Wildguzzi.com
General Category => General Discussion => Topic started by: rodekyll on October 27, 2017, 11:33:25 PM
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Partly because I'm ignorant of wine. The rest is because as of 6:57PM Pacific time my trike's brakes no longer suck.
I've been whining about the brake performance on the trike since I got it. Rears were essentially there to keep from swapping ends, and the front was so effective it locked up on loose or wet pavement. No integration. Drove me nuts. I spent the summer tinkering with them and only achieved varying degrees of suck, somewhere in the middle of the suck bell curve.
The leading link front end stopped a lot of the skid potential without additional brake improvements, but the feeling of the back end pushing me along when using front only was unacceptable. I wanted to be able to haul down from speed using either front or rear. I didn't want to NEED both. It was a design goal I was determined to meet, and the final outstanding technical obstacle to overcome before I could really declare the trike experiment a success. I mean -- it's one thing to get it moving, but sort of the polar opposite to get it stopped again. Given the choice, I like my vehicles to stop as good as or better than they go. Only seems right.
The solution I figured was to integrate the brakes while leaving the front and rear separate. Riiiiight. Having it both ways. But as it turns out, the donor rear calipers had three 25mm pucks per unit, and they were arranged with the two outside pistons joined, but the center puck was on its own hydraulic circuit. With clever matching of front caliper piston size and m/c diameter, I guessed I could join the front calipers to the center pistons of the rear. It was a matter of the math and what I could find to work with. The result I hoped would be to apply a touch of rear brake whenever the fronts were employed -- just enough to trim it out. This left the remaining four pucks in the back brakes to the rear brake control.
I had a lot of my own ineptness to overcome along the way. I designed this floating caliper setup for the leading link, partly because it's seldom used (brackets and mounts are hella complicated) and would attract attention from the leading link crowd, and partly because I measured my Tokico radial calipers (on the shelf for no particular reason) incorrectly. I got the Vernier caliper in there and decided I had 4 30mm pistons. This should have been in range for a 19mm radial master cylinder, and I tinkered up the circuit accordingly.
It failed. I used up all the handle and got nothing. I bled it until I bled and no joy. I shaved on the handle to get more stroke and found a little something just before the lever hit the handlebar, but completely ineffective. I plumbed in hard lines wherever I could to lessen line squish. I replumbed the brake line routes for gravity. I bled till I bled, etc. I replaced the pads. I rebuilt the m/c. I added a 2# residual pressure valve. I bled them till I bled. The best I could get was a little action after about six pumps. Unacceptable.
Then I remembered that the piston seals could bind on the pistons and roll with them instead of letting the pistons slide. Then they unroll, sucking the pistons all the way back. In bad cases the suckback exceeds the stroke of the m/c, and the brakes just don't work. It's worse on narrow pistons, and mine were. The solution is to run the pistons out as far as you can (I put a putty knife between the pads and bungee cord the m/c to hold them tight for a while) and let the seals roll way out. Then when you retract them again they aren't trying to pull the pistons back as fluid pressure goes away. In the process, I decided to measure the pucks again. Hmm. now I got 32/30 where before I was reading 30/30. That changed the math.
But I got a lot of relief with the seal rolling trick. I was feeling spongy calipers toward the bottom of the first stroke. But it felt like I wasn't getting stroke enough, and it bothered me that I couldn't detect any freeplay in the handle. But otherwise the handle was feeling optimistic. I did a test ride to see if everything would somehow magically settle in.
I could feel the brakes getting progressively more solid. And then I felt more brakes. And then they were dragging. And locking up. And smoking. SOMBICH! It was 3AM, so there was no traffic. I pulled over and peered through the smoke. I pushed the bike -- locked up tight. I hit the calipers with the IR thermometer -- way hot, it read. Hmmm. Usually it gives me a number. . . . I opened a bleeder and fluid gushed out under pressure. Ditto the other side. Hmmmm again. The m/c isn't accepting returns. It pumps them up but won't unpump. The m/c piston seal must not be clearing the return hole. Bummer. I bled off the pressure and limped home with the semi-sucky back brakes only.
I put the wheel in the air and sure enough it was locking up after a few strokes of the handle. I disassembled the m/c control, and the lever popped out of place under a little pressure from the m/c piston. I wasn't getting a full back stroke, and so the antibackup seal on the m/c piston wouldn't back up enough to allow the calipers to relax. Each successive pump increased the unrelievable pressure until it became a 3AM embarrassment. I found a lever in my stash (wrong color, but. . .) that fit better. The wheel now spun freely when the lever was released, but it still felt like not enough stroke. I put a spacer in the stroke adjustment (radial, remember) and suddenly felt brakes.
But I could now also feel air in the system -- something I really couldn't before. It must have been trapped in the m/c due to lack of stroke since I started. I removed the front calipers from their mounts and hung them on a ladder about a foot above the m/c level. Using my syringe, I evacuated a crapload of air that had been eluding me through a gallon (literally) of fluid and a year (also literally) of bleeding. The lever came up feeling normal. With the spacer installed, it's a long reach to the handle, but it hauls me down with half a pull. I did a 20 mile circuit, slamming on, riding them, doing stop-and-goes, and checked the temps -- not even getting warm. Yay -- no dragging. I took it down some dirt roads and did reasonable front-only stops without skidding. The integrated rear pucks were working. I returned to the barn.
Now that I knew a 19mm radial m/c would pump two 32/30s plus two 25's, I also knew that my rear brakes semi-suck because I'm using the same 19mm pump against a paltry four 25's in the back. The rule of thumb on brakes is that the smallest m/c bore that will move the slaves gives the best hydraulic advantage. If a 19mm did all that integrated front brake work, it was way too much for the rears.
Of course I can pull a 17mm Nissin radial master cylinder out of my ass whenever I want to, so I did. The tricky part is that my rear brake control lives on the left handlebar, so a brake master cylinder needs to be flopped. Radial M/c's are a natural for this because their reservoirs are not cast into the cylinder. You can put them wherever you want to. But flopping a Nissin means means that the bleeder is on the bottom. I made sure I was getting stroke and then mounted it backwards for the bleed procedure. Using the syringe I primed and bled if in a couple of minutes and then attached it properly.
On the test ride the rear brakes came alive. No binding, good feel at about 2/3 stroke, but a little woody at the hard end. If I can pull a Brembo 16mm pumps out of my ass I can probably get the perfect match. I'll check; the stash is deep. Brembo radial m/c's are a PITA because you can't rebuild them, but unlike Nissins they're ambidextrous -- you can swap the bleeder and the banjo -- so it's a neater fit on the left handlebar. For my money I go with whatever's in the stash.
But I digress. I could comfortably bring it down from speed using either front or rear, and using them both made it immediate. As the new front HH pads bed in it should only get better. From now on they should be unremarkable, which is exactly what you want from your brakes. I took the long way to the Goose (local community co-op grocery) and shot the calipers and disks with the IR gun in the parking lot -- no unusual heat. No binding. No leaks. Then I went in and got this really bad bottle of wine. Once back to the trailer I realized I don't own a corkscrew. I thought it odd that a bottle of this stuff would even have a cork. Shows that all I know about wine is that Chardonnay is way too sweet. I found an axle spacer, a fender washer, and a drywall screw and ran the screw through all of it with the cordless screwdriver. Sucked that cork right out.
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Is this like a math problem ? If a bottle of Chardonnay leaves Seattle at 7:45 heading East at
38 KPH (Metric system since we are already working in French) , and a train with 300 passengers leaves NYC at 45 KPH heading West , how long will it take RK to finish the cheap bottle of wine ?
Oh , glad the brakes are sorted :thumb:
Dusty
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Chardonnay? No, no, no, no, no!
This is clearly a Bollingers moment. Or Bourbon.
:boozing:
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rodekyll, you write an exceedingly good story and always have :thumb:
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Fantastic! It's always a pleasure when you overcome an obstacle that has been a thorn in your side. :thumb: :bow:
ZZ
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Not Chardonnay after all your work on a Guzzi. Keep things Italian. Drink Gavi or Fiano.
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Attaboy.. :smiley: (I don't give those out lightly, ya know..)
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Another quality writeup
Robert M Pirsig would give that :thumb: :thumb:
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I really enjoy reading your trials and tribulations. Glad the results were positive! :popcorn:
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Bloody good story, and even better result.
I could almost smell the brake fluid on my hands ? Gotta' have felt good to kick that problem in the ass !
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I am ignorant of wine.
Last nite a woman plied me with some Arkansas wine and took advantage of my condition.
Got home after noon.
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I am ignorant of wine.
Last nite a woman plied me with some Arkansas wine and took advantage of my condition.
Got home after noon.
Lucky bastard !
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I am ignorant of wine.
Last nite a woman plied me with some Arkansas wine and took advantage of my condition.
Got home after noon.
Arkansas, huh? I ate there once. Bacon grease is very popular. You can even get it in your coffee. I'll bet that was your edge. :food:
This morning I find that I've doubled my wine education and the size of my head. I thought I read somewhere that a bottle is a single serving. :coffee:
I went out and hosed the brake fluid off the trike. (Note to self: Cheap rattle can paint doesn't hold up to brake cleaner. Engine paint is the better choice.) Everything still works, so I didn't imagine it. Now that I can stop it, it's time to make it go. I'm back to work on the fuel mapping.
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I used to be an expert wine consumer, and what you want is a nice fortified wine such as "Night Train Express" :evil: congrats on the brakes, you need good brakes to go fast!
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Yes, most commonsewers proclaim "Night Train" as da bomb. :smiley: :boozing:
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Damn. Saw the title and opened the thread prepared to give you all kinds of poo for drinking Chardonnay. Then you got into technical MC fixin' talk and, well, shut my mouth! You drink what you got :wink:
Steve
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You drink whatever rips ya shorts RK. :thumb: Although, a good Marlborough Sauvignon Blanc is more to my liking.
Good writeup, good read, good result. :thumb:
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Regret you had to go through all of it, but enjoyed the story so much. I've told you before you need to set up a Patreon.
Alternatively we could just send you gift cards for booze.
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What a process! Well done, RK...
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Great write up and job, I would be happy to have a 10th of your ability's, plus everybody knows that you drink Mad Dog 20-20 afterwards so the next morning you can take the ax out of your head and chop up firewood for the next evenings festivity :boozing:
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It's more persistence and a desire to not repeat a mistake than it is ability. I've been at it for a year. :coffee: Back in high school I read that a credible source I admired said "I'm no smarter than anyone else -- I just stick with the problem longer." It's been one of my mottos ever since.
. . . and to update, I was not able to pull a 16mm radial m/c out of my stash. But I had a Brembo radial in 15mm. Rear brakes are even better than they would have been with a 16, but considering the improvement from a 5mm size decrease, I think I can reduce the diameter more and do even better. Anyone know of anything that uses a 13mm radial master cylinder either as brake or clutch?
Oh -- and how about them Seahawks! :thumb:
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Success is 10% inspiration and 90% perspiration. -- T. Edison
That was a shootout for the ages. :smiley:
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I found a 1/2" radial m/c in my stash and replumbed for it. It might be the difference between 1/2" and 13mm too small -- I think a true 13mm would do it. The 1/2" runs out of stroke before the pads grab completely, but it's VERY close. I'm going to go over the bleeders one more time. I might find that missing stroke distance hidden in a bubble. If not, I can live with the 15mm I had there previously until I can afford a quality 13mm unit.
This is a "pit bike" grade m/c -- prolly paid $20 for a pair of them out of China, NIB. It makes sloppy look squared away. The threads are poorly cut; I had to chase threads for the clamp screws. the casting looks like someone made a brembo impression in beach sand and tried to hide the poor counterfeit with hobby paint. It's so sloppy they don't tell you the bore or stroke in the sales literature -- they concentrate on the 22mm handlebar clamp measurement as though it's the important technical spec. When I called and asked about the details I was told they were the hydraulic kind, and that's all I needed to know. The handle is the real joke though. There is no mounting angle or stop adjustment that lets me grab the lever with my fingers while my thumb is still on the grip. The angle of the handle was cast just that completely wrong for the human hand.
Success is 10% inspiration and 90% perspiration. -- T. Edison
That was a shootout for the ages. :smiley:
I've always wondered about that quote. They need to weight those percentages somehow, because without the full 10%, the 90% is a non-starter. And in real life, for any effort greater than opening a chili can, I lose my 10% long before I work up a good 90.
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Ok, so I admit that the brake story is ok. I am really glad for you that the solution was found.
BUT, your electric corkscrew deserves more than just a one liner!!! You need to advertise it! A MAN CAVE corkscrew!!!!!!! Everyone needs one. I think I am going to cobble one up and give it to my daughter for Christmas. I guess I should find a stainless screw for it so it can be washed after use ;)
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Ok, so I admit that the brake story is ok. I am really glad for you that the solution was found.
BUT, your electric corkscrew deserves more than just a one liner!!! You need to advertise it! A MAN CAVE corkscrew!!!!!!! Everyone needs one. I think I am going to cobble one up and give it to my daughter for Christmas. I guess I should find a stainless screw for it so it can be washed after use ;)
Dang! Another manufacturing opportunity dead on the vine.. :smiley:
https://www.amazon.com/dp/B01261VEOG/ref=nav_timeline_asin?_encoding=UTF8&psc=1
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Chuck,
Naw, it has to be a deck or metal screw turned by en electric drill/driver. Maybe using a socket or piece of PVC pipe and washer since the they are more readily available than an axle spacer. For the rich they could use a Hilti drill/driver and Snap on socket :)
All the other gadgets are for the fancy dining room :)
My daughter is the wine drinker. I think I know what I am going to give her for Christmas :)
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Chuck,
Naw, it has to be a deck or metal screw turned by en electric drill/driver. Maybe using a socket or piece of PVC pipe and washer since the they are more readily available than an axle spacer. For the rich they could use a Hilti drill/driver and Snap on socket :)
All the other gadgets are for the fancy dining room :)
My daughter is the wine drinker. I think I know what I am going to give her for Christmas :)
:thumb: I like the way you're thinkin..