FuryRebuild
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| posted on 4/4/12 at 03:23 PM |
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Bearings and Bushes - nothing's ever easy
Well, This post is partially a whinge, and partially seeking advice.
I'm going to change my lower wishbones from bushes to spherical bearings (notice, not cut them and fit rod ends - I want to avoid the Rod End In
Bending problem).
However, getting my calipers into the bush housing reveals the following measurements:
OD: 1.06" (nearly 27mm)
ID: 0.5"
Guess what? spherical bearings (from medway at least) with 1/2" inner have 1" outer sizes, and they rattle around in there when trial fit
one.
So, does anyone know of a source for sphericals to fit these odd dimensions? I think it's far too large a gap to try and hold them in place with
loctite, and if I go for 1.09" outer dimensions then that's a 0.38mm radius the housing's too narrow by - probably too much to press
them in without making them a permanent fixture.
Last case resort is to find a machine shop that will widen the bore to 1.094" and that will mean i'm on 9/16 inner bores. This will mean
buying/borrowing a reamer and getting new bolts. Not the end of the world, but a PITA nonetheless.
Any suggestions?
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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PSpirine
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| posted on 4/4/12 at 03:27 PM |
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I would ream the wishbone tubes out to the next size available.
Otherwise I don't know if you're able to sleeve them and ream out to 1" (not sure the sleeve thickness would be sufficient
though).
Finally, you can do both! Ream the tubes out to get a decent sleeve thickness, and then ream the sleeves out to 1"...
Either way, you'll struggle to avoid a machine shop!
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DIY Si
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| posted on 4/4/12 at 03:29 PM |
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The only way to fit bearings like that is in a reamed to size tube. Anything else will see them rattle about.
If you really want the smaller bearings, and keep the current bones, you'll need to fit new bush tubes, or sleeves. Personally, I'd just
go up a size and not worry about it. At worst you'll need to drill 9/16ths holes in the chassis brackets.
[Edited on 4/4/12 by DIY Si]
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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FuryRebuild
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| posted on 4/4/12 at 04:03 PM |
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Dear PSprine and Si
I think this was the inevitable result - just wondering if i'd missed something in how bearings and bushes are sized.
I'll get them reamed out - any sleeve would have a .3mm radius - it'd be like tinfoil.
In another act of rampant self justification, Medway list the larger bearings as having a radial static load of 73kN rather than 59kN, so I can kerb
it more 
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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Mad Dave
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| posted on 4/4/12 at 04:24 PM |
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I’m not sure if I’m reading this correctly or not. Are you just planning to install spherical bearings in the tubes that previously had
polybushes?
You can’t just slide them in and bolt it all up and say “there, I got rid of the rod end in bending problem” because you have just created something
far more dangerous
The bearing housing or tube needs to be machined (with a shoulder) to the correct sizes & tolerances and holding the bearing in place is a circlip
housed in a groove. Ideally the bearing housing would be welded to the wishbone first and then final machined to ensure the bore is true as the heat
from welding can cause deformation.
Spherical Bearing Housing / Cup - 1/2'size ,Rose Joint | eBay
Loctite should not used to fill gaps and glue them in place so they don’t fall out. Neither should you try and press a bearing into a bore that is
too small. The hoop stress might be too high and the tube could split and cause a major accident!
If the spherical is in the vertical plane then you still have a problem as they are not designed to take large axial forces. They should be
positioned so the forces act radially
Dave
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FuryRebuild
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| posted on 4/4/12 at 05:46 PM |
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Hi Dave
Thanks for the advice. Let me elaborate further - I think this is a good discussion.
My wishbones already have the tubes in place, currently holding bushes which are about 1.5" long, and just over 1" diameter. A 1"
bearing just drops through the tube, hence wanting either the right size, or machining the current tube out to the right dimensions to take a larger
size.
As I said below, the wrong size (too small) just rattle around and I wouldn't want to loctite (or any other adhesive) them in place - they
wouldn't sit true, it's not the right way to hold them in, and they wouldn't be demountable to check for wear and servicing.
Moreover, a lot of adhesives suffer under vibration.
My plan would be to put a pair of spherical bearings in each housing, giving extra support. I would press them in given the right dimensions, and
accept that a circlip is the standard way of securing them in there. Between each I'd put a spacer to ensure they can't move towards
eachother. They'd then be located on the outside buy the hat/spacers between the bearing and the bracket, and on the inside with a spacer. As
such, they shouldn't be subject to being twisted out (I hope).
If I understand correctly, putting two in each tube would mean the forces would then be acting on the edge pushing inwards, rather than trying to
twist the bolt out of the bearing.
I know one of the solutions is to remanufacture the wishbones so the bearings are horizontally mounted, but that for me means chopping brackets off
the chassis and putting new ones in, and I'm trying to avoid that - I can make a jig and maintain precision for the wishbone, but it'll be
trickier with the chassis, and this solution will not have any adjustment so I can't account for fabrication issues if i get the bracket in the
wrong place.
Saying that ... i could make bolt-on brackets.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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phelpsa
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| posted on 4/4/12 at 06:53 PM |
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quote:
Originally posted by FuryRebuild
Hi Dave
Thanks for the advice. Let me elaborate further - I think this is a good discussion.
My wishbones already have the tubes in place, currently holding bushes which are about 1.5" long, and just over 1" diameter. A 1"
bearing just drops through the tube, hence wanting either the right size, or machining the current tube out to the right dimensions to take a larger
size.
As I said below, the wrong size (too small) just rattle around and I wouldn't want to loctite (or any other adhesive) them in place - they
wouldn't sit true, it's not the right way to hold them in, and they wouldn't be demountable to check for wear and servicing.
Moreover, a lot of adhesives suffer under vibration.
My plan would be to put a pair of spherical bearings in each housing, giving extra support. I would press them in given the right dimensions, and
accept that a circlip is the standard way of securing them in there. Between each I'd put a spacer to ensure they can't move towards
eachother. They'd then be located on the outside buy the hat/spacers between the bearing and the bracket, and on the inside with a spacer. As
such, they shouldn't be subject to being twisted out (I hope).
If I understand correctly, putting two in each tube would mean the forces would then be acting on the edge pushing inwards, rather than trying to
twist the bolt out of the bearing.
I know one of the solutions is to remanufacture the wishbones so the bearings are horizontally mounted, but that for me means chopping brackets off
the chassis and putting new ones in, and I'm trying to avoid that - I can make a jig and maintain precision for the wishbone, but it'll be
trickier with the chassis, and this solution will not have any adjustment so I can't account for fabrication issues if i get the bracket in the
wrong place.
Saying that ... i could make bolt-on brackets.
You're making this far far more complicated than it need be.
Putting two sphericals side by side loses the misalignmment ability so it is more than likely that they will end up binding.
I have recently converted my wishbones to spherical outboard using the 1/2" bearing housings from Mcgill. I simply cut off enough of the
original bush tube to put the housing in and welded up. So much easier and gets you exactly what you want. Available for £5 a housing. I'm not a
massive fan of circlips, but located like this there is no way that the bearing can come loose should the circlip fail:
 
Description
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FuryRebuild
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| posted on 4/4/12 at 07:06 PM |
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y'see.
This is why this is such a great forum. At least one good alternate solution. A price that's pleasant. Advice about not ending up with a major
issue on my hands.
Or should I say: "I disagree with you all and I'm off to make a death-trap and I know better!"
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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phelpsa
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| posted on 5/4/12 at 06:42 PM |
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No problemo.
Death trap it is 
P.S. can grab some more photos / measurements if you would like, still got some unused housings.
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