Rear proportioning valve clogged - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 13 (permalink) Old 09-25-2019, 07:17 PM Thread Starter
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Rear proportioning valve clogged

Tried a pressure bleeder on my alfetta and it leaked all over from the two reservoir caps but after I got the pressure to about 5lbs. I then did the bleed old fashion way with a friend pumping brake and I quickly did the two fronts. When I went to the rear brakes, nothing came out. Checked the line and found nothing came out of the rear proportioning (pressure limiting) valve.

Like usual, no US Alfa parts stores have a valve. (Or most anything else for Alfetta’s)

Anyone recommend a replacement? I saw adjustable one at summit racing for $45 which i’ll try tomorrow.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #2 of 13 (permalink) Old 09-26-2019, 03:56 PM Thread Starter
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OK I tired to fit in a wildwood adjustable proportioning valve ($41 summit racing) but the line connections did not fit. Plus with the current hard lines, I have no room to make new flarings to fit. Not enough straight pipe to grab where I need to place clamps. Maybe some other more adept mechanic (me amateur) would be able to do it.

So I first checked centerline and they have none, for no alfas, any models.

Vic Auto and Alfa Parts Berkeley, CA have the spider available for $165, I'll receive it Saturday, from Alfa Parts Berkeley. Its supposed to rain in Reno and snow in the mountains Saturday anyway, good shop day.


I'll post a photo when I'm done.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #3 of 13 (permalink) Old 09-26-2019, 04:14 PM
But Mad North-Northwest
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Wilwood has different models that work with different fittings. I know I got one to replace the proportioning valve on my Milano that used the existing fittings, though that was up front so not sure if the same one would work on the Alfetta. You likely just ordered the wrong part, I'm afraid.

Classic Alfa in the UK has three different versions of the Spider proportioning valve available, depending on what your car has. Their shipping rates and speed to the US are quite reasonable.

https://classicalfa.com/105-spider-p...eatured&page=4

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #4 of 13 (permalink) Old 09-26-2019, 04:49 PM Thread Starter
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John Norman, Alfa Parts Berkeley sold me the BRO12 as in the Classicalfa website. Its the right one, same size shape, make etc, direct fit, as the one currently on the car.

Vic Auto has the newer spider/alfetta/gtv6 BR103, their website says fits everything.

I tried to connect the existing, on car, brakeline connection directly to the wildwood. It threaded on OK but would not "seat" firmly near the last few threads to get the line tight. These things don't take much tightening and I was about to overdo it and I backed off. Maybe the "newer" MIlano connections are more Wilwood compatible than 76 Alfetta connections.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #5 of 13 (permalink) Old 09-26-2019, 10:14 PM
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I had the same issue on my '81 GTV6 and a standard Wilwood adjustable proportioning valve fit with no issues (well, one of the hard lines to the original valve snapped when cracking it loose, so I had to make a new line), but I know the GTV6 uses M10x1.0 thread and DIN bubble flares (as with most Euro cars of the era), though I read that the earlier Alfa 105 series cars used English threads and flares for all of the brake hydraulic fittings except for the metric fittings at the ATE brake calipers! That is quite confusing. But, it sounds like you may have gotten the correct, proper OE valve, so that is good.

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #6 of 13 (permalink) Old 09-27-2019, 05:33 AM
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Quote:
I read that the earlier Alfa 105 series cars used English threads and flares for all of the brake hydraulic fittings except for the metric fittings at the ATE brake calipers!
I replaced the non-adjustable proportioning valve on my 85 GTV6 with an adjustable one from an early 70's 105 and the threads were the same.

Ed Prytherch
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A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #7 of 13 (permalink) Old 09-27-2019, 06:01 AM
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You said you "checked the line" - do you mean you checked the flexible hose in the back that goes from the chassis to the transaxle-mounted splitter? This is the most common problem for fluid restriction.

I've never seen a prop valve totally clog or prevent fluid passage - but have seen many rubber hoses that do.

The amount of corrosion that would have to be present in the prop valve to close of would be significant.

Also, aftermarket (Wilwood, Tilton, etc.) M10x1.0 prop valves fit right in. I've installed them on several cars...I wonder if you had a 3/8 version.

Rob
Alfas first, then everything else.
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post #8 of 13 (permalink) Old 09-27-2019, 06:26 AM Thread Starter
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It’s the valve that’s the blockage. The outlet hose disconnected, pump brake, nothing. Flexible braided hose should be fine.
Connection comes close to seating properly but I would have to exert way too much torque and would probably strip the threads and create more problems.
Wilwood should have worked but it didn’t for me. Another Alfa mystery eh?
In the future I may install the wilwood inside the car near the emergency brake where it belongs. But for now, I’ll install new original parts and enjoy fall driving.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #9 of 13 (permalink) Old 09-27-2019, 02:00 PM Thread Starter
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Ok I now have an answer as to why the Wilwood didn't fit. I purposely bought an English and metric Wilwood thinking one or the other would fit. Tried them both and it didn't work. Took them both back to summit racing and noticed they gave me two of the same English threaded valves at two different prices!! I just assumed one was English and one was metric. With all of the responses saying the Wilwood was a direct fit, I knew something was wrong.

Bought the metric valve and it fits! Mystery solved and I'm on way. I'll be installing a bracket to hold in place too.

Back to the locating the problem and the totally clogged, original valve. I undid the inlet line, pumped the pedal and gushed fluid, soft pedal to the floor. I reconnected inlet and disconnected outlet line, nothing, and the pedal is very solid, no mushy feel. Valve must be really clogged to close off the system to the rear.

So asking all the Wilwood replacement people who have them on their Alfetta, GTV6, Milano, how many turns did you go to get the brake feel you like in the rear? Tech specs say when fully closed, valve turns down the rear bakes 57%. I plan to experiment from fully closed and go on from there and look at my skid marks while braking. I looked it all up on the Miata BB. they go through the same thing.

Is this conversation about braking bias someplace in the AlfaBB performance section?
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'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #10 of 13 (permalink) Old 09-27-2019, 02:22 PM
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You want to adjust the Wilwood it so the rears don't lock up before the fronts. On my Milano this was only like 1 turn in.

Take it out and do some hard stop testing in different conditions. At least on the Milano, two turns worked on dry pavement, but when it was wet that was too much so I dialed it back to 1 turn.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #11 of 13 (permalink) Old 09-27-2019, 03:01 PM Thread Starter
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Thanks, I'll start at 1 turn, and test from there. Seat of the pants feel, seems to be the consensus. I really haven't haven't found anything on the AlfaBB, but there's plenty out recommendations, and a few videos too. I'll get it hooked up and have fun with an old car.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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post #12 of 13 (permalink) Old 09-27-2019, 03:14 PM
But Mad North-Northwest
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You'll be able to tell if the rears lock up first. Car will get all squirrelly.

I've actually got a brake pressure gauge (it screws into the bleeder port) that I used to do the initial setup on the Wilwood to match the stock valve. But at the end of the day the road testing worked better and I don't think you really need the gauge.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #13 of 13 (permalink) Old 09-27-2019, 03:23 PM Thread Starter
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I think I way driving the car without any rear brakes at all since a picked the car up a year ago, not knowing the valve was clogged. Always had a firm brake pedal. Now that I think about it, when I took out the tranny to have it rebuilt, I noticed there wasn't much brake fluid leakage from any of the rear connections.

Lesson learned, change all the fluids when getting a car, AND bleed the brakes.

'76 Alfetta GT, 2013 Fiat 500 Abarth, '78 sports sedan (2 of them) - sold, '91 164L - sold, '83 GTV6 -sold, '87 Milano Verde - sold, '91 spider -sold, '69 MGB GT,
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