Inner fulcrum wishbone mounting brackets shim

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JD-JAG66
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#1 Inner fulcrum wishbone mounting brackets shim

Post by JD-JAG66 » Mon Oct 09, 2017 10:28 am

The service manual mentions that it is necessary to shim between the differential casing and mounting bracket.

I had my brackets powder coated so the thickness of the paint "covered" the shimming (hardly any) I found when dismantling the IRS.

I couldn't find any posts on this topic, so I wonder if shims are only required to locate/insert the fulcrum shaft but nothing else.
Am I overlooking something?

Cheers
Jan
Jan Deurinck
Series 1 - 1966 - 2+2 - LHD - American Import
Si vales, bene est, ego valeo

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abowie
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#2 Re: Inner fulcrum wishbone mounting brackets shim

Post by abowie » Tue Oct 10, 2017 1:31 am

The shims serve to ensure the the brackets are correctly aligned with the holes in the cage, ie that all are concentric.
What I do is attach the bracket to the diff then with the diff in the cage see if the shaft will slide smoothly through all 4 holes. If they don't' loosen the bracket bolts and insert shims trial and error until the shaft slides through. You may find you need more shims at the front than the rear or vice versa. I tend to cut them in half to facilitate this.
If you have excessive powder coat on the back of the bracket you may be better off sanding it off and painting it with paint.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB. 1979 MGB.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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JagWaugh
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#3 Re: Inner fulcrum wishbone mounting brackets shim

Post by JagWaugh » Tue Oct 10, 2017 6:32 am

The shims are just to compensate for manufacturing tolerances between the cage and the casing&brackets.

You'll want to get the powder coat off the mating faces - if the bracket fixing bolts have come loose you may find that the mating faces aren't flat anymore, so stone them to be so. Flip the cage, mount the brackets loose, fit your wishbones and inner fulcrum, then measure the gaps between the pumpkin and brackets with a feeler gauge. Now purchase your shims (or make them from shim stock). Lately the double hole shims aren't available, so clarify that with your supplier, otherwise you'll end up with half as many single hole shims as you need.

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