounting but have at this point possibly decided against the idea. Attachment DeletedAttachment DeletedAll cleaned up and waiting a definitive decision on what to do.
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Post by enigmas on Jun 16, 2015 8:28:00 GMT
Sure Steve, happy to do that for you. Unfortunately I'm currently away for a few days and don't have them to hand. Have you tried the mount in 'extension' by placing load between the 2 halves by using a tyre lever or similar device to see what degree of separation can occur under this type of loading?
I fully understand your hesitance in not wanting to compromise the mounts by welding given the cost of replacements Steve, but it isn't to hard to cobble up a solid facsimile utilizing solid steel bar sections cut to size (then tapped) or thick walled mild steel tube with 1/8" flat plate cut to profile as a base plate. Weld in a suitable nut for the top through bolt and you've got a replacement mount. Start by only fitting 2 at the front. Perhaps that's all that's required to stop any squirm/movement. This would securely anchor the subframe to the car body (at a critical location)
As for stressing the main body structure, I don't believe this is a concern if the suspension is compliant and working correctly. I believe greater stress is created if one component (subframe) is allowed to flex and react against the other. This I believe more adversely affects things like steering and braking especially at speed.
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