Nickp
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| posted on 16/11/11 at 09:12 PM |
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Gearbox as a stressed member?
I'm squeezing a BMW M52 into a Haynes and it's firmly bolted in place on 'Landy' mounts.
I thought I'd test how rigid the engine was with a bar between the top of the chassis and engine as I've got some tight tolerances down
the tunnel. I was quite suprised that the engine barely moves but the whole top of the chassis does!!  Is this normal? I'm now thinking of
bracing from the top of the gearbox (starter bolts, as there's nothing on the head to use) across to the top bulkhead rails effectively making
the gearbox a stressed member. I've got some sturdy looking MR2 roll-bar drop-links and was thinking of using those to brace with and help
rigidity.
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Bare
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| posted on 16/11/11 at 09:21 PM |
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Erm.. Vibration Problems??
To make it even useful as structure, the entire drive train needs bolting rigidly.
Are 'Landy' mounts rigid steel? Dunno never heard the name.
Structural members are not usually rubber mounted :_)
I'd carefully study what's annoyingly flexing and add tubings .. judiciously.. to stop it.
[Edited on 16/11/11 by Bare]
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iank
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| posted on 16/11/11 at 09:31 PM |
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Landy = Land Rover
Rubber, but the diesel ones are as hard as a rock.
Land Rover Range Rover Classic V8 Engine Mount Mounting Rubbers | eBay
or SERIES LAND ROVER DIESEL ENGINE MOUNTING RUBBERS (FOUR) | eBay
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Nickp
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| posted on 16/11/11 at 09:42 PM |
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The drop links are ball jointed at each end so I was thinking this would isolate the chassis from the engine.
Where I've had to cut out a chassis rail I think I've added enough strength to make up for it-
So, it's really a pretty stock Haynes chassis. I wonder where extra strength can be added?
It's just dawned on me that maybe I didnt have the chassis firmly propped up on its blocks when doing this test. DOH!! Anyway, now it's
firmly supported it's not bad at all. Still think I might try the drop-link engine steady/chassis brace idea though 
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Nickp
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| posted on 16/11/11 at 09:47 PM |
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quote:
Originally posted by iank
Landy = Land Rover
Rubber, but the diesel ones are as hard as a rock.
Land Rover Range Rover Classic V8 Engine Mount Mounting Rubbers | eBay
or SERIES LAND ROVER DIESEL ENGINE MOUNTING RUBBERS (FOUR) | eBay
Hmmm, mine are the top ones but do seem pretty hard. Are the diesel ones the same thickness do you know?
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iank
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| posted on 16/11/11 at 09:56 PM |
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Not sure, but I'm someone will.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Nickp
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| posted on 16/11/11 at 10:00 PM |
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Just thinking though. I can see the different design of the diesel mount to limit movement, but wouldn't a diesel mount have to be softer to
isolate the extra vibrations?
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coyoteboy
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| posted on 17/11/11 at 01:02 AM |
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There are some concerns about rigid mounting cast items - vibration, cracking etc.
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Nickp
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| posted on 17/11/11 at 09:14 AM |
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One (or 2) of these could be an option rather than the drop-links-
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180736411437&category=9886&_trksid=p5197.c0.m619
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Neville Jones
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| posted on 17/11/11 at 10:00 AM |
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Gearbox as a stressed member?
Only if it's designed to be from the start.
Flexing in the case will become its demise through broken gears,shafts,or bearings.
How do I know? It's far too long a story, shortened to youthful exuberance and ignorance. 
Cheers,
Nev.
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Bare
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| posted on 17/11/11 at 05:17 PM |
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In mid fifties?? A Chrysler engineer built a Lotus 11 using a 6 cyl engine /trans as part of the chassis structure.
Despite the massive amount of metal the thing was a very good racer. There are images and info 'out there'
Look for it for ideas?
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coyoteboy
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| posted on 24/11/11 at 05:17 PM |
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From a quick think about it, it's a good way to shave a few kilos of steel. But it really is only a few kilos really, as far as I can see. Worth
it if you've got purpose built items and massive budget, but for your average joe bloggs? I won't be doing so, despite having the option
at this stage of design. But on top of everything I wouldn't have part of it rigid mounted and part not - that's a problem that physics
will resolve with pain and broken parts.
[Edited on 24/11/11 by coyoteboy]
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MRLuke
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| posted on 9/1/12 at 03:20 PM |
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In a similar vein to the above poster, you cannot mount the engine on rubber bushes with the gearbox fixed solidly as you will break the gearbox.
I have solid mounted my engine and used a stiff poly mount for the gearbox to resolve any minor movement without cracking.
Haven't got it on the road yet mind..
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