Simon
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| posted on 6/2/03 at 04:29 PM |
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Rod end/Spherical Bearing Q
Chaps,
These things are confusing me.
I want to put them on the rear, inner lower wishbone pivots.
What do I need:
Spherical Bearings or Rod Ends?
Anyone got any ideas on rating / PTFE lined or not, low/high carbon steel etc etc.
Also, any suggestions were to get them. Just tried Raldes - didn't expect to have any in stock till mid march
I was thinking 1/2" bore / 1/2" thread and a rating of about 10,000 lbs.
Cheers chaps
ATB
Simon
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stephen_gusterson
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| posted on 7/2/03 at 08:23 PM |
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i must admit im confused over the difference - i have used rod ends in my suspension - i think rortys your man here.....
i used 16mm cos there is a big jump over 12mm ratings. you have to bear in mind that pulsed loads are 25% of the static load, and about 12% if they
are loaded into the sides of the bearings.
also take into account weightings will go up to double (1G) in braking conditions.
atb
steve
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Simon
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| posted on 10/2/03 at 09:40 AM |
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Steve,
I phoned Tiger, after doing a search on here and reminding myself that Tiger use them on their rear end, and having based my IRS on their setup, and
get a set of 1/2" and inserts from them.
If it's ok for them etc etc
ATB
Simon
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stephen_gusterson
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| posted on 13/2/03 at 11:20 PM |
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do bear in mind there is a huge range of load ratings for any size rod end.
tiger might be using top end rated stuf......
atb
steve
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Simon
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| posted on 14/2/03 at 09:47 AM |
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Steve,
I now have Rose joints from Tiger. I also bought some 12swg 1" dia tube (£1/foot!!) and the threaded, weld in inserts.
The person on the other end of the phone advised they were "..£16.00, because they're the good ones" - whatever that means.
As for your earlier posting regarding "g-forces", if I remember correctly, and as far as acceleration/decceleration are concerned, 1g = 0-55mph in
one sec.
So, assuming my car does that in 4 sec(?), the loading with be .25g, which increases at the rose joint by a given amount (don't know the maths here),
as the angle from the centre of wheel to r/j isn't 45 deg. However, even allowing for 3 times the force, they will only have to cope with 660lbs (1/2
weight of (600kg) car per side?).
That's my theory, and could be complete b*****ks.
If anyone knows any different, please let us know, they is fairly important.
Thanks
ATB
Simon
[Edited on 14/2/03 by Simon]
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kingr
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| posted on 14/2/03 at 11:08 AM |
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Hmmm, not according to my calculations :
force of gravity, g = 9.8 m/s^2
9.8 m/s^2 = 0.006089 miles/s^2
0.006089 mile/s^2 = 3600 x 0.006089 miles/hour/s
= 21.9 miles/hour/s
therefore 1g force will result in 0-60 time of 2.7 seconds, however, your tyres will also be a limiting factor. I think 0.8g is a reasonable figure
for a RWD non aerodynamically assisted car, so 3.4 seconds would appear to be somewhere around the max. Anyway, you're unlikely to rip up bearings
while accelerating, there will be much greater forces if you go into a corner hard and fast, and then go over a bump.
Just as an aside, in the current copy of EVO they put force measuring equipment into various cars and take them round the track, they quote max
lateral acceleration and max longitudinal deceleration, the Radical SR3 scores (IIRC) approx 1.46g for both! 
Kingr
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Simon
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| posted on 14/2/03 at 12:43 PM |
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Kingr
Like I said "..if I remember correctly.." and "don't know the maths here"
Thanks for the lesson though!!
ATB
Simon
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kingr
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| posted on 14/2/03 at 01:45 PM |
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Simon - The crux of this is that you can't go too far wrong using the tiger ones. I would say that tiger over engineers to quite a large degree,
bolts for instance - RC uses 8mm iirc, Tiger uses 1/2", so over 50% greater diameter and verging on 3 times the area, and presumably over 3 times the
weight. Don't know what grade they use, but it seems a bit of a funny way to save money.
Out of curiosity, how much did the inserts cost?
Kingr
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stephen_gusterson
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| posted on 14/2/03 at 11:05 PM |
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actually, i didnt mean acceleration G force.
I meant braking G force. I think I read somewhere a good set of brakes cant even exceed 1G, but take that as a maximum. When you brake , a lot of
weight - like less than 1G or so - will transfer FORWARDS.
another point - much harder to calc - is the actual forces caused by the torque of the drive shafts - im sure they would like to rotate the hub as
well as the wheel, but its the 'bones and joints that are stopping it. So, snap acceleration from stop will also give quite a big pulse load into the
joints.
Im not happy with my 16mm ones - but then im just a worrier!
atb
steve
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stephen_gusterson
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| posted on 14/2/03 at 11:07 PM |
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interesting that people can buy stuff rom tiger now.
a couple years ago I asked about their car (do they still do it?) thats a replica of a morgan. I said I was building a morgan replica, and would they
sell me some panels.
I was told they sell only to buyers of their kits.
silly - I would have taken my money. Perhaps they are on hard times or have woken up to commercial realities?
atb
steve
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Rorty
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| posted on 15/2/03 at 03:36 AM |
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I've been away, and as a result have sort of missed the boat with this thread. However,
Simon:
quote:
Spherical Bearings or Rod Ends?
Spherical bearings, are just that. Rod ends though, are basically SBs with a male/female thread attached. Trackrod ends are the automotive equivalent,
and usually have a captive tapered stud within their bore, and a rubber boot attached.
A 1/2" rod end can vary in USRL from about 7,000 lb/f to almost 30,000 lb/f depending on what they're made from. The difference in real terms is,
you can f**k one with a hammer, and you can't f**k the other in a 300kmh dragster crash!
If Tiger are selling their "good ones", I would assume they are up to the job? It wouldn't do any harm to enquire about part numbers/USLR
figures.
I choose rod ends for my off-road cars based on .75 of total mass. Even though the entire car can land on one wheel at times, from experience I would
prefer one or two rodends to fail if I hit a tree/rock, as opposed to wiping off the chassis/me.
On road based cars, I base the choice on 2.5 times corner mass, and size has to match commensurate fasteners.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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