Lotus Elan

diff bolts

PostPost by: miked » Sun Sep 28, 2014 6:47 pm

Can anybody answer this please? The 5/16 UNC bolts that fasten the diff' to the alloy case!
Are they mean't to be bolts with a shoulder on so they help locate. Not just set studs that are threaded to the back of the head.

I have taken some 1 inch set studs out. Can't help thinking they should be 1 and a 1/4 inches long. When I have done it before I am sure they were bolts.

Mike :?
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PostPost by: Chancer » Mon Sep 29, 2014 9:13 am

Absolutely!

And not just bolts with a plain shank but close tolerance "fitted bolts", its one of the first things we learnt as apprentice engineers.

The same is true for propshaft and flywheel bolts.

Using setscrews (bolts threaded throughout the length) is a recipe for disaster.

Editted, I misread the posting, my comments relate to drive torque fixings.
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PostPost by: CBUEB1771 » Mon Sep 29, 2014 1:52 pm

The Lotus part number is XUCS0516 as shown in the Service Parts list. So these are just plain 5/16"-18 bolts, 1.00" long. They do have a short, unthreaded length of shank under the cap. (You need one bolt to be 1.75" long if the differential housing stiffener is fitted.) This matches the description of the bolts that were originally installed in my +2S. Keep in mind that these bolts have nothing to do with relative position of the pinion and ring gears. They do have some effect on the alignment of the output drive shaft splines as they enter the differential. The aluminum housing would have to be modified with counterbores to take advantage of a bolt with a longer unthreaded shank to prevent the threaded section from experiencing shear loads.
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PostPost by: miked » Tue Sep 30, 2014 5:45 pm

Thanks Russ and Chancer.

I will sort out. Your statement Russ was the bit that concered me and why I asked.

They do have some effect on the alignment of the output drive shaft splines as they enter the differential.


Thanks again for sorting me out with the correct bolt info'.

Regards Mike :D
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