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Need some advice regarding breaks...here goes...
1) break pedel very hard at startup
2) when starting out from stop it sometimes seemsvas if the breaks are still holding
3) rolling...intermittently breaks seems to be still engaged, then releases upon acceleration
More experienced folks will chime in but my thoughts are the following:
1) Sounds like a vacuum problem on the booster. The brakes should get a little softer once the engine starts to produce some vacuum.
2 &3) Doesn't sound related to 1. I agree that you should look at a couple of things on the calipers themselves, or the parking brake, but I don't think it will be a quick fix. Probably the easiest diagnosis is to drive around a little bit and, if you have it available, get a temperature reading on the brakes once you're done. The rears should have the same temperature, and the fronts should also be equal to each other. Fronts and rears (I don't believe) should not be expected to show the same temperature. For reading this, one of those little IR guns should suffice.
I apologize, just couldn't resist the kind of chastisement my English teacher always provided.
Gary,
Do you think English actually makes sense?
As a verb, bow always refers to bending the body in a gesture of respect. As a noun, it can be a gesture of respect, the front of a ship, a weapon, the tool used to play stringed instruments, or a decorative knot. One three letter word pronounced two different ways with 6 meanings and just to add to the confusion we have bough - always a noun and refers to the backbone of a tree- urrgh!
One would have to have a loose screw upstairs to want to teach English!
Had exactly the same symptoms. It's likely that one or more of your brake calipers are "dragging" due to pressure in the system from the brake booster, master cylinder, or rubber brake lines. If you touch one or more of the brake rotors after experiencing the symptoms you will find it too hot to keep your finger there. Ask me how I know (ouch!). Also, be sure that the vacuum system works as designed.
Start with replacing the brake lines. They internally swell, reducing the path that the fluid can flow through so its hard to force fluid to the calipers (stiff pedal) and it's hard for it to flow back from the caliper pistons so they drag.
When you see them dragging cars out of barns on those restoration shows it's usually because the lines have swelled internally forcing fluid to the calipers and locking the brakes.
Get DOT approved stainless lines with the clear cover over the braided stainless and replace them. Your lines should need the banjo bolt fitto G on all 4 calipers (older cars only had that on the rears with a threaded in fitting for the fronts).
Here's an old line I cut apart on my 81 so you can see how narrow and crusty the internal passageway becomes vs the new stainless one.
Start with replacing the brake lines. They internally swell, reducing the path that the fluid can flow through so its hard to force fluid to the calipers (stiff pedal) and it's hard for it to flow back from the caliper pistons so they drag.
When you see them dragging cars out of barns on those restoration shows it's usually because the lines have swelled internally forcing fluid to the calipers and locking the brakes.
Get DOT approved stainless lines with the clear cover over the braided stainless and replace them. Your lines should need the banjo bolt fitto G on all 4 calipers (older cars only had that on the rears with a threaded in fitting for the fronts).
Here's an old line I cut apart on my 81 so you can see how narrow and crusty the internal passageway becomes vs the new stainless one.
I had a similar issue. Also an 89 S4 but probably doesn’t matter. Mine was the master cylinder. Replaced it, no issues since and I still have original braid lines
08-07-2021, 10:47 AM
Perplexing break problem 89s4
