Odd - English bolts on my Suzuki?

[Guest]

Well, I'm fully recovered from surgery and I've been getting to know my GS550 a bit better over the last week. The other night I took it for a "spirited" ride around town. Turning one corner spinning 7k I heard the diminishing tink-tink of something falling off my bike After riding gingerly home I checked her over really well and discovered both of the front left frame bolts to the motor mount were missing. Must not have torqued those down enough. So I took one of the bolts out of the right side and went down to the hardware store to get 4 new ones with lock washers and nuts.

The upshot is, after perusing the metric collection with no success at all, I found that the bolts were 5/16"-18. That struck me as VERY odd on the Japanese bike! But they fit perfectly. There are English bolts holding the rear turn signals on, but that could just be what some PO had laying around that fit well enough. These were threading into what look like the official Suzuki mounts. Is this normal or is this bike the victim of some creative engineering?

[redsoxvw]

Maybe P.O damaged the hole at some point and tapped it with a Standard size tap???

[doctorgonzo]

Maybe P.O damaged the hole at some point and tapped it with a Standard size tap???

That would be my thinking.

[Steve]

Walt Disney Engineering at its best.










(That's Mickey Mouse Engineering in more impressive terms. )

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[Nessism]

Only “english” threads I’ve found on a GS bike is a pipe thread on a temp sensor or similar. I have noticed though that if you go to the hardware store to purchase metric hex head screws, the hex size is different from those that Suzuki used (or any other Japanese vehicle manufacturer for that matter). Pretty annoying when you need a bolt or two and can’t find the proper size.

[flyingace]

I probably have half a dozen non-metric nuts/bolts on my bike. I use whatevers laying around when I do repairs. I guess there are other owners out there who are not OCD.

[mike_of_bbg]

OK, I'm not really worried about it because the whole assembly and fit is solid. Just curiosity as it didn't add up.

In retrospect, those were the only bolts on the bike that took a 13mm socket, which tends to fit 1/2" bolt heads really well. Should have been a clue.

[doctorgonzo]

Only “english” threads I’ve found on a GS bike is a pipe thread on a temp sensor or similar. I have noticed though that if you go to the hardware store to purchase metric hex head screws, the hex size is different from those that Suzuki used (or any other Japanese vehicle manufacturer for that matter). Pretty annoying when you need a bolt or two and can’t find the proper size.

Pet peeve of mine is inability to find SS bolts for 10mm fine thread bolts. All the 10mm on these bikes are fine thread and I have only found them in regular steel.

[Nessism]

Pet peeve of mine is inability to find SS bolts for 10mm fine thread bolts. All the 10mm on these bikes are fine thread and I have only found them in regular steel.

There are a couple of different grades of stainless commonly used for fasteners: A2 or 18-8, and A4 or 316. A4/316 has better corrosion resistance and is more expensive.
Both grades have roughly the same strength, 100 ksi.

SAE grade 5 hardware has similar strength to metric 8.8 - about 117 ksi. The Japanese motor vehicle industry commonly marks grade 8.8 bolts with a “7” on the head.

SAE grade 8 hardware is similar in strength to metric 10.9 – about 150 ksi. Metric 10.9 bolts have a “9” imprinted on the head.

Be careful if you replace any “7” or “9” bolts with stainless since the strength is a good bit less. Japanese bolts with a “4” on the head are most appropriate to replace with stainless since the strength is similar.

[doctorgonzo]

There are a couple of different grades of stainless commonly used for fasteners: A2 or 18-8, and A4 or 316. A4/316 has better corrosion resistance and is more expensive.
Both grades have roughly the same strength, 100 ksi.

SAE grade 5 hardware has similar strength to metric 8.8 - about 117 ksi. The Japanese motor vehicle industry commonly marks grade 8.8 bolts with a “7” on the head.

SAE grade 8 hardware is similar in strength to metric 10.9 – about 150 ksi. Metric 10.9 bolts have a “9” imprinted on the head.

Be careful if you replace any “7” or “9” bolts with stainless since the strength is a good bit less. Japanese bolts with a “4” on the head are most appropriate to replace with stainless since the strength is similar.

Gotacha, yes, I knew the "7" weren't supposed to be replaced with stainless. There are a few 10mm I could go stainless on if I could find it, but so far only 8.8 in the fine thread.

[bwringer]

Suzukis, and all Asian motorcycles, cars and trucks for that matter, use the JIS standard for fasteners instead of the SAE or European standard used elsewhere.

Here in the metrically retarded USA it's the year 2009, there are approximately eleventy billion Asian vehicles in the country, and it's still a problem.

The hardware store has row upon row of gleaming inch size fasteners in every possible configuration, and they're useless for anything except lawn mowers, Harleys, and other agricultural implements. They might have four or five picked-over drawers that used to contain metric goodies, but are perpetually out of stock.

I still have not found a source for socket head cap screws in 10 X 1.25mm thread or 12 X 1.25mm, let alone stainless. Insta-rust zinc or cadmium coated flange bolts are available, but not socket head. Someone out there needs to step up.

Even standard JIS replacement hardware is extremely scarce.