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Benino · Posted: Tue Dec 28, 2004 9:06 am Post subject: 1980 924 brake master cylinder

I think I need a new brake master cylinder. I called the dealer and they want $260 for one. I called an independent VW place that I can usually get parts from for less and they wanted 250. They told me the computer says that that master cylinder was only used in 1980 924 and 931. Is that true. Is it different from every other year? Is there another one that would bolt up that I might be able to get for less? Is it possible to rebuild the old master cylinder? are there kits to do that?
help. 250 bux is a lot of money.

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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

It is true, the version of the master cylinder used on the 924 and 931 in 1980 was unique to those models.

But, the 1981 and later 924 and 931 cars all used a very similar master cylinder that is usually priced $20-$40 lower than the 1980 version.

They two versions of the master cylinder even use the same rebuild kit if you are inclined to try to rebuild yours (rebuilding a master cylinder is not diffficult, just watch out for the internal springs, you will need a set of snap ring pliers with different size tips). Take you old master cylinder apart to make sure that it is rebuildable before you spend the money on the rebuild kit (they run $75-$100) depending one where you get it. NAPA may be the cheapest place.

The only difference between the 1980, and later master cylinders is that the 1980 master cylinder has the brake light switch screwed onto it. On later cars, the brake light switch is bolted to the brake pedal.

To use the 1981 and later master cylinder on your car is easy. Simply disconnect the wires from the brake light switch on the master cylinder. Pull the wires back through the fire wall. Get the brake light switch (salvage yard or new), and attach it to the pedal assembly. Now connect the wires you pulled back from the master cylinder, and you should be good to go.

Check with "Zuffen" to see if he still has the group of new master cylinders that he beat me out of on eBay. If I remember correctly, there may have been one of the later 924 master cylinders in that group that he got fairly cheap.

Smoothie · Posted: Tue Dec 28, 2004 10:02 am Post subject:

If you want to do your own rebuild - http://www.924board.org/viewtopic.php?t=13284&postdays=0&postorder=asc&start=20
Pics - http://www.924board.org/viewtopic.php?t=11050&start=03

More on the MC, incl. pedal brake light switch pics - http://www.924board.org/viewtopic.php?t=11638
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Benino · Posted: Tue Dec 28, 2004 10:38 am Post subject:

ok. I'm probably going to go for the rebuild. The only thing is that I'm not sure why my brakes are so bad. The shoes are only about 1/2 way down and adjusted and the pads are new and I bled the system about a month ago because the brakes had been gradually getting worse and worse to the point of being scarry. I did all that and found almost no improvement at all. Brake fluid is not leaking out anywhere. My next step was going to be to replace the master cylinder, but since they are so expensive I think I'll do the rebild. . . unless there are other suggestions. I'm not sure what else could be wrong. I can't lock up the wheels when I stomp on the brakes. sometimes the pedal goes down further than others before slowing the car but whether the pedal travel is short or long, the stopping power still is not very good.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

Smoothie · Posted: Tue Dec 28, 2004 10:58 am Post subject:

Tried adjusting the rear brakes? (only applies if you have drums, not discs at the rear)
Pedal moving down sometimes more than others, suggests an MC problem.
Excessive effort required to stop, first suggests drive something else until it's fixed, but maybe a brake booster problem or problem with the vacuum line to it.
-Or you might have rusted calipers that need rebuilding or replacement.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Odds are 10 to 1 the problem is rear brake shoe clearance adjustment. 924 has diagonal braking, meaning that each front brake is tied to the rear brake on the opposite side of the car. So if the rear brake shoe clearance is large, the front brake calipers will not begin to work until all if the available brake fluid pressure is used to pump up the rear brakes first. So, no braking.

If you don't adjust all for brake shoes (4 star adjusters, 2 on each side), every 4-6 weeks, that's the kind of brakes you are going to have. The longer you go between rear brake shoe clearnace adjustments, the worse your brakes will be.

The only way to permanently cure the problem is to switch to four wheel disc brakes. Otherwise, plan on adjusting your rear brake shoe clearance every four to six weeks (that's how often I was forced to adjust my rear brakes to keep them high and tight when commuting to work 140 miles a day).

numbbers · Posted: Tue Dec 28, 2004 1:28 pm Post subject:

Oh man, I just trashed a good used one on Sunday. You could have had it for postage. Sorry.
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1980 924 Turbo

Benino · Posted: Tue Dec 28, 2004 1:35 pm Post subject:

I adjusted the rear brakes recently. If I tightened them much more I wouldnt be able to turn the wheels by hand with the e-brake off.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

Benino · Posted: Tue Dec 28, 2004 1:39 pm Post subject:

Paul · Posted: Tue Dec 28, 2004 2:57 pm Post subject:

Cardone 112492

Master Cylinder: Reman.; Import
Pricing

Our Price: $105.99
Core Charge: $35.00

Warranty

Lifetime Limited Warranty

At Advance Auto (Parts America)
www.partsamerica.com
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

numbbers · Posted: Wed Dec 29, 2004 11:03 am Post subject:

Sorry, trash was picked up Monday morning.
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1980 924 Turbo