LancasterBob
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 posted on 13/5/02 at 07:23 AM |
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Multi-part upper ball joints (don't read if easily scared!)
Before reading please understand that this is in no way aimed at scaring, criticising, or anything along those lines.
Had an upper ball-joint fail yesterday.
Cause is hard to ascertain as there isn't much of that corner of the car left (unfortuntely was in a tunnel at the time!)
Looks on first examination that the upper balljoint (nearside) sheared at the root of the thread, causing the prang.
Anyone else had this happen to them?
On the plus side the chassis (homemade) was excellent - all welds remained intact (appart from ripped suspension) and the majority of the impact
deformed the engine bay tubes.
Haven't got a scratch on me, which is nice!
Will post more later when on free connection.
Cheers
LancasterBob
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Dunc
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| posted on 13/5/02 at 09:00 AM |
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Sorry to hear that Bob, glad you're ok. Did the ball joint shear where the end of the thread tapers downward towards the ball joint. I've noticed
this looks quite a bit narrower than the thread and therefore will be weaker.
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Dick Axtell
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 posted on 13/5/02 at 04:22 PM |
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Hi Bob -
Crucial question - who supplied the failed b/j? And did I buy mine from the same place?
Dick
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LancasterBob
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| posted on 14/5/02 at 11:26 AM |
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Bit more background...
Lucy was built roughly around the book except using a 1256cc Chevette as donor. So things like tapers on the uprights were different, so we used VW
transporter rodends for the upper balljoints. Last summer did an engine swap for a 2l injected pinto, which boosted performance and weight.
Thinking about the loadings, under braking the rod end/ball joint is placed in bending as the braking force at the tyre is transmitted to the chassis
through the wishbones (upper wishbone outer end is forced forwards, and rear wishbone outer end is forced rearwards).
Track rod ends are only ever placed in shear parrallel to the axis of the threaded portion - i.e. they are not intended to resist bending loads.
Has anyone used an alternative upper joint; if/when I rebuild I want to bin using a track rod as the upper joint and move to something else?
As an aside went to Barbon Hill-climb on sat, had a wicked time with some excellent machinery on show - 300bhp 4.2l 4wd Dax Rush Quadra was quite
quick to say the least!
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stephen_gusterson
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| posted on 14/5/02 at 01:04 PM |
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AFAIK
the whole world uses Transit tie rod ends for the top joint, and yours wasnt one of those?
Panic over in my camp!
ATB
Steve
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Simon Mc
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| posted on 14/5/02 at 07:02 PM |
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If using a sierra upright, could you make up the adaptor in steel, weld a high tensile bolt to it so it sticks out the top and use a rose joint? just
a thought.
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stephen_gusterson
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| posted on 14/5/02 at 07:08 PM |
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quote:
If using a sierra upright, could you make up the adaptor in steel, weld a high tensile bolt to it so it sticks out the top and use a rose
joint? just a thought.
Yes, you could, and some people do!
However,
A rose joint is strongest in the direction of 'pull' on the joint. Loads sideways into the bearing derate it to about 15% so i am told.
Provided that the lower wishbone takes the shock absorber loads, then there shouldnt be too much 'sideways' loads.
atb
Steve
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