Flywheel retaining bolts

PostPost by: RichardHawkins » Thu Jan 29, 2015 11:08 pm

One of the previous owners of my car was a bit of a gorilla. Many of the engine bolts have been stretched, so I am replacing all crucial fasteners even where no damage is obvious.

I have bought ARP bolts for head, main caps, big ends, and flywheel. All of these were supplied with washers except the flywheel. The literature that accompanied these bolts warns against using ordninary or tab washers as they are soft and will yield in service, allowing the bolts to become loose. The cast iron flywheel is also comparatively soft. Why did ARP omit hardened washers, and should I buy and fit hardened washers? Hardened washers are available from ARP as an accessory.

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PostPost by: JohnDanbyRacing » Thu Jan 29, 2015 11:49 pm

Have never used washers with the flywheel bolts and never had a problem, i always use 648 Loctite or equivalent on them though and not the lubricant supplied.
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PostPost by: StressCraxx » Fri Jan 30, 2015 3:16 am

+1 for John's advice. Yes, the flywheel steel is soft. Ford did not use washers either. Use the proper torque to stretch the bolts and use loctite red on the threads.
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PostPost by: CBUEB1771 » Fri Jan 30, 2015 10:34 pm

Lock tab washers were used on the four-bolt crankshafts. No washers were used on the six-bolt crankshafts, both according to the Service Parts List.
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PostPost by: Craven » Fri Jan 30, 2015 11:00 pm

It may be of interest, in a meeting between Ford & BRM in 1965 a recommendation was made to improve for competition purposes the flywheel fixing ? Four hardened steel washers are used instead of the standard lock tab plate, and the bolts are wired together on final assembly?
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PostPost by: RichardHawkins » Sat Jan 31, 2015 6:02 pm

Ron,

Thanks for the comment. What really bothers me is the inconsistency between similar bolts across the engine i.e. the big ends, which are supplied with hardened washers, presumably to spread the load, whereas the flywheel bolts are not provided with washers. I would expect the con rods to be harder than the cast iron flywheel, and if anything I would have thought there was more need for hardened washers with the flywheel.

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PostPost by: Craven » Sat Jan 31, 2015 9:28 pm

I have only built standard engines using standard parts and followed the workshop manual on torque settings and not experienced any problems with bolts coming loose.
Perhaps it?s a simple matter, say in the case of a 12 bolt flywheel, there is insufficient space to gain any advantage in fitting washers!
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