tomtom1
Thrash Merchant
Leeds
Posts: 355
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Post by tomtom1 on May 26, 2023 13:45:25 GMT 1
Hi all, I put a add wanting a front master cylinder from a 250lc for my 350 YPVS 31k, oldelsiboy recommended a master cylinder from a TDR250 which is (14mm), instead of one from a 250LC,which is(1/2), so I bought one from legend motorcycles. and wow what a massive difference its made, its far better feel at the lever and probably given 30-40% more braking power with the same amount of pull from the lever, so if anyone is trying to improve there front brakes, don't waste your time and money like I did trying 3 or 4 different makes of pads,just get this master cylinder, you will be impressed.
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Post by crogthomas on May 26, 2023 21:36:24 GMT 1
If that was a guess, it's a good one. I just worked out that it would create 29% more braking power.
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Post by elsiefan on May 27, 2023 0:09:44 GMT 1
Hi all, I put a add wanting a front master cylinder from a 250lc for my 350 YPVS 31k, oldelsiboy recommended a master cylinder from a TDR250 which is (14mm), instead of one from a 250LC,which is(1/2), so I bought one from legend motorcycles. and wow what a massive difference its made, its far better feel at the lever and probably given 30-40% more braking power with the same amount of pull from the lever, so if anyone is trying to improve there front brakes, don't waste your time and money like I did trying 3 or 4 different makes of pads,just get this master cylinder, you will be impressed. I'm really pleased you decided on the TDR M/C and not to go for new brake pads. After going that route myself, I know just how impressed you were the first time you tried the new M/C. |
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Post by jon on May 27, 2023 8:59:38 GMT 1
Iām in two minds whether to try this myself. Only difference is I have a pair of blue spots. Would a 5/8ā be better for this setup?
Anyone else post their blue spot master cylinder size/info?
Jon
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Post by wallcraft on May 27, 2023 10:08:44 GMT 1
Hi Jon, Iāve got the complete blue spot set up straight off the 5jj R1. More than enough for our bikes and as for feel, weāll thatās individual thing isnāt it. All I would say is the feel is solid with enough feel with out being to spongey.
Mark.
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Dave B
Drag-strip hero
Posts: 240 
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Post by Dave B on May 27, 2023 10:23:05 GMT 1
The only danger of using a smaller diameter master cylinder is that you could run out of lever movement. To move the same amount of fluid, a narrower cylinder must move further. You will not get an MOT if the lever comes back to the bar, even if the front brake is locked solid at that.
That's why I have a T1000 Suzuki master cylinder on my RG/ YPVS six pot caliper twin disk set up.
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tomtom1
Thrash Merchant
Leeds
Posts: 355
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Post by tomtom1 on May 27, 2023 10:45:10 GMT 1
Hi all, I put a add wanting a front master cylinder from a 250lc for my 350 YPVS 31k, oldelsiboy recommended a master cylinder from a TDR250 which is (14mm), instead of one from a 250LC,which is(1/2), so I bought one from legend motorcycles. and wow what a massive difference its made, its far better feel at the lever and probably given 30-40% more braking power with the same amount of pull from the lever, so if anyone is trying to improve there front brakes, don't waste your time and money like I did trying 3 or 4 different makes of pads,just get this master cylinder, you will be impressed. I'm really pleased you decided on the TDR M/C and not to go for new brake pads. After going that route myself, I know just how impressed you were the first time you tried the new M/C.Ā Hi yes it was a guess,im so impressed with the difference, and was probably quicker to change the M/C than it would have been to change the pads. |
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Post by chrisg on May 27, 2023 16:50:39 GMT 1
Hi all, I put a add wanting a front master cylinder from a 250lc for my 350 YPVS 31k, oldelsiboy recommended a master cylinder from a TDR250 which is (14mm), instead of one from a 250LC,which is(1/2), so I bought one from legend motorcycles. and wow what a massive difference its made, its far better feel at the lever and probably given 30-40% more braking power with the same amount of pull from the lever, so if anyone is trying to improve there front brakes, don't waste your time and money like I did trying 3 or 4 different makes of pads,just get this master cylinder, you will be impressed. Isnt the 250lc MC smaller than the 14mm TDR 250, so giving an even bigger mechanical advantage and performance? š¤ |
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tomtom1
Thrash Merchant
Leeds
Posts: 355
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Post by tomtom1 on May 27, 2023 17:15:49 GMT 1
Yes the M/C from a TDR is 14mm or 9/16th in old money, and the 250Lc Is 13mm or 1/2", but if I understand it right because its a smaller piston it's moves less fluid so the lever pulls slightly further in, so if I had gone 250lc route it probably would be even more of an advantage braking wise, but the lever would feel too spongy, I think of it like a garden hose, if you turn the hose on you get a lot of water but if you pinch the end you get less water but at a higher pressure, (I think)š
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Post by cb250g5 on May 27, 2023 17:28:22 GMT 1
I'm running a single blue spot from my TDR m/c on the valve. Works great, on a 320mm disc. Also keeps the correct, obscure, Yamaha mirror mount.
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tomtom1
Thrash Merchant
Leeds
Posts: 355
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Post by tomtom1 on May 27, 2023 17:37:52 GMT 1
luckily the M/C I bought from legend has the left hand thread, it also has a brake light switch with it that plugs directly into the wiring loom, it looks 95% original, shame the reservoir is a little smaller than the original, because I could have put my yamaha reservoir cap on the new M/C.
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murp
Drag-strip hero
Posts: 239
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Post by murp on May 28, 2023 7:44:35 GMT 1
I use a 1/2 inch master with venhill black braided hoses on my 350lc.... Unbelievable improvement over the 5/8 standard set up.... The lever doesn't come back to anywhere near the handlebars
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crigar
Weekend rider
Posts: 88
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Post by crigar on May 28, 2023 8:00:22 GMT 1
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Post by jon on May 28, 2023 9:11:30 GMT 1
I'm running a single blue spot from my TDR m/c on the valve. Works great, on a 320mm disc. Also keeps the correct, obscure, Yamaha mirror mount. Thanks. I have a similar setup on my LC/TZR hybrid - 320mm single disk with 1 blue spot and a 1/2ā master cylinder. Seems to work great with not too much lever travel. I was interested to see what size master cylinder people are using for a pair of blue spots? Sorry for thread hijack, but itās on topic. Jon |
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Post by midlifecrisisrd on May 28, 2023 9:40:53 GMT 1
I'm running a single blue spot from my TDR m/c on the valve. Works great, on a 320mm disc. Also keeps the correct, obscure, Yamaha mirror mount. Thanks. I have a similar setup on my LC/TZR hybrid - 320mm single disk with 1 blue spot and a 1/2ā master cylinder. Seems to work great with not too much lever travel. I was interested to see what size master cylinder people are using for a pair of blue spots? Sorry for thread hijack, but itās on topic. Jon Yam Fazer uses a 14mm master with its twin blue spots They feel a bit wooden if using the standard 5/8 master on standard size discs Steve |
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Post by jon on May 28, 2023 17:45:42 GMT 1
Thanks. I have a similar setup on my LC/TZR hybrid - 320mm single disk with 1 blue spot and a 1/2ā master cylinder. Seems to work great with not too much lever travel. I was interested to see what size master cylinder people are using for a pair of blue spots? Sorry for thread hijack, but itās on topic. Jon Yam Fazer uses a 14mm master with its twin blue spots They feel a bit wooden if using the standard 5/8 master on standard size discs Steve Thanks Steve, Iāll be using 2 x 297mm Galfers. Jon |
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Post by abar121 on May 28, 2023 19:45:59 GMT 1
I'm using the Fazer m/c with triumph four pots. Works really well.
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Post by midlifecrisisrd on May 28, 2023 21:19:29 GMT 1
I'm also using it with Tokico 6 pots and it's vicious š
Steve
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Post by LC_BOTT on May 28, 2023 21:29:36 GMT 1
I'm also using it with Tokico 6 pots and it's vicious š
Steve Nice to hear that, I've just bought one to try with this combo, as no one's mentioned the 6 pots so far. |
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Post by midlifecrisisrd on May 28, 2023 22:00:32 GMT 1
It works really well
Not spongy at all and pop your eyes out braking
I just warn anybody having a go as if you aren't expecting it they can be grabby at maneuvering speeds
Steve
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Post by elsiefan on May 29, 2023 0:54:43 GMT 1
I'm really pleased you decided on the TDR M/C and not to go for new brake pads. After going that route myself, I know just how impressed you were the first time you tried the new M/C. Hi yes it was a guess, im so impressed with the difference, and was probably quicker to change the M/C than it would have been to change the pads. When I did mine I said something on the lines of it was night and day difference, so I knew you would be impressed. There is more lever travel, but a performance increase and improved control over the brakes is the result. |
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Post by JonW on May 29, 2023 1:21:52 GMT 1
I'm also using it with Tokico 6 pots and it's vicious š
Steve Nice to hear that, I've just bought one to try with this combo, as no one's mentioned the 6 pots so far. Ahh... Ive 6 pots on my 421 with RGV forks... with a radial master off a Suzuki I think, could be an R1 tho... hmm... Anyway, Ive had a bunch of masters on that and its better now than before and that works out to about 14mm... but bleeding the tokico 6 pots is a pain as anyone who's done them knows.  {Not helpful in this thread} I put some very posh 4 pad brembos on the same bike with their original radial master (from an Aprilia RSV-R) and it was an upgrade to what was already more braking than anyone could need with the 6pots, but really easy to modulate as well. A mate with a full Berringer setup on his bike tested them and was a bit shocked at how good they were for a lot less money, me too. Really very much better and an easier install than the 6 pots to bleed and setup too. It was a test tho... they are for another project so the 6 pots went back on. lol Ive worked hard on those 6 pots so they are staying lol |
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crigar
Weekend rider
Posts: 88
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Post by crigar on May 29, 2023 8:49:44 GMT 1
Sorry, I'm going to write in French (translation below) as the technical notions may not be interpreted.
Le bras de levier est important Ć©galement, c'est Ć dire l'Ć©cartement entre la fixation pivotante sur le commodo et le point d'appui sur le piston du maĆ®tre-cylindre. On peut choisir une course assez courte mais plus ferme ou une course plus longue et plus douce.
The lever arm is also important, i.e. the distance between the swivel mount on the commodo and the fulcrum on the master cylinder piston. You can choose a shorter, firmer stroke, or a longer, softer one.
Valid for axial master cylinders.
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Post by KevtheRev on May 29, 2023 9:45:37 GMT 1
I've a Brembo "Goldline" master paired up with Bluespots on standard discs on my LC . Pads aren't fully bedded in yet but feels more than adequate . Could use some new brakelines though .
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Post by crogthomas on May 29, 2023 9:53:32 GMT 1
Yes, that is a very good point. Without checking the lever ratio changing the master cylinder piston diameter might make no difference at all, or worse, actually change things in the opposite direction. The chart that crigar posted above (link here: www.vintagebrake.com/mastercylinder.htm) is a good start at working out what hydraulic ratios would give acceptable 'feel' for a given set of calipers, but it doesn't include the lever ratio. Probably it wasn't necessary when the chart was created, as everything was the same. It seems that most standard master cylinders use a lever ratio of about 4:1. That is the pivot to piston distance is 25mm and the distance from the pivot to the middle finger is somewhere around 100mm. In-fact a useful increase in braking power can be obtained by simply moving the lever as far inboard as possible so that the hand is operating a longer lever. Radial master cylinders seem to have completely changed the norm and use lever ratios very different. For example, the Brembo RCS adjustable levers have a pivot point of 18mm or 20mm, which give a ratio of 5.5 or 5. Doesn't sound much different, but that can be up to a 40% increase in line pressure over a standard Yamaha master, with the same size piston. Of course, the same downsides of increased lever travel apply, so it's not a free lunch. It strikes me that creating a table like that one, but for all the common combinations of parts used on RD specials might be a really useful thing. Finding the piston diameters for calipers and masters is easy (parts catalogues), but the lever pivot distances don't tend to be recorded anywhere. Can anyone confirm what they are for the TDR. R6, Fazer master cylinders, etc (I suspect 25mm though)? |
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Post by mangocrazy on May 29, 2023 19:52:49 GMT 1
{Not helpful in this thread} I put some very posh 4 pad brembos on the same bike with their original radial master (from an Aprilia RSV-R) and it was an upgrade to what was already more braking than anyone could need with the 6pots, but really easy to modulate as well. A mate with a full Berringer setup on his bike tested them and was a bit shocked at how good they were for a lot less money, me too. Really very much better and an easier install than the 6 pots to bleed and setup too. It was a test tho... I've got those 4-pad 4-piston Brembos with a radial m/c on an Aprilia Falco and also an old (quite heavy) VFR750 and they are brilliant brakes - real feel and power. I imagine you'd be peeling your eyeballs off the inside of your visor if you put them on an LC... |
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Post by chrisg on May 30, 2023 10:47:44 GMT 1
I suppose the next phase of the is thread is "has anybody fitted ABS" š¤
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Post by JonW on May 30, 2023 13:44:18 GMT 1
I suppose the next phase of the is thread is "has anybody fitted ABS" š¤ you dont need it with the standard brakes after 30+ years lol |
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Post by crogthomas on Jun 1, 2023 22:43:25 GMT 1
Some really good information in this thread. Knowing how something is going to 'feel' after bolting together a load of random parts never designed to work together is always going to be difficult. Having real world examples is really useful. I did a bit of digging and found a post on another forum where a chap suggests ranges of combined lever and hydraulic ratios and how they would feel. www.wristtwisters.com/threads/calculator-for-finding-the-proper-size-radial-master-cylinder.48345/Mostly the discussion was relating to fitting radial master cylinders which often have very different lever ratios, thus the change in piston size is not the only thing changing. I decided to put together a spreadsheet of the common master cylinders and calipers used on our bikes to see how they compared. This is a first stab at it, some of the information may not be correct and I'm not sure all of the master cylinder diameters I've listed actually exist, but it is interesting all the same. All of them use a 4:1 lever ratio, but I could update it for different levers if I can get the information. The post up there suggests modern bikes have a combined ratio somewhere between 115 and 145. His favoured sweet spot is about 130. The standard RD350 combined ratio is about 92. It would seem that perhaps tastes have changed, people have become more used to powerful brakes since the 1980's. Generally the bigger the number the better (more power), but remember that the bigger the number the more lever travel there will be, which not only means the brake may feel 'mushy' and grabby, but also that it is possible to run out of travel entirely. Which would be a very bad thing. I suspect the Yamaha engineers have designed their systems to still work adequately with the span adjuster at its shortest setting and a bit of air in the system, so be careful going to extremes. Of course this table still doesn't give the full picture since it doesn't include disc and wheel size which will have an effect on the overall braking force generated. Using a pair of blue spot calipers on standard YPVS discs is a very different matter than using them on the 300mm discs from a R6. (about a 30% increase in force just by adding the discs, more if the wheel size is reduced from 18" to 17"). I've highlighted those combinations that were standard on something from the factory.  RDbrakes by crogthomas, on Flickr Anything else I could add? |
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Post by crogthomas on Jun 1, 2023 22:43:42 GMT 1
And because I'm bored I decided to rate your brakes. No offense intended. tomtom1 : TDR master - YPVS calipers. More powerful than stock and in the range of 'modern' brakes. The LC 1/2" master might work but it would be at the extreme end of the range. Lever travel might be an issue. Plus reservoir capacity? jon : Single blue spot with 1/2 LC master. Towards the wooden end of the range, worse than standard, but with a big disc maybe not such a problem. I'd be tempted to try a 11mm master from a YBR or YZF 125. jon again: Twin blue spots, the standard RD 5/8 master would give better brakes than stock but possibly wooden feeling, but, as others have suggested, why not go for the Fazer/R6 master (14mm) that would have been used with them originally? cb250g5 : Single blue spot, TDR master. Poor overall ratio, I would expect it to feel wooden and have very little power, but that might be compensated a little by the large disc you have fitted. It might be worth trying a 11mm master from a YBR or YZF 125. murp : 1/2 250 master, 350 calipers. A classic combination. At the very extreme end of the range, but when you are working with such small discs extreme might be just what you need. If the lever feels mushy, it might be worth considering the 14mm TDR master. abar121 : Fazer 14mm master, Triumph T595 calipers. I would expect it to have a mushy lever feel, plenty of power mind you. Going back to a 5/8 master might improve the lever feel, but still give decent braking. midlifecrisisrd : Tokico 6 pots and Fazer 14mm master? Let me know the piston sizes and I'll do the calculation, just for interests sake. |
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