Author Topic: Replacing Bolts and Screws  (Read 1445 times)

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Offline Bristledisk

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Replacing Bolts and Screws
« on: September 10, 2015, 01:43:23 PM »
Another newbie question but when the parts manual refers to a bolt as 6x12, does it mean 6mm diameter by 12mm length. What about the thread pitch? This is meantioned in the parts manual. Is there anything else I need to consider when I'm buying replacement bolts locally?

Thanks
1977 CB400F, 1976 CB750F1, 1974 CB550K, 1975 CB550K, 1976 CB550K2, 1973 CB350F

Offline Patrick

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Re: Replacing Bolts and Screws
« Reply #1 on: September 10, 2015, 01:55:13 PM »
The threads are standard pitch, but take a bolt or two to the parts house to make sure you get the right one. The second number is indeed the length. You will not find most Honda lengths locally. I hope you have a Dremel with a cutting blade cuz you will have to custom cut a few bolts - or use close sizes. I start with a box of 35mm and cut as I go.

Patrick
« Last Edit: September 10, 2015, 01:57:04 PM by Patrick »
1970 CB750 K0
1982 VF750S Sabre
1987 VT1100 Shadow
1979 Yamaha XS11
1969 Yamaha DT1B
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Offline PeWe

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Re: Replacing Bolts and Screws
« Reply #2 on: September 10, 2015, 02:04:43 PM »
MM threads. M6x 12mm
std head- 12mm lenght of the screw under the head.
Countersunk head, 12mm in total lenght
M6 pitch is 1mm
M8 1.25mm
M10 1.25

M12 1.75 except for the nuts keeping the rear sprocket and rear foot pegs with OEM 4-4 exhaust, these have thread pitch of 1.25mm (CB750). You can math these side by side with an M8 bolt of std pitch
More info here:
https://en.wikipedia.org/wiki/ISO_metric_screw_thread

This is normal here in Europe. I'm grown up with at least M4-M10 thread tools and nuts bolts etcv in the garage. Inch is the strange thing here. Our old Swedish car Volvo from the 60's-70's had som inch bolts/nuts. A thread gauge is sometimes useful to check the pitch.
« Last Edit: September 10, 2015, 02:06:56 PM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Replacing Bolts and Screws
« Reply #3 on: September 10, 2015, 03:19:02 PM »
I've been using a brass wire wheel on my grinder/polisher. Works great with time and patience. Just hold on tight. They like to fly. Many are pretty nasty to start off with.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline RAFster122s

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Re: Replacing Bolts and Screws
« Reply #4 on: September 10, 2015, 03:37:47 PM »
Std zinc plated bolts at the hardware store or home improvement place are cheaply made and may not have a good quality zinc plating. Yellow chromated or blue chromated zinc plating are going to cost more and look different than the silvery white finish of most std zinc plating.
Buying the original Honda bolts is good for some of the fasteners,  especially when they are chromed unless you are going to have yours rechromed and bolts replated.
Depends on the condition of your bolts if you would want to pursue a barrel plating of your old zinc plated bolts.
David- back in the desert SW!

Offline Stev-o

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Re: Replacing Bolts and Screws
« Reply #5 on: September 10, 2015, 03:59:25 PM »
I buy stainless bolts from my local bolt supply store, very fairly priced.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Andrew_FSBC

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Re: Replacing Bolts and Screws
« Reply #6 on: September 10, 2015, 04:15:02 PM »

I'm just starting to research parts for my rebuild. What is the general opinion of the Stainless Bolt kits? I know they don't look like the originals but I'm not doing a full factory restoration.


Offline mrfish2

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Re: Replacing Bolts and Screws
« Reply #7 on: September 10, 2015, 07:29:29 PM »
What is the general opinion of the Stainless Bolt kits?

They're generally a good option. It'll save you both time and money hunting down each individual nut and bolt. There are many suppliers that offer kits, I personally have used an AlloyBoltz kit and can't complain. Just remember to use Anti-seize when screwing a stainless steel bolt into aluminum threads.
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Offline RAFster122s

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Re: Replacing Bolts and Screws
« Reply #8 on: September 10, 2015, 10:16:43 PM »
Bolt supply houses are going to have better quality fasteners than a Lowes or Home Depot,  so c keep thatin mind.  If you need to cut bolts to length putting a couple nuts on the bolt is helpful in not having a thread reverse,  then just a few strokes of the file to taper that ending and clean up the cut end.

Putting a bolt too long in some holes can crack cases or do other damage,  or prevent it from being.torqued properly when it bottoms out.

Nice part of some of the better stainless bolt kits is they sub-package the kit for various areas and that's super helpful.

David
David- back in the desert SW!

Offline Patrick

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Re: Replacing Bolts and Screws
« Reply #9 on: September 10, 2015, 10:47:17 PM »
If you go stainless be sure to use antiseize when you install them. Stainless does not always play well with the aluminum alloy our cases are made of and the corrosion can weld a bolt in place over time. I've run into a few that had to be cut and drilled they were so zen with the case.

Patrick
1970 CB750 K0
1982 VF750S Sabre
1987 VT1100 Shadow
1979 Yamaha XS11
1969 Yamaha DT1B
etc.

Offline 70CB750

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Re: Replacing Bolts and Screws
« Reply #10 on: September 11, 2015, 06:27:24 AM »


This is normal here in Europe. I'm grown up with at least M4-M10 thread tools and nuts bolts etcv in the garage. Inch is the strange thing here. Our old Swedish car Volvo from the 60's-70's had som inch bolts/nuts. A thread gauge is sometimes useful to check the pitch.

I remember cars made by Skoda having seat belts anchored with SAE bolts - or maybe even whitworth thread?? to make sure nobody replaces them with common bolts.  The rest was metric.
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