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Post by mataos on Mar 13, 2023 18:08:42 GMT
I was looking at a rebuild/seal kit, but not worth it if these are any good? Anyone got one? And are they the same for the 400 and 250 ? Thanks  |
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daveh
Full Member
Posts: 417
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Post by daveh on Mar 13, 2023 19:36:45 GMT
I got a very similar one fron Honda Classics for £35.00. Can't say it was exactly the same as these ebay ones, but I'm happy with it and much cheaper than rebuilding old one complete. They don't shown on their website, but you can give them a ring as they have a lot of stuff not shown on the website. www.honda-classics.co.uk/shop |
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willy3pigs
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Post by willy3pigs on Mar 13, 2023 19:51:15 GMT
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ian
Member Of The Year 2019 
Isle of Man
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Post by ian on Mar 14, 2023 20:59:29 GMT
I've used a few of these on my SDs to get them back on the road after resto while I take my time repairing/rebuilding the originals and they've been fine. The only problem is the brake light switch stopped working on one - couldn't find any replacements while HiLevel pattern replacements for the original master cylinder are available from the likes of Wemoto.
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Deleted
Deleted Member
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Post by Deleted on Mar 14, 2023 21:10:51 GMT
I bought one in October '22 from Superdream Parts, an ebay shop, and it works fine and includes the microswitch. Cost about £30 if I recall correctly. It was a bugger to bleed the system but that is the case for any replacement. Perhaps a vacuum bleed device on the (open) brake caliper bleed nipple would help.
Dennis
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Post by mataos on Mar 15, 2023 16:20:59 GMT
Thanks for the help, yes I did see the microswitch was different too, but if it works that's ok.
I have a 400 caliper fitted, and a 750k caliper that's similar to a standard SD one.
So can anyone confirm if the master cylinder is the same for a 400 and a 250
400 being twin smaller calipers
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Deleted
Deleted Member
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Post by Deleted on Mar 15, 2023 19:00:59 GMT
Why not buy the 400 master cylinder to match the caliper? Or am I missing something? Are you saying that you have a 400 caliper on one side and a 750K on the other?
Dennis
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Post by mataos on Mar 16, 2023 17:52:34 GMT
Bike came with a 400 caliper, so that's what's on it still, standard forks, so I only have a caliper on one side and a single brake line. I don't know if the master I have is a 400 or a 250 one.
Im deciding if I need a 400 master.
Or if a 250 master will be fine for the 750k caliper that's very similar to the standard 250 one.
If they are the same it doesn't matter what master caliper combo I end up using
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Post by BritPete on Mar 17, 2023 10:10:41 GMT
Bike came with a 400 caliper, so that's what's on it still, standard forks, so I only have a caliper on one side and a single brake line. I don't know if the master I have is a 400 or a 250 one. Im deciding if I need a 400 master. Or if a 250 master will be fine for the 750k caliper that's very similar to the standard 250 one. If they are the same it doesn't matter what master caliper combo I end up using You need to do some calculations - the area of the master cylinder face and the area of the calliper piston will determine how far you need to pull the brake lever to apply the brakes. Example in the master to calliper areas are a 1 to 10 ratio then a movement of 1mm on the master cylinder will only move the calliper 0.1mm I think the brake lever is about 1 to 5 ratio on the pivot ie a 10mm movement of the brake lever will move the master cylinder 2mm My brake lever moves about 12mm to start to apply Working this through the master cylinder moves about 2.4 mm, the calliper cylinder moves 0.24mm A 400 master cylinder is 5/8 inch which has a face area of 198 square mm (pie r squared) A 250 master is 14mm which will have a face area of 153 square mm Thus the 400 master cylinder will push 30% more brake fluid for the same lever movement The figures and ratios used are my estimates but I’d demonstrates the point Example if you put a second calliper on a bike with the same master cylinder you need to pull the brake lever twice the distance This needs thinking through carefully |
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Post by mataos on Mar 17, 2023 13:29:54 GMT
Great info, thank you. Basically that confirms that I need a 250 master for a single caliper, as they are different (250 Vs 400 master) My current master cylinder has a very short lever pull so without inspecting it I can assume it's off a 400 (as to be expected with one caliper) Front brake started binding slightly even though the caliper is good, which started me looking to rebuild the master I have, or get a new one, and what one to buy. So,my 400 master should not have been fitted to the bike (previous owner) and it's not worth me rebuilding. Ill get £30 Chinese looking 250 master and use that with the 400 caliper. Then to complicate things further I'll try the 750 k calliper (which was also a single caliper setup) with a 250 master when I have reconditioned it  |
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Post by BritPete on Mar 17, 2023 19:19:36 GMT
Great info, thank you. Basically that confirms that I need a 250 master for a single caliper, as they are different (250 Vs 400 master) My current master cylinder has a very short lever pull so without inspecting it I can assume it's off a 400 (as to be expected with one caliper) Front brake started binding slightly even though the caliper is good, which started me looking to rebuild the master I have, or get a new one, and what one to buy. So,my 400 master should not have been fitted to the bike (previous owner) and it's not worth me rebuilding. Ill get £30 Chinese looking 250 master and use that with the 400 caliper. Then to complicate things further I'll try the 750 k calliper (which was also a single caliper setup) with a 250 master when I have reconditioned it Before doing that you should confirm the diameter of the 400 calliper piston and a 250 calliper piston IMHO |
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Post by mataos on Mar 18, 2023 19:35:09 GMT
38 mm on my 400 caliper, I took it apart and checked that the caliper was ok, bottom slider pin was a bit loose in The hole but all good.
Then went for a ride today and it was fine, just a very short lever pull. So a new 250 master should sort that.
I'll prob get a new hose too.
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Post by mataos on Mar 19, 2023 17:54:55 GMT
I also need a new brake hose as I think the one I have is a bit too short. (Prob off a 400)
Please can anyone confirm how long it should be?
Thanks
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Post by BritPete on Mar 19, 2023 18:13:25 GMT
I also need a new brake hose as I think the one I have is a bit too short. (Prob off a 400) Please can anyone confirm how long it should be? Thanks A 400 has 3 hoses a short one and 2 medium ones which would not be anywhere near long enough |
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Post by mataos on Mar 19, 2023 21:02:36 GMT
Yea, just a guess. but anyway it's too short. And as I'm putting a new master on I might as well put a new hose on that's the correct length. If anyone has one they could measure?
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