Split lock washer grade - caliper mounting bolts
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
Split lock washer grade - caliper mounting bolts
Stupid question I'm sure, but every time I apply the 70 ft lb torque to the bolt to re-mount my caliper to the bracket, the split lock washer gives way. What grade / type split lock washer is supposed to be used so this doesn't happen.
Instructor
Joined: Feb 2007
Posts: 114
Likes: 18
From: McKinney TX
I found this question interesting. If you look at information posted by Portland Bolt and Manufacturing Company, you can find this quote:
Generic split Lock washers are not regarded as structural components, since they are just fixing a nut into place, and thus do not have the same amount of scrutiny that nuts and bolts have. Due to this, there is currently no ASTM specification that covers a generic split lock washer. Also, there is no high strength lock washer specification by ASTM and generic lock washers are often used with high strength bolts, since there is no “high strength” lock washer specification or any grades at all for that matter.
Since there are vendors selling split lock washers as grade 8 and possible other grades, I looked to see what others were using for brake calipers. While I've never used them, it seems many are using Nord-Lock washers. I'm curious if other forum members use these Nord-Lock washers and if so, use the old style of the newer X-Series.
Generic split Lock washers are not regarded as structural components, since they are just fixing a nut into place, and thus do not have the same amount of scrutiny that nuts and bolts have. Due to this, there is currently no ASTM specification that covers a generic split lock washer. Also, there is no high strength lock washer specification by ASTM and generic lock washers are often used with high strength bolts, since there is no “high strength” lock washer specification or any grades at all for that matter.
Since there are vendors selling split lock washers as grade 8 and possible other grades, I looked to see what others were using for brake calipers. While I've never used them, it seems many are using Nord-Lock washers. I'm curious if other forum members use these Nord-Lock washers and if so, use the old style of the newer X-Series.
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
There's generally 2 types available, good (usually called hardened, through hardened or gr8) and the the ones that you get and the "general" hardware stores that distort, open and really don't do much (possibly made from cheese but I'm not 100% sure)
M
M
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
You need really, really good split washers for them to have any chance of being useful.
Belleville (spring) washers or Nord-Lock (wedge lock washers are better solutions if you really want the washer to retain the bolt. The spring force of the belleville washer needs to be properly matched to the bolt tension when torqued.
A tab lock washer that you bend one tab over the side of the caliper and another tab against a bolt flat would also work very well to keep the bolt from coming loose.
Belleville (spring) washers or Nord-Lock (wedge lock washers are better solutions if you really want the washer to retain the bolt. The spring force of the belleville washer needs to be properly matched to the bolt tension when torqued.
A tab lock washer that you bend one tab over the side of the caliper and another tab against a bolt flat would also work very well to keep the bolt from coming loose.
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Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
^ what he said. You'd have too have such a high grade spring steel for traditional split lock washers to be able to actually produce any preload that it's almost impossible.
Last edited by L88Plus; Feb 23, 2021 at 09:55 AM.
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
Thanks for all the replies. I originally got stainless steel at Home Depot....they were worthless. Then went to ACE Hardware - who have a much better selection for specialty hardware items - and got Grade 8 Stainless Steel. They held up perfect, so glad I went the extra step.