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+--- Thread: Sump bolt length (/showthread.php?tid=9727)
Sump bolt length - falcott - 23-11-2024
Hi all, can someone tell me the length of the sump bolts please? My sump bolts have been tapped to 5/16" and fitted with 1/2" long cap screws -- not by me, I might add. When I was inspecting it for leaks I found that two of them have departed. I'm wondering if they are supposed to be longer (3/4"?). Thanks.
RE: Sump bolt length - Chris KC - 23-11-2024
Do you have a standard "tin" sump or a cast aluminium one?
RE: Sump bolt length - falcott - 23-11-2024
It's a tin sump.
RE: Sump bolt length - falcott - 24-11-2024
These 5/16" bolts have spring washers under them. I'm thinking of ordering the oval sump washers from the Seven Workshop. If they are fitted with a spring washer also, wouldn't that, in theory, entail a slightly longer bolt to allow more purchase on the threads?
RE: Sump bolt length - Ian Williams - 24-11-2024
The oval washers were std fitment so std length bolts will be perfect
RE: Sump bolt length - falcott - 24-11-2024
Okay, but my sump is fitted with 5/16" cap screws and spring washers. What I want to know is what was the length of the original bolts, because my thought is that 1/2" length isn't quite enough when the thickness of the flange and the washer is taken into consideration. Also, were spring washers fitted as well as the oval washers? Thanks.
RE: Sump bolt length - Howard Wright - 24-11-2024
Hi Geoffrey
A standard 5/16” BSW nut is 1/4” thick so as long as you have at least that depth of contact and don’t torque up too tight (bearing in mind the crankcase is alloy) you should be OK. Don’t make the bolts too long as the holes in the crankcase are blind and it is easy to punch through leading to oil leaks. I know this because some ‘gorilla’ had in the past punctured several sump holes in a crankcase I used recently!
Cheers
Howard
RE: Sump bolt length - Tony Press - 24-11-2024
And the rear bolt under the flywheel is short if I remember correctly
RE: Sump bolt length - falcott - 25-11-2024
Thanks Howard and Tony.