Brakes...mushy?

[TYSHO]

89 SHO
Well guys, I have fairly good brake pads, over 50% left, on all fours. Well after putting it to rest for a little and using the 93 SHO, I go back to it and the braking is a whole different story!

I have PFC pads on all 4's and a good flush with new HD Synthetic Valvoline Dot 4 fluid, on the 93. So, once I touch the brake pedal, it's quick to grab right away and come to a stop. Now, when I went to brake in the 89, it seems toooo mushy compared to the 93! So I just pretty much flushed the brake lines out until the fluid was clear again with, HD Synthetic Valvoline Dot 4. Thinking this would inhance the performance, I was totally wrong. Same performance as before the flush. The fluid is at the correct level and all the bleeding zert thingy's are tighten proper, so I know there's no air in the lines.

Is there something wrong or does the difference have to be with the ATX/MTX and Non-ABS/ABS? shrug

BTW, the 89 also has PFC's up front and Albany's on the back.

So, any thoughts, opinions, reasonings, or replies are welcome!

 

[projectSHO89]

Sounds like it might be some internal leaking in the master cylinder.

While at a stop, pump the brakes to get a "full" pedal. Hold the pedal firmly depressed and look for pedal fade. If it does, then the master cylinder is the cause.


Steve

 

[TYSHO]

When you say "full" pedal, do you mean, like when the pedal gets hard and has less travel in the downward postion? If so, after I finished the flush, I pumped the brakes to 'try' and do that, but all I got was the same thing. You could hear an air noise when I pushed it, everytime.

BTW, when I was in the process of bleeding the brakes, I put a tad bit of fluid over the 'max' line. Would that have caused anything?

<small>[ December 22, 2003, 03:15 PM: Message edited by: TYSHO ]</small>

 

[Shoaz]

Some extra fluid over the reservoir max line won't hurt anything other than the reservoir might overflow if the pads are low and you compress the caliper pistons without the bleed lines open.

There are a number of thing that can cause a soft pedal, the most likely being bad or contaminated fluid. Since you've just flushed the system and the pedal is still soft, the next most likely culprit will be the rubber flex lines if they're old. Since it is an 89, I'm guessing that there is potential that they're the original lines. If this is true, the front rubber flex lines are likely expanding under pressure, which makes the pedal soft. Replacing the front flex lines with new hoses or with stainless steel braided lines may restore a hard pedal. It may not be necessary to change the rear lines since they don't get as much pressure, anyway.

 

[TYSHO]

After thinking today, I remembered that I had forgotten to bleed the master cylinder itself. headbang I hope that's the reason, air in the bore.

Since I forgot to do that before bleeding the lines, is it necessary to bleed the lines 'again' after bleeding the M-cylinder?

Well now, the dang connector piece for the lines to the M-cylinder is starting to strip a tad bit. It seems that I need to find a 15/32" wrench, is that even available? Vise grips didn't help, all it did was rip a piece of metal off and had it stuck in between the teeth. frown

<small>[ December 23, 2003, 02:43 AM: Message edited by: TYSHO ]</small>

 

[Rob94]

If there is air in the bore, then yes, you'll have to rebleed the lines. Forget the 15/32...go with a metric.

 

[TYSHO]

Metric is different too! I'll need an 11.5mm headbang

<small>[ December 23, 2003, 04:28 AM: Message edited by: TYSHO ]</small>