Honda-SOHC

SOHC.co.uk Forums => CB500/550 => Topic started by: Sesman on August 02, 2021, 04:01:23 PM

Title: Double disc conversion
Post by: Sesman on August 02, 2021, 04:01:23 PM: Help please. Almost completed the DD conversion, however have encountered a slight problem. I elected to use the asymmetrical set up, but of course I now need a longer caliper arm spring and adjuster screw. I can preload the spring using washers or a short spacer, but the screw will be too short. Iv’e not noticed mention of this in the articles I’ve read. Is a ready made alternative available,or,do I get one made?

Thanks in anticipation.
Title: Re: Double disc conversion
Post by: Sesman on August 02, 2021, 04:07:22 PM: Scrub that, just reread part 2 of the Blacksquare Article. :-[
Title: Re: Double disc conversion
Post by: Sesman on August 02, 2021, 05:54:23 PM: Shim the spring and place the locknut on the inner fork side. Not a pleasant solution, but effective. In the long term I’ll get a mate to run me up a special, longer item.
Title: Re: Double disc conversion
Post by: Trigger on August 02, 2021, 06:15:31 PM: Just buy a countersunk machine screw. Link >>> http://www.sohc.co.uk/index.php/topic,20419.135.html
Title: Re: Double disc conversion
Post by: Trigger on August 02, 2021, 07:23:35 PM: It has been more than a week now so, can not remember. Just look on ebay for stainless compression springs that you can give all the measurements ;)
Title: Re: Double disc conversion
Post by: Sesman on August 02, 2021, 07:44:24 PM: Cheers trigger. On it…
Title: Re: Double disc conversion
Post by: Sesman on August 03, 2021, 08:38:09 AM: Will do. Found a supplier, just need to get the ruler out…
Title: Re: Double disc conversion
Post by: Trigger on August 03, 2021, 11:14:32 AM: Quote from: Oddjob on August 03, 2021, 08:04:15 AM
Mines still locked up in the garage around the corner Sesman, I presume you'll measure the OE spring length and wire diameter etc. If so can you let me know what it is, I can find some springs but don't want to buy any until I know it will work.

BTW, found some stainless springs that will do for the rear brake rod, saves them rusting in the future, I had mine chromed but of course they don't last that long and rust on the interior part of the coils.

You need the diameter of the wire, outside diameter of the spring and it has to be longer. I mounted the caliper and then measured the distance and put on 5 to 10mm or more ;)
Title: Re: Double disc conversion
Post by: Sesman on August 03, 2021, 02:40:41 PM: Exactly my pal, thanks trigger :)
Title: Re: Double disc conversion
Post by: Sesman on August 03, 2021, 02:41:36 PM: “Plan”, not “pal”. But happy to be your pal.
Title: Re: Double disc conversion
Post by: Yoshi823 on August 26, 2021, 12:54:20 PM: Quote from: Sesman on August 02, 2021, 05:54:23 PM
Shim the spring and place the locknut on the inner fork side. Not a pleasant solution, but effective. In the long term I’ll get a mate to run me up a special, longer item.

I did that shown in the pic back in 1981 on my commuter CB550F1. When I sold the bike I transposed the double discs to my wife's CB550F2
(https://i.postimg.cc/Y0VK71j2/Early-days-034.jpg) (https://postimages.org/)
(https://i.postimg.cc/V6hzRSnt/Girls-Bikes-27.jpg) (https://postimages.org/)
Title: Re: Double disc conversion
Post by: Bro550F on August 31, 2021, 05:17:55 PM: Maybe it's been asked before, but obviously with a twin disc conversion we're looking for better stopping power. Well has anyone changed the master cylinder for a more modern one ??
Title: Re: Double disc conversion
Post by: Johnwebley on August 31, 2021, 08:51:42 PM: Quote from: Bro550F on August 31, 2021, 05:17:55 PM
Maybe it's been asked before, but obviously with a twin disc conversion we're looking for better stopping power. Well has anyone changed the master cylinder for a more modern one ??

you normally change the MC for one from an early goldwing,

they look the same,but have a larger bore to suit twin calipers.

commenting on the spring issue,

I left out the springs ages ago,they are not needed,

and a countersunk screw should be available at any good engineering store,
Title: Re: Double disc conversion
Post by: Bryanj on August 31, 2021, 11:40:11 PM: If you use the see through GL 1000 one you get a micro switch for brake light and canput the second caliper hose where the hydraulic switch goes
Title: Re: Double disc conversion
Post by: Sesman on September 01, 2021, 08:52:32 AM: Hi, Oddjob.

No, but have found a supplier. I’ll post next week as currently charging through France.
Title: Re: Double disc conversion
Post by: Seabeowner on September 02, 2021, 08:39:44 AM: Rather than this route. Anyone with experience of using replacement cast iron disc. Improved braking, warping??
Title: Re: Double disc conversion
Post by: Bryanj on September 02, 2021, 12:56:52 PM: Did it back in the 70's, found out the hard way that a disc locking the wheel with 3 inch of water on road is not a good idea plus wasnt that much better than 1 stainless and not as good as 2
Title: Re: Double disc conversion
Post by: sprinta on September 02, 2021, 04:18:27 PM: I'm using the std CB750 master cylinder on my K2 with twin discs and have no issues with the travel or feel. I think you will find that it is not necessary to change the std M/C to one with a larger piston, such as the one used on the GL1000's.

However, if you feel happier with that then go ahead and fit one with a larger piston. As to using a 'modern' one (I assume newer) there will be no advantage over and earlier one that has the same piston size, though clearly a newer one may have better/newer seals but as long as the seals, and bore are in good order they should both perform the same.
Title: Re: Double disc conversion
Post by: Sesman on September 02, 2021, 04:47:21 PM: I’m using the early GL1000 item as it looks ‘period’ and most of the DDC I’ve read recommend it…..we will see.