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Lower Arm Pin-How Far In?


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#16 tiger99

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Posted 25 June 2017 - 02:27 PM

I am thinking about the changes over the years to the lower arm bushes. At first they were top hat rubber bushes, with no inner steel sleeve, part 2A4294. My MK 1 van had those. Then came the tapered type 21A1882, from the mid 60s till the end of production. I have changed more than a few of both types. The top hats did not have inner sleeves, and I am fairly certain that the tapered type did not either, the amount of compression being set by the shoulder on the pin, which butts up hard against the subframe web when the nut is tightened, and the position of the "washer" on the pin, which is fixed at manufacture, That has never to my knowledge caused problems, and both types of bush are easy to fit.

 

If I am not mistaken from the pictures, your fancy new bushes have inner steel sleeves. Now that is quite normal in many bushes, but if you have a design which requires the pin shoulder to abut the subframe AND the sleeves to be clamped tight, you have an engineering impossibility. Either the pin will be insecure in the subframe and fretting will occur, or the sleeves will slip on the pin, and again, fretting will occur, in both cases leading to damage and possible failure. The sleeves are effectively incompressible.

 

Maybe it is an optical illusion in the photo, but if not, kit shows a complete lack of basic understanding of engineering by whoever chose those bushes to fit there. The bushes may be perfectly fine for some other vehicle.

 

Please do check that I am right by seeing whether there are steel sleeves in the old bushes. It is possible that there may be short ones that don't butt together tightly, but I do not see the point.

 

If I am right, you need to take the bushes back to the supplier and complain. If they are difficult about it, just mention Trading Standards.



#17 Spider

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Posted 25 June 2017 - 08:18 PM

The later 'tapered' factory bushes have inner steel sleeves.



#18 tiger99

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Posted 26 June 2017 - 12:19 PM

So in that case, how do you get the sleeves butting together and the bolt shoulder hard against the subframe? Are they very thin sleeves, which deform as the bolt is tightened? That would make sense. The sleeves in the bushes we see here do not appear to be thin and deformable.

Whatever, the dimension of SOMETHING is wrong, and it has to be the rather expensive bolt or the bushes. The subframe has no direct influence on the matter.




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