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  Topic Review (Newest First)
09-13-2019 07:48 PM
alfa_corsa Turns out that perhaps the 8th or 9th time is a charm.

Following the failure of one of the four brake master cylinders I bought I decided to take the opportunity to tackle a couple things I'd been wanting to take care of. I removed the failed MC, the driveshaft and the transmission output flange. I replaced the output flange seal, the guibo and replaced the MC with another new one I had in the shop that I had assumed was bad, before realizing I had a air leak in one of the fittings.

I put everything back together, bled the brakes, and with some cautious optimism I'll say "hallelujah!" The brake pedal is firm all the time (no pumping up) and the new guibo seems to have quelled the nasty vibration/resonance I'd been experiencing. I haven't driven her on the freeway yet but so far it seems much better. I know there are a couple different styles of guibos and the one that I removed was old, but apparently are known to be too stiff. It was the one with the pressed steel inserts rather than the cast aluminum ones. I sourced the replacement from Centerline.

In any event, but for a few minor items, still the seatbelts and a few other things, Renzo is running well and hopefully will take a back seat to the Super Sprint which is supposed to come home next week.

But for the threat of wildfires this is one of the most pleasant times of years for driving here in the Bay Area, so I'll get out and run 'er a little before the rains come.

Happy Weekend everyone!

-tj in the Cruz Mtn
09-13-2019 08:38 AM
alfa_corsa As soon as they figure out how to use bourbon for hydraulic fluid. Man I hate Dot 4 brake fluid like poison. I'd rather bathe in 90W gear oil than have to deal with brake fluid. It's just nasty.

Quote:
Originally Posted by spydaman View Post
So when are you opening up an Alfa only workshop Brakes a speciality.

-tj
09-13-2019 12:12 AM
spydaman So when are you opening up an Alfa only workshop Brakes a speciality.
09-12-2019 06:38 PM
alfa_corsa As I mentioned in my last post, Renzo's brakes started acting up again. I figured I was still fighting air bubbles. I want to get a few things tidied up because the 1900 is supposed to come home next week and I won't have room or time in the shop to work on them once that happens, so today she went up on jackstands. I'm not sure if I'm happy or pissed that the **** master cylinder is leaking internally. Brake fluid is leaking through the piston/seal/bore and dripping out the rubber boot, so that's why the brake pedal was doing its old tricks again.

Thankfully I have the previous MC and since I am pretty sure the root cause was a loose fitting I reinstalled it.

While I'm under the car I've removed the drive shaft to replace the guibo, and pulled the output flange so I can replace the rear flange oil seal which was leaking transmission oil.

I hope to have her all buttoned up tomorrow and will report back on whether or not I was successful.

-tj in the Cruz Mtns
09-05-2019 11:07 AM
alfa_corsa It's been some time since I've posted about Renzo. We had a nice time in Carmel for Car Week and enjoyed showing her on the lawn at Concorso Italiano.

My brake issue has returned. I will likely have to pursue buying and installing the later style master cylinder. I haven't had much energy to worry about it as since my return from Carmel I went to visit my 1900C SS which will be ready to pick up in the next few weeks and so I've been focusing on getting ready for that happy reunion.

Ciao!

-tj in the Cruz Mtns
07-28-2019 11:50 AM
PSk Copper nickel is what it probably is. Plain copper work hardens ...
Pete
07-28-2019 08:59 AM
alfa_corsa I didnít know that, but assume that itís a suitable alloy.

https://classicalfa.com/br070-1-fron...968-78-copper/



Quote:
Originally Posted by PSk View Post
This is great news.

Copper pipe?, copper alloy I hope as copper is not suitable for a brake line.
Pete
-tj
07-27-2019 02:19 PM
PSk This is great news.

Copper pipe?, copper alloy I hope as copper is not suitable for a brake line.
Pete
07-27-2019 02:11 PM
joegt3cup This is GREAT news... fingers crossed!

Joe
07-27-2019 01:28 PM
alfa_corsa Yeah, the tool I used didnít make a flare that was exactly like the factory line. I think I needed to tighten the fitting enough to get it to seal against the bottom of the bore. The original Alfa lines were steel but we could not get a good flare on the steel with the tool. New copper is much easier to get good results with.

Quote:
Originally Posted by Alfajay View Post
That makes sense. My experience with brake lines - even with factory-made flares - is that you need to tighten them a little like head nuts: torque them down, come back the next day after the flare has flowed a bit, and torque them again. Sometimes it takes me a few rounds of tightening and waiting to get them to seal.

Obviously Toyota doesn't use my technique on their production line, so I don't know if this makes any sense, or if just tightening them more the first time would work as well.
-tj
07-27-2019 11:56 AM
Alfajay
Quote:
Originally Posted by alfa_corsa View Post
Cinching them down required a certain amount of sensitivity and I may just not have been as aggressive as I needed to.
That makes sense. My experience with brake lines - even with factory-made flares - is that you need to tighten them a little like head nuts: torque them down, come back the next day after the flare has flowed a bit, and torque them again. Sometimes it takes me a few rounds of tightening and waiting to get them to seal.

Obviously Toyota doesn't use my technique on their production line, so I don't know if this makes any sense; maybe just tightening them more the first time would work as well.
07-27-2019 09:49 AM
alfa_corsa With a small amount of caution I announce that I believe I've found the root cause of the air that was getting in my brake lines and causing the soft pedal. I went back around the car and checked all the fittings and found that there were two on the brake line junction that is mounted to the firewall that I was able to get another half turn or so on. I know these are compression fittings and that they need to be very tight, but I'd manufactured these lines and put the flares on them with a handheld tool. I also used new copper tubing on a couple of the lines. Getting the flare right with the handheld tool is not easy, and it's possible that the flare wasn't perfectly formed. Cinching them down required a certain amount of sensitivity and I may just not have been as aggressive as I needed to. One of the fittings that wasn't completely tight was the one from the brake booster.

It's curious of course that it would allow air in but not push fluid out (there were no leaks) but when I tightened it and one other, and then went back to bleed the system with a pressure bleeder there were no more air bubbles. The test drive was markedly different and better, with the kind of firm pedal that feels right but still with the ability to modulate braking appropriately.

On to the next....

-tj in the Cruz Mtns
07-19-2019 09:06 PM
Ranz Ok, so there’s one of the three flexible lines.
For the front, you can’t have hard lines all the way to the front callipers. Things move up and down...there’s gotta be a flexible line in each wheel well.
If these are rubber, you can try the isolating thing by clamping them off. This is what I was getting at in post 394. If they are Teflon with a (usually) braided stainless sleeve, maybe not so easy to clamp, as they may crush instead.
07-19-2019 08:22 PM
alfa_corsa No sir....there is only one flexible rubber line and it connects the main line that begins at the junction on the firewall to the junction on the axle.

-tj

Quote:
Originally Posted by Ranz View Post
Ok, but BEFORE the hard lines to the callipers, there are flexible, rubber (and therefore clampable) lines LH front, RH front, and before rear axle, yes? Thatís what I was getting at...clamping these in turn to see if anything changes....sorry if I wasnít clear.
07-19-2019 05:19 PM
Ranz Ok, but BEFORE the hard lines to the callipers, there are flexible, rubber (and therefore clampable) lines LH front, RH front, and before rear axle, yes? That’s what I was getting at...clamping these in turn to see if anything changes....sorry if I wasn’t clear.
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