Honda’s finish codes for motorcycle fasteners

Bob750 · Post by **Bob750** » Wed Mar 27, 2013 11:35 am

I had emailed Bill Silver a question and he tracked down the answer for me and said I could share the info with the forum.

Honda’s finish codes for motorcycle fasteners

Restorers often ask me about what was the original finish on a bike’s various metal parts. The end suffix code on the part number indicates the kind of material and how it was finished. There are duplicate finish treatments with two different codes, but I don’t know the reason behind that, to date.

CODE SUFFIX 1st digit: MATERIAL
0=High Carbon Steel
1=Carbon Steel
3=Brass
4=Stainless

CODE SUFFIX 2nd digit: SURFACE TREATMENT
A= Zinc Plate (White)
0= Zinc Plate (White)
B= Chrome Plate
2= Chrome Plate
C= Nickel Plate
3= Nickel Plate
H= Zinc Plate (Yellow)
8= Zinc Plate (Yellow)
J= Untreated
9=Untreated
G=Black
7=Black

This research started when a question came to me about what are the differences between these 5x25mm bolts listed by part number below.

93500-05025-1H Carbon Steel, Zinc (Yellow)
93500-05025-0A High Carbon Steel, Chrome
93500-05025-0G High Carbon Steel, Black
93500-05025-4J Stainless, Untreated
93500-05025-0B High Carbon Steel, Chrome
93500-05025-0H High Carbon Steel, Zinc (Yellow)

I didn’t have the answer, at the time, but did some research into AHMC departments and my request for information yielded the answers!

Bill Silver

www.vintagehonda.com

G-Man · Post by **G-Man** » Wed Mar 27, 2013 2:07 pm

Nice to see that there's no cadmium finish listed.

Illegal in Europe now owing to toxicity.

G

LOUD MOUSE · Post by **LOUD MOUSE** » Wed Mar 27, 2013 3:45 pm

Works really good in the USA. ...:-).....lm

G-Man wrote:Nice to see that there's no cadmium finish listed.

Illegal in Europe now owing to toxicity.

G

FishingForTheCure · Post by **FishingForTheCure** » Tue Feb 04, 2014 12:54 pm

Glad to see this questions wasn't just mine. As I am tearing down my '63 & '64 bikes for a restore, I've had nothing but troubles with the philips heads & had to drill out most of the machine screws.

My plan is to replace them all with allen head cap screws but questioning material type; nickel steel, stainless, cad plated? Thoughts? Stainless is easy to be had here ... coat the threads with a little never sieze & go stainless?

I guess I still don't understand the "finish schedule" for screws. Here's the P/N I am looking for screws for at the moment: 93500-06000 What/where is the finish "code" within this P/N?

Thanks!

Bill

Bob750 · Post by **Bob750** » Tue Feb 04, 2014 2:07 pm

You'd look for a part number that has -49 or -4J for a stainless screw. The IPM generally won't have this but sometimes will. Where you will see it is at a website selling Honda catalog parts. If you search for 93500-06000 you might get several matches, each with a different suffix. You can use the info above to know which one you want to order.

FishingForTheCure wrote:Glad to see this questions wasn't just mine. As I am tearing down my '63 & '64 bikes for a restore, I've had nothing but troubles with the philips heads & had to drill out most of the machine screws.

My plan is to replace them all with allen head cap screws but questioning material type; nickel steel, stainless, cad plated? Thoughts? Stainless is easy to be had here ... coat the threads with a little never sieze & go stainless?

I guess I still don't understand the "finish schedule" for screws. Here's the P/N I am looking for screws for at the moment: 93500-06000 What/where is the finish "code" within this P/N?

Thanks!

Bill

FishingForTheCure · Post by **FishingForTheCure** » Tue Feb 04, 2014 3:08 pm

So it is considered "acceptable" to replace the steel fasteners with stainless. Not concerned about keeping it original as much as I am about functionality, serviceability, etc...

Bob750 · Post by **Bob750** » Tue Feb 04, 2014 4:44 pm

Hi FishingForTheCure,
Welcome to the forum! Please edit your profile to show your location; others will be more happy to answer questions if you let us know where you are.

As far as what's acceptable...
The material you choose for fasteners on your project basically comes down to preference, with the exception of building a show bike. If you're going for a 100% correct restoration that could win prizes at a show, stick as close to stock as you can wherever you can. Otherwise, go with whatever you prefer or think looks best. There are lots of bikes out there in non-traditional colors and trim. Since you're concerned primarily with serviceability etc, I think stainless makes a lot of sense in many places (on the bike and in certain climates), and I like the look. Stainless on steel isn't so much a problem but stainless in aluminum can seize, so a little anti-seize will go a long way. Also if you go with socket head, be careful not to over-tighten them in the aluminum case and covers. It's easy to over-tighten and then have to re-thread holes. The aluminum will always give out before a steel bolt.

Also, if you start a thread in the restorations section and document your work, the nice folks here will often jump in with encouraging comments and welcomed corrections or advice if you ask. However it's a good idea to search for answers first. Chances are your question has been asked and answered many times already. Good luck on your project. I'm about to start my bike for the first time since I started a year ago this week.

FishingForTheCure wrote:So it is considered "acceptable" to replace the steel fasteners with stainless. Not concerned about keeping it original as much as I am about functionality, serviceability, etc...