19mm from 17mm master cylinder, first impressions Options

[emerygt350]

MC started leaking onto the floor so had to do a quick switch to the 19mm. After reading all the dire warnings from the Holiday Inn physicists on the Pelican pages I was a little worried. I guess maybe their innate ability to understand fluid dynamics didn't extend to brake bleeding?

Anyway, my first impressions (only bled the system once) driving to work this morning is that the pedal has marginally less travel. Nothing really too noticeable but of course I will need to bleed it again after I get some heat cycles through it.

Since my old MC was obviously going this isn't a real A/B but the brakes are behaving quite nicely. Locks up a little easier than before but I am a big guy with pretty strong legs. Perhaps that was part of the problem of those physicists on pelican. Let me be clear, by locking up easier I mean you need to stand on it before there is any hope of locking up. I have newly rebuilt rear calipers (pmb), fronts are original, new brake pads last year. I get the feels that it will be much nicer on the track and in autocross, just in the little bit of my drive to work it felt like a much more linear response than what I had before (again, my before was probably not the best).

Just some notes on the changeout.

1) the washers under the grommets were already in the 19mm MC I got from Pelican (the cheap one). That apparently isn't always the case.

2) installed the MC without removing the feed lines from the car. I put the grommets on the feed lines (wet with brake fluid). Released the catch on the reservoir so it would slide down a few inches. Using a flare nut wrench, I pushed the grommets down into the MC. There was a little swearing but after the first one it only took a few minutes to get the second in. All done laying under the car.

3) did not bench bleed the MC (son stole my bleeder kit). Process I used was, with the guilty son actuating the brake pedal: bled driver front till I got mostly clear brake fluid. Moved to passenger rear. Bled that, then driver rear, then back to passenger rear, then again to driver. Then front pass, front driver, repeat once then called it good. In total I used two and a quarter of the little pint? sized brake fluid bottles.

[mb911]

MC started leaking onto the floor so had to do a quick switch to the 19mm. After reading all the dire warnings from the Holiday Inn physicists on the Pelican pages I was a little worried. I guess maybe their innate ability to understand fluid dynamics didn't extend to brake bleeding?

Anyway, my first impressions (only bled the system once) driving to work this morning is that the pedal has marginally less travel. Nothing really too noticeable but of course I will need to bleed it again after I get some heat cycles through it.

Since my old MC was obviously going this isn't a real A/B but the brakes are behaving quite nicely. Locks up a little easier than before but I am a big guy with pretty strong legs. Perhaps that was part of the problem of those physicists on pelican.

Just some notes on the changeout.

1) the washers under the grommets were already in the 19mm MC I got from Pelican (the cheap one). That apparently isn't always the case.

2) installed the MC without removing the feed lines from the car. I put the grommets on the feed lines (wet with brake fluid). Released the catch on the reservoir so it would slide down a few inches. Using a flare nut wrench, I pushed the grommets down into the MC. There was a little swearing but after the first one it only took a few minutes to get the second in. All done laying under the car.

3) did not bench bleed the MC (son stole my bleeder kit). Process I used was, with the guilty son actuating the brake pedal: bled driver front till I got mostly clear brake fluid. Moved to passenger rear. Bled that, then driver rear, then back to passenger rear, then again to driver. Then front pass, front driver, repeat once then called it good. In total I used two and a quarter of the little pint? sized brake fluid bottles.


Also, is it worth rebuilding the original 17mm to have around?

What brand did you use? Thinking of changing mine out

[emerygt350]

MC started leaking onto the floor so had to do a quick switch to the 19mm. After reading all the dire warnings from the Holiday Inn physicists on the Pelican pages I was a little worried. I guess maybe their innate ability to understand fluid dynamics didn't extend to brake bleeding?

Anyway, my first impressions (only bled the system once) driving to work this morning is that the pedal has marginally less travel. Nothing really too noticeable but of course I will need to bleed it again after I get some heat cycles through it.

Since my old MC was obviously going this isn't a real A/B but the brakes are behaving quite nicely. Locks up a little easier than before but I am a big guy with pretty strong legs. Perhaps that was part of the problem of those physicists on pelican.

Just some notes on the changeout.

1) the washers under the grommets were already in the 19mm MC I got from Pelican (the cheap one). That apparently isn't always the case.

2) installed the MC without removing the feed lines from the car. I put the grommets on the feed lines (wet with brake fluid). Released the catch on the reservoir so it would slide down a few inches. Using a flare nut wrench, I pushed the grommets down into the MC. There was a little swearing but after the first one it only took a few minutes to get the second in. All done laying under the car.

3) did not bench bleed the MC (son stole my bleeder kit). Process I used was, with the guilty son actuating the brake pedal: bled driver front till I got mostly clear brake fluid. Moved to passenger rear. Bled that, then driver rear, then back to passenger rear, then again to driver. Then front pass, front driver, repeat once then called it good. In total I used two and a quarter of the little pint? sized brake fluid bottles.


Also, is it worth rebuilding the original 17mm to have around?

What brand did you use? Thinking of changing mine out

I believe it is the URO

[bkrantz]

As I understand Holiday Inn Express physics a larger diameter MC piston reduces mechanical advantage and should make it harder to lock up the wheels. If you find it easier, that might say more about the state of your previous MC.

[worn]

As I understand Holiday Inn Express physics a larger diameter MC piston reduces mechanical advantage and should make it harder to lock up the wheels. If you find it easier, that might say more about the state of your previous MC.

At the risk of hijacking the thread, I just noticed that a rebuild kit for a master cylinder is almost the same as the cost of a new cylinder. This seems weird to me and wasteful. Wait, I have to chase those kids off of my lawn.

[emerygt350]

I couldn't find a rebuild kit for the 17mm.

I will wait till I get the second bleed complete (off to Hawaii for a couple weeks) but when I get back and get that done I will post my final impressions. Currently they are pretty positive. Nothing earth shattering but none of this "your gonna die" garbage I see posted out there either.

[VaccaRabite]

As I understand Holiday Inn Express physics a larger diameter MC piston reduces mechanical advantage and should make it harder to lock up the wheels. If you find it easier, that might say more about the state of your previous MC.

At the risk of hijacking the thread, I just noticed that a rebuild kit for a master cylinder is almost the same as the cost of a new cylinder. This seems weird to me and wasteful. Wait, I have to chase those kids off of my lawn.

No one can find rebuild kits for the 17 any more. If you found one - it unobtanium. Buy it.

Zach

[rjames]

I didn't notice a huge change from going from 17mm to 19mm, either that or I adapted very quickly. I do have a 17mm that I've been contemplating installing, but then I remember how much fun that job is and come to my senses.