Diff upper mount bolt

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blueyedbiker
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Diff upper mount bolt

Needed to remove the diff to take out the prop shaft (long story) to find the upper mount bolt utterly jammed into the RH metalastic chassis bush which would have been understandable had the car done a few miles but this is a new build (hence long story).  Resorted to the Dremel to remove the bolt head and then drew it out with the nut and an increasing stack of washers whereupon it jammed in the LH bush this time needing a length of ali tube to draw it out.  Ran the micrometer over the bolt and the head end of the shank is +0.6mm over the rest of the shank.  So, moral of the story is run a micrometer over the bolt before you hang the diff on it to save the subsequent grief.

Jonathan Kay
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Original standard factory bolt and bushes?

Jonathan

blueyedbiker
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Yup!  New, or rather, unused chassis and bolt out of the CCC rear axle or suspension fittings pack.

Jonathan Kay
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Thanks.

Have you asked them for a comment (and/or a new bolt)?

Jonathan

SM25T
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Or remove the nut,and hit that end of the bolt with the biggest club hammer you have. .... then use a drift
blueyedbiker
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Tried that and was in danger of trashing the bushes then there really would have been problems.

Will mention it to CCC.

J.

Jim 123
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If you draw the problem bolt as far to the left as you can and then get your Dremel out again, will that mean that the remaining length of bolt is short enough to sit within the innermost faces of both metalastic bushes,and allow you to drop the diff, if you drift the remainder back to the centre?

An alternative might be to get a short length of bolt that is the same diameter as the mounting bolt and pass this in from the right hand side until it meets with the current problem bolt. Then try to drift the problem bolt back out to the right.  With a bit of luck you may get a clean re-entry of the problem bolt back into the right hand metalastic.

In both cases the diff will need to be aligned and supported by a jack/platform. Best of luck.

Jim

John Vine
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I think the OP has extracted the bolt already?  But a good tip re the micrometer!

The problem I had during my build was that the metalastic bushes didn't line up with the holes in the (Ford) diff.  At first, I suspected a chassis fault, but when I queried this with CC, they advised applying a mighty whack on the bolt head with a hammer.  "That's what we do in production", they quipped.  It worked. Not only that, the bolt proved easy to extract later.

JV

Jim 123
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Thanks John just read the OP again. On my build I put a temporary short bolt in the LH side which was the same diameter as the mounting bolt.  The mounting bolt slipped in easily from the right displacing my temporary fixing on the LH side without the need of hammer.

Jim

rockinroyston
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I used temporary bolts on the top too, managed to get the diff in on my own using an engine hoist. A lot less dangerous than balancing on a jack!

https://www.lotus7.club/blogs/diff-almost

 

blueyedbiker
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Well, the prop shaft is now the correct length (shortened by 3/4") so it doesn't trash the tail shaft oil seal,  the diff's back on and centred (top tip - use a stick with a pencil mark on it), the upper mount bolt lightly kissed with emery so it's a snug fit and well copperslipped, the gear box mount spacer's fabricated (15mm billet aluminium £10 off eBay), the reverse light switch access hole's enlarged so the switch is now accessible, the switch connectors modified so they don't snag the beautifully crafted cover plate and the holes in the bottom chassis plate have been adjusted so the gear box misses the chassis rail at the front and the prop shaft clears the chassis rail at the back.  What next I wonder?