Hey all, I've just bought aftermarket risers for my 08 Night Train and the hex cap socket bolts that went into the original top clamp are a little too long for the new risers. I went to the local fastener store to get new bolts but all they had were 18.8 stainless ones. The Harley ones are Grade 8. I know Grade 8 steel is much stronger than 18.8, but my question is if 18.8 is still strong enough for the handlebar clamp.

My instincts are to try and find Grade 8 bolts, I mean Harley must have used such strong bolts for a reason. But, I'm just curious now, and want to know if 18.8 is technically strong enough.

 

I've wondered the same thing but don't really have an answer. I have used stainless hexcaps for things like the primary cover with no bad results. Not sure I'd be ok with them holding the handlebars in place. Since the stock ones are a little long have you considered making them shorter by cutting or grinding to the length needed?

 

They use Grade 8's for a reason. Stronger is better than weaker.
http://www.boltdepot.com/fastener-in...ade-Chart.aspx

 

The handle bars have stress and torque on them. This would add stress and torque to the risers. I wouldn't risk it. Get the Grade 8.

 

I have used them on a 2006 Low Rider and my current 2007 Heritage. I have no issues on the strength. 18-8 Stainless is the same strength as a grade 5 steel bolt.

Note: The threads will strip out of the riser before the bolt will break.

The bolts are a 5/16-18. The charts below will give you the difference between grade 8 and 18-8 or 304 stainless. The second chart is from the marine guide for bolts. It's a little easier to understand.

 

The riser blts are treaded into the risers, which are made of die cast zinc alloy. The tapped holes in the risers will fail LONG before the stainless bolts will break (at least they did on mine).

 

I've been know to hacksaw the offending threads run a die down the bolt and reinstall.

advice to be used at your own risk

 

Thanks for the replies. I had considered cutting the existing grade 8's but wasn't sure how difficult that would be. Guess I'll give that a shot next. I don't like taking chances with the handlebars for obvious reasons.

 

Been running Stainless HW on my rear wheel drive pulley for years now with NP. Way more stress there than a riser will ever see.

 

Put a couple of stainless washers under the head.