Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Rob62 on March 14, 2019, 08:52:48 PM
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I have a very weedy front brake on my CB750K4... i know it will never be up to modern standards but i want it to be as good as possible without resorting to fitting modern calipers or master cylinders etc...i dont really want to do a twin disc conversion either if I can avoid it.. My master cylinder is standard and fully refurbished, so is my caliper, the brake lines are brand new, also the pads are brand new organic from DS... i fitted them last year but they still dont seem to be bedding in or improving....the disc itself is in great condition with virtually no sign of wear or scoring. My question is, what pads do you use for the best performance, I can’t find any sintered pads for sale but I have come across some ceramic pads...but mostly I can only find organic... has anybody tried the ceramic type or is there a better alternative available? Cheers.
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I feel the current (post asbestos) organic pads have a very soft bite and sensitivity to them. Even in cars they seem to need higher brake line pressure to get them generating significant force.
Honda seemed to use a very conservative leverage ratio on these systems, so quite hard to generate high line pressure. Jokingly I've considered these to be an early anti-lock brake system as you'd need hands like a bricky to put enough force into them. :)
The disc is easily big enough to make the torque required, just that you can't exert sufficient pressure through the leverage ratio they use.
Contemporary systems to me seemed to have the Yamaha RD much closer to current systems, with much lower lever pressure able to generate quite potent braking.
The mastercylinder from later 400E, the one with floating calipers and single piston may offer an interesting combination with the Honda caliper on the 750 to test that theory. It may give you an indication of what the disc and caliper could do. Shame they are the square type otherwise would look less out of place.
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Compare it to a tls on a t120 triumph and its wonderful, conversly compare it to a modern "sporty" and its crap.
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Thanks for the comments guys, very interesting.... actually I also have a late E yamaha, mine is the 250 not the 400 but they are almost idential except for the cc. Interesting that you describe the Yamaha system as potent. Amongst the owners I know the brakes on the later E and F are generally regarded as being wooden (and my Yam is no different, although it is slightly better than the Honda). The brake system on the earlier Yams is usually regarded as being better. Also the Yamaha is about half the weight of the Honda..... I do agree that an alternative master cyl may provide a better action and more pressure. Ideally I didn’t want to start swapping master cylinders if I can avoid it... maybe later if I must. I do have a spare Yamaha master cyl as I have fitted an alternative on my Yam and the original is on the shelf.... unfortunately the yam brakes are no better even with a modern master cyl :( I guess I will give the ceramic pads a try first.... Cheers.
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I can share my experience form K7 750
I rebuilt MC and Caliper, put new EBC organic pads. It took approx 500 miles when it started to brake better.
And of course it was squealing badly... I put on back side of left pad anti-squeal tape that helped significantly but did not stop it completely.
DSS claims has genuine Honda pads, I ordered one set, will try them. Just hope they are better than those organic from EBC
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EBC manufacture semi sintered pads I believe:https:
//bikes.ebcbrakeshop.co.uk/info-parts?part-type=brakes&make=HONDA&model=CB+750+F%2FF1&year=1976-1977&search=Part+Number
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These ones : EBC Bike Brakes Kevlar Organic Pad (FA013)
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The semi sintered pads are available from here for the K0 - K5 series:
https://www.ebay.co.uk/itm/EBC-Semi-Sintered-V-Brake-Pads-FA012V/333096339912?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20190212142712%26meid%3D6adb2930aaeb420aa7640a0dc1fe2e69%26pid%3D100037%26rk%3D6%26rkt%3D12%26sd%3D332370987126%26itm%3D333096339912&_trksid=p2047675.c100037.m2107
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Have you thought about braided brake lines ?
Cheers
Dennis
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I found a great improvement when I drilled the discs, Certainly in the wet and in the dry
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Thanks for the info guys, i will check out the various options...
These are the pads I currently have...
https://www.davidsilverspares.co.uk/CB750K4-FOUR-1974-USA/part_105516/
I’ve done about 800 miles i think, they dont seem to be improving.
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I wish I knew what pads are in my 750 as I consider them to be quite good for what they are and would get the same again. There are no markings at all on them unfortunately. :(
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I’ve ordered a pair of semi-sintered “V” pads from EBC.... the advertising blerb promotes them as long-life rather than high-performance..but we will see. The pads from DS came in a plain white box if I remember correctly so I’m guessing they are not branded, they were cheap thats for sure!
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Pads arrived today...so I fitted them this afternoon. Im glad I’m not a Honda mechanic cos I reckon you’d be allotted about 20 mins for the job but it took me about an hour 😄. The pads were painted in quite thick orange paint that had to be scraped off before it would fit into the caliper... Anyway once in i tried them straight away on the drive and there wasn’t any real bite, to be expected i guess as they need bedding in. However after a short 20mile ride they were biting much better and are already a big improvement over the DS ones. Thanks for the pointers! I think I’ll order some for the aircooled RD next....
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I have DSS pads in my 750 they took an age to bed in and there still crap so I give my gearbox hell to scrub speed off.
The brakes on the 550 were even worse and that came with the original Honda pads. I swaped them out for new DSS christmas cracker ones and rebuilt the master cylinder and they feel exactly the same ::)
I find bashing down the box is the best way to scrub speed and it sounds good too. ;D